CN106601854A - Heterojunction solar cell and manufacturing method thereof - Google Patents

Abstract

The invention discloses a heterojunction solar cell and a preparation method thereof. The heterojunction solar cell comprises a silicon substrate, an aluminum oxide film is arranged on the silicon substrate, and a gallium nitride film is arranged on the aluminum oxide film to form GaN /Al ₂ O ₃ /Si heterojunction structure. The preparation method includes polishing, depositing aluminum oxide film, annealing, depositing gallium nitride film, preparing ITO transparent conductive film and silver grid line electrode. The heterojunction solar cell of the present invention has a GaN/Al ₂ O ₃ /Si heterojunction structure, which effectively solves the carrier recombination caused by the lattice mismatch between the gallium nitride and the silicon substrate, and greatly The minority carrier lifetime of the heterojunction battery is improved, and the preparation method has the advantages of simple process and the like.

Description

A kind of heterojunction solar cell and its preparation method

technical field

The invention belongs to the technical field of solar cell device manufacturing, and in particular relates to a heterojunction solar cell and a preparation method thereof.

Background technique

At present, the highest conversion efficiency of silicon-based solar cells in the photovoltaic industry has reached 26.33%, which is quite close to the theoretical efficiency limit of 29% for silicon-based solar cells. For the existing silicon-based solar cells, it is difficult to further improve the conversion efficiency.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a heterojunction solar cell with simple preparation process and high conversion efficiency and a preparation method thereof.

In order to solve the problems of the technologies described above, the technical solution adopted in this application is:

A heterojunction solar cell, the heterojunction solar cell comprises a silicon substrate, an aluminum oxide film is provided on the silicon substrate, and a gallium nitride film is provided on the aluminum oxide film to form a GaN/ _Al2 O ₃ /Si heterojunction structure.

In the above-mentioned heterojunction solar cell, preferably, the thickness of the aluminum oxide thin film is 1 nm to 2 nm.

In the above heterojunction solar cell, preferably, the gallium nitride thin film has a thickness of 100 μm to 300 μm.

As a general technical idea, the present invention also provides a method for preparing the above-mentioned heterojunction solar cell, comprising the following steps:

(1) Polish the surface of the silicon wafer;

(2) Depositing an aluminum oxide film on the surface of the polished silicon wafer in step (1);

(3) annealing the silicon wafer with the aluminum oxide film deposited on the surface obtained in step (2);

(4) depositing a gallium nitride film on the surface of the annealed aluminum oxide film in step (3);

(5) Prepare a layer of ITO transparent conductive film and silver grid line electrodes on the gallium nitride film obtained in step (4).

In the above preparation method, preferably, in the step (2), the aluminum oxide thin film is deposited by atomic layer deposition; in the atomic layer deposition method, the deposition temperature is 150°C-250°C.

In the above preparation method, preferably, in the step (1), alkaline solution is used for polishing; the polishing temperature is 70° C. to 90° C., and the polishing time is 1 minute to 4 minutes.

In the above preparation method, preferably, the alkaline solution is sodium hydroxide solution or potassium hydroxide solution.

In the above preparation method, preferably, in the step (3), the annealing is carried out under the protection of an argon atmosphere; the annealing temperature is 400°C-500°C, and the time is 20min-40min.

In the above preparation method, preferably, in the step (4), the MOCVD method is used to deposit the gallium nitride thin film; the deposition of the gallium nitride thin film includes the following steps: first grow a Gallium nitride with a layer thickness of 25 nanometers is then grown at a temperature between 900°C and 1200°C.

In the above preparation method, preferably, in the step (5), the ITO transparent conductive film is prepared by an electron beam evaporation method; the silver grid electrode is prepared by an electron beam evaporation method.

Compared with the prior art, the advantages of the present application are:

1. The present invention provides a heterojunction solar cell, which includes a silicon substrate, an aluminum oxide film is provided on the silicon substrate, and a gallium nitride film is provided on the aluminum oxide film to form a GaN/Al ₂ O ₃ /Si heterojunction Mass junction structure, in which the GaN/Al ₂ O ₃ /Si heterojunction structure effectively solves the carrier recombination caused by the lattice mismatch between gallium nitride and silicon substrate, greatly improving the heterogeneity The minority carrier lifetime of the junction cell. In addition, the thickness of the aluminum oxide film in the present invention is only 1-2 nanometers, which ensures the electron transmission between the gallium nitride and the silicon substrate, and improves the current of the GaN/Al ₂ O ₃ /Si heterojunction structure. The present invention aims to break through the structure of existing silicon-based solar cells, and adopts a novel GaN/Al ₂ O ₃ /Si heterojunction structure to obtain a heterojunction solar cell with excellent electrical properties, thereby further improving the silicon Improve the conversion efficiency of the base solar cell and reduce the production cost of the solar cell.

2. The present invention also provides a method for preparing a heterojunction solar cell. Compared with conventional silicon-based solar cells, the method has the advantages of simple manufacturing method and low manufacturing cost, and only 5 process steps are required. At the same time, in the preparation method of the present invention, the aluminum oxide film is deposited by ALD, which ensures the uniformity of the aluminum oxide film.

