Operational Stability Analysis of Blue Thermally Activated Delayed Fluorescence Organic Light-Emitting Diodes Using the Capacitance-Voltage Method

Jun Young Park, Soo Jong Park, Byeong Kwon Ju

Research output: Contribution to journalArticlepeer-review

Abstract

We analyzed the degradation features by measuring the capacitance–voltage characteristics after electrically aging blue thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs). The measurement was investigated in terms of the hole transfer layer (HTL) and electron transfer layer (ETL) structures. For the HTL, three different materials—N,N′–bis(naphthalen–1–yl)–N,N′–bis(phenyl)–benzidine (NPB), 4,4′,4″-tris(carbazol–9–yl)triphenylamine (TCTA), and 1,3–bis(carbazol–9–yl)benzene (mCP)—were used at the HTL/emission layer (EML) interface; the TCTA/EML interface had the highest stability among the interfaces. For the ETL, bis [2–(diphenylphosphino)phenyl] ether oxide (DPEPO) without further dopants was used as an exciton blocking layer (ExBL) to effectively confine the excitons at the EML. However, DPEPO has low stability and carrier mobility. Therefore, 0, 10, and 40 nm-thick ExBL devices were investigated; it was found that the 0 nm-thick ExBL device was the most stable. However, the 10 nm-thick ExBL is essential to confine the excitons at the EML, which ensures a high EL performance.

Original languageEnglish
Article number13045
JournalApplied Sciences (Switzerland)
Volume12
Issue number24
DOIs
Publication statusPublished - 2022 Dec

Bibliographical note

Publisher Copyright:
© 2022 by the authors.

Keywords

  • capacitance-voltage
  • degradation
  • organic light-emitting diode
  • thermally activated delayed fluorescence

ASJC Scopus subject areas

  • General Materials Science
  • Instrumentation
  • General Engineering
  • Process Chemistry and Technology
  • Computer Science Applications
  • Fluid Flow and Transfer Processes

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