From 2D to 3D: a facile and effective procedure for fabrication of planar CH3NH3PbI3 perovskite solar cells

Abstract

Herein, new organic–inorganic hybrid perovskite single crystals of complex 1 with the formula of (n-C₃H₇NH₃)₆Pb₄I₁₄ are synthesized from an aqueous HI solution containing PbI₂ and propylammonium iodide. The single crystal X-ray crystallographic study shows that the structure consists of two-dimensional (2D) sheets of corner- and face-sharing [Pb₂I₇]³⁻ octahedra, and the inorganic layers are separated by layers of 3-propylammonium cations. The 2D perovskite material features good film formability upon simple solution deposition. This 2D phase can be easily converted into 3D CH₃NH₃PbI₃ (MAPbI₃) perovskite via an organic-cation displacement approach, exhibiting a compact, ultrasmooth, and textured morphology. Using the film as a light absorber, planar CH₃NH₃PbI₃ perovskite solar cells are fabricated, and the best power conversion efficiency of 19.19% is obtained with good reproducibility.