Two-dimensionally extended π-conjugation of donor-acceptor copolymers via oligothienyl side chains for efficient polymer solar cells

Jaewon Lee, Joo Hyun Kim, Byungho Moon, Heung Gyu Kim, Min Kim, Jisoo Shin, Hyeongjin Hwang, Kilwon Cho

Research output: Contribution to journalArticlepeer-review

64 Citations (Scopus)

Abstract

A series of two-dimensional conjugated polymers containing π-conjugated oligothienyl side chains, namely PBDT2FBT-T1, PBDT2FBT-T2, PBDT2FBT-T3, and PBDT2FBT-T4, was designed and synthesized to investigate the effect of two-dimensionally extended π-conjugation on the polymer solar cell (PSC) performance. The oligothienyl units introduced into the side chains significantly affect the optoelectronic properties of the parent polymers as well as the performances of the resulting solar cell devices by altering the molecular arrangement and packing, crystalline behavior, and microstructure of the polymer:PC71BM blend films. The crystallinity and blend morphology of the polymers can be systematically controlled by tuning the π-conjugation length of side chains; PBDT2FBT-T3 exhibited the most extended UV/vis light absorption band and the highest charge mobility, leading to a high short-circuit current density up to 12.5 mA cm-2 in the relevant PSCs. The PBDT2FBT-T3:PC71BM-based PSC exhibited the best power conversion efficiency of 6.48% among this series of polymers prepared without the use of processing additives or post-treatments. These results provide a new possibility and valuable insight into the development of efficient medium-bandgap polymers for use in organic solar cells.

Original languageEnglish
Pages (from-to)1723-1735
Number of pages13
JournalMacromolecules
Volume48
Issue number6
DOIs
Publication statusPublished - 2015 Mar 24
Externally publishedYes

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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