GaAs solar cell with moth-eye bionic micro-nano structure anti-reflection layer and preparation method of GaAs solar cell

Abstract

The invention belongs to the technical field of solar cell materials, and discloses a GaAs solar cell with a moth-eye micro-nano structure anti-reflection layer and a preparation method of the GaAs solar cell in order to enhance the solar spectrum utilization rate and improve the photoelectric conversion efficiency of the solar cell. The method comprises the following steps: growing a thin film with a nano-column structure on a Si substrate with a SiO2 layer in an MBE autocatalytic growth mode, spin-coating PMMA on the surface of the thin film, and transferring the nano-column structure to a GaAs and carbon nanotube heterojunction solar cell through a two-dimensional material wet transfer technology to prepare the solar cell with the moth-eye micro-nano structure anti-reflection layer. Compared with a nanoimprint lithography technology and a photolithography technology, the method provided by the invention is more convenient to operate and more environment-friendly, and does not need to use some harmful gases and harmful chemicals to etch the micro-nano structure. According to the GaAs heterojunction solar cell with the moth-eye bionic micro-nano structure anti-reflection layer prepared by the method, the material used by the anti-reflection layer is not limited, and the utilization rate of sunlight can be remarkably improved, so that the photoelectric conversion efficiency of a device is remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the field of GaAs solar cells, and more specifically, relates to a GaAs solar cell with a moth-eye bionic micro-nano structure anti-reflection layer and a preparation method thereof. Background Art

[0002] In recent years, GaAs (Gallium Arsenide) solar cells have been widely used in the field of aerospace batteries due to their direct band gap, excellent photoelectric conversion efficiency and radiation resistance. According to the Shockley-Queisser model, the photoelectric conversion efficiency of a single-junction GaAs solar cell can reach 30%. However, due to the limitations of various factors such as interface carrier recombination and surface photon loss, the efficiency of the currently prepared GaAs solar cells is still somewhat different from the theoretical value.

[0003] In order to improve the photoelectric conversion efficiency of GaAs solar cells, a common method is to reduce the optical reflection on the surface of the cell through optical management engineering, improve the absorption and utilization of sunlight, and thus improve the photoelectric conversion efficiency of the device. Currently, the commonly used methods to reduce surface photon loss are to use anti-reflection films and surface light-trapping micro-nano structures. Common surface light-trapping structures are mostly structures with different surface morphologies that mimic moth-eye bionics, such as nanopillars, nanocones, nanospheres, etc. This type of micro-nano structure is generally patterned by photolithography or nanoimprinting, which requires ICP (Inductively Coupled Plasma) or wet etching to prepare, requires the use of a large amount of harmful and hazardous liquids and gases, has high requirements for equipment, complex processes, and high costs.

[0004] Taking the production of micro-nano structures on the surface of GaAs solar cells as an example, Chinese patent application CN202111526602.7 discloses a GaAs nanocone Schottky junction solar cell and a preparation method thereof, and mentions a method of using ICP equipment in combination with BCl3 gas and oxygen for etching to obtain GaAs nanocones. The operation of this scheme is relatively simple, but it requires the use of two dangerous gases, BCl3 and high-purity oxygen, and requires the assistance of ICP equipment, which is somewhat dangerous and directly leads to higher costs. Summary of the invention

[0005] In order to overcome the problems of complex preparation, high cost and high risk of the above-mentioned surface micro-nano structure, the present invention provides a GaAs solar cell with a moth-eye bionic micro-nano structure anti-reflection layer and a preparation method thereof. The micro-nano structure is grown by MBE and then transferred to a GaAs heterojunction solar cell by a two-dimensional material wet transfer method to obtain the required moth-eye bionic micro-nano structure.

[0006] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0007] A GaAs solar cell with a moth-eye bionic micro-nano structure anti-reflection layer comprises a back electrode, a GaAs substrate, a hole transport layer, an anti-reflection layer and a front electrode from bottom to top; the anti-reflection layer is a nanocolumn film with a moth-eye bionic micro-nano structure.

[0008] Preferably, the nanocolumns with the moth-eye bionic micro-nano structure are one or more of GaN, InGaN, and InN, the height of the nanocolumns is 10-100 nm, the diameter is 20-60 nm, and the spacing between the nanocolumns is 5-30 nm.

[0009] Preferably, the hole transport layer is a conductive and light-transmitting two-dimensional material, including one or more of graphene, Mxene, carbon nanotubes, TMDs, and PEDOT:PSS; the thickness of the hole transport layer is 80-120 nm.

[0010] Preferably, the GaAs substrate is an n-type GaAs substrate with a thickness of 250-350 μm and a Si doping concentration of (1-3)×10 18 / cm 3 , the crystal plane is (110) crystal plane.

