Prediction of novel mixed-valence double perovskites Cs2MIAuIIIF6 (M = Cu, Ag, Au) for photovoltaics

Abstract

• The optoelectronic performance of Cs 2 M I Au III F 6 (M = Cu, Ag, Au) is studied. • Cs 2 Ag I Au III F 6 shows good dynamic and mechanical stability. • Cs 2 Ag I Au III F 6 exhibits a suitable bandgap and strong visible-light absorption. • Cs 2 Ag I Au III F 6 is an alternative candidate for perovskite solar cells. Lead-based halide perovskites exhibit great potential as absorber layers in solar cell applications owing to their high conversion efficiency. Nevertheless, challenges such as material instability and lead toxicity have restricted their widespread commercialization. To address this issue we have designed mixed-valence double perovskites via metal cation substitution. In this regard, using first-principles calculations, the structural stability and optoelectronic-relevant properties of novel double perovskites Cs 2 M I Au III F 6 (M = Cu, Ag, Au) are thoroughly examined. After determining the dynamic and mechanical stability, Cs 2 Ag I Au III F 6 is verified to be structurally stable and experimentally synthesizable According to the HSE06 calculations, Cs 2 Ag I Au III F 6 demonstrates an optimal indirect-gap of 1.09 eV, positioning it as a promising material for solar energy conversion. Furthermore, Cs 2 Ag I Au III F 6 exhibits strong optical absorption anisotropy, with its maximum visible absorption coefficient exceeding 2 × 10 5 cm −1 . The theoretical efficiency of Cs 2 Ag I Au III F 6 can reach 25.9 % at the thickness of 1.0 μm. Overall, our study provides meaningful insights into the potential of lead-free Cs 2 Ag I Au III F 6 for applications in perovskite solar cells.