Description of drawings

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, 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.

Fig. 1 is a schematic diagram of the heterojunction solar cell of the present invention.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

The raw materials and instruments used in the following examples are all commercially available.

Example 1

A kind of heterojunction solar cell of the present invention, as shown in Figure 1, this heterojunction solar cell comprises a silicon substrate, an aluminum oxide film is provided on the silicon substrate, a gallium nitride film is provided on the aluminum oxide film, forming GaN/Al ₂ O ₃ /Si heterojunction structure.

In this embodiment, the aluminum oxide thin film has a thickness of 2 nm; the gallium nitride thin film has a thickness of 150 μm.

A method for preparing the heterojunction solar cell in the above embodiment of the present invention, comprising the following steps:

(1) Polish the surface of the silicon wafer with a potassium hydroxide solution with a mass concentration of 10%, wherein the polishing temperature is 80°C, and the polishing time is 2 minutes.

(2) Deposit a layer of 2nm aluminum oxide film on the surface of the polished silicon wafer in step (1) by atomic layer deposition (ALD), and the deposition temperature is 200°C.

(3) Under the protection of an argon atmosphere, anneal the silicon wafer with the aluminum oxide film deposited on the surface obtained in step (2) at a temperature of 425° C., and the annealing time is 30 minutes.

(4) Using MOCVD to grow a layer of gallium nitride film on the surface of the annealed aluminum oxide film in step (3), the specific steps are: first grow a layer of 25 nm gallium nitride at a temperature of 550 ° C, and then Growth is performed at a temperature of 1050° C. until the thickness of the GaN thin film is 150 μm.

(5) First deposit a layer of ITO transparent conductive film on the gallium nitride film obtained in step (4) by electron beam evaporation method, and then prepare silver grid wire electrodes on the front and back sides by electron beam evaporation method, A heterojunction solar cell is obtained, that is, a heterojunction solar cell with a GaN/Al ₂ O ₃ /Si heterojunction structure.

After testing, the open circuit voltage of the heterojunction solar cell prepared in this embodiment can reach 480mV.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with the art, without departing from the spirit and technical solutions of the present invention, can use the methods and technical content disclosed above to make many possible changes and modifications to the technical solutions of the present invention, or modify them to be equivalent Variations of equivalent embodiments. Therefore, any simple modifications, equivalent replacements, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention, which do not deviate from the technical solutions of the present invention, still fall within the protection scope of the technical solutions of the present invention.

Claims (10)

1. A heterojunction solar cell, characterized in that, the heterojunction solar cell comprises a silicon substrate, an aluminum oxide film is provided on the silicon substrate, and a gallium nitride film is provided on the aluminum oxide film , forming a GaN/Al ₂ O ₃ /Si heterojunction structure. 2 . The heterojunction solar cell according to claim 1 , wherein the aluminum oxide thin film has a thickness of 1 nm˜2 nm. 3 . 3. The heterojunction solar cell according to claim 1 or 2, characterized in that the gallium nitride thin film has a thickness of 100 μm˜300 μm. 4. A method for preparing a heterojunction solar cell according to any one of claims 1 to 3, characterized in that it comprises the following steps: (1) Polish the surface of the silicon wafer; (2) Depositing an aluminum oxide film on the surface of the polished silicon wafer in step (1); (3) annealing the silicon wafer with the aluminum oxide film deposited on the surface obtained in step (2); (4) depositing a gallium nitride film on the surface of the annealed aluminum oxide film in step (3); (5) Prepare a layer of ITO transparent conductive film and silver grid line electrodes on the gallium nitride film obtained in step (4). 5. The preparation method according to claim 4, characterized in that, in the step (2), the aluminum oxide film is deposited by atomic layer deposition; in the atomic layer deposition method, the deposition temperature is 150°C-250°C . 6 . The preparation method according to claim 4 or 5 , characterized in that, in the step (1), alkaline solution is used for polishing; the polishing temperature is 70° C. to 90° C. and the time is 1 min to 4 min. 6 . 7. The preparation method according to claim 6, characterized in that, the alkaline solution is sodium hydroxide solution or potassium hydroxide solution. 8. The preparation method according to claim 4 or 5, characterized in that, in the step (3), the annealing is carried out under the protection of an argon atmosphere; the annealing temperature is 400°C-500°C, and the time is It is 20min ~ 40min. 9. The preparation method according to claim 4 or 5, characterized in that, in the step (4), the gallium nitride thin film is deposited by MOCVD; the deposition of the gallium nitride thin film comprises the following steps: first at a temperature A layer of gallium nitride with a thickness of 25 nanometers is grown at 500°C-600°C, and then grown at a temperature of 900°C-1200°C. 10. The preparation method according to claim 4 or 5, characterized in that, in the step (5), the ITO transparent conductive film is prepared by electron beam evaporation; the silver grid electrode is prepared by electron beam Prepared by evaporation method.