Fully chalcogenide transport layers enable efficient, stable FAPbI3 perovskite solar cells

Perovskite solar cells (PSCs) are now recognized as pivotal in photovoltaic research that combine high power conversion efficiency with cost-effective fabrication processes. However, commercial deployment of this technology is still hindered by the standard electron-transport material (ETM) TiO₂ and the hole-transport material (HTM) Spiro-OMeTAD, which suffer from stability, performance, and cost issues. In the present work, we use SCAPS-1D simulations to explore a wide range of alternative transport layers for FA-based FAPbI₃ devices. After validating our model by reproducing the 25.6 % efficiency of a TiO₂/Spiro-OMeTAD reference cell, we systematically evaluated a broad range of ETLs and HTLs and analysed their influence on device performance. The pairing of WS₂ as the electron transport layer and CuGaSe₂ (CGSe) as the hole transport layer emerged as the most effective combination, delivering better energy-level alignment, higher charge mobility, and lower recombination without altering the active layer. Once optimized, this WS₂/CGSe architecture increased the simulated power conversion efficiency to more than 26,55 %. Both materials can be deposited at low temperatures via scalable methods, underscoring their potential as stable, cost-effective transport layers for next-generation PSCs.