WO2019082120A1

WO2019082120A1 - Quantum dots disposed in thin film for portable device

Info

Publication number: WO2019082120A1
Application number: PCT/IB2018/058334
Authority: WO
Inventors: YingJun CHENG; Jian Yang; Jesus Alfonso CARAVEO-FRESCAS
Original assignee: Sabic Global Technologies B.V.
Priority date: 2017-10-25
Filing date: 2018-10-25
Publication date: 2019-05-02

Abstract

An apparatus that includes a thin-film device is described. An example apparatus may comprise one or more stabilized quantum dots disposed in a first thin film layer and configured to emit light. The apparatus may comprise an energy harvester disposed in a second thin film layer and electrically coupled to the one or more stabilized quantum dots. The triboelectric energy harvester may be configured to supply a voltage to the one or more stabilized quantum dots to cause emission of the light by the one or more stabilized quantum dots in response to an event.

Description

QUANTUM DOTS DISPOSED IN THIN FILM FOR PORTABLE DEVICE

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62/639,932, filed on March 7, 2018, and claims the benefit of U.S. Provisional Application No. 62/576,909, filed on October 25, 2017, which are each incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

[0002] Commercially available light emitting diode (LED) optical sensors can be used to monitor health and track fitness, by optical measurement of the change of blood volume in the blood vessels, which is referred to as photoplethysmography (PPG). These conventional LED devices are bulky. Additionally, a conventional LED may be powered by a power source which may contribute to the size of a device. The size of the LED and other accompanying components limit the potential applications. For wearable devices, the size of the LED and accompanying components may limit the comfort of the wearer. Thus, there is a need for smaller light emission devices to allow integration into a greater variety of portable devices.

SUMMARY OF THE INVENTION

[0003] The present disclosure relates to a thin-film device, specifically a thin film device comprising quantum dots (QDs) integrated into portable devices. The present disclosure relates to an innovative approach of integrating triboelectric/piezoelectric energy harvester and air stable quantum dots in the form of a thin film apparatus, which may provide self- powered, wearable and portable light sources with the possibility of various wavelength emission for various purposes and applications.

[0004] An example apparatus may comprise one or more stabilized quantum dots disposed in a first thin film layer and configured to emit light. The apparatus may comprise a triboelectric energy harvester disposed in a second thin film layer and electrically coupled, via an electrical interconnect, to the one or more stabilized quantum dots. The triboelectric energy harvester may be configured to supply a voltage directly, via the electrical interconnect, from the triboelectric energy harvester to the one or more stabilized quantum dots to cause emission of the light by the one or more stabilized quantum dots in response to a contact event. The first thin film layer and the second thin film layer may be disposed adjacent a substrate. The term "adjacent" as used herein means abutting or configured in a stacked configuration with intervening layers and/or gaps. The first thin film layer and the second thin film layer may disposed in a stacked configuration adjacent the substrate. The substrate may be integrated into a flexible wearable device.

[0005] Another apparatus may comprise one or more stabilized quantum dots disposed in a first thin film layer and configured to emit light. The apparatus may comprise a triboelectric energy harvester disposed in a second thin film layer and electrically coupled, via an electrical interconnect, to the one or more stabilized quantum dots. The triboelectric energy harvester may be configured to supply a voltage directly, via the electrical interconnect, from the triboelectric energy harvester to the one or more stabilized quantum dots to cause emission of the light by the one or more stabilized quantum dots in response to a contact event. The apparatus may comprise a photodiode disposed on a third thin film layer and configured to generate a signal in response to detecting the emission of the light by the one or more stabilized quantum dots as reflected from a wearer of the apparatus. The first thin film layer and the second thin film layer may be disposed on a substrate. The substrate may be integrated into a flexible wearable device.

[0006] An example apparatus may comprise a wearable health device. The wearable health device may comprise a flexible body configured to conform to a wearer and one or more stabilized quantum dots disposed in a first thin film layer and configured to emit light. The wearable health device may comprise a triboelectric energy harvester disposed in a second thin film layer and electrically coupled, via an electrical interconnect, to the one or more stabilized quantum dots. The triboelectric energy harvester may be configured to supply a voltage directly, via the electrical interconnect, from the triboelectric energy harvester to the one or more stabilized quantum dots to cause emission of the light by the one or more stabilized quantum dots in response to a contact event. The first thin film layer and the second thin film layer may be disposed above a single substrate configured to flex with the flexible body. The wearable health device may comprise a photodiode disposed on a third thin film and configured to generate a signal in response to detecting emission of the light by the one or more stabilized quantum dots as reflected from the wearer. The wearable health device may comprise a processor in communication with the photodiode and configured to determine a health metric based on the signal.

[0007] Other objects, features and advantages of the present invention will become apparent from the following figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific embodiments of the invention, are given by way of illustration only and are not meant to be limiting. Additionally, it is contemplated that changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. In further embodiments, features from specific embodiments may be combined with features from other embodiments. For example, features from one embodiment may be combined with features from any of the other embodiments. In further embodiments, additional features may be added to the specific embodiments described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Advantages of the present invention may become apparent to those skilled in the art with the benefit of the following detailed description and upon reference to the accompanying drawings.

[0009] FIG. 1A is a block diagram of an example apparatus. [0010] FIG. IB is a circuit diagram of an example apparatus.

[0011] FIG. 2 is a side view of an example apparatus having an energy harvester and a quantum dot light emitting device.

[0012] FIG. 3 is diagram showing connection pads for an energy harvester and a quantum dot light emitting device.

[0013] FIG. 4 is diagram showing connection pads for an energy harvester, a quantum dot light emitting device, and a sensor.

[0014] FIG. 5 is a diagram of a PPG sensor with quantum dots.

[0015] FIG. 6 is a diagram showing optical measurement of biometric data. [0016] FIG. 7 is a diagram showing a heart rate measurement.

[0017] FIG. 8 is a diagram showing determination of oxygen saturation of the blood.

[0018] FIG. 9 is a diagram comparing a quantum dot light emitting device to an organic light emitting device.

[0019] FIG. 10 is a diagram showing a spectrum of electroluminescent quantum dots.

[0020] While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings. The drawings may not be to scale.

DETAILED DESCRIPTION OF THE INVENTION

[0021] The present disclosure describes devices, such as wearable devices, that use thin film quantum dot layers in a variety of applications. An example device may comprise a self- powered quantum dot light emitting device. An energy harvester unit electrically coupled to the quantum dot light emitting device may power the QD light emitting device. The energy harvester may comprise a triboelectric or piezoelectric energy generator that generates energy based on tribo or press forces on the triboelectric or piezoelectric materials. Quantum dots may be excited by electrons generated by the energy harvester to emit light with different wavelength from ultraviolet, visible, and infrared based on the size or the composition of quantum dots.

[0022] The disclosure describes thin film processes for battery-free wearable and portable devices, or smart skin, which is an improvement over the integration of bulky conventional LED as light sources. The thin films described herein may comprise quantum dots that emit light in a variety of different wavelengths. Different wavelength emission can be used for various purposes. For example, ultraviolet light may be used for anti-fake checking. Visible light may be used for illumination, signage, indicator for papers, kids toys, clothing. Infrared can be used for sending control signals. The quantum dots may be heat and/or air stable quantum dots. Thus, barrier protection may not be necessary.

[0023] The disclosure describes wearable health devices that may use quantum dots to generate light for optical analysis of a wearer of the health device. Light (e.g., or other electromagnetic radiation) of a variety of wavelengths generated by the quantum dots may be detected by a sensor and processed to determine pulse rate, blood oxygen level, and/or other health metrics. The use of thin film quantum dots layers (e.g., and power generation with batteries) allows for smaller, more flexible health devices.

[0024] FIG. 1A is a block diagram illustrating an example apparatus 100 in accordance with the present disclosure. The apparatus 100 may be a wearable apparatus. The apparatus 100 may comprise a body 102, such as a flexible body configured to conform to a wearer. For example, the body 102 may comprise a flexible material, such as rubber, plastic, fabric, and/or the like. The body 102 may be configured to be disposed on an extremity (e.g., chest, finger, wrist) of a wearer. The body 102 may comprise a wearable band (e.g., wrist band, arm band, chest band), a smart device (e.g., smart watch, smart apparel, smart glasses). The body 102 may comprise a toy. The body 102 may comprise a mobile device, remote, a sign, and/or the like.

