Performance Promotion through Dual-Interface Engineering of CuSCN Layers in Planar Perovskite Solar Cells

Although perovskite solar cells (PSCs) with organic hole-transporting layers (HTLs) have demonstrated the certified power conversion efficiency (PCE) over 25%. Unavoidable performance degradation in the atmosphere is still one of the key hurdles facing the practical application. In this work, low-temperature solution-processed CuSCN was attempted as the inorganic HTL, which has been expected to provide an appreciable enhancement in device stability. In addition, concerning the potential-induced degradation around the CuSCN/Au interface, a thin PTB7 layer was inserted as a spacer, yielding a dramatically promoted device stability. Furthermore, in order to avoid the destruction to perovskites by the solvent of CuSCN, PTAA was attempted as a protection sheath of perovskites. Consequently, with optimized dual-interface engineering, the best performing cell delivers a PCE of 18.41% (average 17.63%) and maintains approximately 98.8% of the initial value more than 1000 h without encapsulation, manifesting the superior stability. This approach paves a way for achieving PSCs with both high efficiency and long-term durability.