title: Incorporation of Hexa-peri-hexabenzocoronene (HBC) into Carbazole-Benzo-2,1,3-thiadiazole Copolymers to Improve Hole Mobility and Photovoltaic Performance.
abstract: Hexa-peri-hexabenzocoronene (HBC) is a discotic-shaped conjugated molecule with strong π-π stacking property, high intrinsic charge mobility, and good self-assembly properties. For a long time, however, organic photovoltaic (OPV) solar cells based on HBC demonstrated low power conversion efficiencies (PCEs). In this study, two conjugated terpolymers, poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5'-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT)-5 HBC and PCDTBT-10 HBC, were synthesized by incorporating different amounts of HBC as the third component into poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5'-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) through Suzuki coupling polymerization. For comparison, the donor-acceptor (D-A) conjugated dipolymer PCDTBT was also synthesized to investigate the effect of HBC units on conjugated polymers. The HBC-containing polymers exhibited higher thermal stabilities, broader absorption spectra, and lower highest-occupied molecular orbital (HOMO) energy levels. In particular, the field-effect mobilities were enhanced by more than one order of magnitude after the incorporation of HBC into the conjugated polymer backbone on account of increased interchain π-π stacking interactions. The bulk heterojunction (BHJ) polymer solar cells (PSCs) fabricated with the polymers as donor and PC71 BM as acceptor demonstrated gradual improvement of open-circuit voltage (VOC ) and short-circuit current (JSC ) with the increase in HBC content. As a result, the PCEs were improved from 3.21 % for PCDTBT to 3.78 % for PCDTBT-5 HBC and then to 4.20 % for PCDTBT-10 HBC.
authors.affiliation: State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing, 100029, China.|Key Laboratory of Carbon Fiber and Functional Polymers of Ministry of Education, Beijing University of Chemical Technology, Beijing, 100029, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing, 100029, China.
authors.forename: Pei
authors.initials: P
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing, 100029, China.
authors.forename: Keli
authors.initials: K
authors.lastname: Shi
authors.affiliation: State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing, 100029, China.
authors.forename: Di
authors.initials: D
authors.lastname: Ma
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China. liyf@iccas.ac.cn.
authors.forename: Yongfang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China. yugui@iccas.ac.cn.
authors.forename: Gui
authors.initials: G
authors.lastname: Yu
authors.affiliation: Key Laboratory of Carbon Fiber and Functional Polymers of Ministry of Education, Beijing University of Chemical Technology, Beijing, 100029, China. lixy@mail.buct.edu.cn.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Li
authors.affiliation: State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing, 100029, China. wanghaiqiao@mail.buct.edu.cn.|Key Laboratory of Carbon Fiber and Functional Polymers of Ministry of Education, Beijing University of Chemical Technology, Beijing, 100029, China. wanghaiqiao@mail.buct.edu.cn.
authors.forename: Haiqiao
authors.initials: H
authors.lastname: Wang
keywords: C−C coupling; conducting materials; coronene; electrochemistry; polymers