[0025] The apparatus 100 may comprise one or more quantum dots 104. The one or more quantum dots 104 may be configured to emit light. Light may comprise any electromagnetic radiation, such as visible light, infrared light, ultraviolet light, and/or the like. The one or more quantum dots 104 may comprise a first portion of quantum dots configured to emit light in a first wavelength range. The one or more quantum dots 104 may comprise a second portion of quantum dots configured to emit light in a second wavelength range. The one or more quantum dots 104 may comprise a third portion of quantum dots configured to emit light in a third wavelength range. The first wavelength range, the second wavelength range, and the third wavelength range may comprise different ranges (e.g., but may border each other or partially overlap). As an illustration, the first wavelength range may comprise green light (e.g., in a range from about 560 nm to about 520 nm). The second wavelength range may comprise red light (e.g., in a range from about 700 nm to about 635 nm). The third wavelength range may comprise infrared light (e.g., in a range from about 1 mm to about 700 nm).

[0026] The first portion of the one more quantum dots may comprise quantum dots sized from about 1 nanometers (nm) to about 8 nm. The first portion of the one more quantum dots may emit green light with a peak wavelength between about 490 nm to about 580 nm. The second portion of the one more quantum dots may comprise quantum dots sized from about 3 nm to about 10 nm. The second portion of the one more quantum dots may emit red light with a peak wavelength between about 600 nm to about 750 nm. The third portion of the one more quantum dots may comprise quantum dots sized from about 2 nm to about 8 nm. The third portion of the one more quantum dots may emit infrared light with a peak wavelength between about 800 nm to about 1200 nm.

[0027] The one or more quantum dots 104 may comprise one or more stabilized quantum dots. For example, the first portion, the second portion, and/or the third portion of the one or more quantum dots may be stabilized quantum dots. The one or more quantum dots may be disposed without a barrier layer.

[0028] The one or more stabilized quantum dots may be thermally stabilized, air stabilized, moisture stabilized and/or flux stabilized, as described in further detail herein. The inclusion of stabilized quantum dots allows the barrier layer(s) (e.g., protective layers) found in conventional quantum dot films to be eliminated, resulting in a quantum dot film that has improved optical properties as compared to conventional quantum dot films that include one or more barrier layers. In addition, elimination of the barrier layer(s) allows for formation and use of a thinner quantum dot film. Thinner quantum dot films are more useful in various applications, including display applications as discussed further herein.

[0029] The one or more stabilized quantum dots may be stabilized in any suitable manner. In some aspects, the one or more stabilized quantum dots may be stabilized by providing an encapsulation around each of the one or more stabilized quantum dots, the encapsulation including an organic material or an inorganic material. The encapsulation may protect the stabilized quantum dot from damage in the same manner that a barrier layer(s) would protect the quantum dot layer in a conventional quantum dot film.

[0030] The one or more stabilized quantum dots may comprise a plurality of ligands having a length of about 5 nanometers (nm) to about 200 nm. The plurality of ligands may include any ligand type that will interact (e.g., attach) to the quantum dot. The plurality of ligands protect the quantum dot from damage.

[0031] The one or more stabilized quantum dots may comprise a shell having a thickness of about 1 to about 20 nm. The one or more quantum dots may comprise a multi-shell structure, such as but not limited to a first shell including a first material and at least a second shell including a second material that may be the same or different than the first material. The one or more stabilized quantum dots may have a core that is of the same or a different material than the shell or multi-shell structure material(s). [0032] The one or more stabilized quantum dots may comprise a concentration-gradient quantum dot. A concentration-gradient quantum dot may comprise an alloy of at least two semiconductors. The concentration (molar ratio) of the first semiconductor may gradually increase from the core of the quantum dot to the outer surface of the quantum dot, and the concentration (molar ratio) of the second semiconductor gradually decreases from the core of the quantum dot to the outer surface of the quantum dot. Exemplary concentration-gradient quantum dots are described in, e.g., U.S. Patent No. 7,981,667.

[0033] The concentration-gradient quantum dot may comprise two semiconductors, a first semiconductor having the formula

CdxZn 1 -xSy Se 1 -y

[0034] and a maximum molar ratio at the core of the stabilized quantum dot that gradually decreases to a minimum molar ratio at the outer surface of the quantum dot and a second semiconductor having the formula

ZnzSe 1 -zSwSe 1 -w

[0035] and a maximum molar ratio at the outer surface of the stabilized quantum dot that may gradually decrease to a minimum molar ratio at the core of the stabilized quantum dot.

[0036] The concentration-gradient quantum dot may comprise two semiconductors, a first semiconductor having the formula

CdZnxS l-x

[0037] and a maximum molar ratio at the core of the stabilized quantum dot that may gradually decrease to a minimum molar ratio at the outer surface of the quantum dot and a second semiconductor having the formula

ZnCdzSl-z

[0038] and a maximum molar ratio at the outer surface of the stabilized quantum dot that may gradually decrease to a minimum molar ratio at the core of the stabilized quantum dot.

[0039] The one or more stabilized quantum dots may be stabilized based on a core / multi- shell structure. The one or more stabilized quantum dots may be stabilized based on a thickness of one or more of an inner shell or an outer shell of the quantum dot. For example, the thickness of an inner shell and the thickness of an outer shell of the quantum dots may be balanced to provide stability. Lattice strain may be reduced by balancing the thicknesses of the inner and outer shells. The thickness may be chosen to optimize stability. The one or more stabilized quantum dots may be stabilized by tuning lattice parameters of one or more of a core, an inner shell, or an outer shell of the quantum dots. The lattice parameters may be tuned to reduce lattice stress. Exemplary lattice tuning parameters are described in, e.g., U.S. Patent No. 8,343,576.

[0040] In an aspect, the one or more stabilized quantum dots may be stabilized based by using a graded composition (e.g., as further described herein). A quantum dot may comprise a core enclosed by a graded shell. For example, a graded alloy shell may be grown on a core (e.g., a small core, a CdSe core) to minimize internal lattice defects at the core-shell interface.

[0041] In an aspect, the one or more stabilized quantum dots may be stabilized based on a graded intermediate shell (e.g., or graded inner shell). The graded intermediate shell may be configured to reduce strain caused by lattice mismatch between core and shell. For example, the core may comprise CdSe and an outer shell may comprise ZnS. The graded intermediate shell may comprise Cd 1-xZnxSe l-ySy. The graded intermediate shell may transition from a first material of a core to a combination of the first material and a second material of the outer shell. The graded intermediate shell may transition from the combination of the first material / second material to the second material. For example, the quantum dots may transition from CdSe to CdS/ZnSe and from CdS/ZnSe to ZnS.

[0042] In an aspect, the one or more stabilized quantum dots may be stabilized based on modification of the core to match a lattice of the shell material. For example, an InP core may be a lattice mismatch for ZnSezSz-1. The InP core may be modified to match the shell material by adding Zn to form InxZnyP.

[0043] Exemplary quantum dots according to aspects of the disclosure may include, but are not limited to, semiconductor nanocrystals selected from the group consisting of, but not limited to, Group II-VI semiconductor compounds, Group II-V semiconductor compounds, Group III-VI semiconductor compounds, Group III-V semiconductor compounds, Group IV- VI semiconductor compounds, Group II-III-VI compounds, Group II-IV-VI compounds, Group II-IV-V compounds, alloys thereof and combinations thereof. Exemplary Group II elements include Zn, Cd, Hg or a combination thereof. Exemplary Group III elements include Al, Ga, In, Ti or a combination thereof. Exemplary Group IV elements include Si, Ge, Sn, Pb or a combination thereof. Exemplary Group V elements include P, As, Sb, Bi or a combination thereof. Exemplary Group VI elements include O, S, Se, Te or a combination thereof. Exemplary Group II-VI semiconductor compounds include binary compounds, e.g., CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe and HgTe; ternary compounds, e.g., CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS and HgZnSe; and quaternary compounds, e.g., CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe. Exemplary Group III-V semiconductor compounds include binary compounds, e.g., GaN, GaP, GaAs, GaSb, A1N, A1P, AlAs, AlSb, InN, InP, InAs and InSb; ternary compounds, e.g., GaNP, GaNAs, GaNSb, GaPAs, GaPSb, A1NP, AINAs, AINSb, AlPAs, AlPSb, InNP, InNAs, InN Sb, InPAs, InPSb, GaAlNP, AlGaN, AlGaP, AlGaAs, AlGaSb, InGaN, InGaP, InGaAs, InGaSb, AlInN, AllnP, AlInAs and AllnSb; and quaternary compounds, e.g., GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GalnNP, Gain, NAs, GalnNSb, GalnPAs, GalnPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb. Exemplary Group IV-VI semiconductor compounds include binary compounds, e.g., SnS, SnSe, SnTe, PbS, PbSe and PbTe; ternary compounds, e.g., SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe and SnPbTe; and quaternary compounds, e.g., SnPbSSe, SnPbSeTe and SnPbSTe. Exemplary Group IV semiconductor compounds include unary compounds, e.g., Si and Ge; and binary compounds, e.g., SiC and SiGe.

