posted on 2024-01-16, 13:03authored byYiming Wang, Yanchun Yang, Ruijian Liu, Shuyu Li, Hongmei Luan, Lei Wang, Letu Siqin, Chengjun Zhu
Morphology of the absorber plays
a decisive role in photoelectric
conversion efficiency (PCE) of kersterite solar cells. Cu2ZnSn(S,Se)4 (CZTSSe) grain prepared from dimethyl sulfoxide
(DMSO)-based solution easily grows into large grains, which can lead
to the formation of some holes at the back of the absorber. These
holes cause the recombination of photocarriers and greatly weaken
the performance of CZTSSe devices. Here, trace amounts of thioglycolic
acid (TGA) are introduced to the DMSO-based solution, and a combination
of TGA and metal is formed in the absorber, leading to the formation
of fine grains in the CZTSSe absorber. Next, post-annealing (PA) in
a N2 atmosphere is performed to promote Na diffusion, helping
the transition from a fine-grain layer to a low-resistivity carbon
layer at the interface between CZTSSe and Mo and avoiding the drawbacks
of the DMSO-based system. Finally, the champion PCE of the CZTSSe
device can be improved to 10.05% from 8.06%. The conclusions demonstrate
that the construction of a carbon layer can boost the performance
of CZTSSe devices.