Photoenhanced injection currents in organic solar cells

Bulk heterojunction organic solar cells with the general structure: indium tin oxide/polyethylenethioxythiophene (PEDOT)/bulk-heterojunction layer/Al with built-in fields between -0.1 and 1 V have been fabricated by electrochemically doping the PEDOT electrode. The active bulk-heterojunction layer consisted of a blend of MDMO-PPV (poly(2-methoxy-5-(3('),7(')-dimethyl)octyloxy-1,4-phenylenevinylene)) and PCBM ((6,6)-phenyl-C-61-butyric-acid methyl ester)). Measurements of the current-voltage curves with varying light intensities for these devices reveal the presence of light-dependent currents in addition to those from the photogenerated charge carriers. Equivalent circuit modeling indicates that these light-dependent currents most likely originate from photoenhanced injection at the electrodes. (C) 2004 American Institute of Physics.