PEDOT:PSS/CuCl Composite Hole Transporting Layer for Enhancing the Performance of 2D Ruddlesden–Popper Perovskite Solar Cells

Poly­(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) is a popular hole transport layer (HTL) in 2D Ruddlesden–Popper (RP) perovskite solar cell (PSCs) due to its highly conductive, transparent, and solution-processable characteristics. However, fundamental questions such as its strong acidity or mismatched energy level with the 2D RP photoactive layer often restrict the performance and stability of devices. Herein, copper chloride (CuCl), a common direct band gap semiconductor, is doped into PEDOT:PSS, lowering the acidity and tuning the work function of PEDOT:PSS. Due to the improved wettability and the existing chloride in the PEDOT:PSS/CuCl composite substrate, the coated 2D perovskite films exhibit uniform morphology, vertically oriented crystal growth, and enhanced crystallinity. In comparison with controlled devices, the PEDOT:PSS/CuCl based inverted 2D RP PSCs show a maximum power conversion efficiency of 13.36% and long-term stability. The modified PEDOT:PSS overcomes intrinsic imperfections by doping CuCl, indicating that it has a lot of promise for mass production in electrical devices.