Compositionally Tunable Cu2ZnSn(S1-xSex)4 Nanocrystals: Probing the Effect of Se-Inclusion in Mixed Chalcogenide Thin Films

Nanocrystals of multicomponent chalcogenides, such as Cu2ZnSnS4 (CZTS), are potential building blocks for low-cost thin-film photovoltaics (PVs). CZTS PV devices with modest efficiencies have been realized through postdeposition annealing at high temperatures in Se vapor. However, little is known about the precise role of Se in the CZTS system. We report the direct solution-phase synthesis and characterization of Cu2ZnSn(S1-xSex)(4) nanocrystals (0 <= x <= 1) with the aim of probing the role of Se incorporation into CZTS. Our results indicate that increasing the amount of Se increases the lattice parameters, slightly decreases the band gap, and most importantly increases the electrical conductivity of the nanocrystals without a need for annealing.