Optimization of Phenylethylammonium Bromide Post-Treatment for 2D/3D Heterostructure Formation in High-Performance Perovskite Solar Cells

Inverted perovskite solar cells (IPSCs) have gained a lot of attention and a significant amount of research interest in recent years due to their outstanding optoelectronic properties and rapid enhancement of efficiency. However, the IPSCs are still significantly limited by the influence of abundant defects and detrimental nonradiative recombination, especially at the top interface of the perovskite film. Herein, a surface 2D capping layer is constructed to form a 2D/3D heterostructure by systematically regulating the concentration of the PEABr post-treatment solution. An optimal PEABr concentration of 1 mg/mL is identified for the formation of the desired surface 2D capping layer. The perovskite film treated with optimal PEABr exhibits the most pronounced improvements in film morphology, crystallinity enhancement, defect reduction, and suppression of nonradiative recombination. Consequently, the best-performing IPSCs achieve a champion efficiency of 24.58%, together with an open-circuit voltage of 1.15 V, a short-circuit current density of 25.68 mA/cm2, and a fill factor of 82.80%. This work demonstrates that regulating the PEABr concentration is an effective strategy for constructing surface 2D/3D heterostructures and achieving effective interfacial passivation, offering a promising route for advancing interface engineering and enhancing the performance enhancement of IPSCs.