Loading Precursors into Self-Assembling Contacts for Improved Performance and Process Control in Evaporated Perovskite Solar Cells

Organo-lead-halide perovskites are promising materials for solar cell applications with efficiencies now exceeding 26% for single junction, and over 33% for silicon tandem devices. Evaporation has proven viable for industrial scale-up but presents challenges for perovskite materials. Perovskite precursor is introduced into self-assembling MeO-2PACz hole transport layers for application to 4 source perovskite coevaporation. This allows precursors that can be difficult to add via evaporation, like methylammonium chloride. These precursor molecules influence growth during evaporation, film behavior during annealing as measured by photoluminescence, and aid the conversion to perovskite as shown by X-Ray diffraction. Devices have improved power conversion efficiency and stability compared to a control sample within the same evaporation. The best cells reach ≈21% efficiency and comparable performing ≈20% cells maintain their original efficiency after 1000 h of maximum power tracking at 25 °C. This process provides significant process flexibility for perovskite evaporation and requires no additional steps.