A method for improving the back interface modification of Sb2Se3 thin film solar cells photovoltaic performance

Abstract

The present invention discloses a method for modifying the back interface of a Sb2Se3 thin-film solar cell to improve the photovoltaic performance. First, a Mo substrate used to prepare a Sb2Se3 thin-film solar cell device is cleaned with ethanol, detergent, and deionized water. The cleaned Mo substrate is annealed in a furnace under air flow to grow a MoO2 regulating layer. In addition, a solar cell is prepared using an unannealed Mo substrate as a control group. Finally, a series of device performance tests are conducted to effectively reduce the thickness of the MoSe2 interface layer and the back contact barrier. The present invention uses an air annealing process to treat the Mo substrate of the solar cell device, modify the contact characteristics of the Mo / Sb2Se3 back interface in the cell device, and improve the photoelectric conversion efficiency of the Sb2Se3 thin-film solar cell based on the substrate structure.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor materials and semiconductor devices, and in particular to a back interface modification method for improving the photovoltaic performance of Sb2Se3 thin film solar cells. Background Art

[0002] Solar energy is expected to become a carbon-free energy source to meet our energy needs, and one of the ways to achieve the effective use of solar energy is solar cell devices. Antimony selenide (Sb2Se3) is a solar cell thin film material with a suitable band gap, high absorption coefficient and good conductivity. The theoretical photoelectric conversion efficiency of its solar cell devices can exceed 30%. Therefore, Sb2Se3 solar cell devices appear to have great research potential among many new solar cell devices. However, the maximum efficiency (10%) of Sb2Se3 thin film solar cells based on a substrate structure (Mo / Sb2Se3 / CdS / ITO / Ag) is far lower than the theoretical photoelectric conversion efficiency, and there is still a large gap from practical application. In order to further improve the photoelectric conversion efficiency of Sb2Se3 thin film solar cells, the present invention designs a new back interface modification method to improve the photovoltaic performance of Sb2Se3 thin film solar cells to solve the above problems. Summary of the Invention

[0003] The purpose of the present invention is to propose a back interface modification method for improving the photovoltaic performance of Sb2Se3 thin film solar cells, so as to solve at least one technical problem existing in the above-mentioned prior art.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for improving the back interface modification of Sb2Se3 thin film solar cells for photovoltaic performance comprises the following steps:

[0006] Step S1, preparation of MoO2 regulating layer;

[0007] (a1) The Mo substrate used to prepare the Sb2Se3 thin-film solar cell device was first cleaned with ethanol, detergent, and deionized water;

[0008] (b1) The cleaned Mo substrate was annealed in a furnace under air flow to grow a MoO2 regulatory layer;

[0009] Step S2, preparation of the Sb2Se3 absorption layer in the battery device;

[0010] Sb precursor films were prepared on various Mo substrates by radio frequency magnetron sputtering. The Sb precursor films prepared on the Mo substrates were placed in a heat treatment furnace for selenization to prepare Sb2Se3 absorption layers.

[0011] Step S3, preparation of Sb2Se3 thin film solar cells;

[0012] (a3) CdS buffer layers were prepared on multiple samples using a chemical water bath method;

[0013] (b3) After the CdS film is prepared, the film is dried;

[0014] (c3) annealing the Sb2Se3 / CdS heterojunction in a vacuum state;

[0015] (d3) preparing an ITO layer on CdS by magnetron sputtering;

[0016] (e3) preparing the front electrode of the solar cell device by thermal evaporation;

[0017] Step S4, characterizing the performance of Sb2Se3 thin film solar cell devices;

[0018] The JV curve, JV curve of variable temperature dark state, CV-DLCP and admittance spectrum were tested on multiple prepared devices to characterize the relevant performance.

[0019] Preferably, in step S1, (b1), the following treatment steps are performed: the surface of the cleaned Mo substrate is blown dry with a nitrogen gun, placed in a heat treatment furnace, and annealed directly by passing air. The annealing temperatures are 300 and 400°C, respectively, and the annealing time is 15 minutes. MoO2 regulating layers with thicknesses of 80 nm and 800 nm are prepared. In addition, a Mo substrate that is not subjected to air annealing process is used as a control group, and Sb2Se3 solar cell devices are prepared on the three Mo substrates respectively.

