A gallium arsenide heterojunction solar cell, its fabrication method and application

Abstract

This invention discloses a gallium arsenide heterojunction solar cell, its fabrication method, and its applications. The gallium arsenide heterojunction solar cell of this invention comprises a back electrode, a gallium arsenide substrate, a carbon nanotube-graphene oxide composite layer, and a front electrode, sequentially stacked. The carbon nanotube-graphene oxide composite layer consists of carbon nanotubes and sheet-like graphene oxide. The gallium arsenide heterojunction solar cell of this invention has advantages such as high photoelectric conversion efficiency and simple structure. Furthermore, its fabrication process is simple and low-cost, making it suitable for large-scale industrial applications.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, specifically to a gallium arsenide heterojunction solar cell, its fabrication method, and its applications. Background Technology

[0002] A solar cell is a semiconductor device that absorbs solar energy and converts it into electrical energy. It can make good use of solar energy, the cleanest energy source in nature, and can effectively alleviate the energy crisis that humanity will face in the future. Gallium arsenide (GaAs) has excellent properties such as direct bandgap, high carrier mobility, and high light absorption coefficient, and has the theoretically highest photoelectric conversion efficiency, making it very promising to break through the current bottleneck of photoelectric conversion efficiency in solar cell devices.

[0003] However, existing gallium arsenide (GaAs) solar cells are expensive and are mainly used in high-value applications such as aerospace, and have not yet been widely adopted in civilian applications. Furthermore, to effectively improve the light absorption spectrum range of traditional GaAs-based pn junction solar cells, a common approach is to add III-V group semiconductors with different band gaps to different spectral ranges to fabricate multi-junction solar cells. However, increasing the number of junctions not only makes the fabrication process more complex and drastically increases production costs, but also inevitably causes severe lattice mismatch between epitaxial layers, making it difficult to improve the photoelectric conversion efficiency of the device.

[0004] Therefore, it is of great significance to develop a solar cell with high photoelectric conversion efficiency, simple structure, simple fabrication process, and low manufacturing cost. Summary of the Invention

[0005] The purpose of this invention is to provide a gallium arsenide heterojunction solar cell, its preparation method, and its application.

[0006] The technical solution adopted in this invention is:

[0007] A gallium arsenide heterojunction solar cell comprises a back electrode, a gallium arsenide substrate, a carbon nanotube-graphene oxide composite layer, and a front electrode stacked sequentially; the carbon nanotube-graphene oxide composite layer comprises carbon nanotubes and sheet-like graphene oxide.

[0008] Preferably, the back electrode is composed of at least one of gold, silver, titanium, copper, nickel, platinum, tin oxide, antimony oxide, and aluminum doped with zinc oxide.

[0009] Preferably, the carbon nanotubes have a length of 1 μm to 3 μm and a diameter of 1 nm to 2 nm.

[0010] Preferably, the sheet-like graphene oxide has a sheet diameter of 1 nm to 50 nm.

[0011] Preferably, the thickness of the carbon nanotube-graphene oxide composite layer is 50 nm to 250 nm.

[0012] Preferably, the front electrode is composed of at least one of gold, silver, titanium, copper, nickel, platinum, tin oxide, antimony oxide, and aluminum doped with zinc oxide.

[0013] A method for fabricating a gallium arsenide heterojunction solar cell as described above includes the following steps:

[0014] 1) Electrode material is deposited on one side of a gallium arsenide substrate to form a back electrode;

[0015] 2) The carbon nanotube dispersion was filtered to form a carbon nanotube membrane. The carbon nanotube membrane was then attached to the side of the gallium arsenide substrate away from the back electrode to form a back electrode-gallium arsenide substrate-carbon nanotube membrane composite structure. The back electrode-gallium arsenide substrate-carbon nanotube membrane composite structure was used as the working electrode, the Ag / AgCl electrode as the reference electrode, and the platinum electrode as the counter electrode to form a three-electrode system. The system was then placed in a sheet-like graphene oxide dispersion for electrochemical deposition to form a carbon nanotube-graphene oxide composite layer on the side of the gallium arsenide substrate away from the back electrode.

