title: Donor-acceptor-structured 1,4-diazatriphenylene derivatives exhibiting thermally activated delayed fluorescence: design and synthesis, photophysical properties and OLED characteristics.
abstract: A new series of luminescent 1,4-diazatriphenylene (ATP) derivatives with various peripheral donor units, including phenoxazine, 9,9-dimethylacridane and 3-(diphenylamino)carbazole, is synthesized and characterized as thermally activated delayed fluorescence (TADF) emitters. The influence of the donor substituents on the electronic and photophysical properties of the materials is investigated by theoretical calculations and experimental spectroscopic measurements. These ATP-based molecules with donor-acceptor-donor (D-A-D) structures can reduce the singlet-triplet energy gap (0.04-0.26 eV) upon chemical modification of the ATP core, and thus exhibit obvious TADF characteristics in solution and doped thin films. As a demonstration of the potential of these materials, organic light-emitting diodes containing the D-A-D-structured ATP derivatives as emitters are fabricated and tested. External electroluminescence quantum efficiencies above 12% and 8% for green- and sky-blue-emitting devices, respectively, are achieved.
authors.affiliation: Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, Japan; Hodogaya Chemical Co., 45 Miyukigaoka, Tsukuba, Ibaraki, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Takahashi
authors.affiliation: Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, Japan.
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Shizu
authors.affiliation: Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, Japan; Department of Applied Chemistry, Kyushu University, Japan; International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, Japan; PRESTO, Japan Science and Technology Agency (JST), Chiyoda, Tokyo 102-0076, Japan.
authors.forename: Takuma
authors.initials: T
authors.lastname: Yasuda
authors.affiliation: Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, Japan; Hodogaya Chemical Co., 45 Miyukigaoka, Tsukuba, Ibaraki, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Togashi
authors.affiliation: Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, Japan; Department of Applied Chemistry, Kyushu University, Japan; International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, Japan.
authors.forename: Chihaya
authors.initials: C
authors.lastname: Adachi
keywords: 1,4-diazatriphenylene; donor–acceptor; organic light-emitting diodes; thermally activated delayed fluorescence