[0011] Preferably, the back electrode is Au with a thickness of 100 to 120 nm; the front electrode is one or more of silver, titanium, copper, nickel, platinum, and indium tin oxide with a thickness of 100 to 120 nm.

[0012] A method for preparing a GaAs solar cell with a moth-eye bionic micro-nano structure anti-reflection layer comprises the following steps:

[0013] Step 1: using an MBE device to autocatalytically grow moth-eye bionic micro-nanostructure nanocolumns on a Si substrate with a SiO2 layer;

[0014] Step 2: Spin-coat a layer of PMMA on the surface of the nanocolumns grown in step 1, dry them, and place them in a dilute acid or dilute alkali to etch away the SiO2 layer for peeling;

[0015] Step 3, cleaning the GaAs substrate, and then transferring a layer of two-dimensional material film thereon to obtain a GaAs / two-dimensional material heterojunction solar cell;

[0016] Step 4, pick up the micro-nanostructure nanocolumn film peeled off in step 2 and cover it on the surface of the GaAs / two-dimensional material heterojunction solar cell in step 3, and dry it;

[0017] Step 5: clean the battery in step 4 in acetone to remove PMMA;

[0018] Step six, vapor-depositing a back electrode and a front electrode on the device obtained in step five, and finally obtaining a GaAs solar cell with a moth-eye bionic micro-nano structure anti-reflection layer.

[0019] Preferably, the nanocolumn with the moth-eye bionic micro-nano structure described in step 1 can be GaN, InGaN, InN, etc.

[0020] Preferably, the growth temperature of the micro-nanostructure nanocolumns grown by MBE in step 1 is between 400°C and 800°C, the N source RF power is between 300W and 400W, and the Ga source and In source temperatures are between 800°C and 900°C.

[0021] Further preferably, the growth temperature of the micro-nanostructure nanocolumns grown by MBE in step 1 is 750°C to 800°C, the N source RF power is 400W, and the Ga source and In source temperatures are 870°C to 900°C.

[0022] Preferably, the PMMA spin coating speed in step 2 is 1000-3000 rpm, the time is 10-30 s, the drying temperature is 80° C.-100° C., the time is 5-10 min, the acid or alkali concentration is 10%-15%, and the immersion time is 10-15 min.

[0023] Preferably, the two-dimensional material described in step three includes all conductive and light-transmitting materials such as graphene, Mxene, carbon nanotubes, TMDs, and PEDOT:PSS.

[0024] Preferably, the drying temperature in step 4 is 60° C. to 80° C., and the drying time is 5 to 10 minutes.

[0025] Preferably, the soaking time in acetone in step 5 is 10 to 15 minutes.

[0026] Preferably, the acid or base in step 2 can be HF, KOH, NaOH, etc.

[0027] The MBE growth micro-nanostructure method used in the present invention can avoid the complicated steps of photolithography and nanoimprinting, and the need to use dangerous gases and liquids to etch and form micro-nanostructures. The present invention can be simply transferred to GaAs heterojunction solar cells through a wet transfer process, avoiding the damage to the solar cell caused by processes such as photolithography or nanoimprinting and etching on the heterojunction solar cell, separating the moth-eye bionic micro-nanostructure preparation and heterojunction solar cell preparation processes, and effectively protecting the GaAs heterojunction solar cell. The GaAs heterojunction solar cell with a moth-eye bionic anti-reflection layer constructed in this way can not only reduce the process risk, but also has better photoelectric conversion efficiency than a planar reflective layer, and avoids the damage caused to the prepared heterojunction solar cell in the subsequent manufacture of the anti-reflection layer.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] Compared with the existing photolithography and nanoimprint etching methods, the solar cell with a moth-eye bionic micro-nano structure anti-reflection layer prepared by the present invention can also meet the use requirements in the device preparation process. Compared with the solar cell without the moth-eye bionic micro-nano structure anti-reflection layer, the photoelectric conversion efficiency is significantly improved. In addition, the danger brought by the preparation process and the damage to the heterojunction solar cell can be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the structure of a GaAs / carbon nanotube heterojunction solar cell with a moth-eye bionic GaN micro-nanostructure anti-reflection layer obtained in Example 1, which includes, from bottom to top, a gold electrode, a GaAs substrate, a carbon nanotube film, a GaN nanocolumn and a silver electrode.

[0031] Figure 2 This is a scanning electron microscope test image of the GaN nanocolumn with the moth-eye bionic micro-nano structure anti-reflection layer obtained in Example 1.

[0032] Figure 3 The IV curves of the devices prepared in Example 1 and Comparative Example 1 are shown. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any form.

[0034] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the present technical field.

