Simple Molecular-Engineering Approach for Enhancing Orientation and Outcoupling Efficiency of Thermally Activated Delayed Fluorescent Emitters without Red-Shifting Emission

Yi Ting Lee, Po Chen Tseng, Takeshi Komino, Masashi Mamada, Ruby Janet Ortiz, Man Kit Leung, Tien Lung Chiu, Chi Feng Lin, Jiun Haw Lee, Chihaya Adachi, Chao Tsen Chen, Chin Ti Chen

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

The inclusion of a tetraphenylbenzene (4Ph) unit in thermally activated delayed fluorescence emitters is demonstrated as a novel strategy for greatly enhancing the horizontally oriented alignment of the emitters without shifting the emission spectrum to longer wavelengths. Doping of blue-emitting 4PhOXDDMAC or greenish-blue-emitting 4PhOXDPXZ into o-DiCbzBz host layers yielded much higher degrees of horizontally oriented alignment for the emitter (up to 92%) compared to those when the 4Ph unit was excluded (69 and 75%, respectively). The enhanced alignment results in high outcoupling efficiencies of 24 and 35% in organic light-emitting diodes based on 4PhOXDDMAC and 4PhOXDPXZ, respectively, and boosts the external quantum efficiencies to values (8.8 and 29.2%, respectively) that are higher than what would be expected for randomly oriented emitters (outcoupling efficiency of 20%). These enhancements are achieved while avoiding the redshift that often occurs using the common strategy of increasing molecular length and, thereby, conjugation, to increase orientation.

Original languageEnglish
Pages (from-to)43842-43849
Number of pages8
JournalACS Applied Materials and Interfaces
Volume10
Issue number50
DOIs
Publication statusPublished - Dec 19 2018

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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