title: Effect of extended π-conjugation structure of donor-acceptor conjugated copolymers on the photoelectronic properties.
abstract: New donor-acceptor conjugated copolymers based on alkylthienylbenzodithiophene (BDTT) and alkoxynaphthodithiophene (NDT) have been synthesized and compared with their benzo[1,2-b:4,5-b']dithiophene (BDT)-based analogues to investigate the effect of the extended π conjugation of the polymer main chain on the physicochemical properties of the polymers. A systematic investigation into the optical properties, energy levels, field-effect transistor characteristics, and photovoltaic characteristics of these polymers was conducted. Both polymers demonstrated enhanced photovoltaic performance and increased hole mobility compared with the BDT-based analogue. However, the BDTT-based polymer (with π-conjugation extension perpendicular to main chain) gave the highest power conversion efficiency of 5.07% for the single-junction polymer solar cell, whereas the NDT-based polymer (with π-conjugation extension along the main chain) achieved the highest hole mobility of approximately 0.1 cm(2) V(-1)  s(-1) based on the field-effect transistor; this indicated that extending the π conjugation in different orientations would have a significant influence on the properties of the resulting polymers.
authors.affiliation: State Key Laboratory of Organic-Inorganic Composites, Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (P.R. China); Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (P.R. China).
authors.forename: Meng
authors.initials: M
authors.lastname: Wang
authors.forename: Shaowei
authors.initials: S
authors.lastname: Shi
authors.forename: Di
authors.initials: D
authors.lastname: Ma
authors.forename: Keli
authors.initials: K
authors.lastname: Shi
authors.forename: Chen
authors.initials: C
authors.lastname: Gao
authors.forename: Liwei
authors.initials: L
authors.lastname: Wang
authors.forename: Gui
authors.initials: G
authors.lastname: Yu
authors.forename: Yongfang
authors.initials: Y
authors.lastname: Li
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Li
authors.forename: Haiqiao
authors.initials: H
authors.lastname: Wang
keywords: conjugation; donor-acceptor systems; photochemistry; polymers; structure-activity relationships