Understanding the Trends and Origins of Electronic and Carrier-Transport Behaviour in CuSbCh2 (Ch = S, Se, Te) for Solar Energy Conversion

This study investigates the structural, electronic, and photoexcited carrier transport properties of CuSbCh2 (Ch = S, Se, Te) chalcogenides using first-principles calculations. We reveal that despite anisotropic lattice expansion, local coordination environments remain rigid, preserving the overall band-edge topology. Band gap narrowing arises from progressive conduction band minimum lowering due to enhanced Sb(p)-Ch(p) interactions. Carrier mobility is governed by electronic dimensionality and phonon scattering, with CuSbTe2 showing the highest carrier mobility due to reduced polar optical phonon coupling and resilient valence-band dispersion. These insights underscore the potential of chalcogen alloying for optimising charge transport and band alignment in photovoltaic and photoelectrochemical applications.