Zinc oxide nanorod doped graphene for high efficiency organic photovoltaic devices

Abstract

We report the synthesis of zinc oxide nanorod (ZnR) doped graphene (G) for high performance organic photovoltaic (OPV) devices based on a low bandgap polymer, poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) blended with a fullerene derivative (PC₇₁BM). The use of ZnR–G in a PTB7:PC₇₁BM-based inverted OPV device leads to substantial enhancement in device performance in contrast to the reference devices. The improved performance is attributed to the improved charge carrier separation and prolonged lifetime of the generated electron–hole pairs. In addition, we also found that extra pathways for the disappearance of the charge carriers exist due to the interactions between the excited ZnR and G, which shows that the ZnR–G have a lower recombination rate of electrons and holes under UV light illumination.