非晶硅薄膜太阳电池陷光结构的模拟与设计
发布时间：2019-07-02 12:27
【摘要】：与第一代晶体硅太阳电池相比，非晶硅薄膜太阳电池具有节省原材料、制备工艺简单，成本低廉等优势。但是，由于薄膜材料的缺陷态密度较高，厚的非晶硅层虽然能够较好的吸收入射光，但是加剧了复合，载流子的收集效率下降，因此，一般要求电池光吸收层的厚度小于其少数载流子的有效扩散长度；而过薄的非晶硅层显然不能充分吸收入射光，尤其是对带隙附近的光的吸收率很低，同样限制了电池的短路电流和光电转换效率。为了解决上述矛盾，必须为电池设计有效的陷光结构，在电池光吸收层的物理厚度不变的情况下，大大增加其光学厚度，这种电薄光厚的电池可以在保证载流子收集效率的同时，有效改善电池的光吸收。 本学位论文首先介绍了常用的非晶硅薄膜陷光技术，并重点综述了金属纳米结构表面产生的表面等离激元(Surface Plasmon，简称SP)在太阳电池陷光中的应用。在此基础上，分别将一维或二维周期性分布金属纳米结构(即金属纳米光栅)引入非晶硅薄膜电池的前表面或后表面，并结合传统的陷光技术，如减反膜、表面织构等，为非晶硅薄膜电池设计出了多种陷光结构。论文采用基于有限元法的COMSOL数值模拟软件，模拟了不同陷光结构太阳电池的光吸收。通过分析电池在不同波段的光子吸收率、吸收光谱、光吸收层中的电磁场分布以及金属纳米颗粒散射截面等，对上述几种陷光结构进行了优化，阐述了其陷光机理。本文取得的主要研究成果如下： (1)在非晶硅薄膜太阳电池前表面设计一维Ag纳米光栅：在TM波垂直入射的情况下，前表面有一维Ag纳米光栅的电池在短波段的光子吸收率较参考电池有一定下降，但在中长波段的光子吸收率则有较大幅度地提高；当光栅截面半径R=50nm，周期P=350nm时，电池总的光吸收较参考电池提高了29.5%。然而，在TE波入射下，由于Ag光栅表面不能产生表面等离激元，且Ag光栅本身对入射光的有一定的吸收和反射，导致电池在混合波入射时，整个入射光谱(300~800nm)范围内吸收的光子数仅为参考电池的92%。也就是说，在前表面引入一维Ag纳米光栅后，非晶硅薄膜太阳电池的光吸收反而降低。基于上述模拟结果，我们认为：在太阳电池陷光设计中，，不宜将一维金属纳米光栅置于电池前表面。 (2)复合陷光结构的设计与优化：在Ag背电极与硅薄膜之间制备一维金属纳米光栅,并通过保形生长在电池前表面沉积织构的减反膜，该复合陷光结构可获得较好的陷光效果。当背表面一维金属纳米光栅的横截面为三角形时，填充因子FF=0.5的光栅的陷光效果优于FF=1的光栅，与Al光栅相比，Ag光栅的效果更佳。当光栅横截面顶角为θ=80°，面积S=18750nm2时，电池在AM1.5太阳光谱垂直入射下总的光吸收较参考电池提高率Eabs达96%；当背表面一维Ag纳米光栅的横截面为矩形时，矩形高度H=90nm，宽度W=180nm，光栅的周期P=600nm时，Eabs达到最大值103%。上述复合陷光结构设计均可在宽光谱范围内提高非晶硅薄膜电池的光吸收，其中，中短波段光吸收的改善主要归因于前表面减反膜和表面织构的贡献，而长波段光子吸收率的提高则是Ag纳米光栅表面等离激元和波导模共同作用的结果。另外，上述复合陷光结构设计还较大地改善了非晶硅薄膜电池对太阳光入射角度的敏感性。 (3)周期性分布的Ag纳米颗粒对非晶硅薄膜电池光吸收的影响：将Ag纳米颗粒置于电池前表面时，在平面波垂直入射下，电池在中长波段的光子吸收率较参考电池有明显提高；其中，大颗粒在大的分布周期下陷光效果较好，当Ag纳米颗粒半径R取110nm，周期P取500nm时，Eabs达到最大值49%。将Ag纳米颗粒分别置于电池前后表面同一位置时，电池的Eabs可提升至55%。但是，该陷光结构电池对入射光的角度变化较敏感，要取得良好的陷光效果，应保持入射角度在30度以内。
[Abstract]:Compared with the first-generation crystalline silicon solar cell, the amorphous silicon thin-film solar cell has the advantages of saving raw materials, simple preparation process, low cost and the like. However, because the defect state density of the thin film material is high, the thick amorphous silicon layer can absorb the incident light well, but the recombination and the collector efficiency of the carriers are reduced, and therefore, the thickness of the light absorbing layer of the battery is generally required to be less than the effective diffusion length of the minority carriers; And the over-thin amorphous silicon layer obviously cannot fully absorb the incident light, especially the absorption rate of the light in the vicinity of the band gap is low, and the short-circuit current and the photoelectric conversion efficiency of the battery are also limited. In order to solve the above-mentioned contradiction, it is necessary to design an effective light-trapping structure for the battery, greatly increase the optical thickness of the light-absorbing layer of the battery under the condition that the physical thickness of the light-absorbing layer of the battery is not changed, and the light absorption of the battery can be effectively improved while ensuring the carrier collection efficiency. In this thesis, the common amorphous silicon thin-film light-trapping technology is introduced, and the surface plasmon (SP) generated on the surface of the metal nano-structure is mainly reviewed in the light of the solar cell. on the basis of which, a one-dimensional or two-dimensional periodic distribution metal nano-structure (i.e., a metal nano-grating) is introduced into the front surface or the back surface of the amorphous silicon thin-film battery, and the like, a plurality of light-trapping junctions are designed for an amorphous silicon thin-film battery, The paper adopts the COMSOL numerical simulation software based on the finite element method to simulate the light absorption of different light-trapping structure solar cells. By analyzing the photon absorption rate, the absorption spectrum, the distribution of the electromagnetic field in the light-absorbing layer and the scattering cross-section of the metal nano-particles, the light-trapping structure is optimized, and the light-trapping machine is described. The main research results in this paper are as follows: (1) One-dimensional Ag nano-grating is designed on the front surface of the amorphous silicon thin-film solar cell: in the case of vertical incidence of TM wave, one-dimensional Ag nano-grating in the front surface has one-dimensional Ag nano-grating, and the photon absorption rate of the cell in the short wave band is more than that of the reference cell. However, when the radius of the section of the grating is R = 50 nm and the period P = 350 nm, the total light absorption of the battery is higher than that of the reference cell. 5%. However, under the incidence of TE wave, the surface plasmon can not be generated on the surface of the Ag grating, and the Ag grating itself has a certain absorption and reflection on the incident light, so that the number of photons absorbed in the whole incident light spectrum (300-800 nm) is only the reference cell when the mixed wave is incident. 