JP4712366B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light emitting device, and more particularly to a light emitting device capable of displaying an image composed of multiple colors by combining light emission of different colors.

  A light-emitting device using light emission from an electroluminescence element (light-emitting element) is a device that has attracted attention as a display device with a high viewing angle and low power consumption.

  In recent years, in the field of light-emitting device development, research and development of light-emitting devices that can provide high-quality full-color images has been active in order to obtain a market for display devices in various information processing equipment such as TV receivers and car navigation systems. Has been done.

  In order to display a full-color image, areas that emit light of the three primary colors of red (R), green (G), and blue (B) are provided independently, and are displayed by changing the light emission time and light emission luminance in each area. You must control the brightness and chromaticity of the color.

  As a method of changing the brightness and chromaticity, there are a method of changing by changing the light emission time of the light emitting element and a method of changing by changing the luminance of the light emitting element. In the case of using the former method, lightness and chromaticity are changed by variously combining red, green, and blue light emission by changing the light emission time for each light emission color.

  By the way, the luminous efficiency of the light emitting element varies depending on the characteristics of the light emitter and other substances contained in the light emitting element. In one light-emitting device, the light-emitting efficiency is different for each light-emitting element exhibiting each emission color. For this reason, the current required for obtaining light emission with a desired luminance is relatively higher in a light emitting element having a lower light emission efficiency.

  Furthermore, the human eye has different sensitivities for each emission wavelength, and generally has a higher sensitivity to the green emission wavelength than the red and blue emission wavelengths. Therefore, in order to emit blue and red light so that the human eye has the same sensitivity as green, it is necessary to make the luminance of blue and red relatively higher than the luminance of green.

  When a large amount of current is supplied to the light emitting element in order to increase the luminance of the light emitting element, the deterioration of the light emitting element is promoted and the power consumption of the display device is increased. In addition, when the emission wavelength is shifted due to the deterioration of the light emitting element, the color reproducibility of the light emitting device is lowered, and the image quality may be lowered. For this reason, development of a light-emitting body or light-emitting element that can emit light efficiently and has a long lifetime has been attempted. For example, in patent document 1, the device which raises luminous efficiency is adjusted by adjusting the optical path length.

Japanese Patent Laid-Open No. 2002-299062

  It is an object of the present invention to provide a light emitting device that can reduce a burden on a light emitting element with low light emission efficiency and suppress deterioration of the light emitting element, a decrease in color reproducibility accompanying the deterioration, and an increase in power consumption. To do.

  The light-emitting device of the present invention has a light-emitting element that emits each color corresponding to the three primary colors of light, and further has a light-emitting element that emits an intermediate color. The light emitting device of the present invention has a configuration in which a plurality of pixels each having a set of a light emitting element that emits each color corresponding to the three primary colors of light and a light emitting element that emits an intermediate color are arranged.

  In each pixel, a plurality of colors having different brightness and chromaticity are displayed by changing the light emission time or luminance of light emitted from each light emitting element included in the pixel and combining them. Note that at least one light-emitting element that emits an intermediate color may be included in one pixel.

  The three primary colors of light are the three colors red, green, and blue. Here, red means a color having coordinates in a region where x is 0.6 or more and y is 0.35 or less in the chromaticity diagram when expressed in the CIE-XYZ color system. Green is a color having coordinates in a region where x is 0.3 or less and y is 0.6 or more in the chromaticity diagram when expressed in the CIE-XYZ color system. Blue refers to a color having coordinates in a region where x in the chromaticity diagram is 0.15 or less and y is 0.2 or less when expressed in the CIE-XYZ color system. The CIE-XYZ color system is a color system based on tristimulus values X, Y, and Z. The chromaticity diagram represents colors in x, y coordinate space based on tristimulus values X, Y, Z. Note that chromaticity is a quantitative definition of the type of light color excluding lightness.

  Further, the intermediate color refers to a color having coordinates in a region different from the above-described regions representing red, green, and blue in the chromaticity diagram when expressed using the CIE-XYZ color system.

  A light-emitting element that emits an intermediate color plays an auxiliary role for a light-emitting element with a low light-emission efficiency when a light-emitting element with a high light-emission efficiency and a light-emitting element with a low light-emission efficiency are combined to display an intermediate color . Therefore, in a light-emitting element with low light emission efficiency, the luminance necessary for display can be lowered compared to the case where intermediate colors are displayed by combining the three primary colors, and the burden on light emission is reduced. For this reason, the lifetime of a light emitting element with particularly low luminous efficiency can be extended, and deterioration of the light emitting element and degradation of image quality resulting therefrom can be suppressed. Further, by providing a light emitting element that emits an intermediate color, displayable colors are increased and a color reproduction range in the light emitting device is expanded.

  According to the present invention, it is possible to suppress deterioration of a light emitting element and deterioration of image quality due to lightening by reducing a burden on a light emitting element having low light emission efficiency or a light emitting element exhibiting a light emitting color with low sensitivity to human eyes. it can. In addition, it is possible to obtain a light emitting device in which displayable colors are increased and the color reproduction range is widened.

  One mode of the light-emitting device of the present invention will be described with reference to FIGS. FIG. 14 is a chromaticity diagram showing colors in the x and y coordinate spaces based on the tristimulus values X, Y, and Z.

  The light-emitting device of the present invention includes a first light-emitting element 101 that emits red light, a second light-emitting element 102 that emits green light, a third light-emitting element 103 that emits blue light, and a bluish tinge And a fourth light-emitting element 104 that emits green light. Note that the emission color of the fourth light emitting element is not limited to the above, and may be, for example, reddish purple or yellow orange.

