Ge-doping of CZTS nanocrystals and CZTSSe solar absorber films.

CuZnSn(S,Se) (CZTSSe) is a promising material for thin-film photovoltaics, however, the open-circuit voltage () deficit of CZTSSe prevents the device performance from exceeding 13% conversion efficiency. CZTSSe is a heavily compensated material that is rich in point defects and prone to the formation of secondary phases. The landscape of these defects is complex and some mitigation is possible by employing non-stoichiometric conditions.

Recovery Mechanisms in Aged Kesterite Solar Cells.

For successful long-term deployment and operation of kesterites CuZnSn(S Se ) (CZTSSe) as light-absorber materials for photovoltaics, device stability and recovery in kesterite solar cells are investigated. A low-temperature heat treatment is applied to overcome the poor charge extraction that developed in the natural aging process. It is suggested that defect states at aged CZTSSe/CdS heterojunctions were reduced, while apparent doping density in the CZTSSe absorber increased due to Cd/Zn interdiffusion at the heterojunction during the annealing process.