92%. That is, after the one-dimensional Ag nano-grating is introduced on the front surface, the light absorption of the amorphous silicon thin-film solar cell Based on the above simulation results, we believe that one-dimensional metal nano-grating is not suitable to be placed in the cell in the light-trapping design of the solar cell (2) The design and optimization of the composite light trapping structure: a one-dimensional metal nano-grating is prepared between the Ag back electrode and the silicon thin film, and the anti-reflection film of the texture is deposited on the front surface of the battery by a conformal growth, The light trapping effect of the grating with the filling factor of FF = 0.5 is better than that of the grating of FF = 1 when the cross section of the one-dimensional metal nano-grating of the back surface is triangular, and the Ag grating is compared with the Al grating. The effect is better. When the top angle of the cross-section of the grating is n = 80 掳 and the area S = 18750 nm2, the total light absorption under the vertical incidence of the solar spectrum of the AM1.5 is 96% higher than that of the reference cell. When the cross section of the one-dimensional Ag nano-grating on the back surface is rectangular, the height of the rectangle is H = 90 nm, the width W = 180 nm, and the period of the grating is P = 6. at 00 nm, Eabs is the maximum the light absorption of the amorphous silicon thin-film battery can be improved in a wide spectrum range, The contribution of the texture, while the increase of the long-band photon absorption rate is the same as the surface plasmon and waveguide mode of the Ag nano-grating. in addition, the structure of the composite light trapping structure also greatly improves the incident angle of the solar light of the amorphous silicon thin film battery, and (3) the influence of the periodically distributed Ag nano-particles on the light absorption of the amorphous silicon thin-film battery: when the Ag nano-particles are arranged on the front surface of the battery, the photon absorption rate of the battery in the middle long wave section is higher than that of the reference battery under the plane wave vertical incidence; The results show that, when the radius R of the Ag nano-particles is 110 nm and the period P is 500 nm, the effect of the large particles in the large distribution period is better. at the same position of the front and rear surfaces of the battery, the Eabs of the battery It can be raised to 55%. However, the light-trapping structure cell is sensitive to the angle of incident light, and a good light-trapping effect shall be obtained, and the incident angle shall be maintained.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM914.41
本文编号：2508929
[Abstract]:Compared with the first-generation crystalline silicon solar cell, the amorphous silicon thin-film solar cell has the advantages of saving raw materials, simple preparation process, low cost and the like. However, because the defect state density of the thin film material is high, the thick amorphous silicon layer can absorb the incident light well, but the recombination and the collector efficiency of the carriers are reduced, and therefore, the thickness of the light absorbing layer of the battery is generally required to be less than the effective diffusion length of the minority carriers; And the over-thin amorphous silicon layer obviously cannot fully absorb the incident light, especially the absorption rate of the light in the vicinity of the band gap is low, and the short-circuit current and the photoelectric conversion efficiency of the battery are also limited. In order to solve the above-mentioned contradiction, it is necessary to design an effective light-trapping structure for the battery, greatly increase the optical thickness of the light-absorbing layer of the battery under the condition that the physical thickness of the light-absorbing layer of the battery is not changed, and the light absorption of the battery can be effectively improved while ensuring the carrier collection efficiency. In this thesis, the common amorphous silicon thin-film light-trapping technology is introduced, and the surface plasmon (SP) generated on the surface of the metal nano-structure is mainly reviewed in the light of the solar cell. on the basis of which, a one-dimensional or