[0044] Where the one or more stabilized quantum dots are described herein as having a shell or a multi-shell structure (i.e., a core and at least one shell), the core and the shell or plurality of shells may independently be formed of the semiconductor materials described above.

[0045] The semiconductor nanocrystals may have a multilayer structure comprising two or more layers composed of different materials. The multilayer structure of the semiconductor nanocrystals may include at least one alloy interlayer composed of two or more different materials at the interface between adjacent layers. The alloy interlayer may be composed of an alloy having a composition gradient. The one or more stabilized quantum dots may comprise quantum dots stabilized by a combination of two or more of these features. In some aspects one or more of the one or more stabilized quantum dots is a metal nanomaterial or an inorganic nanomaterial. The form of the one or more stabilized quantum dots may include in certain aspects a nanoparticle, a nanofiber, a nanorod, or a nanowire. The one or more stabilized quantum dots may have a size of from about 1 nanometer (nm) to about 100 nm in some aspects, or of from about 1 nm to about 50 nm in particular aspects.

[0046] The apparatus 100 may comprise a scattering material. The at least one extruded polymer layer may in particular aspects include one or more optional additional additives, including but not limited to a dispersant, a scavenger, a stabilizer or a combination thereof. In particular, a scavenger may be provided to absorb oxygen and/or moisture, which could help to protect the stabilized quantum dot from damage in the presence thereof. Exemplary scavenger materials include, but are not limited to, oxygen scavengers such as hydrazine, Carbo-Hz, sodium sulfite, n,n-diethylhydroxylamine (DEHA), methylethyl ketone oxime (MEKO), erythorbate, hydroquinone, and combinations thereof, and moisture scavengers such as calcium oxide, magnesium oxide, strontium oxide, barium oxide, aluminum oxide, silicone oxide, and combinations thereof. The scavenger in some aspects has a particle size of from about 0.1 micrometer (μπι) to about 10 um.

[0047] The apparatus 100 may comprise a plurality of layers (e.g., polymer layers, substrate layers, functional layers). The plurality of layers may be extruded layers (e.g., using co-extrusion or multi-layer extrusion). For example, plurality of layers may be disposed below and/or above the first thin film layer. Each of the plurality of layers may comprise one or more stabilized quantum dots as described above. For example, each layer may comprise phase separated regions with corresponding portions of the plurality of stabilized quantum dots. One or more of the plurality of layers may include texturing for modifying the optical properties of the apparatus 100, as desired. The texturing may be disposed on the bottom side and/or topside of the apparatus 100. The texturing may be disposed on the bottom side and/or topside of any of the plurality of layers.

[0048] The apparatus 100 may not include a barrier layer, such as those found in conventional quantum dot films. As a result, the apparatus 100 may be made with fewer processes, and thinner quantum dot films can be made. These improvements reduce the cost of the quantum dot film and enhance the optical properties of the quantum dot film. In particular, in the case of quantum dot films including a plurality of extruded polymer layers, the plurality of extruded polymer layers may be seamless (e.g., in contrast to conventional quantum dot films including one or more barrier layers), which further enhances the optical properties of the quantum dot film because light emitted by the stabilized quantum dots is not affected as it travels from one extruded polymer layer to the other.

[0049] The one or more stabilized quantum dots included in a quantum dot light emitting device according to aspects of the disclosure have improved properties as compared to quantum dots included in conventional quantum dot light emitting devices. The one or more stabilized quantum dots are one or more of thermally stabilized, air stabilized, moisture stabilized and flux stabilized.

[0050] The one or more stabilized quantum dots may be extruded as one or more layers. The one or more stabilized quantum dots may be thermally stabilized such that the quantum dot film exhibits no appreciable degradation of optical properties during an extrusion process. A typical extrusion temperature of an ordinary polymer may be over about 200 degrees Celsius (°C). An extrusion temperature of polypropylene may be at least about 200°C. An extrusion temperature of polycarbonate may be at least about 330°C. An extrusion temperature of polyetherimide may be at least about 400°C. An example extrusion process may be less than about 5 minutes. The one or more stabilized quantum dots are thermally stabilized such that the quantum dot film exhibits no appreciable degradation of optical properties at a temperature of at least about 200°C. The one or more stabilized quantum dots are thermally stabilized such that the quantum dot film exhibits no appreciable degradation of optical properties at a temperature of at least about 250°C, or at a temperature of at least about 300°C, or at a temperature of at least about 330°C, or at a temperature of at least about 350 °C, or at a temperature of at least about 380°C, or at a temperature of at least about 400 °C.

[0051] As used herein, "appreciable degradation of optical properties" means that, when the stabilized quantum dot is exposed to the stated condition, the emission spectra of the stabilized quantum dot either does not change or does not change to a substantial degree (e.g., the change is less than about 10%). Emission spectra of a quantum dot may be quantified by measuring the width of the Gaussian curve of the emission spectra at half of its maximum value, known as "full width at half maximum," or FWHM. Degradation of a quantum dot under adverse conditions such as those described herein can cause its FWHM to increase and its peak wavelength to shift, resulting in a change in optical properties. An "appreciable degradation of optical properties" may include a change in FWHM of more than about 10% or a shift in peak wavelength of more than about 10%.

[0052] The one or more stabilized quantum dots may be air stabilized such that the quantum dot film exhibits no appreciable degradation of optical properties when exposed to air having a relative humidity of 95% and a temperature of 60 °C for 1000 hours. The one or more stabilized quantum dots may be moisture stabilized such that the quantum dot film exhibits no appreciable degradation of optical properties when exposed to air having a relative humidity of 95% and a temperature of 60 °C for 1000 hours. The one or more stabilized quantum dots may be flux stabilized such that the quantum dot film exhibits no appreciable degradation of optical properties when exposed to an acceleration flux of 350 milliwatt per square centimeter (mW/cm2) for 100 hours. The one or more quantum dots may be flux stabilized and thermal stabilized such that the quantum dot film exhibits no appreciable degradation of optical properties when exposed for 100 hours to an acceleration flux of 350 mW/cm2 in air having a temperature of 60 °C.

[0053] Referring again to FIG. 1, the apparatus 100 may comprise an energy unit 106. The energy unit 106 may comprise a battery. The energy unit 106 may comprise an energy harvester. The energy unit 106 may comprise both the battery and the energy harvester. The battery may be configured to power different components than the energy harvester. For example, the battery may be configured to supply power to one or more of a sensor 108, processor 110, storage unit 112, display 114, communication unit 116, a combination thereof, and/or the like. The energy harvester may be configured to supply power only to the one or more quantum dots. In another scenario, the energy harvester may be configured to supply power to the one or more quantum dots, the sensor 108, the processor 110, the storage unit 112, the display 114, the communication unit 116, a combination thereof, and/or the like. In yet another scenario, the battery and the energy harvester may be configured to supply power to the one or more quantum dots 104, the sensor 108, the processor 110, the storage unit 112, the display 114, the communication unit 116, a combination thereof, and/or the like. The battery may supply additional energy that is not supplied by the energy harvester.

[0054] The energy harvester may comprise a self-generating power source. The energy harvester may comprise a triboelectric energy harvester, a piezoelectric energy harvester, a solar cell (e.g., photovoltaic layer), a mechanical energy harvester, and/or the like. The energy harvester may be configured to output energy (e.g., a current, a voltage) in response to an event. The event may comprise a touch event, pressure event, friction event, contact event, and/or the like. The energy may comprise a signal, such as a voltage pulse. For example, when the energy harvester contacts (e.g., receives a frictional force) a wearer's skin, the energy harvester may output a signal. The energy harvester may comprise at least one of polyvinylidene difluoride (PVDF), a copolymer of PVDF, polydimethylsiloxane (PDMS), poly(methyl methacrylate) (PMMA), Teflon, Polymer foam, poly(methyl methacrylate)-co- poly(lH-lH-perfluoroctyl methacrylate), Parylene, a fluorinated polymer, and an electronegative polymer.