  Here, red is a region where x in the chromaticity diagram is 0.6 or more and y is 0.35 or less when expressed in the CIE-XYZ color system (in FIG. 14, the periphery of the chromaticity diagram and the dotted line 151). And an area surrounded by a dotted line 152). Further, when the green color is expressed in the CIE-XYZ color system, x in the chromaticity diagram is 0.3 or less and y is 0.6 or more (in FIG. 14, the periphery of the chromaticity diagram and the dotted line 155 A color having coordinates in a region surrounded by a dotted line 156. When blue represents the CIE-XYZ color system, an area in which chromaticity diagram x is 0.15 or less and y is 0.2 or less (in FIG. 14, the periphery of chromaticity diagram, dotted line 153 and dotted line 154 A color having coordinates in an area surrounded by. Further, when the intermediate color between green and blue is expressed in the CIE-XYZ color system, x is 0.1 or less and y is 0.25 or more and 0.5 or less in the chromaticity diagram (in FIG. Color having coordinates in the periphery of the degree diagram and the area surrounded by dotted lines 161, 162 and 163, preferably color having coordinates in the area where x is 0.1 or less and y is 0.35 or more and 0.45 or less Say.

  As illustrated in FIG. 1, in the light-emitting device of the present invention, a plurality of pixels each including a first light-emitting element 101, a second light-emitting element 102, a third light-emitting element 103, and a fourth light-emitting element 104 are combined. 110 are arranged.

  In FIG. 1, each of the first light emitting element 101 to the fourth light emitting element 104 is arranged side by side in the row direction. However, there is no particular limitation on the arrangement method, and for example, they are arranged in the column direction. Alternatively, the light emitting element that emits red light and the light emitting element that emits blue light may be adjacent to each other. Also, the shape of each light emitting element is not limited to a rectangle as shown in FIG. 1, but may be a square, other polygons, or a shape having a curvature, for example.

  Further, as shown in FIG. 2, circuits for driving each of the first light emitting element 101 to the fourth light emitting element 104 are connected.

  A circuit connected to each light emitting element includes a driving transistor 121 that determines light emission / non-light emission of the light emitting element according to a video signal, a switching transistor 122 that controls input of the video signal, and the video signal. Regardless, it is composed of an erasing transistor 123 that brings the light emitting element into a non-light emitting state, a source signal line 131, a current supply line 132, a first scanning line 133, and a second scanning line 134.

  Here, a driving method when the second light emitting element 102 emits light will be described. When the first scan line 133 is selected in the writing period, the switching transistor 122 whose gate is connected to the first scan line 133 is turned on. Then, when the video signal input to the source signal line 131 is input to the gate of the driving transistor 121 through the switching transistor 122, a current flows from the current supply line 132 to the second light emitting element 102, and the green signal Emits light. At this time, luminance of light emission is determined by the magnitude of current flowing to the second light emitting element 102.

  Similarly to the second light-emitting element 102, the first light-emitting element 101, the third light-emitting element 103, and the fourth light-emitting element 104 are also driven. In this manner, each light emitting element is independently controlled in light emission time by a circuit connected to each light emitting element, and a desired display color is obtained. Here, the display color refers to a color visually mixed by combining light emission obtained from a plurality of light emitting elements included in one pixel and having different light emission colors.

  Note that the driving method is not limited to that shown in this embodiment, and a digital driving method other than the above may be used. Further, an analog driving method may be used.

  The element structure of each transistor is not particularly limited, and may be a staggered type or an inverted staggered type. Further, a single gate structure or a multi-gate structure may be used. Further, an LDD (Lightly Doped Drain) structure or a single drain structure may be used.

  In the light emitting device of the present invention described above, the fourth light emitting element 104 that emits bluish green, that is, an intermediate color emits light from each light emitting element when displaying the intermediate color, for example, In the case where the light emitting efficiency of the second light emitting element 102 and the third light emitting element 103 are different from each other, it plays an auxiliary role for the light emitting element having the lower light emitting efficiency. Therefore, as compared with the case where intermediate colors are displayed by combining only the three primary colors, the burden on the element having low light emission efficiency is reduced, and the life of the element can be extended. Therefore, a light-emitting device in which display defects due to element deterioration are suppressed can be obtained. In addition, by providing the fourth light-emitting element 104, displayable colors increase, and the color reproduction range in the light-emitting device is expanded.

  Furthermore, when the fourth light-emitting element 104 emits bluish green as in this embodiment, the following effects also occur. Since human eyes usually have high sensitivity to green, for example, in order to make green and blue have the same sensitivity, it is necessary to increase the luminance of blue rather than green. That is, in the display operation, the burden on the third light emitting element 103 that emits blue light is relatively greater than that of the second light emitting element 102 that emits green light. However, like the light emitting device of the present invention, by providing the fourth light emitting element 104 that emits bluish green, the fourth light emitting element 104 plays an auxiliary role with respect to the third light emitting element 103. In addition, the burden on the third light-emitting element 103 can be reduced.

  As described above, by reducing the burden on light emitting elements with low light emission efficiency or light emitting elements with low light emission sensitivity to human eyes, it is possible to suppress deterioration of the light emitting elements and image quality deterioration caused thereby. it can.

  In this example, a light-emitting device of the present invention will be described. However, the light-emitting device of the present invention is not limited to that shown in this embodiment.

