Chinese Journal of Organic Chemistry ›› 2020, Vol. 40 ›› Issue (3): 748-755.DOI: 10.6023/cjoc201907032 Previous Articles     Next Articles


王丽辉, 白锁柱, 李东勇, 周宏   

  1. 内蒙古民族大学化学化工学院 内蒙古通辽 028000
  • 收稿日期:2019-07-23 修回日期:2019-10-01 发布日期:2020-04-02
  • 通讯作者: 王丽辉
  • 基金资助:

Effect of Structure Modification of Benzothiadiazole Acceptor Unit on the D-A-D-A-D Typed Oligothiophene Based Donor Materials for Organic Small Molecules Solar Cells: A Theoretical Study

Wang Lihui, Bai Suozhu, Li Dongyong, Zhou Hong   

  1. College of Chemistry and Chemical Engineering, Inner Mongolia University for Nationalities, Tongliao, Neimenggu 028023
  • Received:2019-07-23 Revised:2019-10-01 Published:2020-04-02
  • Supported by:
    Project supported by the Natural Science Foundation of Inner Mongolia Autonomous Region of China (No. 2017MS0208) and the Inner Mongolia University for Nationalities (IMUN) Doctoral Research Start-up Foundation (No. BS450).

Four D-A-D-A-D structured organic small molecules (OSMs) DOBT-8T, BT-8T, FBT-8T and FFBT-8T have been designed for organic solar cells, which contain tetrathiophene as the core donor unit, bithiophene as the termial donor unit, combining different electron-withdrawing fragments DOBT, BT, FBT and FFBT as acceptor unit, respectively. The designed four OSMs were analyzed using density functional theory (DFT) and time dependent-DFT (TDDFT) calculations at B3LYP/6-31G(d) level. The effects of structure modification of benzothiadiazole acceptor unit on modulating the electron-donating ability of OSMs were fully investigated. Results showed that the geometrical structure, the band-gap, HOMO/LUMO energy levels, orbital spatial distribution, energetic driving force, open-circuit voltage and NPA atomic charge of these OSMs can be systematically altered by varying the electron-withdrawing properties with different benzothiadiazole acceptor units. Compared to other OSMs, FBT-8T displayed the more narrowed Eg and relatively deeper HOMO level with FBT as acceptor. FFBT-8T exhibited the most deep-lying HOMO level of the four designed OSMs and suitable Eg value by using FFBT as acceptor. The power conversion efficiencies (PCEs) of ca. 4.7% and ca. 5.2% were achieved by the photovoltaic devices based on FBT-8T:PC61BM and FFBT-8T:PC61BM systems, respectively, predicting with Scharber models. On the basis of these results, FBT-8T and FFBT-8T as potential OSMs donor materials for high-efficiency organic bulk hetero-junction solar cell were proposed.

Key words: B3LYP/6-31G (d), donor, OSMs, organic solar cell, benzothiadiazole, oligothiophenes