[0020] Preferably, the step S2 performs the following processing steps: Sb precursor films are prepared on the three Mo substrates by radio frequency magnetron sputtering, and the background pressure is 5×10 -4 Pa, the sputtering time was 40 min, and the sputtering pressure of the film was 1 Pa. Then, the Sb precursor films prepared on the three Mo substrates were placed in a heat treatment furnace for selenization to prepare Sb2Se3 absorption layers. Selenium particles were placed on both sides of the sample, with a total mass of 0.4 g. Ar gas was introduced during the selenization process to maintain the pressure at 7×10 4 Pa, the selenization temperature is 410℃, the heating rate is 20℃ / min, the sample selenization time is 15 minutes, and the samples are marked as S Mo1 ,S Mo2 and S Mo3 .

[0021] Preferably, the step S3, (a3) ​​performs the following processing steps: the plurality of samples are SMo1 ,S Mo2 and S Mo3，在 Three samples S Mo1 ,S Mo2 and S Mo3 On the other hand, a CdS buffer layer was prepared by a chemical water bath method. The solution for preparing CdS consisted of CdSO4, ammonia water and thiourea. The temperature of the chemical water bath method was 85°C and the deposition time was 9 minutes.

[0022] Preferably, in step S3, (c3), the following treatment steps are performed: the treatment temperature of the annealing treatment is 325°C, and the annealing time is 5 minutes.

[0023] Preferably, the step S3, (d3) performs the following processing steps: the ITO layer is prepared on the CdS by magnetron sputtering, and the sputtering power, time and gas pressure of the ITO layer are 120W, 25min and 0.4Pa respectively.

[0024] Compared with the prior art, the present invention provides a method for modifying the back interface of Sb2Se3 thin-film solar cells to improve their photovoltaic performance, which has the following beneficial effects:

[0025] The present invention uses an air annealing process to prepare a MoO2 control layer on a Mo substrate. This preparation process is simple and direct. Furthermore, compared with other control layers, the MoO2 control layer not only effectively reduces the thickness of the MoSe2 interface between Mo and Sb2Se3, but also effectively promotes the growth of the Sb2Se3 absorber layer toward the ideal [hk1] orientation, thereby further optimizing the properties of the Sb2Se3 / CdS heterojunction front interface. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a flow chart of the present invention;

[0027] Figure 2 The performance comparison of Sb2Se3 thin film solar cell devices with and without MoO2 regulation layer is shown;

[0028] Figure 3 is the temperature-varying JV curve of the device;

[0029] Figure 4 Characterize the performance of the device at the Sb2Se3 / CdS heterojunction interface;

[0030] Figure 5 Characterization of the Sb2Se3 / CdS heterojunction interface composite of the device. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0032] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0033] Please see the attached Figure 1-5 As shown, in view of the existence of the MoSe2 interface layer and the high back contact barrier that affect the transport of photogenerated carriers at the back interface, a method for oxidizing and modifying the Mo / Sb2Se3 back interface of Mo substrate is proposed. The specific steps are as follows: Step S1, preparation of MoO2 control layer;

[0034] (a1) The Mo substrate used to prepare the Sb2Se3 thin-film solar cell device was first cleaned with ethanol, detergent, and deionized water;

[0035] (b1) The cleaned Mo substrate was annealed in a furnace under air flow to grow a MoO2 regulatory layer;

[0036] In step S1, (b1), the following treatment steps are performed: the surface of the cleaned Mo substrate is blown dry with a nitrogen gun, placed in a heat treatment furnace, and annealed directly with air. The annealing temperatures are 300 and 400°C, respectively, and the annealing time is 15 minutes. MoO2 regulating layers with thicknesses of 80 nm and 800 nm are prepared. In addition, a Mo substrate that is not subjected to the air annealing process is used as a control group, and Sb2Se3 solar cell devices are prepared on the three Mo substrates respectively.

[0037] Step S2, preparation of the Sb2Se3 absorption layer in the battery device;

[0038] Sb precursor films were prepared on various Mo substrates by radio frequency magnetron sputtering. The Sb precursor films prepared on the Mo substrates were placed in a heat treatment furnace for selenization to prepare Sb2Se3 absorption layers.

