3-Ammonium Propionic Acid: A Cation Tailoring Crystal Structure of Hybrid Perovskite for Improving Photovoltaic Performance

Defects in the perovskite photoactive layer will cause severe non-radiative recombination and lead to severe efficiency loss and stability degradation. In this work, a type of cation, 3-APA+, was added to the perovskite precursor to passivate the cation defect and interface/surface defects. Our results reveal that incorporating 3-APA+ with amino and carboxyl functional groups could enhance electronic properties of the interfacial and bulk due to a more efficient charge transfer between the bulk and interfaces and the reduced electronic defect energy levels. The hybrid cation-based perovskite film exhibits a longer photoluminescence lifetime and a lower density of trap states, indicating the effectively passivated vacancies, thus reducing the non-radiative recombination pathway. In addition, the bifunctional group can cross-link the perovskite grains through hydrogen bonds to form a dense perovskite film with a larger grain size. Consequently, the best performing devices with an optimized power conversion efficiency of 20.4% showed an efficiency loss of only 7% at a maximum power tracking of 2000 s at full sunlight intensity. Therefore, directly adding 3-APA+ to the precursor can provide ideas for passivating defects in the perovskite material and improving its stability.