Optical thin film structure and preparation method

Abstract

The invention discloses an optical thin film structure and a preparation method, and belongs to the field of photovoltaic technology, the optical thin film structure comprises a silicon wafer, an aluminum oxide layer and three layers of ultraviolet cut-off thin films, the aluminum oxide layer is arranged on the silicon wafer, and the three layers of ultraviolet cut-off thin films are stacked on the aluminum oxide layer. Each layer of ultraviolet cut-off film comprises a SiO2 layer and a SiNx layer arranged on the SiO2 layer, and the three layers of ultraviolet cut-off films which are prepared by alternately preparing SiO2 with high refractive index and SiNx with low refractive index and are suitable for solar cell industrialization are deposited on the aluminum oxide layer of the silicon wafer, so that the light in the ultraviolet band can be filtered; and the influence of light of an ultraviolet band on cell attenuation is reduced or even eliminated.

Description

Technical Field

[0001] The present invention belongs to the field of photovoltaic technology, and in particular relates to an optical thin film structure and a preparation method thereof. Background Art

[0002] The anti-reflection film of solar cells can affect the photoelectric conversion efficiency of solar cells. The anti-reflection film is mainly used to reduce the reflection loss of light. In solar cells, the reflection loss of light is one of the important factors limiting its efficiency. Therefore, reducing the reflection loss by coating the anti-reflection film on the surface of the cell has become an effective method.

[0003] However, the current anti-reflection film on the front of the solar cell cannot filter out the light in the ultraviolet band, which will cause the cell to be severely attenuated after being affected by the ultraviolet band. Summary of the Invention

[0004] To solve the problems raised in the above background technology, the present invention provides an optical thin film structure and a preparation method to solve the problem in the prior art that the anti-reflection film on the front of the solar cell cannot filter out light in the ultraviolet band.

[0005] To achieve the above object, the present invention provides the following technical solutions: An optical thin film structure, comprising: silicon wafers; Aluminum oxide layer; the aluminum oxide layer is disposed on the silicon wafer; Three layers of ultraviolet cut-off film; the three layers of ultraviolet cut-off film are stacked on the aluminum oxide layer, and each layer of ultraviolet cut-off film includes a SiO2 layer and a SiNx layer arranged on the SiO2 layer.

[0006] Preferably, the three-layer UV cut-off film comprises: a first ultraviolet cutoff film; the first ultraviolet cutoff film is disposed on the aluminum oxide layer, the SiO2 layer of the first ultraviolet cutoff film has a thickness of 35 nm and a refractive index of 1.4, and the SiNx layer of the first ultraviolet cutoff film has a thickness of 57 nm and a refractive index of 2.15; a second UV cutoff film; the second UV cutoff film is disposed on the first UV cutoff film, the SiO2 layer of the second UV cutoff film having a thickness of 45 nm and a refractive index of 1.4, and the SiNx layer of the second UV cutoff film having a thickness of 38 nm and a refractive index of 2.15; The third UV cut-off film is provided on the second UV cut-off film, the SiO2 layer of the third UV cut-off film has a thickness of 90 nm and a refractive index of 1.4, and the SiNx layer of the third UV cut-off film has a thickness of 17 nm and a refractive index of 2.15.

[0007] A method for preparing an optical thin film structure comprises the following steps: S1: Prepare an aluminum oxide layer on the front side of the silicon wafer; S2: Place the silicon wafer with the aluminum oxide layer prepared face up into the deposition chamber of the PECVD equipment, and set the temperature in the deposition chamber to a preset value; S3: adjusting the pressure in the deposition chamber to a first preset pressure, continuously introducing a first preset flow rate of silane and a second preset flow rate of nitrous oxide into the deposition chamber, and performing SiO2 layer deposition at a first preset deposition power for a preset time; S4: adjusting the pressure in the deposition chamber to a second preset pressure, continuously introducing a third preset flow rate of silane and a second preset flow rate of ammonia into the deposition chamber, and performing SiNx layer deposition at the second preset deposition power for a preset time; S5: Repeat S3-S4 until three stacked UV cut-off films are deposited on the aluminum oxide layer, each UV cut-off film consisting of a SiO2 layer and a SiNx layer disposed on the SiO2 layer.

[0008] Preferably, the preset temperature value is 450°C.

