A Critical Review on the Progress of Kesterite Solar Cells: Current Strategies and Insights

Kesterite Cu2ZnSn(S,Se)(4) (CZTSSe) with earth-abundant and environmental-benign constituents has been regarded as a promising solar energy harvesting material for green and cost-effective photovoltaic applications. The record efficiency of CZTSSe solar cells has recently been refreshed twice after years-long stagnation, keeping it in the spotlight. Nevertheless, the champion efficiency of 13.6% is still far behind its counterpart Cu(In,Ga)Se-2 (CIGS) (23.35%) despite being endowed with a similar electronic structure and nearly-identical device architecture. In fact, CZTSSe solar cells are more susceptible to non-radiative recombination at bulk and interfaces, which must be improved for further efficiency advancement. In this review, the state-of-art strategies to enhance the power conversion efficiency of CZTSSe solar cells are summarized and discussed, with focus given to three critical device regions i) kesterite absorber, ii) buffer/kesterite interface, and iii) kesterite/back contact interface. With the further elucidation of the latest progress and disclosure of fundamental mechanisms, novel insights toward high-efficiency kesterite solar cells are proposed.

Automated summary

This article summarizes and discusses the latest strategies to improve the efficiency of CZTSSe solar cells, focusing on critical device regions including kesterite absorber, buffer/kesterite interface, and kesterite/back contact interface. With the elucidation of recent progress and fundamental mechanisms, novel insights towards high-efficiency kesterite solar cells are proposed.