Unravelling Phase-Dependent Electronic Dimensionality and Optoelectronic Properties in Lead-Free Layered A3B2X9 Perovskites for Photovoltaic Applications

The phase stability mechanism of all-inorganic lead-free layered A 3 B 2 X 9 perovskites is revealed and Cs 3 B 2 I 9 (B = Sb and Bi) in trigonal phase are predicted as promising photovoltaic materials with high power conversion efficiencies (∼20%).