3D perovskite solar cells (PSCs) have reached impressive power conversion efficiencies, but their poor resistance to heat, moisture, and light continues to hinder commercialization. Quasi-2D perovskites offer a pathway toward greater stability, yet their performance is often compromised by insulating organic cations and disordered phase distribution.
In a recent study, researchers from China's Jinan University introduced a new multifunctional additive - formamidinium 4-methylbenzenesulfonate (FATsO) - to overcome these challenges. FATsO simultaneously passivates iodide anions and lead ion defects while strengthening the [PbI6]4− framework through hydrogen bonding and Lewis acid–base interactions. The –NH2+ group stabilizes the crystal lattice, while the –SO3− group reduces uncoordinated Pb2+ defects. At the same time, hydrogen bonding between PEA+ and the –SO3− group restricts PEA+ diffusion, ensuring a more uniform phase distribution and facilitating efficient energy transfer.
As a result, FATsO-modified PSCs achieved a power conversion efficiency of 18.28%, said to be the highest reported value for MA-based quasi-2D PSCs with n ≤ 4.
When operated under forward bias as a light-emitting diode, the same device delivered an external quantum efficiency of 2.24%.
Beyond performance gains, the optimized devices showed remarkable resilience against heat and humidity, underscoring the potential of FATsO engineering to push quasi-2D perovskites closer to practical application in both solar cells and optoelectronic devices.