[0035] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0036] Example 1

[0037] A preparation method of a GaAs solar cell with a moth-eye bionic micro-nano structure anti-reflection layer comprises the following steps:

[0038] Step 1: Use MBE equipment to self-catalytically grow GaN moth-eye bionic micro-nanostructure nanocolumns on a Si substrate with a SiO2 layer. The height of the nanocolumns is 50nm, the diameter is 40nm, the spacing between the nanocolumns is 10nm, the growth temperature is 800℃, the Ga source temperature is 900℃, and the N source power is 400W;

[0039] Step 2: Spin-coat a layer of PMMA on the surface of the nanocolumns grown in step 1 at a speed of 3000 rpm for 30 seconds, and dry at 80°C for 10 minutes, then place in a solution with a 10% HF concentration to peel off the SiO2 layer;

[0040] Step 3: a cleaned GaAs substrate with a thickness of 350 μm is transferred onto a carbon nanotube film with a thickness of 100 nm to obtain a GaAs / carbon nanotube heterojunction solar cell;

[0041] Step 4: Pick up the GaN micro-nanostructure nanocolumn film peeled off in step 2, cover it on the surface of the GaAs / carbon nanotube heterojunction solar cell prepared in step 3, and dry it at a drying temperature of 80° C. for 10 minutes;

[0042] Step 5, washing the battery in step 5 in acetone to remove PMMA, the acetone time is 15 minutes, and finally a GaAs heterojunction solar cell with a moth-eye bionic micro-nano structure is obtained, which also includes the following steps:

[0043] (1) Using electron beam evaporation, a 120 nm thick Au layer is deposited on the back side of the GaAs substrate (the side without micro-nano structures) as the back electrode;

[0044] (2) annealing the Au electrode at 330 °C in a nitrogen atmosphere for 30 s to form an ohmic contact;

[0045] (3) The carbon nanotube film transfer method in step 3 is to prepare the carbon nanotube film by suction filtration on the surface of the GaAs substrate (the side with the micro-nano structure) using a PES (polyethersulfone) filter membrane and a carbon nanotube dispersion concentration of 0.05 mg / ml, and then transfer it to the GaAs substrate;

[0046] (4) A 120 nm thick silver layer is evaporated on the prepared film with the moth-eye bionic micro-nano structure anti-reflection layer as a surface electrode, thereby completing the preparation of the GaAs / carbon nanotube heterojunction solar cell with the moth-eye bionic micro-nano structure anti-reflection layer.

[0047] Example 2

[0048] A preparation method of a GaAs solar cell with a moth-eye bionic micro-nano structure anti-reflection layer comprises the following steps:

[0049] Step 1: Use MBE equipment to self-catalytically grow GaN moth-eye bionic micro-nanostructure nanocolumns on a Si substrate with a SiO2 layer. The height of the nanocolumns is 50nm, the diameter is 40nm, the spacing between the nanocolumns is 10nm, the growth temperature is 750℃, the Ga source temperature is 870℃, and the N source power is 400W.

[0050] Step 2: Spin-coat a layer of PMMA on the surface of the nanocolumns grown in step 1 at a PMMA spin-coating speed of 1000 rpm for 15 seconds, and dry at 60°C for 8 minutes, and place in a 10% HF solution to peel off the SiO2 layer;

[0051] Step 3: a cleaned GaAs substrate with a thickness of 350 μm is transferred onto a layer of carbon nanotube film with a thickness of 100 nm to obtain a GaAs / carbon nanotube heterojunction solar cell;

[0052] Step 4: Pick up the GaN micro-nanostructure nanocolumn film peeled off in step 2, cover it on the surface of the GaAs / carbon nanotube heterojunction solar cell prepared in step 3, and dry it at a drying temperature of 60° C. for 5 minutes;

[0053] Step 5, washing the battery in step 5 in acetone to remove PMMA, the acetone time is 10 minutes, and finally a GaAs heterojunction solar cell with a moth-eye bionic micro-nano structure is obtained, which also includes the following steps:

[0054] (1) Using electron beam evaporation, a 120 nm thick Au layer is deposited on the back side of the GaAs substrate (the side without micro-nano structures) as the back electrode;

[0055] (2) annealing the Au electrode at 350 °C in a nitrogen atmosphere for 30 s to form an ohmic contact;

[0056] (3) The carbon nanotube film transfer method in step 3 is to prepare the carbon nanotube film by suction filtration on the surface of the GaAs substrate (the side with the micro-nano structure) using a PES (polyethersulfone) filter membrane and a carbon nanotube dispersion concentration of 0.005 mg / ml, and then transfer it to the GaAs substrate;

[0057] (4) A 120 nm thick silver layer is evaporated on the prepared film with the moth-eye bionic micro-nano structure anti-reflection layer as a surface electrode, thereby completing the preparation of the GaAs / carbon nanotube heterojunction solar cell with the moth-eye bionic micro-nano structure anti-reflection layer.

