Ultrathin antimony selenide thin film solar cell and preparation method thereof

Abstract

The invention belongs to the technical field of antimony selenide thin film solar cells, and discloses an ultrathin antimony selenide thin film solar cell and a preparation method thereof. The solar cell sequentially comprises FTO transparent conductive glass, an electron transport layer, an antimony selenide and selenium light absorption layer and an electrode layer from bottom to top, wherein the electron transport layer is CdS; the light absorption layer is composed of an antimony selenide layer and a selenium layer, and the thickness of the antimony selenide layer is 40-80 nm; the thickness of the selenium layer is 40-60 nm; according to the invention, the antimony selenide layer grows on the upper surface of the CdS electron transport layer by a rapid thermal evaporation method (RTE), the ultrathin antimony selenide film is subjected to post-selenylation treatment, so that the antimony selenide film preferentially grows along the [211] direction, the light absorption layer which is thin in film thickness and is compact and flat is synthesized in two steps, and the thickness of the light absorption layer is far lower than that of the conventional antimony selenide light absorption layer of 500nm. The cost of raw materials is lower, and the performance is also improved.

Description

Technical Field

[0001] The invention belongs to the technical field of antimony selenide thin film solar cells, and in particular relates to a strategy for realizing the preferential orientation growth of an ultra-thin antimony selenide film. Background Art

[0002] Solar energy is a renewable and clean energy. At present, solar energy is utilized through solar cells. Solar cells are an energy conversion element that can directly convert light energy into electrical energy through photoelectric effect or photochemical effect. They are the core part of solar power generation system. According to their composition, solar cells can be divided into crystalline silicon solar cells, thin film solar cells, organic solar cells, etc. Among them, thin film solar cells are usually composed of multiple layers of thin film materials, among which the most critical is the light absorption layer. When solar energy irradiates the surface of the light absorption layer, photons are absorbed and cause electrons in the semiconductor to jump from the valence band to the conduction band, forming electron-hole pairs.

[0003] Antimony selenide (Sb2Se3) has a suitable band gap width (1.1-1.3 eV) and a high light absorption coefficient (>10 5 cm -1 ), and has good stability, and its constituent elements are environmentally friendly and non-toxic, making it suitable for use as a light absorption layer for thin-film solar cells. Antimony selenide (Sb2Se3) is used as a light absorption layer in solar cells. The increase in thickness may cause an increase in the probability of carriers to recombine in the film before reaching the electrode, which will lead to a decrease in the number of collected photogenerated carriers and reduce the efficiency of the solar cell. Thick films may generate stress and cracks during preparation or use due to mismatched thermal expansion coefficients or other physical reasons, which may destroy the structural integrity of the device and reduce its performance and life. And thicker antimony selenide films require more materials, increasing production costs. A key advantage of thin-film technology is to use as little material as possible to reduce costs, so maintaining a suitable film thickness is the key to optimizing cost-effectiveness. However, the reduction and uniformity of the thickness of antimony selenide films have a direct impact on the performance of solar cells. The thickness, composition and crystal orientation of the film need to be precisely controlled to ensure that the thickness is reduced while having efficient photoelectric conversion capabilities.

[0004] Therefore, there is a great need in the art for a method for preferentially oriented growth of an ultra-thin antimony selenide film and the preparation of an antimony selenide film solar cell. Summary of the invention

[0005] In order to solve the problems in the background technology, the present invention uses rapid thermal evaporation (RTE) to grow an antimony selenide layer on the surface of the CdS electron transport layer. The thickness of the antimony selenide layer is 40 to 80 nm. The ultra-thin antimony selenide film is post-selenized, and the thickness of the total light absorption layer is much lower than the conventional 500 nm antimony selenide light absorption layer. And the photoelectric conversion efficiency of the prepared antimony selenide thin film solar cell can reach 7%, which is 5.73% compared with the photoelectric conversion efficiency of the 500 nm thick single antimony selenide light absorption layer device deposited in the normal physical system, and the photoelectric conversion efficiency of the 100-130 nm thick single antimony selenide absorption layer is 4.32%. The present invention synthesizes a dense and smooth light absorption layer, which is not only environmentally friendly and simple in preparation process, but also has a wide range of applications and a good improvement in performance. In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0006] (1) Depositing a CdS electron transport layer on the transparent conductive glass FTO surface by chemical water bath deposition with a thickness of 20 to 40 nm;

