Rational Design of Carbazole- And Carboline-Based Polymeric Host Materials for Realizing High-Efficiency Solution-Processed Thermally Activated Delayed Fluorescence Organic Light-Emitting Diode

Jinhyo Hwang, Chiho Lee, Ji Eun Jeong, Chae Yeong Kim, Han Young Woo, Sungnam Park, Min Ju Cho, Dong Hoon Choi

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Recently, various host materials have been developed for solution-processed thermally activated delayed fluorescent organic light-emitting diodes (TADF-OLEDs). Compared with small-molecule hosts, polymeric hosts are advantageous for inducing a uniform distribution and segregation of dopant molecules in the emissive layer without undesired large-scale phase separation. In this study, new polymer hosts were demonstrated, in which a bipolar conjugative moiety consisting of a carbazole (Cz) donor and an α-carboline (α-Cb) acceptor was bound to the polystyrene backbone through a non-conjugated linker. They exhibited high triplet energies of >2.8 eV, and their emission spectra overlapped with the absorption spectrum of a green TADF emitter, which allowed facile energy transfer from the polymeric host to the small-molecule dopants. High device performance was observed, with external quantum efficiencies (EQEs) of 13.65, 17.09, and 17.48% for solution-processed green TADF-OLEDs using PSCzCz, PSCzCb, and PSCbCz, respectively, as hosts for the EML. The EQEs of bipolar host (PSCzCb and PSCbCz)-based devices were higher than those of unipolar host (poly(N-vinylcarbazole) and PSCzCz)-based devices owing to the well-balanced charge-carrier transport. According to these results, the polymeric host bearing a bipolar Cz and α-Cb coupled moiety is a promising material for solution-processable TADF-OLEDs.

Original languageEnglish
Pages (from-to)8485-8494
Number of pages10
JournalACS Applied Materials and Interfaces
Volume12
Issue number7
DOIs
Publication statusPublished - 2020 Feb 19

Keywords

  • carbazole
  • carboline
  • polymer light-emitting diode
  • polymeric host
  • solution process
  • thermally activated delayed fluorescent

ASJC Scopus subject areas

  • Materials Science(all)

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