Inorganic Pb-Free Perovskite Light Absorbers for Efficient Perovskite Solar Cells with Enhanced Performance

Recently, enormous efforts have been made to develop the efficient, lead (Pb) free and stable perovskite solar cells (PSCs). In this regards, various strategies were applied and the optoelectronic properties of various Pb free perovskites such as (CH₃ NH₃ )₃ Sb₂ I₉ , (CH₃ NH₃ )₃ Bi₂ I₉ , Cs₃ Sb₂ I₉ , Cs₃ Bi₂ I₉ , CH₃ NH₃ SnI₃ and CH₃ NH₃ GeI₃ etc have been investigated. However, the photovoltaic performance of the developed PSCs was still low and presence of organic moieties in common hole-transport materials (HTMs) shows poor stability against moisture and heat. Herein, we have investigated the optoelectronic properties of all inorganic Pb free perovskites (Cs₃ Sb₂ I₉ =1 and Cs₃ Bi₂ I₉ =2) and employed novel strategies (dissolution-recrystallization) to prepare the efficient Pb free PSCs. The band gaps of the 1 and 2 were found to be 2.2 eV and 2.0 eV, respectively. The developed PSCs with 1 and 2 exhibited the power conversion efficiency of 0.68% and 1.087%, respectively.