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

Abstract

In halide perovskite solar cells the formation of secondary-phase excess lead iodide (PbI ₂ ) 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 PbI ₂ into an inactive (PbI ₂ ) ₂ RbCl compound by RbCl doping, which effectively stabilizes the perovskite phase. We obtained a certified PCE of 25.6% for FAPbI ₃ (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.

Managing excess lead iodide

In hybrid perovskite solar cells, the formation of lead iodide (PbI2) can provide some passivation effects but can lead to device instability and hysteresis in current–density changes with voltage. Zhao et al . show that doping with rubidium chloride (RbCl) can create a passive inactive (PbI ₂ ) ₂ RbCl phase that stabilizes the perovskite phase and lowers its bandgap. Devices exhibited 25.6% certified power efficiency and maintained 80% of that efficiency after 500 hours of operation at 85°C. —PDS

Abstract

Converting PbI ₂ into inactive (PbI ₂ ) ₂ RbCl by RbCl doping can stabilize the perovskite phase and increase efficiency.