Efficient solution-processed small-molecule solar cells with titanium suboxide as an electric adhesive layer

Abstract

We demonstrate efficient and air-stable small-molecule bulk heterojunction (SM BHJ) solar cells by introducing titanium suboxide (TiOx) between the active layer and the cathode as an electric adhesive layer. The SM BHJ solar cell with the TiOx interlayer exhibits improved power conversion efficiency of 6.4% as well as greatly enhanced device lifetime. Analysis of the dark diode characteristics and comparison of the current density-voltage characteristics upon heat annealing indicate that the TiOx interlayer improves the electrical contact between the active layer and the cathode, thereby resulting in efficient sweep-out of photogenerated charge carriers. (C) 2014 AIP Publishing LLC.