  FIG. 3 is a schematic view of a light emitting device to which the present invention is applied as viewed from above. In FIG. 3, 6510 indicated by a dotted line is a driver circuit portion (source side driver circuit), 6511 is a pixel portion, and 6512 is a driver circuit portion (gate side driver circuit). The pixel portion 6511 is provided with the light-emitting element of the present invention. The driver circuit portions 6510 and 6512 are connected to an FPC 6503 that is an external input terminal through a wiring group formed on the substrate 6500. When a video signal, a clock signal, a start signal, a reset signal, or the like is received from an FPC (flexible printed circuit) 6503, signals are input to the driver circuit portion 6510 and the driver circuit portion 6512. A printed wiring board (PWB) 6513 is attached to the FPC 6503. The driver circuit portion 6510 is provided with a shift register 6515, a switch 6516, and memories (latch) 6517 and 6518, and the driver circuit portion 6512 is provided with a shift register 6519 and a buffer 6520.

  Note that the driver circuit portion is not necessarily provided over the same substrate as the pixel portion 6511 as described above. For example, an IC chip mounted on an FPC on which a wiring pattern is formed (TCP) or the like is used. It may be used and provided outside the substrate. Further, the circuit configurations of the driver circuit portions 6510 and 6512 are not limited to those described above, and a configuration in which a circuit having a function different from the above is further provided may be used.

  In the pixel portion 6511, a plurality of source signal lines 331 and a plurality of current supply lines 332 extending in the column direction are arranged side by side in the row direction. A plurality of first scanning lines 333 and a plurality of second scanning lines 334 extending in the row direction are arranged side by side in the column direction. In addition, a plurality of pixels 301 each including the first light-emitting element 301a, the second light-emitting element 301b, the third light-emitting element 301c, and the fourth light-emitting element 301d are arranged in a matrix.

  Further, in the pixel 310, the first light-emitting element 301a, the second light-emitting element 301b, the third light-emitting element 301c, and the fourth light-emitting element 301d are similar to the light-emitting device illustrated in FIG. They are arranged side by side in the row direction.

  Each light emitting element has a structure in which a light emitting layer including a light emitter is sandwiched between a pair of electrodes. The light emitting layer may be a single layer composed of only a layer containing a light emitter, or a layer containing a light emitter and a substance or carrier injection property having excellent carrier (electron / hole) transportability. It may be a multi-layered structure composed of a plurality of layers combined with a layer containing a substance excellent in the above.

  The first light-emitting element 301a includes 4-dicyanomethylene-2-methyl-6- (1,1,7,7-tetramethyljulolidyl-9-enyl) -4H-pyran (abbreviation: DCJT) as a light emitter. The second light emitting element 301b emits green light including N, N′-dimethylquinacridone (abbreviation: DMQd) as a light emitter, and the third light emitting element 301c. , Which emits blue light including 9,9′-bianthryl as a light emitter, and the fourth light emitting element 301d emits bluish green light including coumarin 30 as a light emitter. Note that the light emitters included in each light emitting element are not limited to those described above, and other light emitters may be used. For example, as a light-emitting material that emits red light, 4-dicyanomethylene-2-t-butyl-6- (1,1,7,7-tetramethyljulolidyl-9-enyl) -4H-pyran (abbreviation: DPA), perifuranthene, 2,5-dicyano-1,4-bis (10-methoxy-1,1,7,7-tetramethyljulolidyl-9-enyl) benzene, etc. Are 9,10-diphenylanthracene (abbreviation: DPA) and 9,10-bis (2-naphthyl) as luminescent substances emitting blue, such as coumarin 6, coumarin 545T, and tris (8-quinolinolato) aluminum (abbreviation: Alq). ) Bis (2-methyl-8-quinolinolato) -4-phenylphenolato-aluminum (emitters emitting blue-green, such as anthracene (abbreviation: DNA)) Abbreviations: BAlq), bis (2-methyl-8-quinolinolato) -4-phenylphenolato-gallium (abbreviation: BGaq), and the like can be used.

  As shown in FIG. 4, a circuit for driving each light emitting element is connected to the first light emitting element 301a to the fourth light emitting element 301d. Each of the circuits includes a driving transistor 321 (321a, 321b, 321c, 321d) that determines light emission / non-light emission of each of the first light-emitting element 301a to the fourth light-emitting element 301d according to the video signal, and the video signal. Switching transistors 322 (322a, 322b, 322c, 322d) for controlling the input of each of the first light emitting element 301a to the fourth light emitting element 301d in a non-light emitting state regardless of the video signal 323 (323a, 323b, 323c, 323d). Here, the source (or drain) of the switching transistor 322 is connected to the source signal line 331, and the source of the driving transistor 321 and the source of the erasing transistor 323 are source signal lines 331 (331a, 331b, 331c, 331d). It is connected to a current supply line 332 (332a, 332b, 332c, 332d) extending in parallel, and the gate of the switching transistor 322 is connected to the first scanning line 333 and extends in parallel with the first scanning line 333. The gate of the erasing transistor 323 is connected to the second scanning line 334. The driving transistor 321 (321a, 321b, 321c, 321d) and each of the first light-emitting element 301a to the fourth light-emitting element 301d are connected in series. The configuration of the circuit connected to each light emitting element is not limited to that described here, and may be different from the above configuration.

  FIG. 5 is a top view of the pixel portion 6511 of the light emitting device of this embodiment. In FIG. 5, only a part of the pixel portion 6511 is illustrated. Note that the configuration of the pixel portion of the light-emitting device is not limited to that illustrated in FIG. 5, and may have other configurations. In FIG. 5, reference numeral 81 denotes a semiconductor layer, and 82 denotes a gate (gate electrode) of a driving transistor 321, a switching transistor 322, an erasing transistor 323, a first scanning line 333, a second scanning line 334, and the like. A conductive film 83 is a conductive film that functions as the source signal line 331, the current supply line 332, and the like. Reference numeral 84 denotes a portion having a laminated structure in which a light emitting layer is sandwiched between a pair of electrodes.