[0055] The energy harvester may be configured to supply a voltage directly, via the electrical interconnect, from the energy harvester to the one or more quantum dots to cause emission of the light by the one or more stabilized quantum dots in response to a contact event. The energy harvester may be electrically coupled to the one or more quantum dots. The energy harvester may be electrically coupled directly to the one or more quantum dots. For example, the energy harvester may be electrically coupled, via an electrical interconnect, to the one or more quantum dots. The energy harvester may be electrically coupled to the one or more quantum dots without any other circuit elements (e.g., besides the electrical interconnect). The electrical interconnect may comprise no addition circuit elements electrically coupled between the energy harvester and the one or more quantum dots. The electrical interconnect may not be connected (e.g., directly connected) to any electrical lines or other circuit elements other than the energy harvester and the one or more quantum dots. The energy harvester may be electrically coupled to the one or more quantum dots without an energy storage component (e.g., capacitor, battery). In some implementations, the energy harvester may be electrically coupled to a conditioning component configured to condition the signal from the energy harvester for the one or more quantum dots. The conditioning component may comprise a rectifier. The rectifier may be configured to condition the signal from the energy harvester. The conditioning component (e.g., rectifier) may be the only component (e.g., besides an electrical interconnect) coupled between the energy harvester and the one or more quantum dots (e.g., or a portion thereof). The conditioning component (e.g., rectifier) may be configured to generate a DC signal based the signal received from the energy harvester.

[0056] In some implementations, the energy harvester may be electrically coupled to the one or more quantum dots via a switch component configured to make or break an electrical connection between the energy harvester and the one or more quantum dots. The switch component may be the only component (e.g., besides electrical interconnects) electrically coupled between the energy harvester and the one or more quantum dots (e.g., or a portion thereof). The switch component and the conditioning component may be the only components (e.g., besides electrical interconnects) electrically coupled between the energy harvester and the one or more quantum dots (e.g., or a portion thereof). The switch component may be controlled by another component, such as a processor 110. The switch component may comprise a relay, a transistor, and/or the like. The switch component may switch a signal between one or more portions of the one or more quantum dots. For example, one or more switch components may be used to switch on and off electrical coupling of the energy harvester to the first portion, the second portion, and/or the third portion of the one or more quantum dots. In some implementations, a different energy harvester may be coupled to each of the first portion, the second portion, and the third portion of the one or more quantum dots.

[0057] The apparatus 100 may comprise a sensor 108. The sensor 108 may comprise a photodetector, such as a photodiode. The sensor 108 (e.g., photodiode) may be configured to generate a signal based on detection of the light emitted from the one or more quantum dots. The sensor 108 (e.g., photodiode) may be configured to generate a signal based on (e.g., in response to) detection of the light emitted from the one or more quantum dots 105 as reflected from a wearer of the apparatus 100. The sensor 108 may comprise a self-powered photodetector. For example, the sensor 108 may generate a current without having an applied voltage from an external voltage source. The sensor 108 may comprise a thin film sensor. The sensor 108 may be sensitive to low powered light. The sensor 108 may be sensitive to the light generated by the one or more quantum dots 104. The sensor 108 may be sensitive to the light generated by the first portion, the second portion, and third portion of the one or more quantum dots 104. The sensor 108 may comprise a semiconducting material, such as cadmium sulfide (e.g., nanocrystalline CdS). In some implementations, multiple sensors may be used. For example, a first sensor may be configured to sense light from the first portion of the one or more quantum dots. A second sensor may be configured to sense light from the second portion of the one or more quantum dots. A third sensor may be configured to sense light from the third portion of the one or more quantum dots. Each of the sensors may use a different material, have the same materials with different doping amounts, and/or the like. [0058] The apparatus 100 may comprise a processor 110. The processor 110 may receive an output (e.g., a signal) of the sensor 108. The output of the sensor 108 may comprise a plurality of sensor readings. The processor 110 may be configured to store the output in a storage unit 112. The storage unit 112 may comprise a solid state storage device, such as a flash drive. The storage unit 112 may comprise any storage medium appropriate for a wearable device, including a storage disposed on a thin film layer (e.g., flexible layer). The storage unit 112 may comprise software that configures the processor 110 to determine health metrics (e.g., or other metrics), control the QD light emitting device, and/or the like.

[0059] The processor 110 may be configured to determine, based on the output from the sensor, a health metric. The health metric may be associated with a blood flow of the wearer of the apparatus 100. The health metric may comprise one or more of a heart rate, a blood oxygen level, or a heart condition. For example, the heart condition may be determined based on detecting an irregular heartbeat. The irregular heart beat may comprise a heartbeat below a threshold, a heart rate above a threshold. The irregular heart beat may comprise an irregular rhythm. The processor may determine the health metric based on comparison to known thresholds, comparison to prior data, categorization based on machine learning, and/or the like.

[0060] The processor 110 may be configured to determine an optimal wavelength range associated with the additional health metric. The processor 110 being configured to optimize the usage of portions of the one or more stabilized quantum dots for determining the additional health metric may comprise the processor being configured for one or more of enabling or disabling a portion of the one or more stabilized quantum dots based on the optimal wavelength range.

[0061] The processor 110 may be configured to determine a first health metric. The processor 110 may be configured to determine a second health metric. The processor 110 may be configured to optimize usage of portions of the one or more stabilized quantum dots for determining the first health metric and/or second health metric. The processor 110 may activate the first portion, the second portion, and/or the third portion of the one or more quantum dots 104 based on which health metric is to be determined. The first portion of the one or more quantum dots 104 may be associated with a first health metric. The second portion and/or third portion of the one or more quantum dots 104 may be associated with a second health metric. The first portion of the one or more quantum dots 104 may be associated with a specific mode and/or configuration of the apparatus 100. For example, when the apparatus 100 is disposed on a wrist of the wearer, the apparatus 100 may function in a first mode. When the apparatus 100 is disposed on a finger of the wearer, the apparatus 100 may function in a second mode. The first mode may use the first portion of the one or more quantum dots 104. The second mode may use the second portion and/or third portion of the one or more quantum dots 104.

[0062] The processor 110 may be configured to determine the health metric based on Photoplethysmography (PPG). For example, a signal received from the sensor 108 may comprise a physiological waveform, such as a PPG waveform. The signal may be indicative of changes in blood flow volume. For example, the processor 110 may control the one or more quantum dots 104 to emit light. The processor 110 may receive electrical signals from the photodetector representative of light reflected from a subject (e.g., the wearer). The processor 110 may determine a change of blood volume in blood vessels (e.g., or a metric indicative change of volume in blood) of the subject based, at least in part, on the received electrical signals from the sensor 108. The processor 110 may determine an intensity of light (e.g., and changes in the intensity of light) generated by the one or more quantum dots 104 and reflected from a surface (e.g., skin of the wearer). Signals from the sensor 108 may be analyzed to determine an optically-obtained plethysmogram.

[0063] The health metric may comprise a heart rate. The one or more quantum dots 104 may be used as an optical photoplethysmography (PPG) sensor to monitor health and track fitness of human body. The further integration of thin film energy harvester can offer the possibility of self-powered (battery-free), wearable and portable devices with PPG sensing function.

[0064] The heart rate may be determined as follows. Light strikes the body tissue, and then is transmitted, absorbed and reflected (e.g., as shown in FIG. 6) - the larger the irradiated blood volume, the lower the amount of light reflected. As the blood volume in the arteries changes with the cardiac cycle, the heart rate results from the periodicity of the detector signal (e.g., as shown in FIG. 7). This optical measurement of the change of blood volume in the blood vessels is referred to as photoplethysmography. The apparatus 100 may be disposed such that the sensor and one or more quantum dots may be oriented toward the skin of a wearer, such as on the wrist or fingers. Due to the location, measurements may be made at different wavelengths— green light may be when the apparatus 100 is disposed on the wrist, red and infrared light may be used when the apparatus 100 is disposed on the finger. The processor 110 may be configured to cause the one or more quantum dots 104 to emit light waves associated with measuring heart rate. For example, the processor 110 may be configured to cause the one or more quantum dots 104 to emit green light when the apparatus 100 is disposed on a wrist of the wearer. The processor 110 may be configured to cause the one or more quantum dots 104 to emit red light (e.g., and infrared light) when the apparatus 100 is disposed on a finger of the wearer.

[0065] The health metric may comprise a blood oxygen level. For example, the processor 110 may be configured to determine the health metric based on pulse oximetry. The oxygen saturation of the blood can be measured when infrared and red light are used at the same time, as shown in FIG. 8. Pulse oximetry is based on the fact that hemoglobin (Hb) is changing its absorption behavior when hemoglobin binds oxygen (e.g., oxyhemoglobin Hb02). The concentrations of these two variants of hemoglobin can be determined by measuring the absorption at two different wavelengths. Comparison of these measurements yield the oxygen saturation of the blood. Red (e.g., 660 nm) and infrared (e.g., 940 nm) light may be used, because the absorption behavior of the two hemoglobin molecules deviates most from each other. In contrast to the pulse measurement, which is only considering the relative changes in light absorption, the light absorption of arterial blood may be measured in absolute terms. The blood oxygen saturation can be represented as a function of the ratio of the minimum and maximum detector signals (Imin/Imax) at the respective wavelength. Accordingly, the processor may be configured to convert signals from the sensor to blood oxygen saturation values. The processor 110 may be configured to cause the QD light emitting device to emit light waves associated with blood oxygen levels. For example, the processor 110 may be configured to cause the QD light emitting device to emit red light and infrared light when measuring blood oxygen levels.

