Photovoltaic nanocolumn structure and solar cell based on the structure

Abstract

The present invention discloses a photovoltaic nanocolumn structure and a solar cell based on the structure, wherein the nanocolumn structure is an irregular column whose diameter changes periodically along the vertical direction, the irregular column is symmetrical along the central axis, and the cross section in the horizontal direction always remains circular, and the difference between the maximum diameter and the minimum diameter of the irregular column is 80nm to 120nm. The present invention has stronger light absorption capacity and higher light conversion efficiency.

Description

Technical Field

[0001] The invention relates to a solar cell, and in particular to a photovoltaic nanocolumn structure and a solar cell based on the structure. Background Art

[0002] One of the biggest challenges facing mankind in the 21st century is the transition from an energy system based on fossil fuels to an energy system based on sustainable and renewable resources. Solar cells that can directly convert sunlight into electrical energy play an important role in this process. Photovoltaic technology has also developed rapidly and been widely used.

[0003] People are constantly looking for new methods and technologies to manufacture high-efficiency and low-cost solar cells. In recent years, the application of nanostructured materials in solar cells has attracted the attention of scholars. In the past decade, nanocolumn solar cells have developed rapidly. The photoelectric conversion efficiency of solar cells has also been greatly improved, from 5% to more than 15%. In the process of continuous development of nanomaterials, the nanocolumn structure of photovoltaic devices has also developed rapidly. Photovoltaic devices with higher light energy conversion efficiency can be prepared with less material and lower cost. And the characteristics of the nanocolumn structure also make solar cells have stronger optical absorption and produce high photoelectric conversion efficiency. Further optimizing the nanocolumn structure and improving the material are of great significance to enhancing optical absorption and improving light energy conversion efficiency. In the nanocolumn structure, the diameter of the nanocolumn has the greatest influence on its optical mode. The optical resonance of the existing simple cylindrical nanocolumn structure only occurs at a specific resonance wavelength, and the optical absorption is only enhanced in a specific area. Summary of the invention

[0004] Purpose of the invention: In view of the problems existing in the prior art, the present invention provides a photovoltaic nanocolumn structure and a solar cell based on the structure. The nanocolumns and cells of the present invention have better optical absorption effect and higher light energy conversion efficiency.

[0005] Technical solution: The present invention provides a photovoltaic nanocolumn structure, which is an irregular column whose diameter changes periodically along the vertical direction. The irregular column is symmetrical along the central axis, and the cross-section in the horizontal direction always remains circular. The difference between the maximum diameter and the minimum diameter of the irregular column is 80nm to 120nm.

[0006] The present invention also provides another nanocolumn structure, wherein the top is a cylinder, and below the cylinder is an irregular cylinder whose diameter changes periodically along the vertical direction. The irregular cylinder is symmetrical along the central axis, and the cross-section in the horizontal direction always remains circular. The difference between the maximum diameter and the minimum diameter of the irregular cylinder is between 80nm and 120nm, and the diameter of the top cylinder is 1 / 15 to 1 / 5 of the maximum diameter of the irregular cylinder below.

[0007] In the above two nanocolumn structures, the periodic changes of the irregular columns are specifically periodic changes in sinusoidal function patterns, or periodic changes in linear function patterns, or periodic changes in constant function patterns along the vertical direction. The maximum diameter is 460nm to 660nm. The diameter change period is 500nm to 800nnm, and the diameter of the cylinder is 40nm to 80nm. The nanocolumn structure is a semiconductor nanocolumn, and the material is any one of Si, Ge, GaAS, and GaN. Vacancy defects are introduced into the material crystal of the nanocolumn structure.

[0008] The present invention also provides a solar cell, wherein the nanocolumn of the solar cell is one of the two photovoltaic nanocolumn structures mentioned above.

