Rational design of Lewis base molecules for stable and efficient inverted perovskite solar cells

Lewis base molecules that bind undercoordinated lead atoms at interfaces and grain boundaries (GBs) are known to enhance the durability of metal halide perovskite solar cells (PSCs). Using density functional theory calculations, we found that phosphine-containing molecules have the strongest binding energy among members of a library of Lewis base molecules studied herein. Experimentally, we found that the best inverted PSC treated with 1,3-bis(diphenylphosphino)propane (DPPP), a diphosphine Lewis base that passivates, binds, and bridges interfaces and GBs, retained a power conversion efficiency (PCE) slightly higher than its initial PCE of similar to 23% after continuous operation under simulated AM1.5 illumination at the maximum power point and at similar to 40 degrees C for >3500 hours. DPPP-treated devices showed a similar increase in PCE after being kept under open-circuit conditions at 85 degrees C for >1500 hours.

Automated summary

Through density functional theory calculations and experimental tests, it was found that phosphine-containing molecules, including 1,3-bis(diphenylphosphino)propane (DPPP), can strongly bind and passivate undercoordinated lead atoms at interfaces and grain boundaries in metal halide perovskite solar cells. This binding leads to enhanced durability and long-term stability, as demonstrated by the PSCs retaining their high power conversion efficiency (PCE) even after extended operation or exposure to extreme conditions.