Photophysical and photovoltaic properties of a polymer–fullerene system containing CdSe nanoparticles

In this report, the photophysical studies and the photovoltaic performance of the P3HT:PCBM system containing CdSe nanoparticles were investigated. The addition of CdSe into P3HT:PCBM system promoted a decrease in the photocurrent and in the efficiency of the solar cells. The reduction in photocurrent and efficiency observed after addition of even small portions of CdSe can be associated to a strong interaction between polymer and CdSe nanoparticles, as evidenced by absorption and emission measurements. To investigate the possible contribution of a morphological effect induced by CdSe in P3HT:PCBM film, atomic force microscopy images were also obtained. To get a better understanding of how this ternary system works, comparison was made with another system: PCBM:CdSe and poly(9,9-n-dihexyl-2,7-fluorenylenevinylene-alt-2,5-thienylenevinylene (PFT), as reported by de Freitas et al. [Journal of Material Chemistry 20 (2010) 4845]. Our results indicate that the chemical structure of the chosen polymer is an important issue in ternary systems and, and that P3HT, a polymer whose chain contains a large concentration of thiophene units, favors polymer–nanoparticle aggregation.