  Hereinafter, the operation of the light emitting device of this embodiment will be described with reference to FIG. FIG. 6 is a diagram for explaining the operation of the frame over time. In FIG. 6, the horizontal direction represents the time passage, and the vertical direction represents the scanning direction of the scanning line.

In the light emitting device of this embodiment, one frame includes four subframes 501, 502, 503 including a writing period 501a, 502a, 503a, 504a and a holding period 501b, 502b, 503b, 504b as shown in FIG. 504 is time-divided. A light emitting element to which a signal for emitting light is given is in a light emitting state in the holding period. The ratio of the length of the retention period in each subframe is as follows: first subframe 501: second subframe 502: third subframe 503: fourth subframe 504 = 2 ³ : 2 ² : 2 ¹ : 2 ⁰ = 8: 4: 2: 1. As a result, 4-bit gradation can be expressed. However, the number of bits and the number of gradations are not limited to those described here. For example, eight subframes may be provided so that 8-bit gradation can be performed.

  An operation in one frame will be described. First, in the subframe 501, the write operation is performed in order from the first row to the last row. Therefore, the start time of the writing period differs depending on the row. From the row in which the writing period 501a ends, the storage period 501b is started in order. In the holding period, the light-emitting element to which a signal for emitting light is given is in a light-emitting state. Further, the processing proceeds to the next subframe 502 in order from the row in which the holding period 501b ends, and the writing operation is performed in order from the first row to the last row as in the case of the subframe 501. The operation as described above is repeated until the holding period 504b of the subframe 504 ends. When the operation in the subframe 504 is completed, the operation in the next frame is started. Thus, the accumulated time of the light emission in each subframe is the light emission time of each light emitting element in one frame. Various display colors having different brightness and chromaticity can be formed by changing the light emission time for each light emitting element and combining them in various ways within one pixel.

  Note that in the subframe 504 whose holding period is shorter than the writing periods 501c, 502c, and 503c including the writing period from the writing period of the first row to the last row, an erasing period 504d is provided after the holding period 504b to forcibly It is controlled so as to be in a non-light emitting state. This prevents the writing period of the subframe 504 and the writing period of the next subframe from overlapping.

  In this embodiment, the subframes 501 to 504 are arranged in order from the longest holding period. However, the subframes 501 to 504 are not necessarily arranged as in this embodiment, and are arranged in order from the shortest holding period, for example. Alternatively, the long holding period and the short holding period may be arranged at random.

  Next, circuit operation in the writing period will be described. In the writing period, the first scanning line 333 in the n-th row (n is a natural number) is selected, and the switching transistor 322 connected to the first scanning line 333 is turned on. At this time, video signals are simultaneously input to the source signal lines from the first column to the last column. However, the video signals input from the source signal lines 331 in each column are independent from each other. The video signals input simultaneously from the source signal line 331 are input to the gate of the driving transistor 321 through the switching transistor 322 connected to each source signal line. At this time, light emission / non-light emission of each of the first light-emitting element 301 a to the fourth light-emitting element 301 d is determined in accordance with a signal input to the driving transistor 321.

  As writing to the source signal line ends, the writing period in the n-th row (n is a natural number) ends and the holding period starts. Next, the (n + 1) th row is a writing period, and a writing operation similar to the above is performed. The writing operation is performed from the first row to the last row by repeating the above operation.

  A light-emitting device to which the present invention having the above-described structure is applied can reduce deterioration of the light-emitting element by reducing a burden on a light-emitting element with low light emission efficiency or a light-emitting element with low emission sensitivity to human eyes. The deterioration of image quality due to this is suppressed. In addition, the displayable colors are increased and the color reproduction range is expanded.

  In this embodiment, a light-emitting device in which the arrangement of light-emitting elements in one pixel is different from that shown in FIG. 1 will be described.

  As shown in FIG. 7, the light-emitting device of this embodiment includes a first light-emitting element 701 that emits red light, a second light-emitting element 702 that emits green light, and a third light-emitting element that emits blue light. An element 703 and a fourth light-emitting element 704 that emits bluish green light are included.

  In the light emitting device of this embodiment, a plurality of pixels 705 are arranged in which a set of four first light emitting elements 701 to 704 arranged side by side in the row direction and the column direction. . In other words, each of the first light-emitting element 701 to the fourth light-emitting element 704 has four light-emitting elements, which are arranged in two rows in the row direction and in the column direction. The pixel 705 includes four light emitting elements, that is, a first light emitting element 701 to a fourth light emitting element 704. A plurality of pixels 705 are arranged.

  In the light-emitting device of this embodiment, the same light-emitting color as in the first light-emitting element 701, the first light-emitting element 707, the first light-emitting element 708, and the first light-emitting element 709 surrounded by a dotted line 706 is used. The four light-emitting elements are provided as a set, and the four light-emitting elements are arranged in groups of two in the row direction and in the column direction. Note that the group is provided for each light emitting element that emits each light emission color (that is, each light emitting element that emits light of the same color), and a light emitting element that emits red light like the first light emitting element 701 is provided. A first group including four, a second group including four light emitting elements that emit green light such as the second light emitting element 702, and light emission that emits blue light such as the third light emitting element 703 A fifth group 720 includes a third group including four elements and a fourth group including four light emitting elements that emit blue-green light such as the fourth light emitting element 704. The first to fourth groups are arranged in groups of two in the row direction and the column direction. And a certain light emitting element included in the first group, a certain light emitting element included in the second group, a certain light emitting element included in the third group, and a fourth One pixel is formed by combining a certain light emitting element included in the group.