[0016] 3) Electrode materials are deposited on the surface of the carbon nanotube-graphene oxide composite layer to form a front electrode, thus obtaining a gallium arsenide heterojunction solar cell.

[0017] Preferably, the concentration of the carbon nanotube dispersion in step 2) is 1×10⁻⁶. -3 mg / mL~3×10 -3 mg / mL.

[0018] Preferably, the carbon nanotube dispersion in step 2) further contains sodium dodecylbenzenesulfonate with a mass fraction of 0.3% to 0.7%.

[0019] Preferably, the concentration of the sheet-like graphene oxide dispersion in step 2) is 0.01 mg / mL to 0.2 mg / mL.

[0020] Preferably, the electrochemical deposition in step 2) is performed under a voltage of -1.5V to 0.6V, and the number of electrochemical deposition cycles is 1 to 15.

[0021] A power source comprising the aforementioned gallium arsenide heterojunction solar cell.

[0022] The beneficial effects of the present invention are: the gallium arsenide heterojunction solar cell of the present invention has the advantages of high photoelectric conversion efficiency and simple structure, and its preparation process is simple and the preparation cost is low, making it suitable for large-scale industrial application.

[0023] Specifically:

[0024] 1) The gallium arsenide heterojunction solar cell of the present invention contains a carbon nanotube-graphene oxide composite layer (hole transport layer). Compared with the heterojunction solar cell structure of other types of carbon materials, the device structure is simpler, the fabrication process is simpler, and the materials and fabrication costs are lower.

[0025] 2) The gallium arsenide heterojunction solar cell of the present invention contains a carbon nanotube-graphene oxide composite layer. Compared with the carbon nanotube / gallium arsenide heterojunction solar cell, the quality of the gallium arsenide heterojunction is significantly improved. The addition of graphene oxide provides an additional pathway for carrier separation and transport in the heterojunction, which can effectively reduce the carrier transport loss of the gallium arsenide heterojunction solar cell.

[0026] 3) The gallium arsenide heterojunction solar cell of the present invention contains a carbon nanotube-graphene oxide composite layer. The graphene oxide is fully filled between the carbon nanotubes, which can effectively reduce the reflection of incident light and effectively increase the photocurrent density, thereby significantly improving the photoelectric conversion efficiency of the gallium arsenide heterojunction solar cell. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the gallium arsenide heterojunction solar cell of the present invention.

[0028] Explanation of reference numerals in the attached figures: 10, back electrode; 20, gallium arsenide substrate; 30, carbon nanotube-graphene oxide composite layer; 40, front electrode.

[0029] Figure 2 The figures show the short-circuit current density versus open-circuit voltage curves for gallium arsenide heterojunction solar cells in Examples 1-4 and the comparative examples. Detailed Implementation

[0030] The present invention will be further explained and described below with reference to specific embodiments.

[0031] Example 1:

[0032] A gallium arsenide heterojunction solar cell (structural schematic diagram shown) Figure 1 As shown, it is composed of a back electrode 10, a gallium arsenide substrate 20, a carbon nanotube-graphene oxide composite layer 30 and a front electrode 40 stacked sequentially from bottom to top; the carbon nanotube-graphene oxide composite layer 30 is composed of carbon nanotubes and sheet-like graphene oxide.

[0033] The above-mentioned method for fabricating gallium arsenide heterojunction solar cells is as follows:

[0034] 1) The gallium arsenide substrate was ultrasonically cleaned with acetone and ethanol for 5 min each, then acid-washed in 10% hydrochloric acid for 3 min, then washed with deionized water and ethanol, then dried with nitrogen, and then a gold layer with a thickness of 120 nm was deposited on one side of the gallium arsenide substrate by vapor deposition, and then annealed at 330℃ for 1 min to form the back electrode.

