Appraisement of crystal expansion in CH3NH3PbI3 on doping: improved photovoltaics properties.

Three-dimensional hybrid perovskite materials (CH3NH3PbI3) suffer from intrinsic instability due to organic cation evaporation and ion migration. The inclusion of a large organic cation such as guanidinium has been probed to stabilize the structure. In this work, we put forward the inclusion of imidazolium iodide (C3N2H5I) as organic cation inside the CH3NH3PbI3 matrix, as a reservoir to control the spontaneous loss of iodide. The introduction of imidazolium iodide in amounts below 20% has an impact on the crystallization process but not on the optical properties, and positively controls non-radiative recombination and allows to improve the open circuit voltage of the solar cells. The present study paves way for a deep insight into the limit of multi-dimensional perovskite to further push the performance.