Novel indolo[3,2,1-jk]carbazole-based bipolar host material for highly efficient thermally activated delayed-fluorescence organic light-emitting diodes

• Published in: Tetrahedron Vol. 94; pp. 132317 - 132324
• Main Authors: Hiraga, Yasuhide, Kuwahara, Rempei, Hatta, Taizo
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 13.08.2021; Elsevier
• Subjects: Bipolar host material; Chemistry; Chemistry, Organic; Host for TADF OLED; Indolo[3,2,1-jk]carbazole; Indolo[3,2,1-jk]carbazole-pyrimidine; Long lifetime TADF OLED; Physical Sciences; Science & Technology; Host for TADF OLED; Bipolar host material; Indolo[3,2,1-jk]carbazole-pyrimidine; Indolo[3,2,1-jk]carbazole; Long lifetime TADF OLED; 1-jk]carbazole; LIFETIME; 25-PERCENT; 2; PHOSPHORESCENT; PHOLEDS; EXTERNAL QUANTUM EFFICIENCY; 1-jk]carbazole-pyrimidine; Indolo; ENERGIES; LINKAGE; ELECTRON-TRANSFER REACTIONS
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/j.tet.2021.132317

A novel bipolar material (ICzPyr) composed of electron-donating indolo[3,2,1-jk]carbazole and electron-withdrawing pyridmidine was developed and its use as a host material in thermally activated delayed-fluorescence (TADF) organic light-emitting diode (OLED) applications was investigated. This material exhibited practical thermal and morphological stabilities, a high triplet energy, and suitable HOMO and LUMO levels for TADF applications. A 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene-based (4CzIPN-based) TADF OLED using ICzPyr as a host material exhibited a much lower driving voltage, higher luminous efficiency, and a significantly longer lifetime than a conventional 3,3′-di(9H-carbazol-9-yl)-1,1′-biphenyl/4CzIPN-based OLED. [Display omitted] •Bipolar host material based on indolo[3,2,1-jk]carbazol/pyrimidine (ICzPyr) hybrid.•Indolo[3,2,1-jk]carbazol/pyrimidine with well-balanced reorganization energy of hole (λ+) and electron (λ-).•Indolo[3,2,1-jk]carbazol/pyrimidine hybrid for host material of thermally activated delayed-fluorescence (TADF) - OLED.•ICzPyr-based TADF-OLED exhibiting a lower driving voltage, higher luminous efficiency, and a longer lifetime.