Controlling morphology and improving the photovoltaic performances of P3HT/ZnO hybrid solar cells via P3HT-b-PEO as an interfacial compatibilizer

The well-defined rod-coil diblock copolymer poly(3-hexylthiophene)-b-poly(ethylene oxide) (P3HT-b-PEO) was used as the interfacial compatibilizer for P3HT/ZnO (1 : 2 w/w) hybrid heterojunction solar cells. The power conversion efficiency of the device was enhanced from 0.5 to 0.98% in the presence of 0-10 wt% P3HT-b-PEO under illumination of AM 1.5G (100 mW cm(-2)), resulting from the morphology variation. In the P3HT/ZnO/P3HT-b-PEO ternary blends, the block copolymer does not influence the crystallinity of ZnO NPs, but does influence the crystallinity of P3HT and the dispersion of ZnO NPs. An enhanced crystalline and fiber-like P3HT and more uniform dispersion of ZnO NPs are observed with a small amount of P3HT-b-PEO (10 wt%) loading, leading to a smaller domain size, enhanced interfacial area for charge separation and a favored active layer morphology for improving the device performance. On the other hand, the incorporated P3HT-b-PEO could also suppress macrophase separation during long time thermal annealing and improve the device thermal stability. These results demonstrated that the promising effect of the rod-coil diblock copolymers interfacial compatibilizer for controlling the morphology and improving the performance of hybrid bulk heterojunction solar cells.