Earth-Abundant Sb-Based Absorbers for Next-Generation Photovoltaics

New cost-effective photovoltaics are urgently needed to reach the UK’s renewable energy targets. Recently, lead halide perovskites have emerged as a remarkably efficient class of absorbers but are limited by their poor stability and inclusion of toxic lead. Antimony-based materials show promise as photovoltaics due to their dispersive lone-pair states that confer many similar properties to their lead counterparts including strong optical absorption and small effective masses. Compared with conventional lead-containing photovoltaics, antimony is a non-toxic and earth-abundant element that could reduce potential regulatory and environmental barriers to commercialisation. In this work, using relativistic density functional theory (DFT), we study the optoelectronic properties of antimony-based materials for use in single and multi-junction solar cell applications. Full Heusler K₂CsSb and tilted antiperovskites A₃SbP are highlighted for their favourable optoelectronic properties including direct bandgaps, low effective masses and strong optical absorption, as well as high device performance with maximum theoretical efficiencies of 24–31% for 200 nm films. First principles defects calculations reveal the materials do not possess any deep trap states and are not expected to experience large voltage losses from non-radiative recombination.