Thermal Evaporation-Assisted Fabrication of All-Hybrid 3D/3D Tandem Perovskite Layer for Efficient and Stable Solar Cells

This study presents a novel fabrication strategy for an all-hybrid 3D/3D tandem perovskite layer (TPL) to improve the efficiency and stability of single-junction perovskite solar cells (PSCs).The TPL consists of a solution-processed FAPbI3 bottom layer and an FAPbI2.5Br0.5 top layer formed via a hybrid thermal evaporation/spin-coating process.The TPL thickness was precisely controlled by varying the thickness of the co-evaporated PbI1.5Br0.5 layer deposited on FAPbI3, with an optimal thickness of 100 nm producing high-quality crystalline films.The optimized TPL-based PSC achieved a power conversion efficiency (PCE) of 19.53%, representing a 6.66% enhancement over the conventional FAPbI3 device (18.31%), despite employing only about two-thirds of the absorber thickness.Moreover, the device retained nearly 100% of its initial PCE after 140 h of storage under ambient conditions, demonstrating substantially improved stability compared with the conventional PSC.