  Note that the width between light emitting elements included in one group is configured to be narrower than the width between adjacent light emitting elements included in different groups.

  In other words, in the light emitting device of this embodiment, the light emission colors are the same and the width between adjacent light emitting elements is different so that the light emission color is different and the width between adjacent light emitting elements is narrower. Elements are arranged.

  When forming a light emitting layer by a vapor deposition method, the light emitting layer corresponding to the light emitting element which exhibits each luminescent color is created separately by using metal masks. At this time, in order to prevent the light emitting layers of the light emitting elements exhibiting different light emission colors from wrapping around each other from the edge of the mask, the width between the elements of the light emitting elements adjacent to each other that exhibit different light emission colors is 20 to The thickness is about 30 μm.

  However, by using the light emitting device having the structure as shown in FIG. 7, it is not necessary to consider the prevention of color mixing between adjacent light emitting elements that exhibit the same light emission color. The width between elements can be made narrower than adjacent light emitting elements. Therefore, the light emission area (area of the electrode surface from which light emission can be extracted) of each light emitting element can be increased, and as a result, the light emission efficiency, particularly the light emission extraction efficiency can be increased.

  Note that the pixel shown in FIG. 7 has a square shape, but is not limited thereto, and may be a circular shape or the like. In particular, in the case of a circular shape, it is possible to obtain an effect that the deterioration of the light emitting element is difficult to proceed.

  A light-emitting device to which the present invention having the above-described structure is applied can reduce deterioration of the light-emitting element by reducing a burden on a light-emitting element with low light emission efficiency or a light-emitting element with low emission sensitivity to human eyes. The deterioration of image quality due to this is suppressed. In addition, the displayable colors are increased and the color reproduction range of the light emitting device is expanded.

  In this example, a cross-sectional structure of a light-emitting device to which the present invention is applied will be described. However, the structure of the light-emitting device of the present invention and the substances constituting the light-emitting device are not limited to those shown in this embodiment.

  In FIG. 8, a transistor 11 provided for driving the light emitting element 12 is surrounded by a dotted line. Note that the light-emitting element 12 corresponds to any of the first light-emitting element 301a to the fourth light-emitting element 301d shown in Embodiment 1, and the transistor 11 is the driving transistor 321a to the driving transistor 321d shown in Embodiment 1. It corresponds to either one. The light emitting element 12 includes a first electrode 13, a second electrode 14, and a light emitting layer 15 sandwiched between these electrodes. The drain of the transistor 11 and the first electrode 13 are electrically connected by a wiring 17 penetrating the first interlayer insulating film 16 (16a, 16b, 16c). The light emitting element 12 is separated from another light emitting element provided adjacent thereto by a partition wall layer 18. The light emitting device of the present invention having such a configuration is provided on the substrate 10 in this embodiment.

In the light-emitting element 12, the light-emitting layer 15 includes a mixed layer in which a light emitter and a substance having excellent carrier transportability are combined, a layer made of a substance having excellent carrier (electron / hole) transportability, and excellent carrier injectability. A plurality of layers formed by laminating layers made of different materials. The light emission color of the light emitting element 12 is determined by the light emitter included in the light emitting layer 15. In addition, the combination of the substances which comprise the light emitting layer 15 may differ for every light emitting element. Note that any of the light emitters described in the embodiment modes may be used. In addition, among substances having excellent carrier transportability, substances having particularly excellent electron transportability include, for example, tris (8-quinolinolato) aluminum (abbreviation: Alq ₃ ), tris (5-methyl-8-quinolinolato) aluminum ( Abbreviations: Almq ₃ ), bis (10-hydroxybenzo [h] -quinolinato) beryllium (abbreviation: BeBq ₂ ), bis (2-methyl-8-quinolinolato) -4-phenylphenolato-aluminum (abbreviation: BAlq), etc. And metal complexes having a quinoline skeleton or a benzoquinoline skeleton. Examples of the substance having excellent hole transportability include 4,4′-bis [N- (1-naphthyl) -N-phenyl-amino] -biphenyl (abbreviation: α-NPD) and 4,4′-bis. [N- (3-methylphenyl) -N-phenyl-amino] -biphenyl (abbreviation: TPD) or 4,4 ′, 4 ″ -tris (N, N-diphenyl-amino) -triphenylamine (abbreviation: Aromatic amine systems such as TDATA), 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenyl-amino] -triphenylamine (abbreviation: MTDATA) (ie, benzene ring— Compound having a nitrogen bond). Among substances having excellent carrier injecting properties, substances having particularly excellent electron injecting properties include alkali metals such as lithium fluoride (LiF), cesium fluoride (CsF), and calcium fluoride (CaF ₂ ). Alternatively, an alkaline earth metal compound can be given. In addition, a mixture of a substance having a high electron transport property such as Alq ₃ and an alkaline earth metal such as magnesium (Mg) may be used. Examples of the material having a high hole injection property include molybdenum oxide (MoOx), vanadium oxide (VOx), ruthenium oxide (RuOx), tungsten oxide (WOx), and manganese oxide (MnOx). A metal oxide is mentioned. In addition, phthalocyanine compounds such as phthalocyanine (abbreviation: H ₂ Pc) and copper phthalocyanine (CuPC) can be given.

