Efficient photovoltaic cells from low band-gap fluorene-based copolymer
Chin. Phys. B, 2005, 14 (5):
Polymer photovoltaic cells based on low band-gap copolymer, poly[2,7-(9,9-dioctyl)fluorene-co-5,5’-(4,7-diselenophenyl)-2,2’-yl-2,1,3-benzothiadiazole] (PFSeBT), were investigated, focusing on the effects of cathode and blend concentration on device performances. The best device, with active layer from PFSeBT: PCBM=1:2 blend and with LiF/Al as cathode, shows an open-circuit voltage of 1.00 V, a short short-circuit current density of 4.42 mA/cm2, and energy conversion efficiency of 1.67% under AM1.5 illumination (100 mW/cm2). The short-circuit current density shows the dependence of power law dependence to on the incident light intensity with the power index of 0.887. All devices show spectral response until up to 680 nm. The results indicate that PFSeBT is a potential polymer functioning as electron donor in polymer photovoltaic cells.