TiI4-doping induced bulk defects passivation in halide perovskites for high efficient photovoltaic devices

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 nonbonded atoms or surface dangling bonds to passivate the defects. Herein, we introduced TiI4 into CH3NH3PbI3 (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 TiI4 as a new and effective passivator for MAPbI(3) film.

Automated summary

Introducing TiI4 dopant improved the crystal grains and defect density of MAPbI(3) film, leading to higher power conversion efficiency. The champion cell demonstrated remarkable stability with high PCE retention after 300 hours of storage.