Polymer solar cells with electrodeposited CuSCN nanowires as new efficient hole transporting layer

Here, we report for the first time that electrodeposited CuSCN nanowires (NWs) could be successfully used as a new hole transporting layer (HTL) in a conventional polymer solar cell (PSC) with a poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)]:[6,6]-phenyl-C71-butyric acid methyl ester (PCDTBT:PC70BM) blend as an active layer. An efficient PSC with 5.1% power conversion efficiency for 28 mm2 active surface area is fabricated. The performances of the PSCs prepared with electrodeposited CuSCN thin films and nanowires are compared and the obtained results clearly show that the nanostructuring of the HTL leads to an efficient hole extraction. The influence of the HTL thickness on the device performances was studied and it has been found that the thickness of the CuSCN nanowire array should not exceed the active layer thickness in order to keep high performances. An extraordinary high open circuit voltage (>900 mV) and a fill factor about 60% were measured. It is shown that the electrodeposited CuSCN thin films and NWs could be directly used in the polymer solar cells without any subsequent annealing process, which is a crucial point for the reduction of the device costs.