[0066] The processor 110 may determine the health metric based on a history of values stored in the storage unit. For example, the health metric may be determined by comparing a prior signal value (e.g., light intensity value) to a current signal value. The processor 110 may store a count of heart beats detected in the stored values associated with a time period.

[0067] The apparatus 100 may comprise a display 114, such as a liquid crystal display, light emitting device, and/or the like. The display 114 may be disposed on an opposite side of the flexible body as the one or more quantum dots 104. In some scenarios, the display 114 may comprise additional quantum dots (e.g., oriented opposite the one or more quantum dots 104). The display 114 may be configured to present the health metric and/or other information to the wearer. The display 114 may operate a user interface.

[0068] The apparatus 100 may comprise a communication unit 116. The communication unit 116 may be configured to communicate information to and from other devices via a network. For example, the communication unit 1 16 may comprise a wireless transceiver. The communication unit 116 may be configured to form a communication session with a remote device (e.g., mobile device, server, gateway, router, access point). For example, the apparatus 100 may pair with a mobile device of the wearer. The communication unit 116 may send measured values from the sensor, determined health metrics, and/or the like to the remote device. The communication unit 116 may receive software updates from the remote device. The communication unit 116 may receive health metrics determined by the remote device. For example, the remote device may receive sensor data from the apparatus 100 and determine the health metric remotely from the apparatus 100.

[0069] FIG. IB is a diagram illustrating an example circuit of the example apparatus. The energy unit 106 may be configured to supply power to the one or more quantum dots 104, the sensor 108, the processor 110, the storage unit 112, the display 114, the communication unit 116, and/or the like. Though shown as a single block, the energy unit 106 may comprise separate energy components (e.g., which may be located in separate locations in the apparatus 100). The energy harvester may be separate from any battery, storage capacitor, or other energy storage component. The energy harvester may be electrically coupled to the one or more quantum dots 104 without being electrically coupled to the other components of the apparatus 100. The energy harvester may be configured to only provide current and/or voltage to the one or more quantum dots 104. The sensor 108 may not be configured to receive power from the energy unit 106. The sensor 108 may be self-powered. In some implementations, an additional energy harvester may be comprised in the apparatus 100 (e.g., such as in the energy unit 106). The additional energy harvester may be configured to supply power to one or more of the one or more quantum dots 104, the sensor 108, the processor 110, the storage unit 112, the display 114, the sensor 108, and/or the communication unit 116.

[0070] The processor 110 may be configured to communicate to the storage unit 112 and/or the sensor 108 via the communication unit 116. The communication unit 116 may comprise a bus or other communication line. In some implementations the display 114 and/or the one or more quantum dots 104 may be controlled by the processor 110 via the communication unit 116.

[0071] FIG. 2 is a diagram illustrating layers of an example apparatus 200. The apparatus 200 may comprise a substrate 202. The substrate 202 may be configured to flex with the flexible body. The substrate 202 may be integrated into a flexible wearable device. The substrate 202 may be clear. The substrate 202 may comprise glass.

[0072] The apparatus 200 may comprise a quantum dot (QD) light emitting device 204. The QD light emitting device 204 may comprise a first thin film layer 206. The first thin film layer 206 may be disposed above the substrate 202. The one or more quantum dots 104 of FIG. 1 may be disposed in the first thin film layer 206. The one or more quantum dots 104 may direct emitted light through the substrate 202.

[0073] The QD light emitting device 204 may comprise an anode thin film layer 208. The QD light emitting device may comprise a cathode thin film layer 210. The anode thin film layer 208 and/or the cathode thin film layer 210 may be disposed in a material stack with the first thin film layer 206.

[0074] The QD light emitting device 204 may comprise a hole transport thin film layer 212. The hole transport thin film layer 212 may be coupled (e.g., electrically coupled) to the anode thin film layer 208. The hole transport thin film layer 212 may be disposed adjacent the anode thin film layer 208. The hole transport thin film layer 212 may be disposed between the anode thin film layer 208 and the first thin film layer 206. The QD light emitting device 204 may comprise an electron transport thin film layer 214. The electron transport thin film layer 214 may be coupled (e.g., electrically coupled) to the cathode thin film layer 210. The electron transport thin film layer 214 may be disposed adjacent the cathode thin film layer 210. The electron transport thin film layer 214 may be disposed between the cathode thin film layer 210 and the first thin film layer 206. The hole transport thin film layer 212 and/or the electron transport thin film layer 214 may be in the material stack with the first thin film layer 206.

[0075] The apparatus 200 may comprise an energy harvester 216. The energy harvester 216 may be disposed in a second thin film layer 218. The second film layer 218 may comprise a triboelectric material, a piezoelectric material, and/or the like. The energy harvester 216 may comprise a bottom electrode 220. The bottom electrode 220 may be disposed adjacent to (e.g., below) the second thin film layer 218. The bottom electrode 220 may be electrically coupled to a ground, a resistor, a load, and/or the like.

[0076] The energy harvester 216 may be electrically coupled to the QD light emitting device 204. For example, the anode thin film layer 208 and/or the cathode thin film layer 210 of the QD light emitting device 204 may be coupled (e.g., electrically coupled) to the energy harvester 216. The anode thin film layer 208 and/or the cathode thin film layer 210 of the QD light emitting device 204 may be coupled to the bottom electrode 220 of the energy harvester 216. The bottom electrode 220 may be configured to supply a current 222 to the anode thin film layer 208 and/or the cathode thin film layer 210.

[0077] The energy harvester 216 may be electrically coupled to a load 224. The load 224 may couple the energy harvester 216 to the ground. The load 224 may comprise a resistor, transistor, and/or the like. In another implementation, the QD light emitting device 204 may be configured as a load for the energy harvester 216.

[0078] The apparatus 200 may comprise a sensor, such as sensor 108. The sensor may comprise a third thin film layer, such as a thin film photo-detection layer (e.g., photodiode). The third thin film layer may be disposed adjacent the substrate. The third thin film layer may comprise one or more Group II- VI semiconductor, such as ZnO, CdS or ZnS. The third thin film layer may be disposed adjacent the substrate based on a chemical bath deposition. The sensor may comprise one or more metal layers disposed adjacent the third thin film layer. The one or more metal layers may comprise one or more electrodes. The third thin film layer may comprise a self-powered photodiode. The third thin film layer may be configured to output a current based on detection of light.

[0079] The first thin film layer 206, the second thin film layer 218, and/or the third thin film layer may be disposed on different portions of the substrate. For example, the first thin film layer 206 may be disposed on a different part of the substrate than the second thin film layer 218 and/or the third thin film layer. In some implementations, the sensor may be disposed on a different substrate than the first then film layer 206 and/or the second thin film layer 218. The first thin film layer 206 may also be disposed on a different substrate than the second thin film layer 218.

[0080] FIG. 3 is diagram showing connection pads for an energy harvester and a quantum dot light emitting device. In some scenarios, an apparatus may comprise an energy harvester and a quantum dot light emitting device as disclosed further herein. The apparatus may be configured to be integrated into other devices, such as a wearable device. The connection pads allow for electrical connections (e.g., direct electrical connections) between the energy harvester and the quantum dot light emitting device. The connection pads that have dotted lines are bottom electrodes (e.g., disposed on the substrate, or bottom of material stack). The solid lines indicate top electrodes (e.g., disposed on the top of the material stack).

[0081] FIG. 4 is diagram showing connection pads for an energy harvester, a quantum dot light emitting device, and a sensor. In some scenarios, an apparatus may comprise an energy harvester, a quantum dot light emitting device, and a sensor (e.g., photodiode) as disclosed further herein. The apparatus may be configured to be used for determining health data, such as heart rate, blood oxygen level, and/or the like. The connection pads allow for electrical connections (e.g., direct electrical connections) between the energy harvester, the quantum dot light emitting device, and the sensor, and/or the like. The connection pads that have dotted lines are bottom electrodes (e.g., disposed on the substrate, or bottom of material stack). The solid lines indicate top electrodes (e.g., disposed on the top of the material stack). FIG. 5 is a diagram showing of a PPG sensor with quantum dots. In some scenarios, an apparatus may comprise a quantum dot light emitting device and a sensor (e.g., photodiode) as disclosed further herein. The apparatus may have a dedicated power source, a battery, an energy harvester, a combination thereof, and/or the like.

