title: Synthesis and photovoltaic properties of ester group functionalized polythiophene derivatives.
abstract: To increase the open circuit voltage (V(OC)) of polymer solar cells (PSCs) based on polythiophene, two new ester group functionalized polythiophene derivatives, PCTDT and PCTBDT, were designed and synthesized via alternating copolymerization of thiophene-3-carboxylate (CT) with the 2,2'-bithiophene (DT) and benzodithiophene (BDT) units, respectively. The resulting copolymers exhibited broad and strong absorptions in the visible region, which was similar to that of the commonly used poly(3-hexylthiophene) (P3HT). Through cyclic voltammetry measurements, it was found that both copolymers showed lower HOMO energy levels (-5.27 eV for PCTDT and -5.36 eV for PCTBDT) than that of P3HT (-5.03 eV), indicating that the HOMO energy level could be efficiently reduced by introducing the ester group into the polymer side chain. Photovoltaic properties of the copolymers blended with [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM) as electron acceptor were investigated. The obtained two devices possessed both relatively large short circuit current (I(SC)) and higher V(OC) than that of P3HT:PCBM blend. For PCTBDT:PCBM blend, a power conversion efficiency (PCE) up to 2.32%, an I(SC) of 6.94 mA · cm(-2), and a V(OC) of 0.80 V were observed while PCTDT:PCBM system demonstrated a PCE of 1.75% with a V(OC) of 0.68 V.
authors: State Key Lab of Silicon Materials, MOE Key Laboratory of Macromolecule Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, P R China.
authors: Xiaolian
authors: X
authors: Hu
authors: Minmin
authors: M
authors: Shi
authors: Jian
authors: J
authors: Chen
authors: Lijian
authors: L
authors: Zuo
authors: Lei
authors: L
authors: Fu
authors: Yujing
authors: Y
authors: Liu
authors: Hongzheng
authors: H
authors: Chen
mesh_terms: D011211:Electric Power Supplies; D004952:Esters / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D012993:Solar Energy; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D004952:Esters; D011108:Polymers; D013876:Thiophenes; C066730:polythiophene