Solvent influenced morphology control of hole transport layer of CuSCN on performance of organic solar cells

During the last few years, research has significantly attracted in solution-processable deposition of copper(I)thiocyanate (CuSCN) as hole transport layer (HTL) in solar cells. However, the choice of solvents for solution-processable deposition of CuSCN as HTL has been limited. Here we introduce a wide range of solvents (dimethylformamide (DMF), dioxane, acetonitrile, ethylene glycol, propylene carbonate, and as well as previously reported dimethylsulfoxide (DMSO)) for solution-processable deposition of CuSCN as HTL in bulk heterojunction solar cells. The effect of change of solvents on the morphology of HTL and device performances were studied. Two active layers PTB7:PC71BM and PCDTBT:PC71BM were used for solution-processable device fabrication. The use of DMF and DMSO as solvents for solution-processable deposition of HTL give the efficiencies 4.56% and 4.28%, respectively. These photovoltaic performances were evaluated with scanning electron microscopy, atomic force microscopy, X-Ray diffraction and absorption studies. These studies open a new approach towards getting higher PCE and more alternative solvents for the fabrication of solution-processable devices in different solar cells.