The perovskite solar cell technologies are the hope of satisfying the huge demand of tomorrow’s energy requirements. The inorganic, organic and mixed perovskite materials are the backbone of modern solar cells. The energy band gap and refractive index of perovskites help in selecting proper materials for solar cell, solid-state lighting and lasing applications. In this paper, various perovskite materials and different energy band gap–refractive index relations have been studied. A simple empirical relationship between energy gap ‘Eg’ and refractive index ‘n’ for perovskites has been developed and proposed. Using this relationship, refractive indices of 33 different perovskites have been calculated and compared with their reported values. Also, the refractive indexes of about 140 new perovskites have been predicted and reported probably for the first time. The researchers interested in refractive index calculation may use the proposed relation and need not to worry for complex experimental setup
