EFFICIENCY ENHANCEMENT BY PRISTINE C_(70) DOPED IN POLYMER SOLAR CELLS - Effects of Quantum Efficiency of Fullerenes

摘要

The quantum efficiency (QE) values of six kinds of fullerenes were measured to understand the effects of QE values on the characteristics of polymer solar cells. By xerographic discharge method, the order of QE value was obtained as follows; C_(70)>bisPC_(70)BM>PC_(70)BM>PC_(60)BM>C_(60)>PC_(84)BM. The power conversion efficiency (PCE) values of polymer solar cells consisting of fullerenes and P3HT were approximately proportional to QE's of fullerene derivatives. Although pristine C_(70) showed the highest QE value, 0.72 at 640 nm, the highest PCE value was given by PC_(70)BM cell. Among the fullerene derivatives, bisPC_(70)BM gave the highest QE and Voc. By doping pristine C_(70) into the active layer consisting of P3HT and PC_(70)BM, PCE enhancement was observed, especially in the cases of lower molecular weight P3HT.