[0007] First, clean the glass substrate covered with FTO layer, stick double-sided conductive adhesive on the back of the glass substrate, put it in ozone for treatment for minutes, and then put it in a square reaction tank. Add 20mL of 0.015mol / L cadmium salt (CdSO4), 0.75mol / L thiourea ((NH2)2CS), 28% ammonia water (NH3·H2O) and 1ml of 5mol / L potassium hydroxide (KOH) to deionized water, stir evenly, and pour the mixed solution into the square tank and cover the FTO glass. Stir the reaction continuously in a 65℃ water bath. After the reaction is completed, pour the waste liquid into the waste liquid bucket, remove the FTO glass, rinse it with deionized water and dry it to obtain a CdS layer. Optionally, the water bath reaction time is 10 to 15min, and a CdS layer with a thickness of 20 to 40nm can be obtained. The cadmium salt is cadmium chloride, cadmium sulfate or cadmium nitrate. (2) CdS surface treatment: Grind cadmium chloride (CdCl2) powder and dissolve it in anhydrous methanol to prepare a cadmium chloride-methanol solution (0.2g / 10mL). Use cadmium chloride-methanol (CdCl2-CH3OH) solution to treat the CdS layer. Adsorb the FTO glass with CdS on the spin coater, use a pipette with a range of 10-100μL to absorb the cadmium chloride-methanol solution and evenly cover the CdS surface with the solution. Set the spin coater speed to 3000r / min, the spin coating time to 30 seconds, and start spin coating. After the spin coating is completed, place the spin-coated FTO glass on a heating table heated to 400℃, anneal in air for ten minutes, then turn off the hot table and cool naturally to room temperature. It should be noted that CdS film is easily oxidized in the air, and CdCl2 passivation can provide a certain protective effect, reduce oxidation, and improve the chemical stability of the film. Moreover, CdCl2 treatment and thermal annealing can promote the growth of grains in CdS thin films, improve crystallinity, and reduce grain boundaries and crystal defects. If CdS is not surface treated, although it will not affect the formation of ultra-thin antimony selenide layers, it will affect the quality of the electron transport layer in the battery, thereby affecting the final device performance.

[0008] (3) A rapid thermal evaporation (RTE) method is used to grow an antimony selenide layer on the surface of the CdS electron transport layer; the thickness of the antimony selenide film is 40 to 80 nm.

[0009] Put the antimony selenide powder into an oven and set the oven temperature to 90°C. After 24 hours, weigh 0.6-0.8g of the dried antimony selenide powder on an electronic balance and evenly cover the antimony selenide powder on a glass sheet.

[0010] Open the rapid annealing furnace chamber, install an AIN ceramic sheet on the heating table, and place the glass sheet on which the antimony selenide powder has been spread in the step on the AIN ceramic sheet;

[0011] The glass substrate on which the electron transport layer of CdS is deposited in step 2) is arranged opposite to the antimony selenide powder, and the distance between the glass substrate and the antimony selenide powder is 5 to 10 mm. A graphite block is covered on the substrate to maintain the substrate temperature.

[0012] The rapid annealing furnace chamber was evacuated to 2.0 × 10 -3 Torr, heating the antimony selenide powder and the glass substrate on which the CdS electron transport layer is deposited to 300°C and keeping the temperature for 1200S; after the insulation, heating the antimony selenide powder and the glass substrate on which the CdS electron transport layer is deposited to 580°C for the deposition time; and growing an antimony selenide film on the upper surface of the CdS electron transport layer.

[0013] (4) Depositing a selenium layer on the surface of the antimony selenide layer, the thickness of the selenium layer is 40 to 60 nm

[0014] The substrate on which the antimony selenide light absorption layer was deposited was fixed on the sample stage and placed in a vacuum chamber. The magnetron sputtering target was directly opposite to the upper surface of the antimony selenide light absorption layer, with a distance of 10 cm. The chamber was evacuated to a vacuum degree of 2×10 -4 Torr, the sample was heated to 150°C;

[0015] A Se target with a purity of 4N and a working pressure of 1 to 5 Torr was used. A 40 to 50 W RF power was used to sputter a selenium film onto the upper surface of the antimony selenide light absorption layer. The sputtering time was 3 to 10 minutes. The sample stage rotated at 20 r / min to ensure uniform thickness of the Se film. After the sputtering was completed, when the chamber temperature dropped to room temperature, the sample was taken out.

[0016] (5) The prepared film is taken out from the magnetron sputtering chamber and the electrode is evaporated after cooling. The electrode thickness is 50 to 100 nm.

