In recent years, three-dimensional hybrid perovskites (CH3NH3PbX3) with X=I, Br, and Cl have raised great attention due to their facile production methods and encouraging energy conversion efficiency in solar cells based on perovskite. A majority of the systematic studies on the regulation of the band gap in the family of organolead halide perovskites have focused on changing thecompositions of halogens. However, organic portion can provide a wider structural diversity in band gap and dimensionality in perovskite structures.Thus, Investigation of the structural and optical properties of organic-inorganic perovskitesby changing the organic portion seems to be necessary. The main focus of this work is the tetraphenylphosphonium substitutions at the organic portionin the hybrid perovskite structures.In this paper, fabrication of organic−inorganic hybrid perovskite TPP2PbX4, (TPP = P(C6H5)4; X = Cl), is reported.Thesynthesis method, crystal structure, and optical behavior of the synthesized perovskiteswere investigated. The organic cation effect on the optical properties and bandgap tuning were studied experimentally. The remarkable electronics and optical properties of 2D perovskite structurescould provide a different perspective and suggest the potential of these materials for photonics applications. Manuscript profile