Manipulating the Electronic Excited State Energies of Pyrimidine-Based Thermally Activated Delayed Fluorescence Emitters to Realize Efficient Deep-Blue Emission

Ryutaro Komatsu, Tatsuya Ohsawa, Hisahiro Sasabe, Kohei Nakao, Yuya Hayasaka, Junji Kido

Research output: Contribution to journalArticlepeer-review

79 Citations (Scopus)

Abstract

The development of efficient and robust deep-blue emitters is one of the key issues in organic light-emitting devices (OLEDs) for environmentally friendly, large-area displays or general lighting. As a promising technology that realizes 100% conversion from electrons to photons, thermally activated delayed fluorescence (TADF) emitters have attracted considerable attention. However, only a handful of examples of deep-blue TADF emitters have been reported to date, and the emitters generally show large efficiency roll-off at practical luminance over several hundreds to thousands of cd m-2, most likely because of the long delayed fluorescent lifetime (d). To overcome this problem, we molecularly manipulated the electronic excited state energies of pyrimidine-based TADF emitters to realize deep-blue emission and reduced d. We then systematically investigated the relationships among the chemical structure, properties, and device performances. The resultant novel pyrimidine emitters, called Ac-XMHPMs (X = 1, 2, and 3), contain different numbers of bulky methyl substituents at acceptor moieties, increasing the excited singlet (ES) and triplet state (ET) energies. Among them, Ac-3MHPM, with a high ET of 2.95 eV, exhibited a high external quantum efficiency (ηext,max) of 18% and an ηext of 10% at 100 cd m-2 with Commission Internationale de l′Eclairage chromaticity coordinates of (0.16, 0.15). These efficiencies are among the highest values to date for deep-blue TADF OLEDs. Our molecular design strategy provides fundamental guidance to design novel deep-blue TADF emitters.

Original languageEnglish
Pages (from-to)4742-4749
Number of pages8
JournalACS Applied Materials and Interfaces
Volume9
Issue number5
DOIs
Publication statusPublished - Feb 8 2017
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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