[0017] Weigh gold and place it in the evaporation boat of the vacuum coating machine as the evaporation source. Start the vacuum system and evacuate the system to reduce the system pressure to 7×10 -4 Pa. Before starting evaporation, preheat the evaporation source appropriately so that the metal reaches the appropriate evaporation temperature. The preheating time is five minutes, and the preheating temperature is adjusted by the current of the boat control. The current size in the preheating stage is 75A. Adjust the current size to 85A and start heating the metal to evaporate gold and deposit it on the surface of the absorption layer. The gold electrode is deposited. Stop the evaporation of the metal and turn off the vacuum system. Ensure that the shutdown process is smooth to avoid affecting the quality of the film. Let the system cool to room temperature, and gradually release the vacuum, restore the chamber pressure to normal pressure, and take out the sample.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention uses a rapid thermal evaporation method (RTE) to grow an antimony selenide layer on the surface of the CdS electron transport layer. The thickness of the antimony selenide layer is about 40 to 80 nm, which is much lower than the conventional 500 nm antimony selenide light absorption layer. The present invention synthesizes a light absorption layer (antimony selenide layer + selenium layer) with a film thickness of about 100 nm and a dense and flat surface in a physical system in two steps, performs post-selenization treatment on the ultra-thin antimony selenide film and optimizes the treatment conditions, so that the Sb2Se3 grains obtained by the preferential growth of the antimony selenide film along the

[211] direction grow vertically on the substrate, which is very beneficial to reducing interface recombination. The cost of the raw materials used is lower. Compared with the normal 500 nm thick absorption layer, not only is the preparation process environmentally friendly and simple, but it also has a wide range of applications and a good improvement in performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The antimony selenide thin film solar cell structure of Example 2;

[0021] Figure 2 This is a SEM image of the light absorbing layer described in Example 1 without post-selenization treatment;

[0022] Figure 3 This is a SEM image of the light absorbing layer after post-selenization treatment described in Example 2;

[0023] Figure 4 This is an EDS image of the light absorbing layer after post-selenization treatment described in Example 2;

[0024] Figure 5 JV diagrams of the devices described in Examples 1-6 and Comparative Examples 1-3;

[0025] Figure 6 It is a box plot of the efficiency of the devices described in Example 2 and Comparative Examples 1-4. DETAILED DESCRIPTION

[0026] like Figure 1 As shown, the antimony selenide thin film solar cell of Example 2 comprises, from bottom to top, FTO transparent conductive glass, electron transport layer, antimony selenide + selenium light absorption layer and electrode layer;

[0027] The antimony selenide layer is an antimony selenide film with high (hk1) crystal plane abundance and a thickness of 50nm; the electron transport layer is CdS and a thickness of 20nm; the transparent conductive metal oxide layer is FTO and a thickness of 150nm; and the electrode is a gold electrode and a thickness of 60nm.

[0028] Example 1

[0029] The specific preparation method is as follows:

[0030] 1) Buy a glass substrate coated with a FTO layer as a substrate;

[0031] Place the glass substrate coated with the FTO layer in a beaker and ultrasonicate it with glass cleaning liquid and deionized water for 30 minutes each. After discarding the waste liquid, ultrasonicate it with deionized water for 3-5 times, each time for 10 minutes. The water temperature should not exceed 40°C during the ultrasonication. Then discard the water and add isopropanol for 30 minutes. Finally, ultrasonicate it with anhydrous ethanol for 30 minutes, blow it dry with an air pump and put it in a drying cabinet for later use.

[0032] 2) Depositing a CdS electron transport layer on the transparent conductive glass FTO surface by chemical water bath deposition with a thickness of 20 nm;

[0033] 2.1) Take out the glass cleaned in step 1), stick double-sided conductive adhesive on the back of the glass substrate, put it in ozone for 15 minutes, and then put it in a square reaction tank. Add 20mL each of 0.015mol / L cadmium sulfate (CdSO4), 0.75mol / L thiourea ((NH2)2CS), 28% ammonia (NH3·H2O), and 1ml of 5mol / L potassium hydroxide (KOH) to 140mL of deionized water, stir evenly, and pour the mixed solution into the square tank and cover the FTO glass. Stir the reaction continuously in a 65℃ water bath for 10 minutes. After the reaction is completed, pour the waste liquid into the waste liquid bucket, remove the FTO glass, rinse with deionized water, and dry it.

