Kun Wang†, Bing Guo†, Zhuo Xu†, Xia Guo*†（国霞）， Maojie Zhang*†（张茂杰）and Yongfang Li*†‡ （李永舫）
† Laboratory of Advanced Optoelectronic Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
‡ Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
ACS Appl. Mater. Interfaces, 2015, 7 (44), pp 24686–24693
A new planar D2-A-D1-A-D2 structured organic molecule with bithienyl benzodithiophene (BDT) as central donor unit D1 and fluorine-substituted benzothiadiazole (BTF) as acceptor unit and alkyl-dithiophene as end group and donor unit D2, BDT-BTF, was designed and synthesized for the application as donor material in organic solar cells (OSCs). BDT-BTF shows a broad absorption in visible region, suitable highest occupied molecular orbital energy level of −5.20 eV, and high hole mobility of 1.07 × 10–2 cm2/(V s), benefitted from its high coplanarity and strong crystallinity. The OSCs based on BDT-BTF as donor (D) and PC71BM as acceptor (A) at a D/A weight ratio of 3:1 without any extra treatment exhibit high photovoltaic performance with Voc of 0.85 V, Jsc of 10.48 mA/cm2, FF of 0.66, and PCE of 5.88%. The morphological study by transmission electron microscopy reveals that the blend of BDT-BTF and PC71BM (3:1, w/w) possesses an appropriate interpenetrating D/A network for the exciton separation and charge carrier transport, which agrees well with the good device performance. The optimized D/A weight ratio of 3:1 is the lowest acceptor content in the active layer reported so far for the high-performance OSCs, and the organic molecules with the molecular structure like BDT-BTF could be promising high-performance donor materials in solution-processable OSCs.
链接：//pubs.acs.org/doi/10.1021/acsami.5b07085
