Bulk heterojunction organic photovoltaic devices based on low band gap small molecule BTD-TNP and perylene-anthracene diimide

Bulk heterojunction (BHJ) photovoltaic devices were fabricated from the blends of compounds BTD-TNP (electron donor) and P-A (electron acceptor) and characterized through current-voltage measurements under illumination. Compound BTD-TNP contains dithyenyl-benzothiadiazole central unit and cyanovinylene-p-nitrophenyl terminal moieties. Compound P-A is a symmetrical perylene-anthracene diimide with tert-butylphenoxy side groups at the 1,7-bay positions. Both the absorption spectra and the incident photon to the current conversion efficiency (IPCE) spectra of the device were extended up to 800 nm. A power conversion efficiency of 2.85% with short-circuit current density of 6.8 mA/cm(2), open-circuit voltage of 0.88V and fill factor of 0.47 were obtained. It was found that the hole and electron mobility in the active layer were about 4.6 x 10(-5) and 8.8 x 10(-4) cm(2)/Vs, respectively, which indicates the fairly balanced charge transport in the device. (C) 2009 Elsevier B. V. All rights reserved.