[0034] 2.2) CdS surface treatment: grind 0.2 g of cadmium chloride (CdCl2) and dissolve it in 10 mL of anhydrous methanol to prepare a cadmium chloride-methanol solution. Use cadmium chloride-methanol (CdCl2-CH3OH) solution to treat the CdS layer. Adsorb 2.1) FTO glass with CdS on the spin coater, use a pipette with a range of 10-100 μL to absorb 70 μL of cadmium chloride-methanol solution and evenly cover the CdS surface with the solution, set the spin coater speed to 3000 r / min, the spin coating time to 30 seconds, and start spin coating. After the spin coating is completed, place the spin-coated FTO glass sheet on a heating table heated to 400°C, anneal in air for ten minutes, then turn off the hot table and cool naturally to room temperature.

[0035] 3) growing an antimony selenide layer with a thickness of 50 nm on the surface of the CdS electron transport layer by rapid thermal evaporation (RTE);

[0036] 3.1) Put the antimony selenide powder into an oven and set the oven temperature to 90° C. After 24 hours, weigh the dried antimony selenide powder on an electronic balance and evenly cover the antimony selenide powder on a glass sheet.

[0037] 3.2) Open the rapid annealing furnace chamber, install an AlN ceramic sheet on the heating table, and place the glass sheet with antimony selenide powder in step 3.1) on the AlN ceramic sheet.

[0038] 3.3) The glass substrate on which the electron transport layer of CdS is deposited in step 3) is placed opposite to the antimony selenide powder, and the distance between the glass substrate and the antimony selenide powder is 10 mm. A graphite block is covered on the substrate to maintain the substrate temperature.

[0039] 3.4) Evacuate the rapid annealing furnace chamber to 2.0×10 -3 Torr, heat the antimony selenide powder and the glass substrate with CdS electron transport layer deposited to 300°C and keep it warm for 1200S; after the insulation, heat the antimony selenide powder and the glass substrate with CdS electron transport layer deposited to 580°C, and the growth time is 60S; grow an antimony selenide film on the upper surface of the CdS electron transport layer, and the thickness of the antimony selenide film is 50nm.

[0040] 4) The prepared film is taken out from the rapid annealing furnace, and after cooling, a gold electrode with a thickness of 60 nm can be evaporated; 0.14 g of gold is weighed and placed in an evaporation boat of a vacuum coating machine as an evaporation source.

[0041] 4.1) Start the vacuum system and evacuate the system to reduce the system pressure to 7×10 -4 Pa. Before starting evaporation, the evaporation source is properly preheated to allow the metal to reach the appropriate evaporation temperature. The preheating time is five minutes, and the preheating temperature is adjusted by the current controlled by the boat. The current size in the preheating stage is 100A.

[0042] 4.2) Adjust the current to 115A and start heating the metal. Keep heating for 10 minutes to evaporate the gold and deposit it on the surface of the absorption layer. After 10 minutes, a 60nm thick gold electrode is deposited.

[0043] 4.3) Stop the evaporation of the metal and close the vacuum system. Ensure that the closing process is smooth to avoid affecting the film quality. Let the system cool to room temperature, and gradually release the vacuum to restore the chamber pressure to normal pressure and remove the sample.

[0044] Embodiment 2:

[0045] The difference from Example 1 is limited to: after the growth of the antimony selenide film in step 3 is completed, a selenium layer is deposited on the upper surface of the antimony selenide light absorption layer by magnetron sputtering, and the thickness of the selenium layer is 50 nm.

[0046] The specific preparation method is as follows:

[0047] 3) Buy a glass substrate coated with a FTO layer as a substrate;

[0048] Place the glass substrate coated with the FTO layer in a beaker and ultrasonicate it with glass cleaning liquid and deionized water for 30 minutes each. After discarding the waste liquid, ultrasonicate it with deionized water for 3-5 times, each time for 10 minutes. The water temperature should not exceed 40°C during the ultrasonication. Then discard the water and add isopropanol for 30 minutes. Finally, ultrasonicate it with anhydrous ethanol for 30 minutes, blow it dry with an air pump and put it in a drying cabinet for later use.

[0049] 4) Depositing a CdS electron transport layer on the transparent conductive glass FTO surface by chemical water bath deposition with a thickness of 20 nm;

[0050] 2.1) Take out the glass cleaned in step 1), stick double-sided conductive adhesive on the back of the glass substrate, put it in ozone for 15 minutes, and then put it in a square reaction tank. Add 20mL each of 0.015mol / L cadmium sulfate (CdSO4), 0.75mol / L thiourea ((NH2)2CS), 28% ammonia (NH3·H2O), and 1ml of 5mol / L potassium hydroxide (KOH) to 140mL of deionized water, stir evenly, and pour the mixed solution into the square tank and cover the FTO glass. Stir the reaction continuously in a 65℃ water bath for 10 minutes. After the reaction is completed, pour the waste liquid into the waste liquid bucket, remove the FTO glass, rinse with deionized water, and dry it.

