Infrared photocurrent spectral response from plastic solar cell with low-band-gap polyfluorene and fullerene derivative

Abstract

Plastic solar cells were fabricated using a low-band-gap alternating copolymer of fluorene and a donor–acceptor–donor moiety (APFO-Green1), blended with [6,6]-phenyl-C61-butyric acid methylester or 3′-(3,5-Bis-trifluoromethylphenyl)-1′-(4-nitrophenyl)pyrazolino[60]fullerene as electron acceptors. The polymer shows optical absorption in two wavelength ranges from 300<λ<500nm and 650<λ<1000nm. Devices based on APFO-Green1 blended with the later fullerene exhibit an outstanding photovoltaic behavior at the infrared range, where the external quantum efficiency is as high as 8.4% at 840nm and 7% at 900nm, while the onset of photogeneration is found at 1μm. A photocurrent density of 1.76mA∕cm2, open-circuit voltage of 0.54V, and power conversion efficiency of 0.3% are achieved under the illumination of AM1.5 (1000W∕m2) from a solar simulator.