Narrowband deep-blue organic light-emitting diode featuring an organoboron-based emitter

• Published in: Nature photonics Vol. 13; no. 10; pp. 678 - 682
• Main Authors: Kondo, Yasuhiro, Yoshiura, Kazuki, Kitera, Sayuri, Nishi, Hiroki, Oda, Susumu, Gotoh, Hajime, Sasada, Yasuyuki, Yanai, Motoki, Hatakeyama, Takuji
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.10.2019; Nature Publishing Group
• Subjects: 119/118; 140/131; 140/146; 639/301/1019/1020/1091; 639/624/1020/1091; 639/638/298/398; Applied and Technical Physics; Benzene; Boron; Coupling (molecular); Emission; Emissions; Emitters; Energy gap; Excitation; Fluorescence; Letter; Light emitting diodes; Localization; Molecular orbitals; Narrowband; Nitrogen; Nitrogen atoms; Organic light emitting diodes; Physics; Physics and Astronomy; Quantum efficiency; Quantum Physics
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/s41566-019-0476-5

Luminescent materials that exhibit narrowband emission are vital for full-colour displays. Here, we report a thermally activated delayed-fluorescence material that exhibits ultrapure blue emission with full-width at half-maximum of just 14 nm. The emitter consists of five benzene rings connected by two boron and four nitrogen atoms and two diphenylamino substituents. The multiple resonance effect of the boron and nitrogen atoms induces significant localization of the highest occupied and lowest unoccupied molecular orbitals on different atoms to minimize not only the vibronic coupling between the ground state (S 0 ) and the singlet excited state (S 1 ) but also the energy gap between the S 1 state and triplet excited state (T 1 ). Organic light-emitting diode devices employing the emitter emit light at 469 nm with full-width at half-maximum of 18 nm with an external quantum efficiency of 34.4% at the maximum and 26.0% at 1,000 cd m −2 . A blue emitter based on thermally activated delayed fluorescence is narrowband and efficient.