PREPARATION AND PHOTO-INDUCED CHARGE TRANSFER OF COMPOSITES BASED ON PCPDTBT

Poly [2, 6-(4, 4-bis-(2-ethylhexyl)-4H-cyclopenta [2, 1-b; 3, 4-b ] dithiophene)-alt-4, 7-(2, 1, 3-benzothiadiazole)] (PCPDTBT) is a new kind of low band-gap polymers for applications in organic photovoltaic devices. However, PCPDTBT was studied as the donor to form the photoactive composites only with organic acceptors (fullerene derivatives) so far. In this article, PCPDTBT was synthesized, and its chemical structure, thermal stability and energy levels were identified and characterized by NMR, GPC, TGA, and CV, respectively. Furthermore, the composites of PCPDTBT with two electron acceptors of 1-(3-methoxycarbonylpropyl)-1-phenyl[6,6]C-61 (PCBM) and ZnO nanoparticles were prepared by solution-blending. Both composites showed fluorescence quenching, indicating that the photo-induced charge transfer occurred due to the energy level offset between the donor PCPDTBT and the acceptor. Nevertheless, from the SEM images of the two composites, it was disclosed that PCBM molecules were well dispersed all over the PCPDTBT- PCBM composite whereas ZnO nanoparticles aggregated to some extent in the PCPDTBT-ZnO composite, leading to a more effective photo-induced charge transfer between PCPDTBT and PCBM.