title: Dialkylthio Substitution: An Effective Method to Modulate the Molecular Energy Levels of 2D-BDT Photovoltaic Polymers.
abstract: Dialkylthio-substituted thienyl-benzodithiophene (BDT-DST) was designed and synthesized as a building block to modulate the molecular levels of the conjugated polymers, and three copolymers named PDST-BDD, PDST-TT and PDST-DPP were prepared and applied in polymer solar cells (PSCs). Theoretical calculations and electrochemical cyclic voltammetry (CV) measurement suggested that the dialkylthio group could decrease the molecular energy levels of the resulting polymers distinctly. The open-circuit voltage (VOC) of PSC devices based on PDST-BDD, PDST-TT, and PDST-DPP are as high as 1.0, 0.98, and 0.88 V, respectively, which are ∼0.15 V higher than those of the corresponding alky-substituted analogues. Moreover, the influence of the dialkylthio group on the absorption spectra, crystalline properties, hole mobilities, and blend morphologies of the polymers was also investigated. The results indicate that the dialkythio substitution is an effective method to modulate the molecular energy levels and that the BDT-DST unit has potential for constructing high-efficiency photovoltaic polymers.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, China.
authors.forename: Huifeng
authors.initials: H
authors.lastname: Yao
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, China.
authors.forename: Long
authors.initials: L
authors.lastname: Ye
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, China.
authors.forename: Wenchao
authors.initials: W
authors.lastname: Zhao
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, China.
authors.forename: Shaoqing
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, China.
authors.forename: Jianhui
authors.initials: J
authors.lastname: Hou
keywords: conjugated polymer; dialkylthio substitution; molecular energy levels; photovoltaic polymer; polymer solar cell