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

Abstract

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 FA0.85MA0.15PbI3 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 degrees 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 degrees C and 65 % RH, simulating real-world operating conditions.