[0039] The step S2 performs the following processing steps: Sb precursor films are prepared on the three Mo substrates by radio frequency magnetron sputtering, and the background pressure is 5×10 -4Pa, the sputtering time was 40 min, and the sputtering pressure of the film was 1 Pa. Then, the Sb precursor films prepared on the three Mo substrates were placed in a heat treatment furnace for selenization to prepare Sb2Se3 absorption layers. Selenium particles were placed on both sides of the sample, with a total mass of 0.4 g. Ar gas was introduced during the selenization process to maintain the pressure at 7×10 4 Pa, the selenization temperature is 410℃, the heating rate is 20℃ / min, the sample selenization time is 15 minutes, and the samples are marked as S Mo1 ,S Mo2 and S Mo3 .

[0040] Step S3, preparation of Sb2Se3 thin film solar cells;

[0041] (a3) CdS buffer layers were prepared on multiple samples using a chemical water bath method;

[0042] (b3) After the CdS film is prepared, the film is dried;

[0043] (c3) annealing the Sb2Se3 / CdS heterojunction in a vacuum state;

[0044] In step S3, (c3), the following treatment steps are performed: the annealing temperature is 325°C, and the annealing time is 5 minutes.

[0045] (d3) preparing an ITO layer on CdS by magnetron sputtering;

[0046] The step S3, (d3) performs the following processing steps: the ITO layer is prepared on the CdS by magnetron sputtering, and the sputtering power, time and gas pressure of the ITO layer are 120W, 25min and 0.4Pa respectively.

[0047] (e3) preparing the front electrode of the solar cell device by thermal evaporation;

[0048] Step S4, characterizing the performance of Sb2Se3 thin film solar cell devices;

[0049] The JV curve, JV curve of variable temperature dark state, CV-DLCP and admittance spectrum were tested on multiple prepared devices to characterize the relevant performance.

[0050] Figure 2The performance of Sb2Se3 thin-film solar cell devices with and without MoO2 control layer is compared. The MoO2 control layer with appropriate thickness (80nm) can promote the growth of Sb2Se3 absorption layer along (211) orientation, so that the grain size of Sb2Se3 absorption layer increases and the formation of MoSe2 interface layer is inhibited. Compared with the performance of Sb2Se3 device without MoO2 control layer, the MoO2 control layer can increase the device efficiency from 5.75% to 8.14%, and the back contact barrier of the device is also reduced.

[0051] Figure 3 Shown are the results of further measurement of the device's variable temperature JV curve. From the variable temperature JV curve, it can be seen that compared with the device without the MoO2 control layer, after adding the MoO2 control layer at the Mo / Sb2Se3 back interface, the back contact barrier can be effectively reduced from 217meV to 73.9meV, and the recombination at the Sb2Se3 / CdS heterojunction interface can also be reduced; the MoO2 control layer can not only modify the Mo / Sb2Se3 back interface contact characteristics, but also improve the performance of the Sb2Se3 / CdS heterojunction.

[0052] Figure 4 The results further demonstrate that adding a MoO2 control layer to the Mo / Sb2Se3 structure of the battery device can reduce defects at the Sb2Se3 / CdS heterojunction interface, increase the Sb2Se3 / CdS heterojunction's built-in potential, and promote the transport of photogenerated carriers across the heterojunction interface. Furthermore, device admittance spectroscopy testing shows that the MoO2 control layer reduces Se vacancy defects in the Sb2Se3 absorber layer, further improving device performance.

[0053] Figure 5 It shows that after the Mo / Sb2Se3 back interface is modified, the recombination rate at the Sb2Se3 / CdS heterojunction interface can be reduced, and the performance of the Sb2Se3 / CdS heterojunction interface can be optimized. This further proves that the MoO2 regulatory layer can effectively inhibit the formation of the MoSe2 interface layer, reduce the back contact barrier, and optimize the Sb2Se3 / CdS heterojunction interface.

[0054] In summary, the present invention uses an air annealing process to treat the Mo substrate of the solar cell device, modifying the contact characteristics of the Mo / Sb2Se3 back interface in the cell device, thereby improving the photoelectric conversion efficiency of the Sb2Se3 thin film solar cell based on the substrate structure;

[0055] Compared to other solar cell device back-interface control processes, the MoO2 control layer fabricated on a Mo substrate using an air annealing process is simple and straightforward. Furthermore, compared to other control layers, the MoO2 control layer not only effectively reduces the thickness of the MoSe2 interface between Mo and Sb2Se3 but also effectively promotes the growth of the Sb2Se3 absorber layer toward the ideal [hk1] orientation, thereby further optimizing the properties of the Sb2Se3 / CdS heterojunction front interface.

