A newly designed benzodithiophene building block: tuning of the torsional barrier for non-halogenated and non-aromatic solvent-processible photovoltaic polymers

Hye Won Cho, Sang Young Jeong, Ziang Wu, Hyojin Lim, Won Woo Park, Woojin Lee, Jonnadula Venkata Suman Krishna, Oh Hoon Kwon, Jin Young Kim, Han Young Woo

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

A new benzodithiophene (BDT) building block, 4,8-bis(5-(2-ethylhexyl)-3-fluoro-4-hexylthiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene (3-FBDT), was designed by tailoring the positions and number of alkyl and F substituents by adjusting the torsional energy barrier. The incorporation of 3-FBDT into a representative BDT-based polymer donor (PBDB-T-2F) yielded a new photovoltaic copolymer (PBDB-T-2F(3/4)) with a decreased valence band level and considerably improved solubility in non-halogenated and non-aromatic solvents such as tetrahydrofuran (THF). Side-chain engineering has been widely studied to control solution processability in eco-friendly solvents, but the torsional property control of conjugated main chains has rarely been attempted. Although PBDB-T-2F showed a significant drop in power conversion efficiencies (PCEs: 17.46 to 9.73%) owing to serious aggregation caused by replacing chloroform with THF as a processing solvent, the THF-processed PBDB-T-2F(3/4) device maintained a high PCE (14.3 to 13.86%) with little detrimental effect. Charge carrier dynamics and film morphology analyses suggested that the electronic and morphological properties of PBDB-T-2F(3/4) are mainly governed by the majority moiety of the PBDB-T-2F blocks. Owing to its high solubility and outstanding photoelectrical properties, PBDB-T-2F(3/4) was successfully employed to fabricate flexible, semi-transparent, and large-area THF-processed devices. The incorporation of the 3-FBDT building block into various BDT-based photovoltaic polymers can be an effective strategy to improve the solution processability and broaden the solvent selection for fabricating eco-friendly solar cells without significantly disrupting their photoelectrical properties.

Original languageEnglish
Pages (from-to)7053-7065
Number of pages13
JournalJournal of Materials Chemistry A
Volume11
Issue number13
DOIs
Publication statusPublished - 2023 Feb 28

Bibliographical note

Publisher Copyright:
© 2023 The Royal Society of Chemistry.

ASJC Scopus subject areas

  • General Chemistry
  • Renewable Energy, Sustainability and the Environment
  • General Materials Science

Fingerprint

Dive into the research topics of 'A newly designed benzodithiophene building block: tuning of the torsional barrier for non-halogenated and non-aromatic solvent-processible photovoltaic polymers'. Together they form a unique fingerprint.

Cite this