Performance improvement of inverted polymer solar cells thermally evaporating CuI as an anode buffer layer

The p -type semiconductor copper iodide (CuI) was incorporated into P3HT:ICBA bulk heterojunction polymer solar cells (PSCs) as a novel anode buffer layer. The power conversion efficiency of PSCs with 2   nm CuI is 3.84%, about 1.6 times higher than that of the reference device without CuI, which is due to the simultaneous enhanced photocurrent ( J sc ), open current voltage ( V oc ) and fill factor (FF). The CuI buffer layer can module the Schottky barrier and form an ohmic contact at the P3HT:ICBA/Au interface, which act as both holes transport layer and electron block layer. The complex impedance spectra indicate that CuI buffer layer can also effectively decrease the series resistance of whole device.