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.