Depletion region effect of highly efficient hole conductor free CH ₃NH₃PbI₃ perovskite solar cells

The inorganic-organic perovskite is currently attracting a lot of attention due to its use as a light harvester in solar cells. The large absorption coefficients, high carrier mobility and good stability of organo-lead halide perovskites present good potential for their use as light harvesters in mesoscopic heterojunction solar cells. This work concentrated on a unique property of the lead halide perovskite, its function simultaneously as a light harvester and a hole conductor in the solar cell. A two-step deposition technique was used to optimize the perovskite deposition and to enhance the solar cell efficiency. It was revealed that the photovoltaic performance of the hole conductor free perovskite solar cell is strongly dependent on the depletion layer width which was created at the TiO₂-CH₃NH ₃PbI₃ junction. X-ray diffraction measurements indicate that there were no changes in the crystallographic structure of the CH ₃NH₃PbI₃ perovskite over time, which supports the high stability of these hole conductor free perovskite solar cells. Furthermore, the power conversion efficiency of the best cells reached 10.85% with a fill factor of 68%, a V_oc of 0.84 V, and a J_sc of 19 mA cm^-2, the highest efficiency to date of a hole conductor free perovskite solar cell. This journal is