Conjugated Polymer Consisting of Quinacridone and Benzothiadiazole as Donor Materials for Organic Photovoltaics: Coplanar Property of Polymer Backbone
作者:Ho-Jun Song、Doo-Hun Kim、Eui-Jin Lee、Soo-Won Heo、Jang-Yong Lee、Doo-Kyung Moon
DOI:10.1021/ma301466m
日期:2012.10.9
Highly soluble poly[quinacridone-alt-benzothiadiazole] (PQCDTB) has been synthesized through the Suzuki coupling reaction by introducing planar quinacridone and highly absorbing benzothiadiazole. The PQCDTB dissolved in general organic solvents, and the M-n was 49.8 kg/mol. The optical band gap energy was 1.92 eV, which was similar to the band gap of benzothiadiazole. The HOMO and LUMO levels of PQCDTB were -5.24 eV and -3.32 eV, respectively. According to the XRD measurement, PQCDTB showed the formation of ordered lamellar structure as an out-of-plane peak (h00) by the alkyl side chain of quinacridone and conventional edge-on pi- stacking. This study also evaluated the OPV characteristics by fabricating a bulk-heterojunction-type polymer solar cell. When PQCDTB and PC71BM were fabricated in a 1:1 weight ratio, the open-circuit voltage (V-OC), short-circuit current (J(SC)), fill factor (FF), and power conversion efficiency (PCE) were 0.79 V, 5.6 mA cm(-2), 55.8% and 2.5%, respectively. In particular, PQCDTB exhibited higher FFs compared with poly[carbazole-alt-benzothiadiazole] (PCZDTB).