A comprehensive study on RbGeI3 based inorganic perovskite solar cell using green synthesized CuCrO2 as hole conductor

•Green synthesized CuCrO2 has a band gap of 3.0 eV that is ideal for inverted perovskite solar cells.•Morphological analysis shows that CuCrO2 is formed as polygonal crystal structure with particle sizes ranges 104.6 to 240 nm.•Delafossite CuCrO2 as promising HTL (Hole transport material) for RbGeI3 based inverted Inorganic Perovskite Solar Cell giving device efficiency of 23.8 % for optimum condition.•High defect tolerance limit (1012 cm−3) for at CuCrO2/RbGeI3 interfaces indicates superior material combination that is more suitable for real device fabrication.•The structure shows very good result on thermal stability and 70 % of its PCE retain at 400 K.