two-dimensional periodic distribution metal nano-structure (i.e., a metal nano-grating) is introduced into the front surface or the back surface of the amorphous silicon thin-film battery, and the like, a plurality of light-trapping junctions are designed for an amorphous silicon thin-film battery, The paper adopts the COMSOL numerical simulation software based on the finite element method to simulate the light absorption of different light-trapping structure solar cells. By analyzing the photon absorption rate, the absorption spectrum, the distribution of the electromagnetic field in the light-absorbing layer and the scattering cross-section of the metal nano-particles, the light-trapping structure is optimized, and the light-trapping machine is described. The main research results in this paper are as follows: (1) One-dimensional Ag nano-grating is designed on the front surface of the amorphous silicon thin-film solar cell: in the case of vertical incidence of TM wave, one-dimensional Ag nano-grating in the front surface has one-dimensional Ag nano-grating, and the photon absorption rate of the cell in the short wave band is more than that of the reference cell. However, when the radius of the section of the grating is R = 50 nm and the period P = 350 nm, the total light absorption of the battery is higher than that of the reference cell. 5%. However, under the incidence of TE wave, the surface plasmon can not be generated on the surface of the Ag grating, and the Ag grating itself has a certain absorption and reflection on the incident light, so that the number of photons absorbed in the whole incident light spectrum (300-800 nm) is only the reference cell when the mixed wave is incident. 92%. That is, after the one-dimensional Ag nano-grating is introduced on the front surface, the light absorption of the amorphous silicon thin-film solar cell Based on the above simulation results, we believe that one-dimensional metal nano-grating is not suitable to be placed in the cell in the light-trapping design of the solar cell (2) The design and optimization of the composite light trapping structure: a one-dimensional metal nano-grating is prepared between the Ag back electrode and the silicon thin film, and the anti-reflection film of the texture is deposited on the front surface of the battery by a conformal growth, The light trapping effect of the grating with the filling factor of FF = 0.5 is better than that of the grating of FF = 1 when the cross section of the one-dimensional metal nano-grating of the back surface is triangular, and the Ag grating is compared with the Al grating. The effect is better. When the top angle of the cross-section of the grating is n = 80 掳 and the area S = 18750 nm2, the total light absorption under the vertical incidence of the solar spectrum of the AM1.5 is 96% higher than that of the reference cell. When the cross section of the one-dimensional Ag nano-grating on the back surface is rectangular, the height of the rectangle is H = 90 nm, the width W = 180 nm, and the period of the grating is P = 6. at 00 nm, Eabs is the maximum the light absorption of the amorphous silicon thin-film battery can be improved in a wide spectrum range, The contribution of the texture, while the increase of the long-band photon absorption rate is the same as the surface plasmon and waveguide mode of the Ag nano-grating. in addition, the structure of the composite light trapping structure also greatly improves the incident angle of the solar light of the amorphous silicon thin film battery, and (3) the influence of the periodically distributed Ag nano-particles on the light absorption of the amorphous silicon thin-film battery: when the Ag nano-particles are arranged on the front surface of the battery, the photon absorption rate of the battery in the middle long wave section is higher than that of the reference battery under the plane wave vertical incidence; The results show that, when the radius R of the Ag nano-particles is 110 nm and the period P is 500 nm, the effect of the large particles in the large distribution period is better. at the same position of the front and rear surfaces of the battery, the Eabs of the battery It can be raised to 55%. However, the light-trapping structure cell is sensitive to the angle of incident light, and a good light-trapping effect shall be obtained, and the incident angle shall be maintained.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM914.41
【参考文献】
相关期刊论文 前2条
1 沈宏君;卢辉东;程学珍;;一维衍射光栅和一维光子晶体组成的硅薄膜太阳能电池背反射器[J];发光学报;2012年06期
2 明海;王小蕾;王沛;鲁拥;;表面等离激元的调控研究与应用[J];科学通报;2010年21期
本文编号：2508929
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