衬底温度对共蒸发法制备Cu_2ZnSnSe_4太阳电池的影响

Influence of Substrate Temperature on Cu_2ZnSnSe_4 Thin Film Solar Cells Fabricated by Co-evaporation Process

采用共蒸发法在不同衬底温度下沉积Cu_2ZnSnSe_4(简称CZTSe)薄膜,分析了衬底温度对CZTSe材料性质及电池性能的影响。研究表明:当衬底温度较低时(380℃),CZTSe薄膜中含有SnSe_x使电池失效;随着衬底温度的升高,CZTSe薄膜的结晶质量明显提升,电池开路电压增加。但当衬底温度达到460℃时,电池的转换效率反而下降;结合CZTSe的生长机理及器件模型分析了电池效率下降可能的原因。最终在衬底温度420℃的条件下制备出效率为3.12%(有效面积0.34 cm^2)的CZTSe太阳电池。

Substrate temperature has very important influences on the performance of Cu2ZnSnSe4(CZTSe) thin film solar cells. In this paper, CZTSe absorbers and solar cells prepared by co-evaporation process at different substrate temperatures are investigated. XRD results show additional reflections of SnSex of films deposited at substrate temperature(380 ℃). SEM measurements reveal that the quality of crystallization of CZTSe films improves with increasing substrate temperatures;meanwhile the open circuit voltage increases due to decreased grain-boundary recombination. However, J-V tests show that the efficiency of CZTSe solar cells fabricated at 460 ℃ is lower. The reason might be that CZTSe film growth starts with the formation of ZnSe at higher substrate temperature(460 ℃). And the ZnSe could form a barrier at the back contact which could reduce the short circuit current and fill factor. The best solar cell with an efficiency of 3.12% is obtained at medium substrate temperature of 420 ℃(active area 0.34 cm2).