CN111403558A - High-efficiency flexible laminated thin-film solar cell and preparation method thereof - Google Patents

Abstract

The invention discloses a high-efficiency flexible laminated thin-film solar cell and a preparation method thereof. The bottom cell adopts a narrow-forbidden band copper indium selenium solar cell, can prepare flexible cells by taking various flexible materials as a substrate, combines the narrow-forbidden band copper indium selenium solar cell and a wide-forbidden band solar cell to grow on the flexible substrate, forms a laminated cell by adjusting the forbidden band width, and is formed by laminating the solar cells according to the band gap width, thereby achieving the purpose of covering different absorption wavelength ranges, optimizing the efficiency of the flexible and bendable laminated cell, flexibly selecting the forbidden band width to distribute the light absorption effect by adopting a mechanical stacking method, having no need of current matching and having simpler preparation process.

Description

High-efficiency flexible laminated thin-film solar cell and preparation method thereof

technical field

The invention relates to the technical field of solar cells, in particular to a high-efficiency flexible laminated thin-film solar cell and a preparation method thereof.

Background technique

At present, the efficiency of single-layer cells is close to the theoretical limit efficiency, and its improvement space is small. The tandem solar cell technology provides an effective method to improve the efficiency of solar cells. By combining two or more solar cells with different absorption bands to obtain a wider range of wavelength of solar radiation.

An effective way to improve the efficiency of polymer solar cells is also to use a tandem structure to minimize the thermalization loss of photon energy by utilizing a wider spectrum of solar radiation. However, for polymer solar cells, the performance of tandem devices significantly lags behind that of single-layer solar cells due to the lack of suitable low-bandgap polymers. In addition, the currently commonly used tandem battery with a bottom cell made of crystalline silicon has the disadvantage that the silicon wafer is thick and cannot be bent, which also limits its application range.

SUMMARY OF THE INVENTION

In view of the deficiencies in the prior art, the present invention provides a high-efficiency flexible laminated thin film solar cell and a preparation method thereof. The laminated thin film solar cell not only has various advantages of thin film solar cells, but also can ensure tandem performance, Improving the battery efficiency has the advantages of simple preparation method, low cost, and wider application range.

In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme:

A preparation method of a high-efficiency flexible laminated thin-film solar cell, comprising:

preparing a bottom battery, the P-type semiconductor absorption layer of the bottom battery is a copper indium selenide absorption layer;

preparing a top cell, the top cell having a wider band gap than the bottom cell;

The top cell is stacked on the bottom cell using a mechanical stacking method.

As one of the embodiments, the step of preparing the bottom cell includes:

providing a flexible first substrate;

forming a back electrode on the first substrate;

preparing the copper indium selenide absorber layer on the back electrode by a three-step co-evaporation method;

Alkali metal post-deposition treatment is performed on the copper indium selenide absorption layer, and a first semiconductor buffer layer, a first window layer and a first transparent front electrode are sequentially prepared on the treated copper indium selenide absorption layer.

As one of the embodiments, the step of preparing the bottom cell includes:

In the first stage of preparing the copper indium selenide absorption layer by the three-step co-evaporation method, indium is grown in the first stage, copper is grown in the second stage, and indium is grown in the third stage to form a copper-poor phase;

Wherein, sodium fluoride is added during the third-stage growth process, and rubidium fluoride is added during the alkali metal post-deposition process after the third-stage growth is completed.

As one of the embodiments, the growth process of the first stage includes: simultaneously evaporating In and Se on the back electrode under a background vacuum condition of 5.0×10 ^-5 Pa to 1.0×10 ^-4 Pa The evaporation source temperatures of the two elements, In and Se, are 810-830°C and 240-300°C, respectively, the temperature of the first substrate is 350°C-400°C, and the deposition time is 25-40min;

The growth process of the second stage includes: under the vacuum condition of 1.0 × 10 ^-2 Pa to 2.0 × 10 ^-2 Pa, on the basis of the previous stage, two elements of Cu and Se are simultaneously evaporated, and the two elements of Cu and Se are The evaporation source temperatures of the elements are respectively 1150-1300°C and 240-300°C, the temperature of the first substrate is 500-600°C, and the deposition time is 15-25min;

The growth process of the third stage includes: under the vacuum condition of 2.0×10 ^-2 Pa to 3.0×10 ^-2 Pa, simultaneously evaporating In and Se, and In and Se on the film layers formed in the first two stages The evaporation source temperatures of the elements are respectively 730-770°C and 240-300°C, the temperature of the first substrate is 500-600°C, and the deposition time is 15-30 minutes.