[0035] 2) The concentration of carbon nanotubes (length 1μm~3μm, diameter 1nm~2nm) was 1.27×10⁻⁶. -3 A carbon nanotube membrane was prepared by filtration of a carbon nanotube aqueous dispersion containing 0.5% sodium dodecylbenzenesulfonate at a concentration of mg / mL. The carbon nanotube membrane was then attached to the side of a gallium arsenide substrate away from the back electrode and dried at 70°C to form a back electrode-gallium arsenide substrate-carbon nanotube membrane composite structure. The back electrode-gallium arsenide substrate-carbon nanotube membrane composite structure was then used as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum electrode as the counter electrode to form a three-electrode system. Electrochemical deposition was then performed in an aqueous dispersion of sheet-like graphene oxide (sheet diameter 1nm~50nm) at a concentration of 0.1mg / mL under conditions of -1.5V~0.6V, with one electrochemical deposition cycle. The gallium arsenide substrate was then removed, washed, and dried to form a carbon nanotube-graphene oxide composite layer (thickness approximately 150nm) on the side of the gallium arsenide substrate away from the back electrode.

[0036] 3) The silver paste is uniformly coated on the surface of the carbon nanotube-graphene oxide composite layer and then dried at 90°C to form the front electrode, thus obtaining the gallium arsenide heterojunction solar cell.

[0037] Performance testing:

[0038] The photovoltaic conversion efficiency of the gallium arsenide heterojunction solar cell in this embodiment was tested using a solar simulation test system consisting of a Keithley 2400 digital source meter and a 3A solar simulator (Oriel, Newport). The radiant power under AM 1.5G conditions was 100 mW·cm⁻¹. -2 Using a standard silicon solar cell as calibration, this system applies voltage to the upper and lower electrodes of a GaAs / CNT heterojunction. Under illumination, the voltage value is varied to control the change in the heterojunction interface barrier, and the corresponding current (density) is recorded. The resulting short-circuit current density-open-circuit voltage relationship curve is shown below. Figure 2 As shown.

[0039] Depend on Figure 2 It can be seen that the open-circuit voltage V of the gallium arsenide heterojunction solar cell in this embodiment is... oc The voltage is 0.69V, and the short-circuit current density is J. sc 22.99 mA·cm-2 The fill factor FF is 56.36%, and the photoelectric conversion efficiency is 8.45%.

[0040] Example 2:

[0041] A gallium arsenide heterojunction solar cell is identical to Example 1 except that the number of electrochemical deposition cycles in step 2) is changed from "1 cycle" to "2 cycles".

[0042] Performance testing (testing method is the same as in Example 1):

[0043] The short-circuit current density-open-circuit voltage curve of the gallium arsenide heterojunction solar cell in this embodiment is as follows: Figure 2 As shown.

[0044] Depend on Figure 2 It can be seen that the open-circuit voltage V of the gallium arsenide heterojunction solar cell in this embodiment is... oc The voltage is 0.75V, and the short-circuit current density is J. sc 26.88 mA·cm -2 The fill factor FF is 68.35%, and the photoelectric conversion efficiency is 13.08%.

[0045] Example 3:

[0046] A gallium arsenide heterojunction solar cell is identical to Example 1 except that the number of electrochemical deposition cycles in step 2) is changed from "1 cycle" to "5 cycles".

[0047] Performance testing (testing method is the same as in Example 1):

[0048] The short-circuit current density-open-circuit voltage curve of the gallium arsenide heterojunction solar cell in this embodiment is as follows: Figure 2 As shown.

[0049] Depend on Figure 2 It can be seen that the open-circuit voltage V of the gallium arsenide heterojunction solar cell in this embodiment is... oc The voltage is 0.75V, and the short-circuit current density is J. sc 27.44 mA·cm -2 The fill factor FF is 65.67%, and the photoelectric conversion efficiency is 12.79%.

[0050] Example 4:

[0051] A gallium arsenide heterojunction solar cell is identical to Example 1 except that the number of electrochemical deposition cycles in step 2) is changed from "1 cycle" to "10 cycles".

