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

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- C 61 -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 < 500 nm and 650 < λ < 1000 nm . 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 840 nm and 7% at 900 nm , while the onset of photogeneration is found at 1 μ m . A photocurrent density of 1.76 mA ∕ cm 2 , open-circuit voltage of 0.54 V , and power conversion efficiency of 0.3% are achieved under the illumination of AM1.5 ( 1000 W ∕ m 2 ) from a solar simulator.