[0009] Beneficial effects: The present invention greatly increases the optical path by adopting a structure with periodic diameter changes in the nanocolumn structure, which is particularly beneficial for non-incident sunlight, enhances the light absorption capacity, and makes the light energy conversion efficiency higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a structural diagram of an embodiment of a photovoltaic nanocolumn structure provided by the present invention;

[0011] Figure 2 is a schematic diagram of the variation of light energy absorption rate of nanorods with diameter;

[0012] Figure 3 is a structural diagram of another embodiment of the photovoltaic nanorod structure provided by the present invention;

[0013] Figure 4 is a structural diagram of another embodiment of the photovoltaic nanocolumn structure provided by the present invention;

[0014] Figure 5 It is a structural diagram of yet another embodiment of the photovoltaic nanocolumn structure provided by the present invention. DETAILED DESCRIPTION

[0015] Example 1

[0016] This embodiment provides a photovoltaic nanocolumn structure, which is a semiconductor nanocolumn, and the material is any one of Si, Ge, GaAS, and GaN. Figure 1 As shown, the nanocolumn structure is an irregular column whose diameter changes in a periodic sinusoidal function pattern along the vertical direction. The irregular column is symmetrical along the central axis, and the horizontal cross section always remains circular. The maximum diameter d of the irregular column max With minimum diameter d min The difference is 80nm~120nm. The maximum diameter d maxThe diameter of the nanorod is 460nm to 660nm, and the diameter variation period T is 500nm to 800nm. Due to the periodic variation characteristics of this embodiment, light can be reflected multiple times after entering the nanorod, which prolongs the optical path. The optical resonance is also stronger than that of ordinary cylindrical nanorods, which enhances the optical absorption capacity, especially for non-incident light. In order to further increase the light absorption efficiency, vacancy defects are artificially introduced into the material crystal of the nanorod structure.

[0017] The maximum diameter dmax, minimum diameter dmin, and diameter variation period T of the irregular cylinder were experimentally compared and it was found that when the diameter is 80-800nm, the optical absorption effect is as follows: Figure 2 Through experiments, it is found that the diameter of the nano-column is related to the light energy absorption rate. When the diameter of the cylinder is 560nm, the absorption rate is the highest, that is, the effect is the best. When the diameter is less than 560nm, the smaller the diameter, the smaller the absorption rate. When the diameter is greater than 560nm, the absorption rate will decrease.

[0018] Example 2

[0019] This embodiment provides a nanocolumn structure, which is a semiconductor nanocolumn, and the material is any one of Si, Ge, GaAS, and GaN. Figure 3 As shown, the top is a cylinder, and below the cylinder is an irregular cylinder whose diameter changes in a sinusoidal function pattern along the vertical direction.

[0020] The diameter of the top cylinder is 40nm to 80nm. Sunlight enters from the top cylinder and enters the lower irregular cylinder, so that photons are absorbed by the material as much as possible, thereby improving the light energy conversion efficiency. The diameter of the top cylinder is 1 / 15 to 1 / 5 of the maximum diameter of the lower irregular cylinder, that is, the diameter of the top cylinder is much smaller than the diameter of the lower irregular cylinder, so that the photons of the top cylinder are not easy to be emitted from the upper surface, that is, it has a low reflectivity, so that the solar energy is irradiated to the surface of the material, which is conducive to effective photon capture and downward transmission to the lower irregular cylinder, generating more photogenerated carriers, and greatly improving the light energy conversion efficiency of the solar cell. Through experiments, it is found that the diameter of the top cylinder is related to the reflectivity. When the diameter of the top cylinder is 60nm, the reflectivity is the lowest, that is, the effect is the best. The larger the diameter, the greater the reflectivity. When the diameter is less than 40nm, the reflectivity will increase accordingly, and a cylinder with too small a diameter may not be made in practical applications.