As one of the embodiments, the process of adding sodium fluoride in the third-stage growth process is as follows: the vacuum is 2.0×1 ^0-2 Pa～3.0× ^10-2 Pa, and the temperature of the first substrate reaches 380 Under the condition of ℃, the sodium fluoride source is passed into the environment of Se, and the deposition time is 8-15min;

The process of adding rubidium fluoride during the alkali metal post-deposition treatment is as follows: when the temperature of the first substrate reaches 320° C., a source of rubidium fluoride is introduced in the Se environment, and the deposition time is 15-20 minutes.

Another object of the present invention is to provide a high-efficiency flexible laminated thin-film solar cell, comprising a bottom cell and a top cell stacked on the bottom cell, wherein the P-type semiconductor absorber layer of the bottom cell is a copper indium selenide absorber layer , the band gap of the top cell is wider than that of the bottom cell.

As one of the embodiments, the upper surface of the copper indium selenide absorber layer of the bottom cell facing the top cell is covered with a deposition layer of an alkali metal compound.

As one of the embodiments, the alkali metal compound deposition layer is formed by deposition of sodium fluoride and rubidium fluoride.

As one embodiment, the bottom cell includes a copper indium selenide absorber layer, a back electrode disposed under the copper indium selenide absorber layer, and a back electrode disposed on the copper indium selenide absorber layer in sequence from bottom to top The alkali metal compound deposition layer, the first semiconductor buffer layer, the first window layer, and the first transparent front electrode.

As one of the embodiments, the semiconductor absorber layer of the top cell is a copper gallium selenide absorber layer (20), a perovskite absorber layer or CdTe.

The bottom cell of the invention adopts a narrow-bandgap copper indium selenide solar cell, and can use various flexible materials as a substrate to prepare a flexible battery, and the narrow-bandgap copper indium selenide solar cell and the wide-bandgap solar cell are combined to grow on the flexible substrate On the other hand, by adjusting the forbidden band width to form a tandem cell, the solar cells are superimposed according to the width of the band gap, so as to achieve the purpose of covering different absorption wavelength ranges and optimize the efficiency of the flexible and bendable tandem cell. By using the mechanical stacking method, the forbidden band width can be flexibly selected to distribute the light absorption effect, and no current matching is required, and the preparation process is simpler.

In addition, the present invention improves the hole concentration by using the alkali metal post-deposition treatment in the absorption layer of the narrow-gap copper indium selenide solar cell, thereby increasing the open circuit voltage, thereby significantly improving the efficiency of the narrow-gap band copper indium selenide solar cell.

Description of drawings

FIG. 1 is a schematic structural principle diagram of a high-efficiency flexible laminated thin-film solar cell according to Embodiment 1 of the present invention;

2 is a flow chart of a method for preparing a high-efficiency flexible laminated thin-film solar cell according to Embodiment 1 of the present invention;

3 is a flow chart of a method for preparing a copper indium selenide bottom battery according to Embodiment 1 of the present invention;

4 is a schematic structural diagram of a top cell according to Embodiment 2 of the present invention;

The labels in the figure are explained as follows:

1 - Bottom battery;

1a - back electrode;

10-copper indium selenide absorber layer;

11-Alkali metal compound deposition layer;

12- the first semiconductor buffer layer;

13- The first window layer;

14- the first transparent front electrode;

2- top battery;

2a-transparent electrode;

20-copper gallium selenide absorber layer;

21- the second semiconductor buffer layer;

22- The second window layer;

23 - the second transparent front electrode;

201 - photoanode;

202 - electron transport layer;

203-perovskite absorber layer;

204-hole transport layer;

205 - back electrode;

A-first substrate;

B-Second substrate.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

Example 1

1 and 2, the present invention provides a high-efficiency flexible laminated thin-film solar cell and a preparation method thereof. The preparation method includes:

S01, prepare a bottom cell 1, and the P-type semiconductor absorption layer of the bottom cell 1 is a copper indium selenide absorption layer 10;

S02, prepare a top cell 2, and the band gap of the top cell 2 is wider than that of the bottom cell 1;

S03. Using a mechanical stacking method, stack the top cell 2 on the bottom cell 1.

