Organohalide based perovskites have emerged as an important class of material for solar cell applications. The variations/substitution in organohalide cations and anions is employed for the optimization of the band gap, carrier diffusion length, and power conversion efficiency of perovskites based solar cells. Organohalide based perovskites have emerged as an important class of material for solar cell applications. The variations/substitution in organohalide cations and anions is employed for the optimization of the band gap, carrier diffusion length, and power conversion efficiency of perovskites based solar cells.