Compositional dynamics of the electron transport layer (ZnO:PEIE) in P3HT:PC61BM organic solar cells

Abstract

This study elucidates a comparison between zinc oxide (ZnO) and zinc oxide:Polyethylenimine ethoxylated (ZnO:PEIE) nanocomposite as an electron transport layer (ETL). The impact of ZnO:PEIE annealing temperature to increase the fill factor (FF) and current density (Jsc) of the devices was first studied after optimizing the doping concentration of PEIE. It was found that 0.4 wt% concentration and 150 °C annealing temperature of ZnO:PEIE ETL showed a superior performance for the devices. The introduction of PEIE promoted the charge transport by decreasing the work function of ZnO, which caused an improvement in the conductivity and current density of devices. For ZnO, the efficiency was 1.25%, which was enhanced to 1.46% with 0.4 wt% PEIE doping and further enhanced to 1.53% at 150 °C annealing temperature. The crystallinity of the ETL can be enhanced by choosing an effective annealing temperature that assists in increasing the current density and fill factor. This research work offers a desirable approach for the synthesis of high-performance organic solar cells.