Mechanochromic Delayed Fluorescence Switching in Propeller-Shaped Carbazole-Isophthalonitrile Luminogens with Stimuli-Responsive Intramolecular Charge-Transfer Excited States

Minlang Yang; In Seob Park; Yasuhiro Miyashita; Katsunori Tanaka; Takuma Yasuda

doi:10.1002/anie.202005584

Mechanochromic Delayed Fluorescence Switching in Propeller-Shaped Carbazole-Isophthalonitrile Luminogens with Stimuli-Responsive Intramolecular Charge-Transfer Excited States

Angew Chem Int Ed Engl. 2020 Aug 10;59(33):13955-13961. doi: 10.1002/anie.202005584. Epub 2020 Jun 5.

Authors

Minlang Yang^{1

2}, In Seob Park¹, Yasuhiro Miyashita³, Katsunori Tanaka³, Takuma Yasuda^{1

2}

Affiliations

¹ INAMORI Frontier Research Center (IFRC), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
² Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
³ Odawara Research Center, Nippon Soda Co., Ltd., 345 Takada, Odawara, Kanagawa, 250-0280, Japan.

PMID: 32369229
DOI: 10.1002/anie.202005584

Abstract

Herein, the universal design of high-efficiency stimuli-responsive luminous materials endowed with mechanochromic luminescence (MCL) and thermally activated delayed fluorescence (TADF) functions is reported. The origin of the unique stimuli-triggered TADF switching for a series of carbazole-isophthalonitrile-based donor-acceptor (D-A) luminogens is demonstrated based on systematic photophysical and X-ray analysis, coupled with theoretical calculations. It was revealed that a tiny alteration of the intramolecular D-A twisting in the excited-state structures governed by the solid morphologies is responsible for this dynamic TADF switching behavior. This concept is applicable to the fabrication of bicolor emissive organic light-emitting diodes using a single TADF emitter.

Keywords: charge transfer; mechanochromism; organic light-emitting diodes; solid-state luminescence; thermally activated delayed fluorescence.

Abstract

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