In this embodiment, the narrow-bandgap bottom cell 1 and the wide-bandgap top cell 2 can be fabricated independently, and then formed in a 4-terminal stack structure by a mechanical stacking method. Not only can the band gap width be flexibly selected to allocate light absorption, but also Need current matching, easier to prepare. After the top cell 2 is stacked on the bottom cell 1, a top ohmic contact electrode is prepared on the top cell 2 as a collector electrode, and the fabrication of the stacked thin film solar cell can be completed. The top ohmic contact electrode can be prepared by electron beam evaporation and screen printing.

In this embodiment, according to the difference in the band gap of the two sub-cells and the difference in the absorption spectrum range, the utilization of the absorption spectrum is complementary to expand the spectrum utilization rate, thereby improving the cell efficiency. Since copper indium selenide (CuInSe ₂ , referred to as CIS) is a direct bandgap material, the light absorption rate is as high as 10 ⁵ order, and the thickness of the fabricated cell can be 2-3 μm, which is very suitable for thin-film solar cells. The consumption of expensive materials, which can be made of stainless steel or high temperature polymer as the substrate, the prepared flexible battery can be used in the curved roof of buildings, etc., and can also be made into a foldable power supply, which is convenient to carry, and can also supply small The use of mobile devices in the fields of instrument computers and military communication GPS can greatly expand its application fields.

As shown in FIG. 1, the bottom cell 1 includes a flexible first substrate A, a back electrode 1a, a copper indium selenide absorber layer 10, an alkali metal compound deposition layer 11, The first semiconductor buffer layer 12 , the first window layer 13 , and the first transparent front electrode 14 .

As shown in FIG. 3 , in this embodiment, the steps of preparing the bottom battery 1 mainly include:

S011. Provide a flexible first substrate A, and the first substrate A is preferably made of flexible stainless steel.

First, clean the 10*10 flexible stainless steel with warm deionized water and alkaline cleaning agent, and clean it with absolute ethanol in the ultrasonic machine for 15 minutes, control the low speed with a nitrogen air gun to blow off the excess water on the surface, and then put it in the oven drying.

Then, the first substrate A is placed in a vacuum chamber at a predetermined center position in the substrate holder.

S012, forming a back electrode 1a on the first substrate A.

The material of the back electrode 1a is preferably molybdenum (Mo). The back electrode 1a is formed on the first substrate A by evaporating Mo. The parameters used to evaporate Mo are 2.0Pa, 350W, 20 times for the first layer; 0.3Pa, 1000w, 10 times for the second layer, and the thickness of the back electrode 1a is about 1.1 μm; XRF (X Ray Fluorescence, that is, X-ray fluorescence spectroscopy) analysis) count was 1044.

S013, adopting a three-step co-evaporation method to prepare a copper indium selenide absorption layer 10 on the back electrode 1a.

Wherein, in the first stage of preparing the copper indium selenide absorption layer 10 by the three-step co-evaporation method, indium is grown in the first stage, copper is grown in the second stage, indium is grown in the third stage to form a copper-poor phase, and in the third stage growth process is added Sodium Fluoride. Adding sodium fluoride during the third stage growth process can improve the open circuit voltage and fill factor under the premise that its incorporation in the third stage has little effect on the crystallinity of the film surface. Therefore, the corresponding solar cell can show better performance.