[0082] FIG. 6 is a diagram showing optical measurement of biometric data. The sensor is emitting green (e.g., 530 nm), red (e.g., 660 nm), and/or infrared light (e.g., 940 nm). The light may irradiate the skin or tissue and is absorbed or reflected. The amount of reflected light varies with the amount of blood in the arteries. The measurements of reflected light may be based on green light when measuring the wrist. The measurements of reflected light may be based on red and/or infrared light when measuring the finger. FIG. 7 is a diagram showing a heart rate measurement. The periodicity of the detector signal I corresponds to the pulsation of the amount of blood in the arteries. For example, a cardiac cycle may be determined based on time between minimum (e.g., Imin) or maximum (e.g., Imax) values of the detected signal I. As another example, a heart rate may be determined based on counting a number of times the cardiac cycle, the minimum signal, the maximum signal, and/or the like occurs within a time period. The ratio of the minimum and maximum signal values may be used to determine oxygen saturation of the blood. FIG. 8 is a diagram showing determination of oxygen saturation of the blood. The absorption behavior of blood (e.g., the blood pigment hemoglobin (Hb)) changes when the blood receives oxygen (e.g., oxyhemoglobin or HbC ). By measuring the absorption of the red and infrared light, the oxygen saturation of the blood may be determined.

[0083] FIG. 9 is a diagram comparing quantum dot light emitting device to an organic light emitting device. The use of quantum dot light emitting devices (e.g., shown on left) results in a simpler device with fewer layers to form in the fabrication process as compared to organic light emitting devices (e.g., shown on right). Thus, quantum dot light emitting devices are an improvement over conventional devices, such as the organic light emitting device. The example QLED shown in FIG. 9 may comprise a top electrode layer (e.g., aluminum), an electron transport layer (e.g., zinc oxide) an emission layer (EML) (e.g., a quantum dot layer), a hole transport layer (HTL), a conductive polymer layer (e.g., poly(3,4- ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)), a bottom electrode layer (e.g., Indium tin oxide), and/or the like. The example OLED may comprise a top electrode (e.g., aluminum), an electron injection layer (EIL), an electron transport layer (ETL), a hole blocking layer (HBL), an emission layer (EML), an electron blocking layer (EBL), a hole transport layer (HTL), a hole injection layer (HIL), and a bottom electrode (e.g., indium tin oxide). The structure of an electroluminescent quantum dots light emitting devices (QD- LED) is compared to the basic design of an OLED, as shown in FIG. 9. One major difference between the QD-LED and the OLED is that the light emitting materials in the QD- LED comprise colloidal quantum dots nanocrystal materials, such as cadmium selenide. A layer of quantum dots may be disposed (e.g., sandwiched) by solution printing process between layers of electron-transporting and hole-transporting organic materials. The total thickness of the QD-LED may be in the level of micrometers.

[0084] FIG. 10 is a diagram showing a spectrum of electroluminescent quantum dots. The quantum dots may be manufactured of a variety of sizes to allow for the emission of different light sources. An applied electric field causes electrons and holes to move into a quantum dot layer (e.g., a layer comprising one or more quantum dots), where the electrons are captured in the quantum dot and recombine, and emitting photons. The spectrum of photon emission may be narrow, characterized by its peak wavelength and full width at half the maximum value. The emission peak wavelength may be varied from ultraviolet, visible to infrared by tuning the size and composition of quantum dots nanocrystal materials, as shown in FIG. 10. Numerous types of QD-LEDs may been successfully integrated in to the apparatus as described herein. In an example implementation, blue, green and red QD LED may have the brightness of 1000 cd/m² at the voltage of 4.8V, 3,3V and 2.7V respectively. 9.6 mW, 9.9 mW and 2.7 nW may be used to realize the brightness with emitting area of 10 mm by 10 mm. Table 1 shows example specifications of a variety of quantum dots.

Table 1.

Aspects of the Disclosure

[0085] In various aspects, the present disclosure pertains to and includes at least the following aspects.

[0086] Aspect 1. An apparatus comprising, consisting of, or consisting essentially of: one or more stabilized quantum dots disposed in a first thin film layer and configured to emit light; a triboelectric energy harvester disposed in a second thin film layer and electrically coupled, via an electrical interconnect, to the one or more stabilized quantum dots, wherein the triboelectric energy harvester is configured to supply a voltage directly, via the electrical interconnect, from the triboelectric energy harvester to the one or more stabilized quantum dots to cause emission of the light by the one or more stabilized quantum dots in response to a contact event; and wherein the first thin film layer and the second thin film layer are disposed adjacent a substrate, and wherein the substrate is integrated into a flexible wearable device.

[0087] Aspect 2. The apparatus of Aspect 1, wherein the triboelectric energy harvester being configured to supply the voltage directly, via the electrical interconnect, from the triboelectric energy harvester to the one or more stabilized quantum dots in response to the contact event comprises the triboelectric energy harvester being electrically coupled to the one or more stabilized quantum dots without an energy storage component.

[0088] Aspect 3. The apparatus of any of Aspects 1-2, wherein the triboelectric energy harvester comprises at least one of polyvinylidene difluoride (PVDF), a copolymer of PVDF, polydimethylsiloxane (PDMS), poly(methyl methacrylate) (PMMA), Teflon, Polymer foam, poly(methyl methacrylate)-co-poly(lH-lH-perfluoroctyl methacrylate), Parylene, a fluorinated polymer, and an electronegative polymer.

[0089] Aspect 4. The apparatus of any of Aspects 1-3, wherein the one or more stabilized quantum dots comprise a first portion of stabilized quantum dots configured to emit light in a first wavelength range, a second portion of stabilized quantum dots configured to emit light in a second wavelength range, and a third portion of stabilized quantum dots configured to emit light in a third wavelength range.

[0090] Aspect 5. The apparatus of any of Aspects 1-4, further comprising an anode thin film layer and a cathode thin film layer in a material stack with the first thin film layer, and wherein the anode thin film layer and the cathode thin film layer are coupled to the triboelectric energy harvester and to the one or more stabilized quantum dots.

[0091] Aspect 6. The apparatus of Aspect 5, further comprising: a hole transport thin film layer coupled to the anode thin film layer; and an electron transport thin film layer coupled to the cathode thin film layer, wherein the hole transport thin film layer and the electron transport thin film layer are in the material stack with the first thin film layer.

[0092] Aspect 7. The apparatus of any of Aspects 1-6, further comprising a sensor configured to generate a signal based on detection of the light emitted from the one or more stabilized quantum dots as reflected from a wearer of the apparatus and a processor configured to determine, based on the signal, a health metric associated with a blood flow of the wearer. [0093] Aspect 8. An apparatus comprising, consisting of, or consisting essentially of: one or more stabilized quantum dots disposed in a first thin film layer and configured to emit light; a triboelectric energy harvester disposed in a second thin film layer and electrically coupled, via an electrical interconnect, to the one or more stabilized quantum dots, wherein the triboelectric energy harvester is configured to supply a voltage directly, via the electrical interconnect, from the triboelectric energy harvester to the one or more stabilized quantum dots to cause emission of the light by the one or more stabilized quantum dots in response to a contact event; a photodiode disposed on a third thin film layer and configured to generate a signal in response to detecting the emission of the light by the one or more stabilized quantum dots as reflected from a wearer of the apparatus; and wherein the first thin film layer and the second thin film layer are disposed on a substrate, and wherein the substrate is integrated into a flexible wearable device.

[0094] Aspect 9. The apparatus of Aspect 8, wherein the third thin film layer is disposed on the substrate.

[0095] Aspect 10. The apparatus of any of Aspects 8-9, wherein the first thin film layer is disposed on a different part of the substrate than the second thin film layer.

[0096] Aspect 11. The apparatus of any of Aspects 8-10, wherein the triboelectric energy harvester being configured to supply the voltage directly, via the electrical interconnect, from the triboelectric energy harvester to the one or more stabilized quantum dots in response to the contact event comprises the triboelectric energy harvester being electrically coupled to the one or more stabilized quantum dots without an energy storage component.

[0097] Aspect 12. The apparatus of any of Aspects 8-11, wherein the triboelectric energy harvester comprises at least one of polyvinylidene difluoride (PVDF), a copolymer of PVDF, polydimethylsiloxane (PDMS), poly(methyl methacrylate) (PMMA), Teflon, Polymer foam, poly(methyl methacrylate)-co-poly(lH-lH-perfluoroctyl methacrylate), Parylene, a fluorinated polymer, and an electronegative polymer.

