Enhanced Performance of Polymer Solar Cells Comprising Diketopyrrolopyrrole-Based Regular Terpolymer Bearing Two Different π-Extended Donor Units

Eun Yi Ko, Gi Eun Park, Dae Hee Lee, Hyun Ah Um, Jicheol Shin, Min Ju Cho, Dong Hoon Choi

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

New regular and random diketopyrrolopyrrole (DPP)-based terpolymers (i.e., Reg-PBDPPT and Ran-PBDPPT, respectively) bearing DPP as an electron deficient unit and 2,2′-bithiophene and (E)-1,2-di(thiophen-2-yl)ethene as electron donating units were designed and synthesized, and their performance in photovoltaic cells was investigated precisely. The absorption properties and highest occupied molecular orbital (HOMO) of Reg-PBDPPT were found to be different from those of Ran-PBDPPT. The results of grazing incidence X-ray diffraction experiments revealed that Ran-PBDPPT typically had a predominantly edge-on chain orientation on the substrate, whereas Reg-PBDPPT showed mixed chain orientation both in pristine and thermally annealed films. Although Reg-PBDPPT exhibited a lower degree of edge-on chain orientation on the substrate, the corresponding TFTs showed a high hole mobility of 0.42-0.96 cm2 V-1 s-1 and maintained a high current on/off ratio (>106). A polymer solar cell (PSC) composed of Reg-PBDPPT and PC71BM exhibited power conversion efficiencies (PCE) of 5.24-5.45%, which were higher than those of the Ran-PBDPPT-based PSCs. The enhanced efficiency was supported by an increase in the short circuit current, which is strongly related to the unique internal crystalline morphology and pronounced nanophase segregation behavior in the blend films. These results obviously manifested that this synthetic strategy for regular conjugated terpolymers could be employed to control morphological properties to obtain high-performance PSCs.

Original languageEnglish
Pages (from-to)28303-28310
Number of pages8
JournalACS Applied Materials and Interfaces
Volume7
Issue number51
DOIs
Publication statusPublished - 2015 Dec 30

Keywords

  • crystalline morphology
  • polymer semiconductor
  • polymer solar cell
  • terpolymer
  • thin-film transistor

ASJC Scopus subject areas

  • Materials Science(all)

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