  The transistor 11 is a top gate type. However, the structure of the transistor 11 is not particularly limited, and may be, for example, an inverted staggered type as illustrated in FIG. In the case of an inverted staggered type, a semiconductor film in which a protective film is formed on a semiconductor layer for forming a channel (channel protective type) as shown in FIG. 9B may be used, or a semiconductor layer for forming a channel may be used. A part of which is concave (channel etch type) may be used. Note that 21 is a gate electrode, 22 is a gate insulating film, 23 is a semiconductor layer, 24 is an n-type semiconductor layer, 25 is an electrode, and 26 is a protective film.

  Further, the semiconductor layer included in the transistor 11 may be either crystalline or non-crystalline. Moreover, a semi-amorphous etc. may be sufficient.

The semi-amorphous semiconductor is as follows. A semiconductor having an intermediate structure between amorphous and crystalline (including single crystal and polycrystal) and having a third state that is stable in terms of free energy, has a short-range order, and has a lattice distortion. It contains a crystalline region. Further, at least a part of the region in the film contains crystal grains of 0.5 to 20 nm. The Raman spectrum is shifted to the lower wavenumber side than 520 cm ⁻¹ . In X-ray diffraction, diffraction peaks of (111) and (220) that are derived from the Si crystal lattice are observed. At least 1 atomic% or more of hydrogen or halogen is contained as a neutralizing agent for dangling bonds. It is also called a so-called microcrystalline semiconductor (microcrystal semiconductor). A silicide gas is formed by glow discharge decomposition (plasma CVD). As the silicide gas, SiH ₄ , Si ₂ H ₆ , SiH ₂ Cl ₂ , SiHCl ₃ , SiCl ₄ , SiF ₄ or the like can be used. This silicide gas may be diluted with H ₂ , or H ₂ and one or more kinds of rare gas elements selected from He, Ar, Kr, and Ne. The dilution rate is in the range of 2 to 1000 times. The pressure is generally in the range of 0.1 Pa to 133 Pa, and the power supply frequency is 1 MHz to 120 MHz, preferably 13 MHz to 60 MHz. The substrate heating temperature may be 300 ° C. or less, preferably 100 to 250 ° C. As an impurity element in the film, impurities of atmospheric components such as oxygen, nitrogen, and carbon are desirably 1 × 10 ²⁰ atoms / cm ³ or less, and in particular, the oxygen concentration is preferably 5 × 10 ¹⁹ atoms / cm ³ or less. Is 1 × 10 ¹⁹ atoms / cm ³ or less. Note that the mobility of a TFT (thin film transistor) using a semi-amorphous semiconductor is approximately 1 to 10 m ² / Vsec.

  Further, specific examples of the crystalline semiconductor layer include those made of single crystal or polycrystalline silicon, silicon germanium, or the like. These may be formed by laser crystallization, or may be formed by crystallization by a solid phase growth method using nickel or the like, for example.

  Note that in the case where the semiconductor layer is formed of an amorphous material, for example, amorphous silicon, the transistor 11 and other transistors (transistors constituting a circuit for driving a light emitting element) are all configured by N-channel transistors. It is preferable that the light-emitting device have a structured circuit. Other than that, a light-emitting device having a circuit including any one of an N-channel transistor and a P-channel transistor, or a light-emitting device including a circuit including both transistors may be used.

  Further, the first interlayer insulating film 16 may be a multilayer as shown in FIGS. 8A and 8C, or may be a single layer. Note that 16a is made of an inorganic material such as silicon oxide or silicon nitride, and 16b is acrylic or siloxane (a substance having a skeletal structure composed of a bond of silicon (Si) and oxygen (O) and containing at least hydrogen as a substituent). Or a material having self-flatness such as silicon oxide that can be coated and formed. Further, 16c is made of a silicon nitride film containing argon (Ar). In addition, there is no limitation in particular about the substance which comprises each layer, You may use things other than what was described here. Moreover, you may further combine the layer which consists of substances other than these. Thus, the 1st interlayer insulation film 16 may be formed using both an inorganic substance and an organic substance, or may be formed by any one of an inorganic film and an organic film.

  The partition layer 18 preferably has a shape in which the radius of curvature continuously changes at the edge portion. The partition layer 18 is formed using acrylic, siloxane, resist, silicon oxide, or the like. The partition wall layer 18 may be formed of any one of an inorganic film and an organic film, or may be formed using both.

  In FIGS. 8A and 8C, only the first interlayer insulating film 16 is provided between the transistor 11 and the light-emitting element 12, but as shown in FIG. 8B, the first interlayer insulating film 16 is provided. In addition to the insulating film 16 (16a, 16b), the second interlayer insulating film 19 (19a, 19b) may be provided. In the light emitting device shown in FIG. 8B, the first electrode 13 penetrates through the second interlayer insulating film 19 and is connected to the wiring 17.

  Similar to the first interlayer insulating film 16, the second interlayer insulating film 19 may be a multilayer or a single layer. 19a is a substance having self-flatness such as acrylic or siloxane (a substance having a skeletal structure composed of a bond of silicon (Si) and oxygen (O) and having at least hydrogen as a substituent), silicon oxide capable of being coated and formed. Consists of. Further, 19b is made of a silicon nitride film containing argon (Ar). In addition, there is no limitation in particular about the substance which comprises each layer, You may use things other than what was described here. Moreover, you may further combine the layer which consists of substances other than these. As described above, the second interlayer insulating film 19 may be formed using both an inorganic material and an organic material, or may be formed of any one of an inorganic film and an organic film.