Specifically, the growth process of the first stage of the three-step co-evaporation method includes: placing the back electrode 1a into a cavity with a background vacuum condition of 5.0×10 ^-5 Pa to 1.0×10 ^-4 Pa, and under the background vacuum condition At the same time, two elements of In and Se are evaporated on the back electrode 1a. The evaporation source temperatures of In and Se are 810-830°C and 240-300°C respectively, and the temperature of the first substrate A is 350°C-400°C. The deposition time is 25-40min;

The growth process of the second stage includes: under the vacuum condition of 1.0×10 ^-2 Pa ~ 2.0×10 ^-2 Pa, on the basis of the previous stage, two elements of Cu and Se, and two elements of Cu and Se are simultaneously evaporated The temperature of the evaporation source is 1150-1300°C and 240-300°C respectively, the temperature of the first substrate A is 500-600°C, and the deposition time is 15-25min;

The growth process of the third stage includes: under the vacuum condition of 2.0×10 ^-2 Pa ~ 3.0×10 ^-2 Pa, on the films formed in the first two stages, In and Se are simultaneously evaporated, and In and Se are deposited on the film layers. The temperature of the evaporation source is 730-770°C and 240-300°C respectively, the temperature of the first substrate A is 500-600°C, and the deposition time is 15-30min.

The process of adding sodium fluoride in the third-stage growth process is as follows: under the conditions that the vacuum is 2.0×1 ^0-2 Pa ^～ 3.0× ^10-2 Pa and the temperature of the first substrate A reaches 380°C, under the conditions of the Se Sodium fluoride (NaF) source was passed into the environment, and the deposition time was 8-15min.

S014 , performing an alkali metal post-deposition process on the copper indium selenide absorption layer 10 , and during this process, rubidium fluoride needs to be added.

In this embodiment, rubidium fluoride is added after the growth of the absorber layer is completed, so that the heavier alkali metal forms the secondary phase of RbInSe ₂ at the grain boundary, thereby acting as a passivation defect.

The process of adding rubidium fluoride during the alkali metal post-deposition treatment is as follows: when the temperature of the first substrate A reaches 320° C., a source of rubidium fluoride is introduced in the Se environment, and the deposition time is 15-20 min.

S015 , a first semiconductor buffer layer 12 , a first window layer 13 , and a first transparent front electrode 14 are sequentially prepared on the treated copper indium selenide absorption layer 10 .

The material of the N-type first semiconductor buffer layer 12 may be any one of cadmium sulfide, zinc sulfide, cadmium-doped zinc sulfide, zinc magnesium oxide, zinc sulfur oxide, and indium selenide, with a thickness of 50nm-80nm. Here, cadmium sulfide (CdS) is preferably used. The first semiconductor buffer layer 12 can be prepared by chemical water bath, magnetron sputtering or atomic layer deposition.

The first semiconductor buffer layer 12 is preferably prepared by a chemical water bath method, specifically: dissolve 0.184g of cadmium sulfate in 60ml of deionized water, 5.694g of thiourea in 150ml of deionized water, rinse copper indium selenide with deionized water The surface of the absorbing layer 10 is then put into a large beaker, 45ml of concentrated ammonia water (28-30%) is mixed with the above-mentioned cadmium sulfate solution and poured into the large beaker, and the thiourea solution is also poured into the large beaker, and then the large beaker is placed. Put it into a 69°C water bath, stir with a magnetic stirrer at a constant speed for 9 minutes, take it out, rinse it with deionized water, dry it with high-purity nitrogen, and quickly put it in a 160°C oven for 2 minutes for annealing.

The thickness of the copper indium selenide absorption layer 10 is 2-3 μm, the thickness of the first semiconductor buffer layer 12 of cadmium sulfide is 50 nm, and the gate type collector electrode (ohmic contact electrode) is nickel/aluminum/nickel (Ni/Al/Ni) three Laminated layers or chromium/nickel/gold (Cr/Ni/Au), nickel/aluminum/nickel (or chromium/nickel/gold) with thicknesses of 100nm/8000nm/100nm, respectively, can be stacked sequentially by e-beam evaporation. When the Ni/Al/Ni grid collector electrode is prepared by electron beam thermal evaporation, the uppermost layer of Ni can prevent the second layer of Al from reacting with air to be oxidized, and the lowermost layer of Ni can make the electrode not easy to fall off.

