Performance improvement of organic bulk heterojunction solar cells by using dihydroxybenzene as additive

We report the enhanced performance of organic solar cells (OSCs) based on regioregular poly(3-hexylthiophene) (P3HT) and methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM) blend by using dihydroxybenzene as additive in the active layer. The effect of the content of the additives on electrical characteristics of the device is studied. The device with 0.2 wt% dihydroxybenzene additive achieves the best power conversion efficiency (PCE) of 4.58% with Jsc of 12.5 mA/cm2, Voc of 0.65 V, and FF of 66. 6% under simulated solar illumination of AM 1. 5G (100 mW/cm2), compared with the control device with PCE of 3. 39% (35% improvement compared with the control device). The XRD measurement reveals that the addition of additives induces the crystallization of P3HT and establishes good inter-network to increase the contact area of donor and acceptor, and then helps charge to be effectively transferred to the electrode to reduce the chance of recombination. All evidences indicate that the dihydroxybenzene is likely to be a promising new type additive that can enhance the performance of organic bulk heterojunction solar cells. © 2011 Tianjin University of Technology and Springer-Verlag Berlin Heidelberg.