[0098] Aspect 13. The apparatus of any of Aspects 8-12, wherein the one or more stabilized quantum dots comprise a first portion of stabilized quantum dots configured to emit light in a first wavelength range, a second portion of stabilized quantum dots configured to emit light in a second wavelength range, and a third portion of stabilized quantum dots configured to emit light in a third wavelength range. [0099] Aspect 14. The apparatus of any of Aspects 8-9, wherein the one or more stabilized quantum dots are one or more of air stabilized or heat stabilized.

[00100] Aspect 15. A wearable health device comprising, consisting of, or consisting essentially of: a flexible body configured to conform to a wearer; one or more stabilized quantum dots disposed in a first thin film layer and configured to emit light; a triboelectric energy harvester disposed in a second thin film layer and electrically coupled, via an electrical interconnect, to the one or more stabilized quantum dots, wherein the triboelectric energy harvester is configured to supply a voltage directly, via the electrical interconnect, from the triboelectric energy harvester to the one or more stabilized quantum dots to cause emission of the light by the one or more stabilized quantum dots in response to a contact event, wherein the first thin film layer and the second thin film layer are disposed adjacent a single substrate configured to flex with the flexible body; a photodiode disposed on a third thin film and configured to generate a signal in response to detecting emission of the light by the one or more stabilized quantum dots as reflected from the wearer; and a processor in communication with the photodiode and configured to determine a health metric based on the signal.

[00101] Aspect 16. The wearable health device of Aspect 15, wherein the health metric comprises one or more of a heart rate, a blood oxygen level, or a heart condition.

[00102] Aspect 17. The wearable health device of any of Aspects 15-16, wherein the processor is configured to determine an additional health metric, and wherein the processor is configured to optimize usage of portions of the one or more stabilized quantum dots for determining the additional health metric.

[00103] Aspect 18. The wearable health device of Aspect 17, wherein the processor is configured to determine an optimal wavelength range associated with the additional health metric, and wherein the processor being configured to optimize the usage of portions of the one or more stabilized quantum dots for determining the additional health metric comprises the processor being configured for one or more of enabling or disabling a portion of the one or more stabilized quantum dots based on the optimal wavelength range.

[00104] Aspect 19. The wearable health device of any of Aspects 15-18, wherein the triboelectric energy harvester being configured to supply the voltage directly, via the electrical interconnect, from the triboelectric energy harvester to the one or more stabilized quantum dots in response to the contact event comprises the triboelectric energy harvester being electrically coupled to the one or more stabilized quantum dots without an energy storage component.

[00105] Aspect 20. The wearable health device of any of Aspects 15-19, wherein the one or more stabilized quantum dots comprise a first portion of stabilized quantum dots configured to emit light in a first wavelength range, a second portion of stabilized quantum dots configured to emit light in a second wavelength range, and a third portion of stabilized quantum dots configured to emit light in a third wavelength range.

[00106] It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. As used in the specification and in the claims, the term "comprising" can include the embodiments "consisting of and "consisting essentially of." Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. In this specification and in the claims which follow, reference will be made to a number of terms which shall be defined herein.

[00107] As used herein, the term "combination" is inclusive of blends, mixtures, alloys, reaction products, and the like.

[00108] Ranges can be expressed herein as from one value (first value) to another value (second value). When such a range is expressed, the range includes in some aspects one or both of the first value and the second value. Similarly, when values are expressed as approximations, by use of the antecedent 'about,' it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as "about" that particular value in addition to the value itself. For example, if the value "10" is disclosed, then "about 10" is also disclosed. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[00109] As used herein, the terms "about" and "at or about" mean that the amount or value in question can be the designated value, approximately the designated value, or about the same as the designated value. It is generally understood, as used herein, that it is the nominal value indicated ±10% variation unless otherwise indicated or inferred. The term is intended to convey that similar values promote equivalent results or effects recited in the claims. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but can be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. In general, an amount, size, formulation, parameter or other quantity or characteristic is "about" or "approximate" whether or not expressly stated to be such. It is understood that where "about" is used before a quantitative value, the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

[00110] As used herein, the terms "optional" or "optionally" means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where said event or circumstance occurs and instances where it does not. For example, the phrase "optional additional additives" means that the additional additives can or cannot be included and that the description includes compositions that both include and do not include additional additives.

[00111] Disclosed are the components to be used to prepare the compositions of the disclosure as well as the compositions themselves to be used within the methods disclosed herein. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds cannot be explicitly disclosed, each is specifically contemplated and described herein. For example, if a particular compound is disclosed and discussed and a number of modifications that can be made to a number of molecules including the compounds are discussed, specifically contemplated is each and every combination and permutation of the compound and the modifications that are possible unless specifically indicated to the contrary. Thus, if a class of molecules A, B, and C are disclosed as well as a class of molecules D, E, and F and an example of a combination molecule, A-D is disclosed, then even if each is not individually recited each is individually and collectively contemplated meaning combinations, A-E, A-F, B-D, B-E, B-F, C-D, C-E, and C-F are considered disclosed. Likewise, any subset or combination of these is also disclosed. Thus, for example, the sub-group of A-E, B-F, and C-E would be considered disclosed. This concept applies to all aspects of this application including, but not limited to, steps in methods of making and using the compositions of the disclosure. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific aspect or combination of aspects of the methods of the disclosure.

[00112] References in the specification and concluding claims to parts by weight of a particular element or component in a composition or article, denotes the weight relationship between the element or component and any other elements or components in the composition or article for which a part by weight is expressed. Thus, in a compound containing 2 parts by weight of component X and 5 parts by weight component Y, X and Y are present at a weight ratio of 2:5, and are present in such ratio regardless of whether additional components are contained in the compound.

[00113] A weight percent of a component, unless specifically stated to the contrary, is based on the total weight of the formulation or composition in which the component is included. As used herein the terms "weight percent," "wt%," and "wt. %," which can be used interchangeably, indicate the percent by weight of a given component based on the total weight of the composition, unless otherwise specified. That is, unless otherwise specified, all wt% values are based on the total weight of the composition. It should be understood that the sum of wt% values for all components in a disclosed composition or formulation are equal to 100.

[00114] Unless otherwise stated to the contrary herein, all test standards are the most recent standard in effect at the time of filing this application. Each of the materials disclosed herein are either commercially available and/or the methods for the production thereof are known to those of skill in the art. It is understood that the compositions disclosed herein have certain functions. Disclosed herein are certain structural requirements for performing the disclosed functions and it is understood that there are a variety of structures that can perform the same function that are related to the disclosed structures, and that these structures will typically achieve the same result.

[00115] Throughout this document, values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of "about 0.1% to about 5%" or "about 0.1% to 5%" should be interpreted to include not just about 0.1% to about 5%, but also the individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. The statement "about X to Y" has the same meaning as "about X to about Y," unless indicated otherwise. Likewise, the statement "about X, Y, or about Z" has the same meaning as "about X, about Y, or about Z," unless indicated otherwise. The term "about" as used herein can allow for a degree of variability in a value or range, for example, within 10%, within 5%, or within 1% of a stated value or of a stated limit of a range, and includes the exact stated value or range. The term "substantially" as used herein refers to a majority of, or mostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%. While "about" permits some tolerance, a person of ordinary skill in the art would read the specification in light of his knowledge and skill for guidance on the level of that tolerance, and be reasonably apprised to a reasonable degree the metes and bounds of the claims.

[00116] In this document, the terms "a," "an," or "the" are used to include one or more than one unless the context clearly dictates otherwise. The term "or" is used to refer to a nonexclusive "or" unless otherwise indicated. The statement "at least one of A and B" has the same meaning as "A, B, or A and B." In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting; information that is relevant to a section heading may occur within or outside of that particular section.

[00117] In the methods described herein, the acts can be carried out in any order without departing from the principles of the invention, except when a temporal or operational sequence is explicitly recited. Furthermore, specified acts can be carried out concurrently unless explicit claim language recites that they be carried out separately. For example, a claimed act of doing X and a claimed act of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process. [00118] As used herein, "quantum dots" or "QDs" (or QD, singular) refers to semiconductor nanometer structures that confine conduction band electrons, valence band holes and excitons in three spatial directions. This confinement can be attributed to the factors: electrostatic potential (generated by external electrodes, doping, stress or impurity), interface between two different semiconductor materials (for example in self-assembling quantum dots), semiconductor surface (such as semiconductor nanocrystal) or a combination of the above. QD's have a discrete quantized energy spectrum, and the corresponding wave function is located in the quantum dot in space, but extends across several crystal lattice periods. One quantum dot has a small amount of electrons (e.g., from about 1 to about 100), holes or hole-electron pairs, that is, the quantity of electricity it carries is an integral multiple of element of electric-charges. Since electrons and holes are quantumly confined, the continuous energy band structure is transformed into a discrete energy level structure with molecular characteristics, which can emit fluorescence after being stimulated.

