Fluorination on electron-deficient units of benzothiadiazole-based donor-acceptor conjugated polymers for novel fullerene-based organic solar cells

Zhengkun Du, Xichang Bao, Christoffer Pajbjerg Andersen, Charlotte Bøgild Didriksen, Junyi Wang, Meng Chang Lin, Zhong Cao, Donghong Yu

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Three new donor-acceptor (D-A) conjugated polymers based on benzo[1,2-b:4,5-b′]dithiophene (BDT) and benzo[c][1,2,5]thiadiazole (BT), namely, PB-BT, PB-BTf and PB-BTPf, were synthesized with different substituents (Hydrogen atoms, Fluorine atoms and fluorophenyl groups) on BT unit. Experimental results and theoretical calculations indicate that molecularly tuning of side chains on BT moeity simultaneously influences the energy levels and intermolecular packing of the resulted polymers by modulating their electron affinity and molecular coplanarity. The polymer solar cells (PSCs) based on a blend of PB-BTf/[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) exhibits the best photovoltaic performance among the three copolymers, with a open-circuit voltage (Voc) of 0.79 V and a power conversion efficiency (PCE) of 8.43%. Furthermore, polymer PB-BTPf containing fluorophenyl groups shows a higher Voc of 0.99 V due to its more low-lying highest occupied molecular orbital (HOMO) compared with other two structural polymeric analogues. The results here provide further fundamental insights into the relationship between the fluorination on electron-withdrawing moiety and the photovoltaic performance for the conjugated polymers applied in fullerene organic solar cells.

Original languageEnglish
Pages (from-to)864-872
Number of pages9
JournalSolar Energy
Volume220
DOIs
Publication statusPublished - May 15 2021
Externally publishedYes

Keywords

  • Benzothiadiazole
  • Donor-acceptor
  • Fluorination
  • Polymer solar cells
  • Steric hindrance

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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