Improved efficiency of bulk heterojunction poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester photovoltaic devices using discotic liquid crystal additives

Well established poly(3-hexylthiophene):[6,6]-phenyl-C-61-butyric acid methyl ester (P3HT:PC61BM) bulk-heterojunction organic photovoltaics (BHJ OPVs) were improved by incorporating a small portion of the discotic liquid crystal (DLC) additives with a strong self-assembling ability and high mobility. Under simulated solar illumination of AM 1.5 (100 mW/cm(2)), the devices fabricated using P3HT:PC61BM (1:1.2 w:w) layer blended with 3 wt % of 2,3,6,7,10,11-hexaacetoxytriphenylene (DLC 2) achieved an average power conversion efficiency (PCE) of 3.97% after thermal annealing, compared to the reference cells with PCE=3.03%. DLCs have been proven here to be a promising new type of additive that can remain embedded in the active layer of high efficiency P3HT:PC61BM BHJ OPVs. (C) 2010 American Institute of Physics. [doi:10.1063/1.3395391]