Tin(II) thiocyanate Sn(SCN)2 as an ultrathin anode interlayer in organic photovoltaics

We report the application of a coordination polymer semiconductor, tin(II) thiocyanate [Sn(SCN)2], as an ultrathin anode interlayer in organic photovoltaics (OPVs). Sub-10 nm layers of Sn(SCN)2 with high smoothness and excellent transparency having an optical bandgap of 3.9 eV were deposited from an alcohol-based solution at room temperature without post-deposition annealing. Inserting Sn(SCN)2 as an anode interlayer in polymer:fullerene OPVs drastically reduces the recombination loss due to the exciton-blocking energy levels of Sn(SCN)2. At the optimum thickness of 7 nm, an average power conversion efficiency (PCE) of 7.6% and a maximum of 8.1% were obtained. The simple processability using common solvents gives Sn(SCN)2 a distinct advantage over the more well-known copper(I) thiocyanate (CuSCN). The electronic and optical properties of Sn(SCN)2 make it interesting for applications in large-area electronic devices.