The first window layer 13 is preferably made of zinc oxide (ZnO), and the thickness of the zinc oxide is 100 nm. The first transparent front electrode 14 is preferably aluminum doped zinc oxide, the aluminum doping ratio is 0.2%, the thickness is 200nm-400nm, the transmittance is >85%, and the electrical conductivity is <6×10 ^-4 Ω.cm ² .

The first window layer 13 and the first transparent front electrode 14 can be formed by magnetron sputtering. For example, when the first window layer 13 is fabricated, the flow rate of argon gas is 20 sccm, the flow rate of oxygen gas is 2.0 sccm, and the sputtering power is 120 W. Under the condition of 4 times sputtering, then the power was adjusted to 220W for 16 times of sputtering. When sputtering the first transparent front electrode 14 , the temperature of the first substrate A is heated to 90° C., the flow rate of argon gas is 20 sccm, the flow rate of hydrogen gas is 2.5 sccm, and the sputtering power is 750W for 12 times.

The top cell 2 of this embodiment is a copper gallium selenide (CGS) solar cell, and its semiconductor absorption layer is a copper gallium selenide absorption layer 20, which is made from three raw materials, copper, gallium and selenium, and the thickness of the obtained absorption layer is 2-3 μm. The top cell 2 mainly includes a second substrate B, a transparent electrode 2a, a copper gallium selenide absorber layer 20, a second semiconductor buffer layer 21, a second window layer 22, a Two transparent front electrodes 23 .

The transparent electrode 2a can be fully transparent or semi-transparent ITO, and the light transmittance is greater than or equal to 85%. The material used is a zinc oxide-doped aluminum transparent conductive film with a thickness of 150 nm. The materials and thicknesses and processes of the second substrate B, the second semiconductor buffer layer 21 , the second window layer 22 , the second transparent front electrode 23 and the processes may be the same as those of the first substrate A and the first semiconductor buffer layer 12 in the bottom cell 1 . , the first window layer 13 and the first transparent front electrode 14 are the same.

The copper gallium selenide absorption layer 20 is prepared by a three-step co-evaporation method of copper, gallium and selenium elements, and the substrate temperature is detected by the thermocouple behind the substrate. The substrate temperature in the first step is 450°C, and in the second step The substrate temperature was 600°C in the third step, the deposition rate of Ga was 4A°/s, the deposition rate of Cu was 3A°/s, and the deposition rate of Se remained stable in all three steps. at 30A°/s. At the end of the second step, the substrate temperature is lowered by 2°C to form a copper-rich phase, and in the third step, the substrate temperature is increased by 2°C, and Ga is added to form a copper-poor phase. Since there is a certain distance between the thermocouple and the substrate, the substrate temperature detected by the thermocouple is 30-50°C lower than the actual substrate surface temperature.

Another object of the present invention is to provide a high-efficiency flexible laminated thin-film solar cell, comprising a bottom cell 1 and a top cell 2 stacked on the bottom cell 1, and the P-type semiconductor absorption layer of the bottom cell 1 is a copper indium selenide absorption layer 10. The band gap of the top cell 2 is wider than that of the bottom cell 1.

Correspondingly, the upper surface of the copper indium selenide absorber layer 10 of the bottom cell 1 facing the top cell 2 is covered with an alkali metal compound deposition layer 11 . The alkali metal compound deposition layer 11 is formed by deposition of sodium fluoride and rubidium fluoride.

Example 2

Different from Embodiment 1, the top cell 2 of the stacked thin film solar cell in this embodiment can be a perovskite (perovskite) cell or a cadmium telluride (CdTe) cell, and the semiconductor absorber layer corresponding to the top cell 2 is a perovskite absorber. layer or CdTe. Using a CIS flexible cell with a band gap of about 1.0 eV as the bottom cell 1, combined with a wide band gap flexible perovskite and cadmium telluride thin-film solar front cell with a band gap of about 1.7 eV, the efficiency can be as high as 30% or more. Two-section tandem flexible solar cells.

