Maximizing solar cell performance by optimizing the perovskite active layer with tungsten dichalcogenides

The inorganic-organic lead halide MAPbI₃ is a widely studied component in perovskite solar cells (PSCs). A new FA cation-based perovskite composition, FAPbI₃, emerges as a promising alternative to MAPbI₃ due to its dynamic interface properties, however, the phase stability of FAPbI₃ limits its potential for improved power conversion efficiency (PCE). As a solution, we develop the FA_0.85MA_0.15PbI₃ active layer for PSC devices, achieving a PCE of 19 %. Additionally, to further enhance PSC efficiency, we incorporate the 2D tungsten dichalcogenides (WX₂, where X = S , Se, and Te) into the active layer. The addition of different ratios of WSe₂, WTe₂, and WS₂ to create a homogeneous film improves charge carrier mobility, facilitates favorable energy level alignment, and accelerates charge transfer. The device constructed with WTe₂-integrated perovskite demonstrates outstanding performance, achieving a PCE of 22.86 % with an increase of 18 % from pure. Moreover, the WTe₂-doped active layer exhibits remarkable stability under various conditions, including dark, light, and at 85 °C with 30 %, 25 %, and 65 % relative humidity (RH), respectively. Experimental results show that unencapsulated PSCs with WTe₂ in the active layer retain 95 % of their initial efficiency after 300 h in an N₂ environment at 85 °C and 65 % RH, simulating real-world operating conditions.