[0052] Performance testing (testing method is the same as in Example 1):

[0053] The short-circuit current density-open-circuit voltage curve of the gallium arsenide heterojunction solar cell in this embodiment is as follows: Figure 2 As shown.

[0054] Depend on Figure 2 It can be seen that the open-circuit voltage V of the gallium arsenide heterojunction solar cell in this embodiment is... oc The voltage is 0.71V, and the short-circuit current density is J. sc 18.24 mA·cm -2 The fill factor FF is 67.82%, and the photoelectric conversion efficiency is 8.29%.

[0055] Comparative example:

[0056] A gallium arsenide heterojunction solar cell is identical to the gallium arsenide heterojunction solar cell of Example 1, except that the carbon nanotube-graphene oxide composite layer is replaced with a carbon nanotube layer of the same thickness.

[0057] Performance testing (testing method is the same as in Example 1):

[0058] The short-circuit current density-open-circuit voltage curve of the gallium arsenide heterojunction solar cell in this comparative example is shown below. Figure 2 As shown.

[0059] Depend on Figure 2 It can be seen that the open-circuit voltage V of the gallium arsenide heterojunction solar cell in this comparative example is... oc The voltage is 0.72V, and the short-circuit current density is J. sc 26.50 mA·cm -2 The fill factor FF is 36.81%, and the photoelectric conversion efficiency is 6.67%.

[0060] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for fabricating a gallium arsenide heterojunction solar cell, characterized in that, Includes the following steps: 1) Electrode material is deposited on one side of a gallium arsenide substrate to form a back electrode; 2) The carbon nanotube dispersion was filtered to form a carbon nanotube membrane. The carbon nanotube membrane was then attached to the side of the gallium arsenide substrate away from the back electrode to form a back electrode-gallium arsenide substrate-carbon nanotube membrane composite structure. The back electrode-gallium arsenide substrate-carbon nanotube membrane composite structure was used as the working electrode, the Ag / AgCl electrode as the reference electrode, and the platinum electrode as the counter electrode to form a three-electrode system. The system was then placed in a sheet-like graphene oxide dispersion for electrochemical deposition to form a carbon nanotube-graphene oxide composite layer on the side of the gallium arsenide substrate away from the back electrode. 3) Electrode materials are deposited on the surface of carbon nanotube-graphene oxide composite layer to form a front electrode, thus obtaining a gallium arsenide heterojunction solar cell. The gallium arsenide heterojunction solar cell comprises a back electrode, a gallium arsenide substrate, a carbon nanotube-graphene oxide composite layer, and a front electrode stacked sequentially; the carbon nanotube-graphene oxide composite layer comprises carbon nanotubes and sheet-like graphene oxide.

2. The preparation method according to claim 1, characterized in that: Step 2) The concentration of the carbon nanotube dispersion is 1×10⁻⁶. -3 mg / mL~3×10 -3 mg / mL; Step 2) The concentration of the sheet-like graphene oxide dispersion is 0.01 mg / mL to 0.2 mg / mL.

3. The preparation method according to claim 1 or 2, characterized in that: Step 2) The electrochemical deposition is performed under a voltage of -1.5V to 0.6V, and the number of electrochemical deposition cycles is 1 to 15.

4. The preparation method according to claim 1, characterized in that: The carbon nanotubes have a length of 1 μm to 3 μm and a diameter of 1 nm to 2 nm.

5. The preparation method according to claim 1 or 4, characterized in that: The sheet-like graphene oxide has a sheet diameter of 1 nm to 50 nm.

6. The preparation method according to claim 1 or 4, characterized in that: The thickness of the carbon nanotube-graphene oxide composite layer is 50 nm to 250 nm.

7. The preparation method according to claim 1 or 4, characterized in that: The back electrode is composed of at least one of the following: gold, silver, titanium, copper, nickel, platinum, antimony tin oxide, and aluminum doped with zinc oxide.

8. The preparation method according to claim 1 or 4, characterized in that: The front electrode is composed of at least one of the following: gold, silver, titanium, copper, nickel, platinum, antimony tin oxide, and aluminum doped with zinc oxide.

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