title: Organic luminescent molecule with energetically equivalent singlet and triplet excited states for organic light-emitting diodes.
abstract: We demonstrate an organic molecule with an energy gap between its singlet and triplet excited states of almost zero (ΔE(ST) ∼ 0 eV). Such separation was realized through proper combination of an electron-donating indolocarbazole group and a diphenyltriazine electron-accepting moiety. Calculated and measured ΔE(ST) were 0.003 and 0.02 eV, respectively. A total photoluminescence efficiency of 59% ± 2% with 45% ± 2% from a delayed component and 14% ± 2% from a prompt component was obtained for a doped film. Organic light emitting diodes containing this molecule as an emitting dopant exhibited an unexpectedly high external electroluminescence efficiency of η(EQE) = 14% ± 1%.
authors.affiliation: Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395, Japan.
authors.forename: Keigo
authors.initials: K
authors.lastname: Sato
authors.affiliation: Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395, Japan.
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Shizu
authors.affiliation: Basic Research Laboratories, Nippon Steel Chemical Co., Ltd., 46-80 Nakabaru, Sakinohama, Tobata, Kitakyushu, Fukuoka 804-8503, Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Yoshimura
authors.affiliation: Functional Materials Laboratories, Nippon Steel Chemical Co., Ltd., 46-80 Nakabaru, Sakinohama, Tobata, Kitakyushu, Fukuoka 804-8503, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kawada
authors.affiliation: Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395, Japan and Functional Materials Laboratories, Nippon Steel Chemical Co., Ltd., 46-80 Nakabaru, Sakinohama, Tobata, Kitakyushu, Fukuoka 804-8503, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miyazaki
authors.affiliation: Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395, Japan and International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395, Japan.
authors.forename: Chihaya
authors.initials: C
authors.lastname: Adachi
mesh_terms: D002227:Carbazoles / Q000737:chemistry*; D008163:Luminescent Measurements / Q000379:methods*; D008958:Models, Molecular; D055668:Photochemical Processes; D011789:Quantum Theory; D013816:Thermodynamics; D014226:Triazenes / Q000737:chemistry*
chemical_list: D002227:Carbazoles; D014226:Triazenes