[0058] Comparative Example 1

[0059] Different from Example 1, Comparative Example 1 is a GaAs / carbon nanotube heterojunction solar cell without a moth-eye bionic micro-nano structure anti-reflection layer, and the other aspects are the same.

[0060] Table 1

[0061]

[0062]

[0063] The device parameter comparison of the solar cell prepared in Example 1 and the solar cell prepared in Comparative Example 1 is shown in Table 1. The IV curves of the solar cells in Example 1 and Comparative Example 1 are shown in Table 1. Figure 3 shown.

Claims

1. A GaAs solar cell with a moth-eye bionic micro-nano structure anti-reflection layer, characterized in that: It comprises a back electrode, a GaAs substrate, a hole transport layer, an anti-reflection layer and a front electrode from bottom to top; the anti-reflection layer is a nano-column film with a moth-eye bionic micro-nano structure.

2. The GaAs solar cell with a moth-eye bionic micro-nano structure anti-reflection layer according to claim 1, characterized in that: The nanocolumns with moth-eye bionic micro-nano structures are one or more of GaN, InGaN, and InN. The nanocolumns have a height of 10-100 nm, a diameter of 20-60 nm, and a spacing of 5-30 nm between the nanocolumns.

3. The GaAs solar cell with a moth-eye bionic micro-nano structure anti-reflection layer according to claim 1, characterized in that: The hole transport layer is a conductive and light-transmitting two-dimensional material, including one or more of graphene, Mxene, carbon nanotubes, TMDs, and PEDOT:PSS; the thickness of the hole transport layer is 80-120nm.

4. The GaAs solar cell with a moth-eye bionic micro-nano structure anti-reflection layer according to claim 1, characterized in that: The GaAs substrate is an n-type GaAs substrate with a thickness of 250-350 μm and a Si doping concentration of (1-3)×10 18 / cm 3 , the crystal plane is (110) crystal plane.

5. The GaAs solar cell with a moth-eye bionic micro-nano structure anti-reflection layer according to claim 1, characterized in that: The back electrode is Au with a thickness of 100-120 nm; the front electrode is one or more of silver, titanium, copper, nickel, platinum, and indium tin oxide with a thickness of 100-120 nm.

6. A method for preparing a GaAs solar cell having a moth-eye bionic micro-nano structure anti-reflection layer according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: using an MBE device to autocatalytically grow moth-eye bionic micro-nanostructure nanocolumns on a Si substrate with a SiO2 layer; Step 2: Spin-coat a layer of PMMA on the surface of the nanocolumns grown in step 1, dry them, and place them in a dilute acid or dilute alkali to etch away the SiO2 layer for peeling; Step 3, transferring a layer of two-dimensional material film onto the cleaned GaAs substrate to obtain a GaAs / two-dimensional material heterojunction solar cell; Step 4, pick up the micro-nanostructure nanocolumn film peeled off in step 2 and cover it on the surface of the GaAs / two-dimensional material heterojunction solar cell in step 3, and dry it; Step 5: clean the battery in step 4 in acetone to remove PMMA; Step six, vapor-depositing a back electrode and a front electrode on the device obtained in step five, and finally obtaining a GaAs solar cell with a moth-eye bionic micro-nano structure anti-reflection layer.

7. The method for preparing a GaAs solar cell with a moth-eye bionic micro-nano structure anti-reflection layer according to claim 6, characterized in that: In step 1, the growth temperature of the micro-nanostructure nanocolumns grown by MBE is between 400°C and 800°C, the N source RF power is between 300W and 400W, and the Ga source and In source temperatures are between 800°C and 900°C.

8. The method for preparing a GaAs solar cell with a moth-eye bionic micro-nano structure anti-reflection layer according to claim 6, characterized in that: In step 2, the PMMA spin coating speed is 1000-3000 rpm, the time is 10-30s, the drying temperature is 80°C-100°C, the time is 5-10min, the acid or alkali concentration is 10wt%-15wt%, the immersion time is 10-15min, and the dilute acid or dilute alkali is one or more of HF, KOH, and NaOH.

9. The method for preparing a GaAs solar cell with a moth-eye bionic micro-nano structure anti-reflection layer according to claim 6, characterized in that: The drying temperature in step 4 is 60° C. to 80° C., and the drying time is 5 to 10 minutes.

10. The method for preparing a GaAs solar cell with a moth-eye bionic micro-nano structure anti-reflection layer according to claim 6, characterized in that: The immersion time in acetone in step 5 is 10 to 15 minutes.

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