Emerging chalcogenides for sustainable energy and environmental applications

Abstract

Copper–zinc–tin–sulfide (Cu2ZnSnS4, CZTS) kesterites a promising earth-abundant and non-toxic absorber for next-generation thin-film photovoltaics. However, sulfur-based CZTS solar cells remain limited in performance, largely due to intrinsic defects and interfacial recombination losses. Impact of solvent chemistry and extrinsic doping and compositional engineering on the quality of solution-processed CZTS absorbers is revealed. Cd-alloyed CZTS (CZCTS) improves the solar cells efficiencies promoting nearly defect -free due to a quasi-epitaxy between CZCTS and CdS. A synergistic compositional strategy combining silver (Ag) – cadmium (Cd) co-alloying with lithium (Li) doping is introduced to suppress cation disorder, passivate grain-boundary defects, and enhance carrier transport. As a result, champion devices with power conversion efficiency over 10% are obtained, placing it among the highest efficiencies reported for solution-processed, selenium-free CZTS solar cells.