[00119] The term "radiation" as used herein refers to energetic particles travelling through a medium or space. Examples of radiation are visible light, infrared light, microwaves, radio waves, very low frequency waves, extremely low frequency waves, thermal radiation (heat), and black-body radiation. The term "UV light" as used herein refers to ultraviolet light, which is electromagnetic radiation with a wavelength of about 10 nm to about 400 nm.

[00120] The term "surface" as used herein refers to a boundary or side of an object, wherein the boundary or side can have any perimeter shape and can have any three- dimensional shape, including flat, curved, or angular, wherein the boundary or side can be continuous or discontinuous. While the term surface generally refers to the outermost boundary of an object with no implied depth, when the term 'pores' is used in reference to a surface, it refers to both the surface opening and the depth to which the pores extend beneath the surface into the substrate.

[00121] As used herein, the term "polymer" refers to a molecule having at least one repeating unit and can include copolymers and homopolymers. The polymers described herein can terminate in any suitable way. In some embodiments, the polymers can terminate with an end group that is independently chosen from a suitable polymerization initiator, -H, - OH, a substituted or unsubstituted (Cl-C20)hydrocarbyl (e.g., (Cl-ClO)alkyl or (C6- C20)aryl) interrupted with 0, 1, 2, or 3 groups independently selected from -0-, substituted or unsubstituted -NH-, and -S-, a poly(substituted or unsubstituted (Cl-C20)hydrocarbyloxy), and a poly (substituted or unsubstituted (Cl-C20)hydrocarbylamino).

[00122] Although embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the embodiments as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the above disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein can be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims

1. An apparatus comprising:

one or more stabilized quantum dots disposed in a first thin film layer and configured to emit light; and

a triboelectric energy harvester disposed in a second thin film layer and electrically coupled, via an electrical interconnect, to the one or more stabilized quantum dots, wherein the triboelectric energy harvester is configured to supply a voltage directly, via the electrical interconnect, from the triboelectric energy harvester to the one or more stabilized quantum dots to cause emission of the light by the one or more stabilized quantum dots in response to a contact event,

wherein the first thin film layer and the second thin film layer are disposed adjacent a substrate, and wherein the substrate is integrated into a flexible wearable device.

2. The apparatus of claim 1, wherein the triboelectric energy harvester being configured to supply the voltage directly, via the electrical interconnect, from the triboelectric energy harvester to the one or more stabilized quantum dots in response to the contact event comprises the triboelectric energy harvester being electrically coupled to the one or more stabilized quantum dots without an energy storage component.

3. The apparatus of claim 1, wherein the triboelectric energy harvester comprises at least one of polyvinylidene difluoride (PVDF), a copolymer of PVDF, polydimethylsiloxane (PDMS), poly(methyl methacrylate) (PMMA), Teflon, Polymer foam, poly(methyl methacrylate)-co-poly( 1H- lH-perfluoroctyl methacrylate), Parylene, a fluorinated polymer, and an electronegative polymer.

4. The apparatus of claim 1, wherein the one or more stabilized quantum dots comprise a first portion of stabilized quantum dots configured to emit light in a first wavelength range, a second portion of stabilized quantum dots configured to emit light in a second wavelength range, and a third portion of stabilized quantum dots configured to emit light in a third wavelength range.

5. The apparatus of claim 1, further comprising an anode thin film layer and a cathode thin film layer in a material stack with the first thin film layer, and wherein the anode thin film layer and the cathode thin film layer are coupled to the triboelectric energy harvester and to the one or more stabilized quantum dots.

6. The apparatus of claim 5, further comprising: a hole transport thin film layer coupled to the anode thin film layer; and an electron transport thin film layer coupled to the cathode thin film layer, wherein the hole transport thin film layer and the electron transport thin film layer are in the material stack with the first thin film layer.

7. The apparatus of claim 1, further comprising a sensor configured to generate a signal based on detection of the light emitted from the one or more stabilized quantum dots as reflected from a wearer of the apparatus and a processor configured to determine, based on the signal, a health metric associated with a blood flow of the wearer.

8. An apparatus comprising:

one or more stabilized quantum dots disposed in a first thin film layer and configured to emit light;

a triboelectric energy harvester disposed in a second thin film layer and electrically coupled, via an electrical interconnect, to the one or more stabilized quantum dots, wherein the triboelectric energy harvester is configured to supply a voltage directly, via the electrical interconnect, from the triboelectric energy harvester to the one or more stabilized quantum dots to cause emission of the light by the one or more stabilized quantum dots in response to a contact event; and

a photodiode disposed on a third thin film layer and configured to generate a signal in response to detecting the emission of the light by the one or more stabilized quantum dots as reflected from a wearer of the apparatus,

wherein the first thin film layer and the second thin film layer are disposed on a substrate, and wherein the substrate is integrated into a flexible wearable device.

9. The apparatus of claim 8, wherein the third thin film layer is disposed on the substrate.

10. The apparatus of claim 8, wherein the first thin film layer is disposed on a different part of the substrate than the second thin film layer.

11. The apparatus of claim 8, wherein the triboelectric energy harvester being configured to supply the voltage directly, via the electrical interconnect, from the triboelectric energy harvester to the one or more stabilized quantum dots in response to the contact event comprises the triboelectric energy harvester being electrically coupled to the one or more stabilized quantum dots without an energy storage component.

12. The apparatus of claim 8, wherein the triboelectric energy harvester comprises at least one of polyvinylidene difluoride (PVDF), a copolymer of PVDF, polydimethylsiloxane (PDMS), poly(methyl methacrylate) (PMMA), Teflon, Polymer foam, poly(methyl methacrylate)-co-poly( 1H- lH-perfluoroctyl methacrylate), Parylene, a fluorinated polymer, and an electronegative polymer.

13. The apparatus of claim 8, wherein the one or more stabilized quantum dots comprise a first portion of stabilized quantum dots configured to emit light in a first wavelength range, a second portion of stabilized quantum dots configured to emit light in a second wavelength range, and a third portion of stabilized quantum dots configured to emit light in a third wavelength range.

14. The apparatus of claim 8, wherein the one or more stabilized quantum dots are one or more of air stabilized or heat stabilized.

15. A wearable health device comprising:

a flexible body configured to conform to a wearer;

a triboelectric energy harvester disposed in a second thin film layer and electrically coupled, via an electrical interconnect, to the one or more stabilized quantum dots, wherein the triboelectric energy harvester is configured to supply a voltage directly, via the electrical interconnect, from the triboelectric energy harvester to the one or more stabilized quantum dots to cause emission of the light by the one or more stabilized quantum dots in response to a contact event, wherein the first thin film layer and the second thin film layer are disposed adjacent a single substrate configured to flex with the flexible body;

a photodiode disposed on a third thin film and configured to generate a signal in response to detecting emission of the light by the one or more stabilized quantum dots as reflected from the wearer; and

a processor in communication with the photodiode and configured to determine a health metric based on the signal.

16. The wearable health device of claim 15, wherein the health metric comprises one or more of a heart rate, a blood oxygen level, or a heart condition.

17. The wearable health device of claim 15, wherein the processor is configured to determine an additional health metric, and wherein the processor is configured to optimize usage of portions of the one or more stabilized quantum dots for determining the additional health metric.

18. The wearable health device of claim 17, wherein the processor is configured to determine an optimal wavelength range associated with the additional health metric, and wherein the processor being configured to optimize the usage of portions of the one or more stabilized quantum dots for determining the additional health metric comprises the processor being configured for one or more of enabling or disabling a portion of the one or more stabilized quantum dots based on the optimal wavelength range.

19. The wearable health device of claim 15, wherein the triboelectric energy harvester being configured to supply the voltage directly, via the electrical interconnect, from the triboelectric energy harvester to the one or more stabilized quantum dots in response to the contact event comprises the triboelectric energy harvester being electrically coupled to the one or more stabilized quantum dots without an energy storage component.

20. The wearable health device of claim 15, wherein the one or more stabilized quantum dots comprise a first portion of stabilized quantum dots configured to emit light in a first wavelength range, a second portion of stabilized quantum dots configured to emit light in a second wavelength range, and a third portion of stabilized quantum dots configured to emit light in a third wavelength range.