| 摘要： |
To construct efficient low band gap polymers, increasing the Quinone structure of the polymer backbone could be one desirable strategy. In this work, two D-Q-A-Q polymers P1 and P2 were designed and synthesized with thiophenopyrrole diketone (TPD) and benzothiadiazole (BT) unit as the core and ester linked thieno[3,4-b]thiophene (TT) segment as pi-bridging, and the main focus is to make a comparative analysis of different cores in the influence of the optical, electrochemical, photochemical and morphological properties. Compared with the reported PBDTTEH-TBTTHD-i, P1 exhibited the decreased HOMO energy level of -5.38 eV and lower bandgap of 1.48 eV. Furthermore, when replaced with BT core, P2 showed a red-shifted absorption profile of polymer but with up-shifted HOMO energy level. When fabricated the photovoltaic devices in conventional structure, just as expected, the introduction of ester substituent made an obvious increase of V-OC from 0.63 to 0.74 V for P1. Besides, due to the deep HOMO energy level, higher hole mobility and excellent phase separation with PC71BM, a superior photovoltaic performance (PCE = 7.13%) was obtained with a short-circuit current density (J(SC)) of 14.9 mA/cm(2), significantly higher than that of P2 (PCE = 2.23%). Generally, this study highlights that the strategy of inserting quinoid moieties into D-A polymers could be optional in LBG-polymers design and presents the importance and comparison of potentially competent core groups. (C) 2019 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved. |