As shown in Figure 4, it is a schematic diagram of the structure of the perovskite top cell.

The perovskite top cell 2 is mainly composed of a photoanode 201 , an electron transport layer (ETL) 202 , a perovskite absorption layer 203 , a hole transport layer (HTL) 204 , and a back electrode 205 . The photoanode 201 is generally a fluoride-doped oxide (FTO), and the back electrode 205 is generally a gold (Au) or silver (Ag) electrode.

The preparation method of the perovskite absorption layer 203 is a solution method with a simple process and no vacuum, and specifically involves a two-step method. First, metal halide (usually lead iodide PbI2) is deposited on the film, and then the metal halide is reacted with cationic halide (MAI, FAI, etc.) by gas phase or liquid phase method to form the perovskite absorber layer 203.

The specific implementation method is as follows: first, prepare potassium amine iodide (MAI) powder, mix the hydroiodic acid aqueous solution and methylamine methanol solution, stir under bathing conditions for two hours, then rotate at 50 ° C for one hour, wash with ether for 3 After several times, vacuum drying was performed to obtain MAI powder. Then, PbI ₂ was dissolved in polar solvent DMF at a concentration of 1.2 M and stirred until completely dissolved. 40 μL of PbI ₂ solution was dropped onto the TiO ₂ film for 30 s, and then spin-coated at 2000 rpm for 60 s. After spin coating, the film was heated on a 90°C hot stage for 5 min to remove the remaining solvent in the film. After cooling to room temperature, the membrane was immersed in MAI solution with a concentration of 10 mg/mL (dissolved in isopropanol). After PbI ₂ was converted into MAPbI ₃ Titanite absorber layer 203 .

The prepared perovskite cell is used as the top cell of the tandem cell, and the prepared CIS bottom cell is in a 4-terminal stack structure, and the perovskite cell is directly stacked on the CIS cell, that is, the perovskite/copper indium selenide cell is obtained. Tandem solar cells.

To sum up, the bottom cell of the present invention adopts a narrow-bandgap copper indium selenide solar cell, and can use various flexible materials as a substrate to prepare a flexible battery, and the narrow-bandgap copper indium selenide solar cell and the wide-bandgap solar cell are combined to grow on the On the flexible substrate, the tandem cell is formed by adjusting the band gap width, and the solar cells are superimposed according to the width of the band gap, so as to achieve the purpose of covering different absorption wavelength ranges, making the flexible and bendable tandem cell efficient. For optimization, by using the mechanical stacking method, the forbidden band width can be flexibly selected to distribute the light absorption effect, and no current matching is required, and the preparation process is simpler. Moreover, the present invention increases the hole concentration by using the alkali metal post-deposition treatment method in the absorption layer of the narrow-gap copper indium selenide solar cell, thereby increasing the open circuit voltage, thereby significantly improving the efficiency of the narrow-gap copper indium selenide solar cell. The tandem battery has the advantages of low cost, flexibility and bendability, and high efficiency, and has broad application prospects.

The above are only specific embodiments of the present application. It should be pointed out that for those skilled in the art, without departing from the principles of the present application, several improvements and modifications can also be made. It should be regarded as the protection scope of this application.

Claims (10)

1. A preparation method of a high-efficiency flexible laminated thin-film solar cell is characterized by comprising the following steps:

preparing a bottom battery (1), wherein a P-type semiconductor absorption layer of the bottom battery (1) is a copper indium selenide absorption layer (10);

preparing a top cell (2), wherein the band gap of the top cell (2) is wider than that of the bottom cell (1);

the top cell (2) is stacked on the bottom cell (1) using a mechanical stacking method.

2. Method for manufacturing a high efficiency flexible laminated thin film solar cell according to claim 1, characterized in that the step of manufacturing the bottom cell (1) comprises:

providing a flexible first substrate (a);

forming a back electrode (1a) on the first substrate (a);

preparing the copper indium selenium absorption layer (10) on the back electrode (1a) by adopting a three-step co-evaporation method;

and carrying out alkali metal post-deposition treatment on the copper indium selenium absorption layer (10), and sequentially preparing a first semiconductor buffer layer (12), a first window layer (13) and a first transparent front electrode (14) above the treated copper indium selenium absorption layer (10).

