Solution-Processed Hybrid Cathode Interlayer for Inverted Organic Solar Cells

A novel hybrid material CdS/2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (CdS·BCP) was prepared from the decomposition of its organic soluble precursor complex Cd­(S2COEt)2·(BCP) by low-temperature treatment. CdS·BCP, which integrated the favorable properties of solvent durability, and high electron mobility of CdS as well as the good hole blocking property of BCP, was designed and developed as the interface modification material to improve electron collection in bulk heterojunction organic solar cells (OSCs). The inverted OSCs with CdS·BCP as buffer layer on ITO showed improved efficiency compared with the pure CdS or BCP. Devices with CdS·BCP as interlayer exhibited excellent stability, only 14.19% decay of power conversion efficiencies (PCEs) was observed (from 7.47% to 6.41%) after stored in glovebox for 3264 h (136 days). Our results demonstrate promising potentials of hybrid materials as the interface modification layers in OSCs, and provide new insights for the development of new interface modification materials in the future.