Enhancing Triplet-Triplet Upconversion Efficiency and Operational Lifetime in Blue Organic Light-Emitting Diodes by Utilizing Thermally Activated Delayed Fluorescence Materials

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

1 Scopus Citations
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Author(s)

  • Thanh B. Nguyen
  • Hajime Nakanotani
  • Chin-Yiu Chan
  • Shunta Kakumachi
  • Chihaya Adachi

Detail(s)

Original languageEnglish
Pages (from-to)23557-23563
Number of pages7
Journal / PublicationACS Applied Materials and Interfaces
Volume15
Issue number19
Online published5 May 2023
Publication statusPublished - 17 May 2023
Externally publishedYes

Abstract

In the process of triplet-triplet upconversion (TTU), a bright excited singlet can be generated because of the collision of two dark excited triplets. In particular, the efficiency of TTU is crucial for achieving a high exciton production yield in blue fluorescence organic light-emitting diodes (OLEDs) beyond the theoretical limit. While the theoretical upper limit of TTU contribution yield is expected to be 60%, blue OLEDs with the maximum TTU contribution are still scarce. Herein, we present a proof of concept for realizing the maximum TTU contribution yield in blue OLEDs, achieved through the doping of thermally activated delayed fluorescence (TADF) molecules in the carrier recombination zone. The bipolar carrier transport ability of TADF materials enables direct carrier recombination on the molecules, resulting in the expansion of the recombination zone. Although the external electroluminescence quantum efficiency of OLEDs is slightly lower than that of conventional TTU-OLEDs due to the low photoluminescence quantum yield of the doped layer, the TTU efficiency approaches the upper limit. Furthermore, the operational device lifetime of OLEDs employing TADF molecules increased by five times compared to the conventional ones, highlighting the expansion of the recombination zone as a crucial factor for enhancing overall OLED performance in TTU-OLEDs. ©2023 American Chemical Society

Research Area(s)

  • charge-transfer interface, organic light-emitting diode, thermally activated delayed fluorescence, triplet energy transfer, triplet−triplet upconversion

Citation Format(s)

Enhancing Triplet-Triplet Upconversion Efficiency and Operational Lifetime in Blue Organic Light-Emitting Diodes by Utilizing Thermally Activated Delayed Fluorescence Materials. / Nguyen, Thanh B.; Nakanotani, Hajime; Chan, Chin-Yiu et al.
In: ACS Applied Materials and Interfaces, Vol. 15, No. 19, 17.05.2023, p. 23557-23563.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review