[0056] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for improving the back interface modification of Sb2Se3 thin film solar cells photovoltaic performance, characterized in that: The steps include: Step S1, preparation of MoO2 regulating layer; (a1) The Mo substrate used to prepare the Sb2Se3 thin-film solar cell device was first cleaned with ethanol, detergent, and deionized water; (b1) The cleaned Mo substrate was annealed in a furnace under air flow to grow a MoO2 regulatory layer; Step S2, preparation of the Sb2Se3 absorption layer in the battery device; Sb precursor films were prepared on various Mo substrates by radio frequency magnetron sputtering. The Sb precursor films prepared on the Mo substrates were placed in a heat treatment furnace for selenization to prepare Sb2Se3 absorption layers. Step S3, preparation of Sb2Se3 thin film solar cells; (a3) CdS buffer layers were prepared on multiple samples using a chemical water bath method; (b3) After the CdS film is prepared, the film is dried; (c3) annealing the Sb2Se3 / CdS heterojunction in a vacuum state; (d3) preparing an ITO layer on CdS by magnetron sputtering; (e3) preparing the front electrode of the solar cell device by thermal evaporation; Step S4, characterizing the performance of Sb2Se3 thin film solar cell devices; The JV curve, JV curve of variable temperature dark state, CV-DLCP and admittance spectrum were tested on multiple prepared devices to characterize the relevant performance.

2. The method for improving the back interface performance of Sb2Se3 thin film solar cells according to claim 1, characterized in that: In step S1, (b1), the following treatment steps are performed: the surface of the cleaned Mo substrate is blown dry with a nitrogen gun, placed in a heat treatment furnace, and annealed directly with air. The annealing temperatures are 300 and 400°C, respectively, and the annealing time is 15 minutes. MoO2 regulating layers with thicknesses of 80 nm and 800 nm are prepared. In addition, a Mo substrate that is not subjected to the air annealing process is used as a control group, and Sb2Se3 solar cell devices are prepared on the three Mo substrates respectively.

3. The method for improving the photovoltaic performance of a Sb2Se3 thin film solar cell rear interface according to claim 2, characterized in that: The step S2 performs the following processing steps: Sb precursor films are prepared on the three Mo substrates by radio frequency magnetron sputtering, and the background pressure is 5×10 -4 Pa, the sputtering time was 40 min, and the sputtering pressure of the film was 1 Pa. Then, the Sb precursor films prepared on the three Mo substrates were placed in a heat treatment furnace for selenization to prepare Sb2Se3 absorption layers. Selenium particles were placed on both sides of the sample, with a total mass of 0.4 g. Ar gas was introduced during the selenization process to maintain the pressure at 7×10 4 Pa, the selenization temperature is 410℃, the heating rate is 20℃ / min, the sample selenization time is 15 minutes, and the samples are marked as S Mo1 ,S Mo2 and S Mo3 .

4. The method for improving the photovoltaic performance of a Sb2Se3 thin film solar cell rear interface according to claim 3, characterized in that: The step S3, (a3) ​​performs the following processing steps: the plurality of samples are S Mo1 ,S Mo2 and S Mo3，在 Three samples S Mo1 ,S Mo2 and S Mo3 On the other hand, a CdS buffer layer was prepared by a chemical water bath method. The solution for preparing CdS consisted of CdSO4, ammonia water and thiourea. The temperature of the chemical water bath method was 85°C and the deposition time was 9 minutes.

5. The method for improving the photovoltaic performance of a Sb2Se3 thin film solar cell rear interface according to claim 4, characterized in that: In step S3, (c3), the following treatment steps are performed: the annealing temperature is 325°C, and the annealing time is 5 minutes.

6. The method for improving the photovoltaic performance of a Sb2Se3 thin film solar cell rear interface according to claim 5, characterized in that: The step S3, (d3) performs the following processing steps: the ITO layer is prepared on the CdS by magnetron sputtering, and the sputtering power, time and gas pressure of the ITO layer are 120W, 25min and 0.4Pa respectively.

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