薄膜电池周期纳米结构的广谱陷光设计与性能分析

The light-trapping of thin film solar cells by using nano-particle has attracted extensive attention. However, the light-trapping at wide-range wavelength has not been solved resultfully and the researches on corresponding mechanism also need further penetration. This work has analyzed and designed the front and back field of thin film solar cells, which are high-efficiency light-trapping structure. Based on the mechanisms of scattering, diffraction and waveguide, we will analyze and clarify the influence of nano-structure size on the scattering coupling efficiency, waveguide and diffraction efficiency at short wavelength (300~500 nm) and on the transmission at long wavelength (700~1200 nm). Then, we will design the front surface of thin film solar cell with high-efficiency light trapping at short wavelength and high-efficiency transmission at long wavelength. Based on the mechanisms of surface plasmon polaritions, diffraction and waveguide, we will analyze and make known the influence of the size and shape of metal grating on plasmon polaritions, diffraction and waveguide efficiency at long wavelength. Then, we will design the back surface field of thin film solar cells with high efficiency of reflectivity at long wavelength. This work will be of important theoretical and practical value for experimental research.

利用纳米颗粒对薄膜电池表面进行陷光，已经引起了广泛关注。然而，已有的研究未能有效解决广谱波段的陷光问题，相应的机理研究也待进一步深入。本课题拟分析和设计一种前表面和背场都具有陷光性能的薄膜电池。基于散射、衍射和波导的机理，我们将分析并明确在短波长光谱范围（300~500nm），电池前表面的三维周期性介质纳米结构的尺寸对散射耦合效率、波导效应和衍射效应的影响，以及在长波段范围（700~1200nm）与透射率的相关性，从而设计对短波长具有高陷光效率和对长波长具有高透射率的电池前表面。基于表面等离子激元、衍射和波导的机理，我们将分析并阐明在长波长光谱范围，电池背场的二维金属反射光栅尺寸和形貌对表面等离子激元、衍射效应和波导效应的影响，从而设计具有高反射率的金属光栅背场。本课题的研究结果对薄膜电池的实验研究具有重要的理论意义和实际价值。

对薄膜太阳电池的陷光研究已引起广泛关注，但还未有效解决广谱限光。利用数值计算研究纳米颗粒对薄膜电池的广谱陷光，需高配置的硬件、耗费较多时间。本项工作着力于解决这些问题，主要包括三个方面的内容。首先，讨论了影响纳米颗粒陷光效应的主要机制包括等离子激元，光栅波导和散射。然后，基于麦克斯韦方程组，解析分析了纳米结构对波长为（300~1200nm）波段范围的陷光效应影响。将三维周期性金属纳米结构置于电池上表面时，纳米结构具有小占空比有利于减小电池上表面反射率，而将纳米结构置于SiO2中与置于空气中对电池上表面反射率无影响。在电池背场，增加纳米结构高度，不利于电池的陷光效应；降低占空比，有助于提高背场反射率，从而增加陷光效应。最后，分析了一维金属光栅结构涂覆于磁光材料基底或普通介电材料基底，TM极化波都会发生显著的非互易透射现象，增强该非互易透射现象可用于提高电池的陷光效应。本项目的研究结果对薄膜电池的实验研究具有重要的理论意义和实际价值。