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Indexed by:期刊论文

Date of Publication:2014-06-01

Journal:ORGANIC ELECTRONICS

Included Journals:EI、SCIE

Volume:15

Issue:6

Page Number:1138-1148

ISSN No.:1566-1199

Key Words:Triphenylamine (TPA); Benzothiadiazole (BT); pi-Linkage; Small molecular solar cells; Bulk heterojunction (BHJ); Solution-processed

Abstract:Two novel small molecular photovoltaic (PV) materials, BDPTBT and BDATBT were designed and synthesized, consisting of 5,6-bis-(octyloxy) benzo[c][1,2,5] thiadiazole (DOBT) as electron-withdrawing core (A), and triphenylamine (TPA) as electron-donating side group (D). Moreover, the benzene and ethynylbenzene as pi-linkage were introduced to form donor-pi-acceptor-pi-donor (D-pi-A-pi-D) typed molecular structures, respectively. To fully investigate the linkage effect of a series of small molecules, two reference compounds BDCTBT and BDETBT were also studied systematically, consisting of 2-phenylacrylonitrile and styrene as p-linkage, respectively. As a result, the p-linkage units, benzene, styrene, ethynylbenzene and 2-phenylacrylonitrile played an important role in modifying molecular structure and improving PV performance. Bulk heterojunction (BHJ) solar cells based on BDPTBT/PC61BM and BDATBT/PC61BM yielded the power conversion efficiencies (PCEs) of 2.99% and 2.03%, respectively. Notably, BDATBT based device showed a high open-circuit voltage (Voc) of 1.03 V. Compared to the results we have reported previously, the reference devices based on BDCTBT/PC61BM and BDETBT/PC61BM with the optimized weight ratio showed dramatically enhanced PCEs of 4.84% and 3.40%, respectively, and BDCTBT based device showed a high Voc of 1.08 V. To our knowledge, the Voc of 1.08 V is the highest voltage reported to date for devices prepared from solution-processed small-molecule-donor materials, and the PCE of 4.84% is the highest efficiency reported so far for D-A-D-typed benzothiadiazole (BT)-TPA based solution-processed small molecules PV devices. (C) 2014 Elsevier B.V. All rights reserved.