Optical properties of Sb(Se,Te)I and photovoltaic applications

•The SbXI (X = Se, Te) are ferroelectric semiconductors with a high optical absorption.•The absorption coefficients have been split into different contributions to understand the cause of the high absorption.•Using the first-principles results the maximum efficiency of this photovoltaic absorber material has been estimated.•The efficiency of this compound is near the maximum efficiency for single-gap solar cells even using small-width devices.•The coexistence of the R-PV and R-PV effects has been evaluated.

SbXI (X = Se, Te) are ferroelectric semiconductors that allow a variety of applications including optoelectronic and photovoltaic applications. An analysis of the optical properties is carried out starting from first-principles density-functional theory with orbital-dependent one-electron potentials. To go into the contributions to the optical properties more deeply, the absorption coefficients have been split into inter- and intra-species contributions and into atomic angular momentum contributions. The optical results are used to evaluate the efficiencies when this material is used to absorb sunlight at several sunlight concentrations and the usual radiative and the ferroelectric photovoltaic mechanisms. The results indicate their applicability in photovoltaic devices as absorbent of the solar spectrum with high conversion efficiency.