Halide

Chemistry

Materials science

Optoelectronics

Engineering

Physics

Hysteresis

Formamidinium

Crystallography

Organic chemistry

Energy conversion efficiency

Perovskite (structure)

Quantum mechanics

Thermal stability

Phase (matter)

Inorganic chemistry

Chemical engineering

Iodide

Doping

Science

In halide perovskite solar cells the formation of secondary-phase excess lead iodide (PbI2) has some positive effects on power conversion efficiency (PCE) but can be detrimental to device stability and lead to large hysteresis effects in voltage sweeps. We converted PbI2 into an inactive (PbI2)2RbCl compound by RbCl doping, which effectively stabilizes the perovskite phase. We obtained a certified PCE of 25.6% for FAPbI3 (FA, formamidinium) perovskite solar cells on the basis of this strategy. Devices retained 96% of their original PCE values after 1000 hours of shelf storage and 80% after 500 hours of thermal stability testing at 85°C.

Inactive (PbI <sub>2</sub> ) <sub>2</sub> RbCl stabilizes perovskite films for efficient solar cells

Inactive (PbI 2 ) 2 RbCl stabilizes perovskite films for efficient solar cells

Inactive (PbI ₂ ) ₂ RbCl stabilizes perovskite films for efficient solar cells