Low-bandgap polymers with quinoid unit as π bridge for high-performance solar cells

• 来源期刊: 能源化学
• 年，卷（期）: 2020,（1）
• 页码范围: 180-187
• 页数: 8页
• 语种: 英文

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 π-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 Voc 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 (Jsc) of 14.9 mA/cm2,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.