Fine dispersion and self-assembly of ZnO nanoparticles driven by P3HT-b-PEO diblocks for improvement of hybrid solar cells performance

Abstract

The rod-coil conjugated diblock copolymers of poly(3-hexylthiophene)-b-poly(ethylene oxide) (P3HT-b-PEO), acting as an electron donor, were blended with ZnO nanoparticles to fabricate the hybrid bulk-heterojunction (BHJ) solar cells. According to the ultraviolet-visible (UV-vis) absorption spectroscopy, the intensity at 610 nm, derived from a strong inter-molecular interaction of π–π stacking and the high crystallizability of the P3HT main chains, was higher in P3HT-b-PEO/ZnO blend films than that in P3HT/ZnO blend films especially after thermal treatment, revealing that PEO segments could make P3HT form more densely stacked and orderly structured. Due to the nature of block copolymers and the interaction between the oxygen atoms of the PEO chains and the ZnO polar surface, the surface defects of ZnO were passivated and the fine dispersion and self-assembly of ZnO in the polymer matrix driven by the P3HT-b-PEO diblock copolymer was obtained, leading to the improvement of device power conversion efficiency and thermal stability. Overall, this work demonstrated that the application of conjugated block copolymers in hybrid BHJ solar cells was a promising approach to improve the device performance and thermal stability.