Approach to a block polymer precursor from poly(3-hexylthiophene) nitroxide-mediated in situ polymerization for stabilization of poly(3-hexylthiophene)/ZnO hybrid solar cells

Abstract

A cross-linked block copolymer poly(3-hexylthiophene)-b-poly(zinc dimethacrylate) (P3HT-b-PZn(MA)2), which acted as precursor for the preparation of poly(3-hexylthiophene)/ZnO (P3HT/ZnO) hybrid film by in-situ hydrolysis, was rationally designed and synthesized via nitroxide-mediated in-situ polymerization of zinc methacrylate (Zn(MA)2) using poly(3-hexylthiophene) alkoxyamine (P3HT-TIPNO) as macroinitiator for the purpose of stabilizing the P3HT/ZnO hybrid solar cells. The cross-linking was confirmed by the insolubility of the film in organic solvents and Fourier-transform infrared experiment. With the function of the cross-linked template, the diffusion of ZnO nanoparticles prepared by in-situ hydrolysis could be lowered to suppress the formation of large aggregations, which favored the formation of a better and more stable interpenetrating network and provided more heterojunction interfaces for exciton dissociation. As a result, the inverted device based on cross-linked P3HT/ZnO hybrid film obtained by in situ hydrolyzing P3HT-b-PZn(MA)2 block copolymer yielded a power conversion efficiency of 0.45% under AM 1.5G illumination from a calibrated solar simulator with an intensity of 100mW/cm2, and the deterioration of the photoconversion performance was suppressed in the hybrid solar cells with the cross-linked P3HT/ZnO compared to cells with non-cross-linked P3HT/ZnO obtained by in situ hydrolyzing P3HT-TIPNO/Zn(MA)2 blend film.