Hydrophobic diphenylguanidine additive improves the performance and stability of perovskite solar cells

Perovskite solar cells (PSCs) demonstrate promising application prospects owing to their outstanding power conversion efficiency (PCE) and low-temperature solution preparation process. However, defects in perovskite films and poor environmental stability pose significant obstacles to their commercialization. This study leverages the simple and effective strategy of additive engineering to introduce diphenylguanidine (DPG), a hydrophobic molecule, into the perovskite precursor solution. The guanidine groups effectively passivate lead-related defects in perovskite films and enhance crystallinity, facilitating a champion PCE of 20.303% in DPG-optimized PSCs, while the hydrophobicity of the phenyl groups supports superior long-term stability in unencapsulated devices, maintaining 78% of the original efficiency after 1000 h of exposure to the ambient environment. This work provides a new strategy for achieving efficient and stable PSCs based on guanidine additives.