  In the light-emitting element 12, when both the first electrode 13 and the second electrode 14 are formed using a light-transmitting material such as indium tin oxide (ITO), white dots in FIG. As shown by the arrow, light emission can be extracted from both the first electrode 13 side and the second electrode 14 side. In addition, in the case where only the second electrode 14 is formed using a light-transmitting substance, light emission is extracted only from the second electrode 14 side as represented by a white arrow in FIG. 8B. be able to. In this case, it is preferable that the first electrode 13 is made of a material having a high reflectivity, or a film (reflective film) made of a material having a high reflectivity is provided below the first electrode 13. In addition, in the case where only the first electrode 13 is formed using a light-transmitting substance, light emission is extracted only from the first electrode 13 side as represented by a white arrow in FIG. 8C. be able to. In this case, it is preferable that the second electrode 14 is made of a highly reflective material, or a reflective film is provided above the second electrode 14.

  The light-emitting element 12 may have a configuration in which the first electrode 13 functions as an anode and the second electrode 14 functions as a cathode, or the first electrode 13 functions as a cathode, and the second The electrode 14 may function as an anode. However, in the former case, the transistor 11 is a P-channel transistor, and in the latter case, the transistor 11 is an N-channel transistor.

  A light-emitting device to which the present invention having the above-described structure is applied can reduce deterioration of the light-emitting element by reducing a burden on a light-emitting element with low light emission efficiency or a light-emitting element with low emission sensitivity to human eyes. The deterioration of image quality due to this is suppressed. In addition, the displayable colors are increased and the color reproduction range is expanded.

  In this example, a light-emitting element having a circuit configuration different from that illustrated in FIG. 4 will be described with reference to FIG.

  As shown in FIG. 10, the light emitting element 801 is connected to a circuit for driving each light emitting element. The circuit includes a driving transistor 824 that determines light emission / non-light emission of the light-emitting element 801 according to a video signal, a switching transistor 822 that controls input of the video signal, and a light-emitting element 801 that does not emit light regardless of the video signal. It has an erasing transistor 823 to be put in a state and a current control transistor 821 for controlling the magnitude of the current supplied to the light emitting element 801. Here, the source (or drain) of the switching transistor 822 is connected to the source signal line 831, and the source of the driving transistor 824 and the source of the erasing transistor 823 are extended in parallel with the source signal line 831. 832, the gate of the switching transistor 822 is connected to the first scanning line 833, and the gate of the erasing transistor 823 extending in parallel with the first scanning line 833 is connected to the second scanning line 834. Yes. Further, a current control transistor 821 is sandwiched between the driving transistor 824 and the light emitting element 801 and connected in series. The gate of the current control transistor 821 is connected to the power supply line 835. Note that the current control transistor 821 is configured and controlled so that a current flows in a saturation region in the voltage-current (Vd-Id) characteristic. Thus, the current value of the current flowing through the current control transistor 821 The size can be determined.

  A driving method when the light-emitting element 801 emits light will be described. When the first scan line 833 is selected in the writing period, the switching transistor 822 whose gate is connected to the first scan line 833 is turned on. Then, the video signal input to the source signal line 831 is input to the gate of the driving transistor 824 through the switching transistor 822. Further, current flows from the current supply line 832 to the light-emitting element 801 through the driving transistor 824 and the current control transistor 821 which is turned on in response to a signal from the power supply line 835, and light emission is performed. At this time, the magnitude of the current flowing to the light emitting element is determined by the current control transistor 821.

  10 illustrates one light-emitting element 801. In the light-emitting device of this embodiment, four light-emitting elements that are operated by the same circuit as that connected to the light-emitting element are the same as in FIG. A plurality of pixels are arranged in a line and arranged as a set. Note that light-emitting elements included in one pixel exhibit different emission colors.

  FIG. 11 is a top view of a pixel portion of a light emitting device having a circuit configuration as shown in this embodiment. In FIG. 11, only a part of the pixel portion is illustrated. Note that the configuration of the pixel portion of the light-emitting device is not limited to that illustrated in FIG. 11, and may have other configurations. In FIG. 11, 91 is a semiconductor layer, and 92 is a gate (gate electrode) for the current control transistor 821, switching transistor 822, erasing transistor 823, driving transistor 824, first scan lines 833 and 834, and the like. A conductive film 93 is a conductive film functioning as a source signal line 831, a current supply line 832, a power supply line 835, and the like. Reference numeral 94 denotes a portion having a laminated structure in which a light emitting layer is sandwiched between a pair of electrodes.

  A light-emitting device to which the present invention having the above-described structure is applied can reduce deterioration of the light-emitting element by reducing a burden on a light-emitting element with low light emission efficiency or a light-emitting element with low emission sensitivity to human eyes. The deterioration of image quality due to this is suppressed. In addition, the displayable colors are increased and the color reproduction range is expanded.

  The light emitting device to which the present invention is applied as shown in Examples 1 to 4 is mounted on various electronic devices after the external input terminal is mounted and sealed.

  In the electronic device to which the present invention is applied, the light emitting device to which the present invention is applied can suppress the deterioration of the light emitting element and the deterioration of the image quality caused by the light emitting element and can obtain a good display. In addition, the displayable colors are increased and the color reproduction range is expanded.

  In this embodiment, a light-emitting device to which the present invention is applied and an electronic device in which the light-emitting device is mounted will be described with reference to FIGS. However, what is shown in FIGS. 12 and 13 is an example, and the configurations of the light-emitting device and the electronic device are not limited thereto.