[0021] The irregular cylinder is symmetrical along the central axis, and the horizontal cross section always remains circular. The maximum diameter d of the irregular cylinder is max With minimum diameter d min The difference is 80nm~120nm. The maximum diameter d maxThe diameter of the nanorod is 460nm to 660nm, and the diameter variation period T is 500nm to 800nm. Due to the periodic variation of the structure, light can be reflected multiple times after entering the nanorod, which prolongs the optical path. The optical resonance is also stronger than that of ordinary cylindrical nanorods, which enhances the optical absorption capacity, especially for non-directed incident light. In order to further increase the light absorption efficiency, vacancy defects are artificially introduced into the material crystal of the nanorod structure.

[0022] Example 3

[0023] This embodiment provides a photovoltaic nanocolumn structure. The difference between this embodiment and embodiment 2 is that: Figure 4 As shown, the nanocolumn structure is an irregular column whose diameter changes in a periodic linear function pattern along the vertical direction, and the other parts are the same as those of Example 2. Due to the periodic change characteristics of the structure of this embodiment, light can be reflected multiple times after entering the nanocolumn, which prolongs the optical path, and the optical resonance is stronger than that of ordinary cylindrical nanocolumns, thereby enhancing the optical absorption capacity, which is particularly beneficial for non-illegally incident light.

[0024] Example 4

[0025] This embodiment provides a photovoltaic nanocolumn structure. The difference between this embodiment and embodiment 2 is that: Figure 5 As shown, the nanocolumn structure is an irregular column whose diameter changes in a periodic constant function pattern along the vertical direction, and the other parts are the same as those of Example 2. Due to the periodic change characteristics of the structure of this embodiment, light can be reflected multiple times after entering the nanocolumn, which prolongs the optical path, and the optical resonance is stronger than that of ordinary cylindrical nanocolumns, thereby enhancing the optical absorption capacity, which is particularly beneficial for non-illegally incident light.

[0026] Example 5

[0027] This embodiment provides a solar cell, wherein the nanocolumns of the solar cell are any one of the above four photovoltaic nanocolumn structures.

[0028] The above disclosure is only the preferred embodiment of the present invention, which cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A photovoltaic nanocolumn structure, characterized in that: The nanocolumn structure is an irregular column whose diameter changes periodically along the vertical direction. The irregular column is symmetrical along the central axis, and the cross section in the horizontal direction always remains circular. The difference between the maximum diameter and the minimum diameter of the irregular column is 80nm to 120nm.

2. A photovoltaic nanocolumn structure, characterized in that: The top of the nanocolumn structure is a cylinder, and below the cylinder is an irregular cylinder whose diameter changes periodically along the vertical direction. The irregular cylinder is symmetrical along the central axis, and the cross-section in the horizontal direction always remains circular. The difference between the maximum diameter and the minimum diameter of the irregular cylinder is between 80nm and 120nm, and the diameter of the top cylinder is 1 / 15 to 1 / 5 of the maximum diameter of the irregular cylinder below.

3. The photovoltaic nanorod structure according to claim 1 or 2, characterized in that: The periodic change of the irregular column is specifically a periodic sinusoidal function pattern change, a periodic linear function pattern change, or a periodic constant function pattern change along the vertical direction.

4. The photovoltaic nanorod structure according to claim 1 or 2, characterized in that: The maximum diameter of the irregular column is 460nm-660nm.

5. The photovoltaic nanorod structure according to claim 2, characterized in that: The diameter of the cylinder is 40nm-80nm.

6. The photovoltaic nanorod structure according to claim 1 or 2, characterized in that: The diameter variation period of the irregular cylinder is 500nm-800nm.

7. The photovoltaic nanorod structure according to claim 1 or 2, characterized in that: The nanocolumn structure is a semiconductor nanocolumn, and the material is any one of Si, Ge, GaAS and GaN.

8. The photovoltaic nanorod structure according to claim 1 or 2, characterized in that: Vacancy defects are introduced into the material crystal of the nanorod structure.

9. A solar cell, characterized in that: The nanocolumn of the solar cell is the photovoltaic nanocolumn structure described in claim 1 or 2.

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