An eco-friendly and inexpensive solvent for solution processable CuSCN as a hole transporting layer in organic solar cells

During past few years, significant research on solution-processable deposition of copper(I)thiocyanate (CuSCN) as an efficient hole transporting layer (HTL) for excitonic solar cells have been successfully reported. Surprisingly, till now only two solvents diisopropyl sulfide and diethyl sulfide are known which have been used for CuSCN film deposition as a HTL for device fabrication. Here, we have used eco-friendly and inexpensive solvent dimethyl sulfoxide (DMSO) for solution processed thin film deposition of CuSCN for organic solar cells. The photovoltaic devices were fabricated using two different donor polymers PCDTBT and PTB7 blended with PC71BM as an acceptor material with device structure of ITO/CuSCN/active layer/Al. The power conversion efficiency (PCE) based on CuSCN using DMSO as a deposition solvent have been achieved up to 4.20% and 3.64% respectively, with relative higher fill factor (FF) as compared to previously reported values in literature. The resultant HTLs were characterized by UV-vis-NIR spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM) and atomic force microscope (AFM) for better understanding.