posted on 2020-04-01, 12:35authored byTzu-Ming Cheng, Chung-Hao Cai, Wei-Chih Huang, Wei-lun Xu, Lung-Hsin Tu, Chih-Huang Lai
Improving
power conversion efficiency of photovoltaic devices has been widely
investigated; however, most research studies mainly focus on the modification
of the absorber layer. Here, we present an approach to enhance the
efficiency of Cu(In,Ga)(S,Se)2 (CIGSSe) thin-film solar
cells simply by tuning the CdS buffer layer. The CdS buffer layer
was deposited by chemical bath deposition. Indium doping was done
during the growth process by adding InCl3 into the growing
aqueous solution. We show that the solar cell efficiency is increased
by proper indium doping. Based on the characteristics of the single
CdS (with or without In-doping) layer and of the CIGSSe/CdS interface,
we conclude that the efficiency enhancement is attributed to the interface-defect
passivation of heterojunction, which significantly improves both open
circuit voltage and fill factor. The results were supported by SCAPS
simulations, which suggest that our approach can also be applied to
other buffer systems.