[0009] Preferably, the first preset flow rate is 700 sccm, the second preset flow rate is 9000 sccm, and the third preset flow rate is 2000 sccm.

[0010] Preferably, the first preset pressure is 12300 mBar, and the second preset pressure is 12500 mBar.

[0011] Preferably, the first preset deposition power is 12500W, and the second preset deposition power is 11700W.

[0012] Preferably, the deposition time of the SiO2 layer and the SiNx layer of the first UV cutoff film is 35 min and 28 min respectively, the deposition time of the SiO2 layer and the SiNx layer of the second UV cutoff film is 45 min and 20 min respectively, and the deposition time of the SiO2 layer and the SiNx layer of the third UV cutoff film is 90 min and 9 min respectively.

[0013] Compared with the prior art, the present invention has the following beneficial effects: This application sets a three-layer UV cutoff film suitable for the industrialization of solar cells on the aluminum oxide layer of the silicon wafer. The three-layer UV cutoff film is made of alternating high-refractive index SiO2 and low-refractive index SiNx, which can filter out light in the ultraviolet band and reduce or even eliminate the impact of ultraviolet band light on battery attenuation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the structure of the optical film; The following are marked in the figure: 1-silicon wafer; 2-aluminum oxide layer; 3-first UV cutoff film; 4-second UV cutoff film; 5-third UV cutoff film. DETAILED DESCRIPTION

[0015] To facilitate those skilled in the art to understand the technical content of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific examples. It should be understood that the specific examples described herein are only used to explain the present invention and are not intended to limit the present invention.

[0016] like Figure 1 As shown, an optical film structure includes: Silicon wafer 1; Aluminum oxide layer 2; aluminum oxide layer 2 is provided on silicon wafer 1; Three layers of ultraviolet cut-off film; the three layers of ultraviolet cut-off film are stacked on the aluminum oxide layer 2, and the three layers of ultraviolet cut-off film include; The first ultraviolet cut-off film 3 is provided on the aluminum oxide layer 2. The thickness of the SiO2 layer of the first ultraviolet cut-off film 3 is 35 nm and the refractive index is 1.4. The thickness of the SiNx layer of the first ultraviolet cut-off film 3 is 57 nm and the refractive index is 2.15. The second UV cut-off film 4 is provided on the first UV cut-off film 3. The SiO2 layer of the second UV cut-off film 4 has a thickness of 45 nm and a refractive index of 1.4. The SiNx layer of the second UV cut-off film 4 has a thickness of 38 nm and a refractive index of 2.15. The third UV cut-off film 5 is provided on the second UV cut-off film 4. The SiO2 layer of the third UV cut-off film 5 has a thickness of 90 nm and a refractive index of 1.4. The SiNx layer of the third UV cut-off film 5 has a thickness of 17 nm and a refractive index of 2.15.

[0017] A method for preparing an optical thin film structure comprises the following steps: S1: preparing an aluminum oxide layer 2 on the front side of a silicon wafer 1; S2: Place the silicon wafer 1 with the aluminum oxide layer 2 formed thereon face-up into the deposition chamber of the PECVD equipment, and set the temperature in the deposition chamber to 450° C. S3: Adjust the pressure in the deposition chamber to 12,300 mBar, continuously introduce 700 sccm of silane and 9,000 sccm of nitrous oxide into the deposition chamber, and deposit the SiO2 layer at a deposition power of 12,500 W for a preset time. S4: The pressure in the deposition chamber is adjusted to 12500 mBar, silane at a set flow rate of 2000 sccm and ammonia at 9000 sccm are continuously introduced into the deposition chamber, and a SiNx layer is deposited at a deposition power of 11700 W for a preset time; S5: Repeat S3-S4 until three stacked UV cut-off films are deposited on the aluminum oxide layer 2, each UV cut-off film consisting of a SiO2 layer and a SiNx layer arranged on the SiO2 layer. The deposition time of the SiO2 layer and the SiNx layer of the first UV cut-off film 3 is 35 minutes and 28 minutes respectively, the deposition time of the SiO2 layer and the SiNx layer of the second UV cut-off film 4 is 45 minutes and 20 minutes respectively, and the deposition time of the SiO2 layer and the SiNx layer of the third UV cut-off film 5 is 90 minutes and 9 minutes respectively.

