Cs/MAPbI3 composite formation and its influence on optical properties.

Abstract The stability issue is very critical for organic hybrid perovskite CH 3 NH 3 PbI 3 to be used in solar cell applications; whereas CsPbI 3 is reported to be more stable than that of CH 3 NH 3 PbI 3. In the present work, we attempt to substitute Cs+ in the organic hybrid perovskite CH 3 NH 3 PbI 3 matrix to form Cs x (CH 3 NH 3) 1-x PbI 3 with 0 ≤ x ≤ 0.4 in ambient conditions i.e., at room temperature and in air via solid state reaction route. The structural studies reveal presence of both CH 3 NH 3 PbI 3 (tetragonal, I 4/ mcm) and CsPbI 3 (orthorhombic, Pnma) phases for x > 0. It is appearing that partial solid solution formation has occurred up to x = 0.2 but for x > 0.2, the composite formation dominates. The optical band gap is slightly increased by ∼0.02 eV with substitution. These compounds keep the basic feature of parent CH 3 NH 3 PbI 3 along with stability of CsPbI 3. Highlights • Composite formation of Cs x (CH 3 NH 3) (1-x) PbI 3 processed via cold sintering method. • Composite formation is studied using structural and optical properties. • Further, this composite formation has also been verified thermodynamically. [ABSTRACT FROM AUTHOR]