Power Efficiency Improvement of White Phosphorescent Organic Light-Emitting Diode with Thin Double-Emitting Layers and Hole-Trapping Mechanism

Fuh Shyang Juang, Lin-Ann Hong, Shun Hsi Wang, Yu Sheng Tsai, Ming-Hong GaoF, Yun Chi, Han-Ping Shieh, Jen-Sung Hsu

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

This study is carried out to discuss how to reduce the driving voltage of blue phosphorescent organic light-emitting diodes (PHOLEDs) by using a thin double-emission layer. A hole transport-type host (TCTA) is inserted between the hole transport layer (TAPC) and the emitting layer (EML), constituting a buffer layer between them with the aim of improving charge carrier balance. Furthermore, in this study, we also utilize the interface between double light-emitting layers of devices by codoping them with a red phosphorescent dopant [Os(bpftz)(2)(PPh2Me)(2)]. An Os complex with a high-lying highest occupied molecular orbital (HOMO) energy level (trapping holes) is codoped at the interface between emitting layers and an exciton-formation zone is expanded to obtain a white PHOLED with high efficiency. From the results, the optimal structure of the white device exhibits a yield of 35 cd A(-1), a power efficiency of 22 lm W-1, and CIE coordinates of (0.33; 0.38) at a luminance of 1000 cdm(-2). Furthermore, the power efficiency can be improved to 30 lm W-1 by attaching the outcoupling enhancement film. (C) 2011 The Japan Society of Applied Physics
Original languageEnglish
Article number04DK04
JournalJapanese Journal of Applied Physics
DOIs
StatePublished - Apr 2011
EventInternational Conference on Solid State Devices and Materials (SSDM 2010) - Tokyo, Japan
Duration: 22 Sep 201024 Sep 2010

Keywords

  • DEVICES
  • OSMIUM COMPLEX
  • IRIDIUM COMPLEX

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