  FIG. 12 is a cross-sectional view after sealing a light emitting device to which the present invention is applied. 12 corresponds to FIG. 3 described above. A substrate 6500 and a sealing substrate 6501 are attached to each other with a sealant 6502 so that the transistor and the light-emitting element of the present invention are interposed therebetween. Further, an FPC (flexible printed circuit) 6503 serving as an external input terminal is attached to an end portion of the substrate 6500. Note that a region sandwiched between the substrate 6500 and the sealing substrate 6501 is filled with an inert gas such as nitrogen or a resin material.

  An example of an electronic device in which the light-emitting device to which the present invention is applied is shown in FIG.

  FIG. 13 illustrates a laptop personal computer manufactured by applying the present invention, which includes a main body 5521, a housing 5522, a display portion 5503, a keyboard 5524, and the like. A display device can be completed by incorporating a light-emitting device having the light-emitting element of the present invention into a personal computer.

  Note that in this embodiment, a laptop personal computer is described; however, in addition to this, a light emitting device having the light emitting element of the present invention is mounted on a mobile phone, a television receiver, a car navigation system, or a lighting device. It doesn't matter.

3A and 3B each illustrate a pixel provided in a light-emitting device of the present invention and an arrangement of light-emitting elements that form the pixel. 4A and 4B illustrate a light-emitting element provided in a light-emitting device of the present invention and a circuit for driving the light-emitting element. The schematic diagram which looked at the light-emitting device to which this invention was applied from the upper surface. 4A and 4B illustrate a light-emitting element provided in a light-emitting device to which the present invention is applied and a circuit for driving the light-emitting element. FIG. 6 is a top view of a pixel portion of a light emitting device to which the present invention is applied. The figure explaining operation | movement of the flame | frame with progress of time of the light-emitting device to which this invention is applied. 4A and 4B illustrate a pixel provided in a light-emitting device to which the present invention is applied and an arrangement of light-emitting elements that form the pixel. 4A and 4B illustrate a cross-sectional structure of a light-emitting device to which the present invention is applied. 4A and 4B illustrate a cross-sectional structure of a light-emitting device to which the present invention is applied. 4A and 4B illustrate a light-emitting element provided in a light-emitting device to which the present invention is applied and a circuit for driving the light-emitting element. FIG. 6 is a top view of a pixel portion of a light emitting device to which the present invention is applied. Sectional drawing after sealing of the light-emitting device to which this invention is applied. FIG. 14 is a diagram of an electronic device mounted with a light-emitting device manufactured by applying the present invention. The figure which represented the color in x, y coordinate space based on tristimulus value X, Y, Z.

Explanation of symbols

101 First light emitting element 102 Second light emitting element 103 Third light emitting element 104 Fourth light emitting element 110 Pixel 151 Dotted line 152 Dotted line 153 Dotted line 154 Dotted line 155 Dotted line 161 Dotted line 162 Dotted line 163 Dotted line 121 Driving transistor 122 Switching Transistor 123 erasing transistor 131 source signal line 132 current supply line 133 first scanning line 134 second scanning line 301 pixel 301a first light emitting element 301b second light emitting element 301c third light emitting element 301d fourth Light emitting element 310 Pixel 321 Driving transistor 322 Switching transistor 323 Erasing transistor 331 Source signal line 332 Current supply line 333 First scanning line 334 Second scanning line 501 Subframe 502 Subframe 503 Subframe 504 subframe 501a writing period 502a writing period 503a writing period 504a writing period 501b holding period 502b holding period 503b holding period 504b holding period 501c period 504d erasing period 701 first light emitting element 702 second light emitting element 703 third light emitting element 704 Fourth light emitting element 705 Pixel 706 Dotted line

Claims (4)

A light-emitting device having a plurality of light-emitting elements having different emission colors,
A first group including four first light emitting elements that emit light of a first color, wherein the first light emitting elements are arranged two by two in a row direction and a column direction;
A second group including four second light emitting elements that emit light of the second color, wherein the second light emitting elements are arranged two by two in the row direction and the column direction;
A third group including four third light-emitting elements that emit light of the third color, wherein the third light-emitting elements are arranged two by two in the row direction and the column direction;
A fourth group including four fourth light emitting elements emitting light of the fourth color, wherein the fourth light emitting elements are arranged two by two in the row direction and the column direction,
The first group and the second group are adjacent in the row direction;
The first group and the third group are adjacent in the column direction;
The second group and the fourth group are adjacent in a column direction;
The third group and the fourth group are adjacent in the row direction;
One of the first light emitting elements included in the first group, one of the second light emitting elements included in the second group, and one of the third light emitting elements included in the third group; A light-emitting device, wherein one pixel is formed by one of the fourth light-emitting elements included in the fourth group. In claim 1 ,
A light emitting device, wherein a width between adjacent light emitting elements included in the same group is smaller than a width between adjacent light emitting elements included in different groups. In claim 1 or 2,
The first color is a color having coordinates in a region where x is 0.6 or more and y is 0.35 or less in the chromaticity diagram when expressed in the CIE-XYZ color system.
The second color is a color having coordinates in a region where x in the chromaticity diagram is 0.3 or less and y is 0.6 or more when expressed in the CIE-XYZ color system.
The third color is a color having coordinates in a region where x in the chromaticity diagram is 0.15 or less and y is 0.2 or less when expressed in the CIE-XYZ color system.
The fourth color is a color having coordinates in a region where x is 0.1 or less and y is 0.25 or more and 0.5 or less when expressed in the CIE-XYZ color system. A light emitting device characterized. Electronic equipment comprising a light emitting device according to any one of claims 1 to 3.

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