3. Method for manufacturing a high efficiency flexible laminated thin film solar cell according to claim 2, characterized in that the step of manufacturing the bottom cell (1) comprises:

growing indium in the first stage of preparing the copper indium selenide absorption layer (10) by a three-step co-evaporation method, growing copper in the second stage, and growing indium in the third stage to form a copper-poor phase;

wherein, sodium fluoride is added in the growth process of the third stage, and rubidium fluoride is added in the post-deposition treatment process of the alkali metal after the growth of the third stage is finished.

4. The method according to claim 3, wherein the flexible laminated thin-film solar cell is characterized in that,

the growth process of the first stage comprises a growth process at 5.0 × 10^-5Pa～1.0×10^-4Simultaneously evaporating two elements of In and Se on the back electrode (1a) under the background vacuum condition of Pa, wherein the evaporation source temperatures of the In and Se are respectively 830 ℃ and 300 ℃ of 240-;

the growth process of the second stage comprises the step of performing growth at 1.0 × 10^-2Pa～2.0×10^-2Under the vacuum condition of Pa, simultaneously evaporating two elements of Cu and Se on the basis of the previous stage, wherein the evaporation source temperatures of the two elements of Cu and Se are 1150-minus 1300 ℃ and 240-minus 300 ℃, the temperature of the first substrate (A) is 500-minus 600 ℃, and the deposition time is 15-25 min;

the growth process of the third stage comprises 2.0 × 10^-2Pa～3.0×10^-2And In and Se are simultaneously evaporated on the film layer formed In the first two stages under the vacuum condition of Pa, the evaporation source temperatures of the two elements of In and Se are respectively 730-770 ℃ and 240-300 ℃, the temperature of the first substrate (A) is 500-600 ℃, and the deposition time is 15-30 min.

5. The method according to claim 4, wherein the flexible laminated thin-film solar cell is characterized in that,

the sodium fluoride is added during the third stage of growth under vacuum of 2.0 × 1^0-2Pa～3.0×10^-2Pa, introducing a sodium fluoride source in the Se environment under the condition that the temperature of the first substrate (A) reaches 380 ℃, and depositing for 8-15 min;

the process of adding rubidium fluoride in the post-deposition treatment process of alkali metal comprises the following steps: when the temperature of the first substrate (A) reaches 320 ℃, introducing a rubidium fluoride source in a Se environment, and the deposition time is 15-20 min.

6. The high-efficiency flexible laminated thin film solar cell is characterized by comprising a bottom cell (1) and a top cell (2) stacked on the bottom cell (1), wherein a P-type semiconductor absorption layer of the bottom cell (1) is a copper indium selenium absorption layer (10), and a band gap of the top cell (2) is wider than that of the bottom cell (1).

7. Method for manufacturing a high efficiency flexible laminated thin film solar cell according to claim 6 characterized in that the upper surface of the copper indium selenide absorber layer (10) of the bottom cell (1) facing the top cell (2) is covered with an alkali metal compound deposition layer (11).

8. The high efficiency flexible laminated thin film solar cell according to claim 7, characterized in that the alkali metal compound deposition layer (11) is formed by sodium fluoride and rubidium fluoride deposition.

9. The method of manufacturing a high efficiency flexible laminated thin film solar cell according to claim 7, wherein the bottom cell (1) comprises a copper indium selenium absorption layer (10), a back electrode (1a) disposed under the copper indium selenium absorption layer (10), and the alkali metal compound deposition layer (11), a first semiconductor buffer layer (12), a first window layer (13), a first transparent front electrode (14) sequentially stacked from bottom to top on the copper indium selenium absorption layer (10).

10. The high-efficiency flexible laminated thin-film solar cell according to any one of claims 6 to 9, characterized in that the semiconductor absorption layer of the top cell (2) is a copper gallium selenium absorption layer (20), a perovskite absorption layer or CdTe.

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