[0051] 2.2) CdS surface treatment: grind 0.2 g of cadmium chloride (CdCl2) and dissolve it in 10 mL of anhydrous methanol to prepare a cadmium chloride-methanol solution. Use cadmium chloride-methanol (CdCl2-CH3OH) solution to treat the CdS layer. Adsorb 2.1) FTO glass with CdS on the spin coater, use a pipette with a range of 10-100 μL to absorb 70 μL of cadmium chloride-methanol solution and evenly cover the CdS surface with the solution, set the spin coater speed to 3000 r / min, the spin coating time to 30 seconds, and start spin coating. After the spin coating is completed, place the spin-coated FTO glass sheet on a heating table heated to 400°C, anneal in air for ten minutes, then turn off the hot table and cool naturally to room temperature.

[0052] 3) growing an antimony selenide layer with a thickness of 50 nm on the surface of the CdS electron transport layer by rapid thermal evaporation (RTE);

[0053] 3.1) Put the antimony selenide powder into an oven and set the oven temperature to 90° C. After 24 hours, weigh the dried antimony selenide powder on an electronic balance and evenly cover the antimony selenide powder on a glass sheet.

[0054] 3.2) Open the rapid annealing furnace chamber, install an AlN ceramic sheet on the heating table, and place the glass sheet with antimony selenide powder in step 3.1) on the AlN ceramic sheet.

[0055] 3.3) The glass substrate on which the electron transport layer of CdS is deposited in step 3) is placed opposite to the antimony selenide powder, and the distance between the glass substrate and the antimony selenide powder is 10 mm. A graphite block is covered on the substrate to maintain the substrate temperature.

[0056] 3.4) Evacuate the rapid annealing furnace chamber to 2.0×10 -3 Torr, heat the antimony selenide powder and the glass substrate with CdS electron transport layer deposited to 300°C and keep it warm for 1200S; after the insulation, heat the antimony selenide powder and the glass substrate with CdS electron transport layer deposited to 580°C, and the growth time is 60S; grow an antimony selenide film on the upper surface of the CdS electron transport layer, and the thickness of the antimony selenide film is 50nm.

[0057] 4) After the growth of the antimony selenide film in step 3) is completed, a selenium layer is deposited on the upper surface of the antimony selenide light absorption layer by magnetron sputtering, and the thickness of the selenium layer is 50 nm.

[0058] 4.1) The substrate after depositing the antimony selenide light absorption layer is fixed on the sample stage and placed in a vacuum chamber, with the magnetron sputtering target facing the upper surface of the antimony selenide light absorption layer, with a distance of 10 cm;

[0059] 4.2) Evacuate the chamber to a vacuum degree of 2×10 -4 Torr, the sample was heated to 150°C;

[0060] 4.3) A Se target material with a purity of 4N and a working pressure of 1 to 5 Torr was used. A 50 W RF power was used to sputter a selenium film onto the upper surface of the antimony selenide light absorption layer. The sputtering time was 5 minutes. The thickness of the selenium film was 50 nm. The sample stage rotated at a speed of 20 r / min to ensure the uniformity of the Se film thickness.

[0061] 4.4) After sputtering, when the chamber temperature drops to room temperature, take out the sample.

[0062] 5) The prepared film is taken out from the magnetron sputtering chamber, and after cooling, a gold electrode is evaporated to a thickness of 60 nm; the preparation conditions of the gold electrode are the same as those in Example 1.

[0063] Embodiment 3:

[0064] The difference from Example 2 is limited to: after the growth of the antimony selenide film in step 3 is completed, a selenium layer is deposited on the upper surface of the antimony selenide light absorption layer by magnetron sputtering, and the thickness of the selenium layer is 20 nm.

[0065] Step (1) to step (3) are the same as in Example 2.

[0066] 4) After the growth of the antimony selenide film in step 3) is completed, a selenium layer is deposited on the upper surface of the antimony selenide light absorption layer by magnetron sputtering. The thickness of the selenium layer is 20 nm.

