TiI_4-doping induced bulk defects passivation in halide perovskites for high efficient photovoltaic devices

摘要

Power conversion efficiency (PCE) and stability are two important properties of perovskite solar cells (PSCs). Particularly, defects in the perovskite films could cause the generation of trap states, thereby increasing the nonradiative recombination. To address this issue, suitable dopants can be incorporated to react with non-bonded atoms or surface dangling bonds to passivate the defects. Herein, we introduced TiI_4 into CH_3NH_3PbI_3 (MAPbI_3) film and obtained a dense and uniform morphology with large crystal grains and low defect density. The champion cell based on 0.5% TiI4-doped MAPbI_3 achieved a PCE as high as 20.55%, which is superior to those based on pristine MAPbI_3 (17.64%). Moreover, the optimal solar cell showed remarkable stability without encapsulation. It retained 88.03% of its initial PCE after 300 h of storage in ambient. This work demonstrates TH_4 as a new and effective passivator for MAPbI_3 film.