宽禁带铜铟镓硒薄膜电池内深能级缺陷机理及表征研究

CIGS solar cells possess broad prospect, however, for wide-gap CIGS (high Ga content) solar cells, the efficiency is still low. The influence of deep-level defects is one important reason limiting the efficiency, however, the study on the mechanism that how the deep-level defects influence the efficiency loss is still unclear. This program will employ two-wavelength photo-electro characterization methods including two-wavelength photo-capacitance spectroscopy and two-wavelength time-resolved photoluminescence method to obtain as much of the properties of deep-level defects as possible, including the energy distribution of deep-level defects, the role of the defects and the contribution of the defects to the carrier recombination. Then we will investigate the relationship between all the properties and Ga content which may help to understand the contribution of deep-level defects to the efficiency loss in wide-gap CIGS solar cells, this would further help to develop effective method to control the defects to improve the efficiency. The implementation of this program is meaningful for developing the wide-gap CIGS solar cells as potential candidate for the top or intermediate layer of the more efficient tandem solar cells of the next generation.

铜铟镓硒薄膜太阳能电池具有重要的应用前景，但仍然存在宽禁带铜铟镓硒（高镓含量）电池的效率较低的问题。深能级缺陷是导致其效率低的重要因素之一，而目前关于深能级缺陷导致效率损失的机理研究依然不完善。本项目将利用以双光源为基础的光电表征技术，包括双光源光电容法以及双光源时间分辨光致发光法，来获取宽禁带铜铟镓硒电池深能级缺陷的详细信息，包括深能级缺陷分布、缺陷的作用、缺陷对载流子复合的贡献等；系统研究深缺陷的各种特性随镓含量的变化关系，探究深能级缺陷对宽禁带铜铟镓硒电池效率损失的贡献，进而指导开发通过控制缺陷以提高电池效率的有效方法。此项目的开展对于发展宽禁带铜铟镓硒电池作为下一代更高效的多结太阳能电池的顶部或中间吸收层材料具有重要的指导意义。

铜铟镓硒薄膜太阳能电池具有重要的应用前景，但仍然存在宽禁带铜铟镓硒（高镓含量）电池的效率较低的问题。深能级缺陷是导致其效率低的重要因素之一，而目前关于深能级缺陷导致效率损失的机理研究依然不完善。本项目利用单光源及双光源光电容法，结合时间分辨光致发光法来获取宽禁带铜铟镓硒电池深能级缺陷的详细信息，包括深能级缺陷分布、缺陷的作用、缺陷对载流子复合的贡献等。首先研究了宽禁带铜镓硒电池内的缺陷分布情况，确定了距价带顶部0.8eV的一深能级缺陷并发现此缺陷存在亚稳态能级；其次研究了硒元素的含量对宽禁带铜镓硒电池内深能级缺陷的影响，随着硒的减少，深能级缺陷虽然能级位置未改变，但是缺陷密度及缺陷的载流子俘获截面却增加，证明硒元素是影响深能级缺陷的一个重要因素；最后研究了铜镓元素含量之比对于铜镓硒电池内深能级缺陷的影响，发现深能级缺陷位置不受铜镓元素之比而变化，但是随着铜比镓的含量减小，缺陷复合效应增加，说明铜镓比也是影响深能级缺陷的一个重要因素。本项目的研究成果对于宽禁带铜铟镓硒薄膜电池内深能级缺陷机理能够得出更清晰的认识，而对于目前效率较低的宽禁带铜铟镓硒电池，深能级缺陷是限制其效率的重要因素之一，因此本研究成果能够为宽禁带铜铟镓硒电池的效率损失机制提供理论依据，有利于针对性的开发减少成果中发现的深能级复合缺陷的技术并提高电池效率。