[0067] 4.1) The substrate after depositing the antimony selenide light absorption layer is fixed on the sample stage and placed in a vacuum chamber, with the magnetron sputtering target facing the upper surface of the antimony selenide light absorption layer, with a distance of 10 cm;

[0068] 4.2) Evacuate the chamber to a vacuum degree of 2×10 -4 Torr, the sample was heated to 150°C;

[0069] 4.3) A Se target material with a purity of 4N and a working pressure of 1 to 5 Torr was used. A 40W RF power was used to sputter a selenium film onto the upper surface of the antimony selenide light absorption layer. The sputtering time was 5 minutes. The thickness of the selenium film was 20nm. The sample stage rotated at a speed of 20r / min to ensure the uniformity of the Se film thickness.

[0070] 4.4) After sputtering, when the chamber temperature drops to room temperature, take out the sample.

[0071] 5) The prepared film is taken out from the magnetron sputtering chamber, and after cooling, a gold electrode is evaporated to a thickness of 60 nm; the preparation conditions of the gold electrode are the same as those in Example 1.

[0072] Embodiment 4:

[0073] The difference from Example 2 is limited to: after the growth of the antimony selenide film in step 3 is completed, a selenium layer is deposited on the upper surface of the antimony selenide light absorption layer by magnetron sputtering, and the thickness of the selenium layer is 40 nm.

[0074] Step (1) to step (3) are the same as in Example 2.

[0075] 4) After the antimony selenide film is grown in step 3), a selenium layer is deposited on the upper surface of the antimony selenide light absorption layer by magnetron sputtering.

[0076] 4.1) The substrate after depositing the antimony selenide light absorption layer is fixed on the sample stage and placed in a vacuum chamber, with the magnetron sputtering target facing the upper surface of the antimony selenide light absorption layer, with a distance of 10 cm;

[0077] 4.2) Evacuate the chamber to a vacuum degree of 2×10 -4 Torr, the sample was heated to 150°C;

[0078] 4.3) A Se target material with a purity of 4N and a working pressure of 1 to 5 Torr was used. A 40W RF power was used to sputter a selenium film onto the upper surface of the antimony selenide light absorption layer. The sputtering time was 10 minutes. The thickness of the selenium film was 40nm. The sample stage rotated at a speed of 20r / min to ensure the uniformity of the Se film thickness.

[0079] 4.4) After sputtering, when the chamber temperature drops to room temperature, take out the sample.

[0080] 5) The prepared film is taken out from the magnetron sputtering chamber, and after cooling, a gold electrode is evaporated to a thickness of 60 nm; the preparation conditions of the gold electrode are the same as those in Example 1.

[0081] Embodiment 5:

[0082] The difference from Example 2 is limited to: after the growth of the antimony selenide film in step 3 is completed, a selenium layer is deposited on the upper surface of the antimony selenide light absorption layer by magnetron sputtering, and the thickness of the selenium layer is 30 nm.

[0083] Step (1) to step (3) are the same as in Example 2.

[0084] 4) After the antimony selenide film is grown in step 3), a selenium layer is deposited on the upper surface of the antimony selenide light absorption layer by magnetron sputtering.

[0085] 4.1) The substrate on which the antimony selenide light absorption layer is deposited is fixed on a sample stage and placed in a vacuum chamber, with the magnetron sputtering target facing the upper surface of the antimony selenide light absorption layer, with a distance of 10 cm;

[0086] 4.2) Evacuate the chamber to a vacuum degree of 2×10 -4 Torr, the sample was heated to 150°C;

[0087] 4.3) Using a Se target material with a purity of 4N and a working pressure of 1 to 5 Torr, a selenium film was sputtered onto the upper surface of the antimony selenide light absorption layer using a 50W RF power. The sputtering time was 3 minutes, and the thickness of the selenium film was 30nm. The sample stage rotated at 20r / min to ensure the uniformity of the Se film thickness.

[0088] 4.4) After sputtering, when the chamber temperature drops to room temperature, take out the sample.

[0089] 5) The prepared film is taken out from the magnetron sputtering chamber, and after cooling, a gold electrode is evaporated to a thickness of 60 nm; the preparation conditions of the gold electrode are the same as those in Example 1.

[0090] Embodiment 6:

[0091] The difference from Example 2 is limited to: after the growth of the antimony selenide film in step 3 is completed, a selenium layer is deposited on the upper surface of the antimony selenide light absorption layer by magnetron sputtering, and the thickness of the selenium layer is 100 nm.

[0092] Step (1) to step (3) are the same as in Example 2.

[0093] 4) After the antimony selenide film is grown in step 3), a selenium layer is deposited on the upper surface of the antimony selenide light absorption layer by magnetron sputtering.

