Thermally activated delayed fluorescent phenothiazine–dibenzo[a,j]phenazine–phenothiazine triads exhibiting tricolor-changing mechanochromic luminescence

Okazaki, Masato; Takeda, Youhei; Data, Przemyslaw; Pander, Piotr; Higginbotham, Heather; Monkman, Andrew P.; Minakata, Satoshi

Abstract

Novel U-shaped donor–acceptor–donor (D–A–D) π-conjugated multi-functional molecules comprising dibenzo[a,j]phenazine (DBPHZ) as an acceptor and phenothiazines (PTZ) as donors have been developed. Most importantly, the D–A–D compounds exhibit not only distinct tricolor-changeable mechanochromic luminescence (MCL) properties but also efficient thermally activated delayed fluorescence (TADF). Quantum chemical calculations, X-ray diffraction analysis, and systematic studies on the photophysical properties indicated that the “two-conformation-switchable” PTZ units play a highly important role in achieving multi-color-changing MCL. Time-resolved photophysical measurements revealed that the developed D–A–D compounds also exhibit efficient orange-TADF. Furthermore, organic light-emitting diode (OLED) devices fabricated with the new TADF emitters have achieved high external quantum efficiencies (EQEs) up to 16.8%, which significantly exceeds the theoretical maximum (∼5%) of conventional fluorescent emitters.

Citation

Okazaki, M., Takeda, Y., Data, P., Pander, P., Higginbotham, H., Monkman, A. P., & Minakata, S. (2017). Thermally activated delayed fluorescent phenothiazine–dibenzo[a,j]phenazine–phenothiazine triads exhibiting tricolor-changing mechanochromic luminescence. Chemical Science, 8(4), 2677-2686. https://doi.org/10.1039/c6sc04863c

• Journal Article Type: Article
• Acceptance Date: Jan 7, 2017
• Online Publication Date: Jan 11, 2017
• Publication Date: Apr 1, 2017
• Deposit Date: May 16, 2017
• Publicly Available Date: May 16, 2017
• Journal: Chemical Science
• Print ISSN: 2041-6520
• Electronic ISSN: 2041-6539
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 8
• Issue: 4
• Pages: 2677-2686
• DOI: https://doi.org/10.1039/c6sc04863c
• Public URL: https://durham-repository.worktribe.com/output/1359029