Improving the efficiency and stability of inverted perovskite solar cells by CuSCN-doped PEDOT:PSS

Hole transport layer (HTL) is important in inverted perovskite solar cells (PSCs) to facilitate the hole extraction and suppress the charge recombination for high device performance. Based on the widely used HTL material of poly(ethylenedioxythiophene) (PEDOT):poly(styrenesulfonate) (PSS), we proposed a new HTL modification method using the widely available copper(I) thiocyanate (CuSCN); the doping of CuSCN NH3 [aq] in PEDOT:PSS followed by low-temperature annealing results in reduced energy barrier, improved charge extraction efficiency and increased the mean size of perovskite crystal of the PEDOT:PSS-CuSCN HTL-based inverted PSCs. Significantly improved device performance was observed with open current voltage over 1.0 V and power conversion efficiency (PCE) up to 15.3%, which is 16% higher in PCE than that of the PEDOT:PSS-based PSCs. More impressively, with a lower acidity than PEDOT:PSS, the PEDOT:PSS-CuSCN HTL enables excellent long-term stability of the inverted PSCs, exhibiting almost doubly improved device stability at the same storage condition. Thus, the successful application of CuSCN doping in PEDOT:PSS HTLs should provide a novel approach for the development of high-performance HTLs for highly efficient and stable PSCs.