[0094] 4.1) The substrate on which the antimony selenide light absorption layer is deposited is fixed on a sample stage and placed in a vacuum chamber, with the magnetron sputtering target facing the upper surface of the antimony selenide light absorption layer, with a distance of 10 cm;

[0095] 4.2) Evacuate the chamber to a vacuum degree of 2×10 -4 Torr, the sample was heated to 150°C;

[0096] 4.3) A Se target material with a purity of 4N and a working pressure of 1 to 5 Torr was used. A 50 W RF power was used to sputter a selenium film onto the upper surface of the antimony selenide light absorption layer. The sputtering time was 10 minutes. The thickness of the selenium film was 100 nm. The sample stage rotated at a speed of 20 r / min to ensure the uniformity of the Se film thickness.

[0097] 4.4) After sputtering, when the chamber temperature drops to room temperature, take out the sample.

[0098] 5) The prepared film is taken out from the magnetron sputtering chamber, and after cooling, a gold electrode is evaporated to a thickness of 60 nm; the preparation conditions of the gold electrode are the same as those in Example 1.

[0099] Comparative Example 1

[0100] Comparative Example 1 is different from Example 1 in that an antimony selenide layer is grown on the upper surface of the CdS electron transport layer by rapid thermal evaporation (RTE), and the thickness of the antimony selenide film is 100 nm. The antimony selenide thin film solar cell obtained is composed of FTO transparent conductive glass, electron transport layer (20 nm), antimony selenide (100 nm) and gold electrode layer (60 nm) from bottom to top.

[0101] Comparative Example 2

[0102] Comparative Example 2 is different from Example 1 in that an antimony selenide layer is grown on the surface of the CdS electron transport layer by rapid thermal evaporation (RTE), and the thickness of the antimony selenide film is 500 nm. The antimony selenide thin film solar cell obtained is composed of FTO transparent conductive glass, electron transport layer (20 nm), antimony selenide (500 nm) and gold electrode layer (60 nm) from bottom to top.

[0103] Comparative Example 3

[0104] Comparative Example 3 is compared with Example 1, except that: an antimony selenide layer is grown on the upper surface of the CdS electron transport layer by rapid thermal evaporation (RTE), and the thickness of the antimony selenide film is 100 nm. After the growth of the antimony selenide film is completed, a 50 nm selenium layer is deposited on the upper surface of the antimony selenide light absorption layer by magnetron sputtering. The obtained antimony selenide thin film solar cell is FTO transparent conductive glass, electron transport layer (20 nm), antimony selenide (100 nm), selenium layer (50 nm) and gold electrode layer (60 nm) from bottom to top.

[0105] Comparative Example 4

[0106] Comparative Example 4 is compared with Example 1, except that: an antimony selenide layer is grown on the upper surface of the CdS electron transport layer by rapid thermal evaporation (RTE), and the thickness of the antimony selenide film is 100 nm. After the growth of the antimony selenide film is completed, a 100 nm selenium layer is deposited on the upper surface of the antimony selenide light absorption layer by magnetron sputtering. The obtained antimony selenide thin film solar cell is FTO transparent conductive glass, electron transport layer (20 nm), antimony selenide (100 nm), selenium layer (100 nm) and gold electrode layer (60 nm) from bottom to top.

[0107] Performance analysis of antimony selenide thin film solar cells prepared in Example 1, Examples 2 to 6, and Comparative Examples 1 to 4:

[0108] The SEM test results of Example 1 show that ( Figure 2 ) The antimony selenide light absorption layer without magnetron sputtering selenium supplementation is distributed with a large number of hole defects. The presence of holes will cause the antimony selenide to absorb light poorly, affecting the final efficiency of the device. The final efficiency of the device in Example 1 is only 3.79%, and the corresponding JV curve is Figure 5 The SEM test results of Example 2 ( Figure 3 ) is significantly better than Example 1. When a thin selenium layer is deposited on the antimony selenide layer, it can be seen that the thin film of the absorption layer is uniform and dense, and can completely cover the antimony selenide layer, thereby reducing the presence of holes in the antimony selenide layer. The specific element distribution of Example 2 is as follows Figure 4 In Examples 2 to 6, different parameters of magnetron sputtering of selenium were adjusted, and the corresponding JV curves were Figure 5 Among them, Example 2 achieved the highest efficiency of 7.13%. Comparative Example 1 is a device with an antimony selenide absorption layer of 500nm thickness, Comparative Example 1 is a device with an antimony selenide absorption layer of 100nm thickness, Comparative Example 2 is a device with an antimony selenide absorption layer of 500nm thickness, Comparative Example 3 is a device with an antimony selenide of 100nm thickness + a 50nm selenium layer, and Comparative Example 4 is a device with an antimony selenide of 100nm thickness + a 100nm selenium layer. The efficiency box curve diagram of the optimal embodiment 2 device and comparative examples 1-4 is as follows Figure 6 shown.

