title: Control of the Singlet-Triplet Energy Gap in a Thermally Activated Delayed Fluorescence Emitter by Using a Polar Host Matrix.
abstract: The photoluminescence properties of a thermally activated delayed fluorescence emitter, 1,2-bis(carbazol-9-yl)-4,5-dicyanobenzene (2CzPN), doped in a host matrix consisting of 1,3-bis(9-carbazolyl)benzene and a polar inert molecule, camphoric anhydride (CA), in various concentrations have been investigated. It is found that the addition of CA stabilizes only the lowest singlet excited state (S1) of 2CzPN without changing the energy level of the lowest triplet excited state (T1), leading to a reduction in the energy gap between S1and T1. The maximum reduction of energy gap achieved in this work has been determined to be around 65 meV from the shift of the fluorescence spectrum and the temperature dependence of the photoluminescence decay rate.
authors.affiliation: Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuencho, Naka, Sakai, 599-8531, Japan.
authors.forename: Shota
authors.initials: S
authors.lastname: Haseyama
authors.affiliation: Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuencho, Naka, Sakai, 599-8531, Japan.
authors.forename: Akitsugu
authors.initials: A
authors.lastname: Niwa
authors.affiliation: Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuencho, Naka, Sakai, 599-8531, Japan.|Research Institute of Molecular Electronic Devices (RIMED), Osaka Prefecture University, 1-1 Gakuencho, Naka, Sakai, 599-8531, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuencho, Naka, Sakai, 599-8531, Japan.|Research Institute of Molecular Electronic Devices (RIMED), Osaka Prefecture University, 1-1 Gakuencho, Naka, Sakai, 599-8531, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nagase
authors.affiliation: Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan.|Adachi Molecular Exciton Engineering Project, ERATO, Japan Science and Technology Agency (JST), 744 Motooka, Nishi, Fukuoka, 819-0395, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Goushi
authors.affiliation: Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan.|Adachi Molecular Exciton Engineering Project, ERATO, Japan Science and Technology Agency (JST), 744 Motooka, Nishi, Fukuoka, 819-0395, Japan.
authors.forename: Chihaya
authors.initials: C
authors.lastname: Adachi
authors.affiliation: Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuencho, Naka, Sakai, 599-8531, Japan. naito@pe.osakafu-u.ac.jp.|Research Institute of Molecular Electronic Devices (RIMED), Osaka Prefecture University, 1-1 Gakuencho, Naka, Sakai, 599-8531, Japan. naito@pe.osakafu-u.ac.jp.
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Naito
keywords: Electronic permittivity; Photoluminescence spectroscopy; Polar host matrix; Thermally activated delayed fluorescence (TADF)