[0018] In the present application, a three-layer UV cutoff film suitable for the industrialization of solar cells is arranged on the aluminum oxide layer 2 of the silicon wafer 1. The three-layer UV cutoff film is made of alternating high-refractive-index SiO2 and low-refractive-index SiNx, which can filter out light in the ultraviolet band, reduce or even eliminate the impact of ultraviolet light on battery attenuation. In actual applications, the thickness and refractive index of each SiO2 layer and SiNx layer are controlled to fluctuate within 5% of the values ​​shown in this specific embodiment to achieve a good filtering effect of ultraviolet light.

Claims

1. An optical film structure, characterized in that: include: Silicon wafer (1); Aluminum oxide layer (2); An aluminum oxide layer (2) is disposed on a silicon wafer (1); Three layers of UV cut-off film; Three layers of ultraviolet cut-off films are stacked and arranged on the aluminum oxide layer (2), and each layer of ultraviolet cut-off film comprises a SiO2 layer and a SiNx layer arranged on the SiO2 layer.

2. An optical film structure according to claim 1, characterized in that: The three-layer UV cut-off film includes; A first ultraviolet cutoff film (3); the first ultraviolet cutoff film (3) is arranged on the aluminum oxide layer (2); the SiO2 layer of the first ultraviolet cutoff film (3) has a thickness of 35 nm and a refractive index of 1.4; the SiNx layer of the first ultraviolet cutoff film (3) has a thickness of 57 nm and a refractive index of 2.15; A second ultraviolet cut-off film (4); the second ultraviolet cut-off film (4) is arranged on the first ultraviolet cut-off film (3); the SiO2 layer of the second ultraviolet cut-off film (4) has a thickness of 45 nm and a refractive index of 1.4; the SiNx layer of the second ultraviolet cut-off film (4) has a thickness of 38 nm and a refractive index of 2.15; A third ultraviolet cut-off film (5); the third ultraviolet cut-off film (5) is arranged on the second ultraviolet cut-off film (4); the SiO2 layer of the third ultraviolet cut-off film (5) has a thickness of 90 nm and a refractive index of 1.4; the SiNx layer of the third ultraviolet cut-off film (5) has a thickness of 17 nm and a refractive index of 2.

15.

3. A method for preparing an optical thin film structure, applied to an optical thin film structure as claimed in any one of claims 1 to 2, characterized in that: The following steps are involved: S1: preparing an aluminum oxide layer (2) on the front side of a silicon wafer (1); S2: placing the silicon wafer (1) on which the aluminum oxide layer (2) is prepared with its front side facing upward into a deposition chamber of a PECVD device, and setting the temperature in the deposition chamber to a preset value; S3: adjusting the pressure in the deposition chamber to a first preset pressure, continuously introducing a first preset flow rate of silane and a second preset flow rate of nitrous oxide into the deposition chamber, and performing SiO2 layer deposition at a first preset deposition power for a preset duration; S4: adjusting the pressure in the deposition chamber to a second preset pressure, continuously introducing a third preset flow rate of silane and a second preset flow rate of ammonia into the deposition chamber, and performing SiNx layer deposition at the second preset deposition power for a preset time; S5: Repeat S3-S4 until three stacked UV cut-off films are deposited on the aluminum oxide layer (2), each UV cut-off film consisting of a SiO2 layer and a SiNx layer disposed on the SiO2 layer.

4. The method for preparing an optical thin film structure according to claim 3, characterized in that: In S2, the preset value of the temperature is 450°C.

5. The method for preparing an optical thin film structure according to claim 4, characterized in that: The first preset flow rate is 700 sccm, the second preset flow rate is 9000 sccm, and the third preset flow rate is 2000 sccm.

6. The method for preparing an optical thin film structure according to claim 5, characterized in that: The first preset pressure is 12300 mbar, and the second preset pressure is 12500 mbar.

7. The method for preparing an optical thin film structure according to claim 6, characterized in that: The first preset deposition power is 12500W, and the second preset deposition power is 11700W.

8. The method for preparing an optical thin film structure according to claim 7, characterized in that: The deposition time of the SiO2 layer and the SiNx layer of the first UV cutoff film (3) is 35 min and 28 min respectively, the deposition time of the SiO2 layer and the SiNx layer of the second UV cutoff film (4) is 45 min and 20 min respectively, and the deposition time of the SiO2 layer and the SiNx layer of the third UV cutoff film (5) is 90 min and 9 min respectively.

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