Enhancement of polymer photovoltaic performances by doping with modified carbon black nanoparticles

Low-cost carbon black nanoparticle (CBNP) was chemically modified by grafting with flexible alkyl groups. The modified CBNP (m-CBNP) forms a spider-like cluster with a considerably enhanced solubility, thereby enabling their uniform dispersal into a polymer matrix or active layers of bulk hetero-junction polymer photovoltaic cells, such as a blend of poly(3-hexylthiophene) and (6,6)-phenyl C61 butyric acid methyl ester. The performance of devices containing the m-CBNP was substantially improved. Charge carrier mobility enhancement was found to play a key role, leading to a 30 % improvement in the short-circuit current of the devices.