Claims

1. An ultra-thin antimony selenide thin film solar cell, characterized in that: The solar cell consists of FTO transparent conductive glass, electron transport layer, antimony selenide + selenium light absorption layer and electrode layer from bottom to top; the electron transport layer is CdS; the light absorption layer is composed of antimony selenide layer and selenium layer, wherein the thickness of antimony selenide layer is 40 to 80nm; the thickness of selenium layer is 40 to 60nm.

2. The ultra-thin antimony selenide thin film solar cell according to claim 1, characterized in that: The thickness of the electron transport layer is 20-40 nm; the transparent conductive metal oxide layer is FTO with a thickness of 150 nm; and the electrode is a gold electrode with a thickness of 50-100 nm.

3. The method for preparing the ultra-thin antimony selenide thin film solar cell according to claim 1 or 2, characterized in that: The preparation steps are: (1) Depositing a CdS electron transport layer on the transparent conductive glass FTO surface by chemical water bath deposition; (2) CdS surface treatment: prepare a cadmium chloride-methanol solution, and use the cadmium chloride-methanol solution to perform surface treatment on the CdS layer; (3) growing an antimony selenide layer on the surface of the surface treated CdS electron transport layer by rapid thermal evaporation, and controlling the thickness of the antimony selenide film to be 40 to 80 nm; (4) using magnetron sputtering technology to sputter a selenium film onto the upper surface of the antimony selenide light absorption layer, the thickness of the selenium film being 40 to 60 nm; (5) The prepared film is taken out from the magnetron sputtering chamber, and after cooling, a gold electrode is evaporated and deposited on the surface of the absorption layer.

4. The method for preparing the ultra-thin antimony selenide thin film solar cell according to claim 3, characterized in that: The CdS surface treatment method in step (2) is as follows: cadmium chloride powder is ground and dissolved in anhydrous methanol to prepare a cadmium chloride-methanol solution; the solid-liquid ratio of cadmium chloride to anhydrous methanol is 0.2 g / 10 mL; the cadmium chloride-methanol solution is used to perform surface treatment on the CdS layer, that is, the cadmium chloride-methanol solution is evenly covered on the CdS surface by a spin coater, and after the spin coating is completed, the spin-coated FTO glass sheet is placed on a heating table heated to 400° C., annealed in air, and naturally cooled to room temperature after annealing.

5. The method for preparing the ultra-thin antimony selenide thin film solar cell according to claim 3, characterized in that: The preparation method of the antimony selenide layer in step (3) is as follows: the antimony selenide powder is evenly covered on the glass sheet after drying; the rapid annealing furnace chamber is opened, an AIN ceramic sheet is installed on the heating table, and the glass sheet covered with the antimony selenide powder is placed on the AIN ceramic sheet; The glass substrate on which the CdS electron transport layer is deposited is arranged opposite to the antimony selenide powder, and the glass substrate and the antimony selenide powder are 10 mm apart, and a graphite block is used to cover the substrate to maintain the substrate temperature; The rapid annealing furnace chamber was evacuated to 2.0 × 10 -3 Torr, heating the antimony selenide powder and the glass substrate on which the CdS electron transport layer is deposited to 300°C and keeping the temperature for 1200S; after the heat preservation, heating the antimony selenide powder and the glass substrate on which the CdS electron transport layer is deposited to 580°C for deposition; and growing an antimony selenide film on the upper surface of the CdS electron transport layer.

6. The method for preparing the ultra-thin antimony selenide thin film solar cell according to claim 3, characterized in that: The specific preparation method of the selenium film in step (4) is as follows: fix the substrate on which the antimony selenide light absorption layer is deposited on a sample stage, place it in a vacuum chamber, and place the magnetron sputtering target material directly opposite to the upper surface of the antimony selenide light absorption layer with a distance of 10 cm; evacuate the chamber to a vacuum degree of 2×10 -4 Torr, the sample was heated to 150°C; A Se target material with a purity of 4N and a working pressure of 1 to 5 Torr was used. A RF power of 40 to 50 W was used to sputter the selenium film onto the upper surface of the antimony selenide light absorption layer. The sputtering time was 3 to 10 minutes. The sample stage rotated at a speed of 20 r / min to ensure the uniformity of the Se film thickness. After the sputtering was completed, when the chamber temperature dropped to room temperature, the sample was taken out.

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