Pyrimidine-based bipolar host materials for high efficiency solution processed green thermally activated delayed fluorescence OLEDs

Jiwon Yoon, Chiho Lee, Su Hong Park, Dong Won Kang, Hyojin Kim, Ji Eun Jeong, Han Young Woo, Chang Seop Hong, Sungnam Park, Min Ju Cho, Dong Hoon Choi

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Abstract

The development of bipolar host materials for solution-processable thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs) is challenging because few host materials for TADF-OLEDs have been reported. Solution-processable bipolar host materials should have good solubility in various organic solvents and should exhibit good thermal stability and film-forming properties. In this study, three bipolar host materials (i.e.Py2Cz, Py2BFCz, and Py2ICz) for solution-processable green-emitting TADF-OLEDs were synthesized by coupling 2,4-diphenylpyrimidine to mCP and modifying the carbazole-donating units in the mCP structure. Thus, the effects of different host structures on the performance of green TADF-OLEDs could be investigated. The three host materials exhibited high thermal stability and fine morphologies in film states. Therefore, all three host materials were utilized to fabricate solution-processed green TADF-OLEDs with a green-emitting dopant. Particularly, the Py2ICz-based device displayed outstanding performance with a maximum external efficiency of 24.1% because Py2ICz has superior charge balance in the emitting layer than the others. These results unambiguously demonstrated that mCP derivatives with a pyrimidine core are suitable bipolar host materials for solution-processed green TADF-OLEDs.

Original languageEnglish
Pages (from-to)2196-2204
Number of pages9
JournalJournal of Materials Chemistry C
Volume8
Issue number6
DOIs
Publication statusPublished - 2020 Feb 14

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ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Chemistry

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