title: 2-(2-Hydroxyphenyl)benzimidazole-based four-coordinate boron-containing materials with highly efficient deep-blue photoluminescence and electroluminescence.
abstract: Two novel four-coordinate boron-containing emitters 1 and 2 with deep-blue emissions were synthesized by refluxing a 2-(2-hydroxyphenyl)benzimidazole ligand with triphenylborane or bromodibenzoborole. The boron chelation produced a new π-conjugated skeleton, which rendered the synthesized boron materials with intense fluorescence, good thermal stability, and high carrier mobility. Both compounds displayed deep-blue emissions in solutions with very high fluorescence quantum yields (over 0.70). More importantly, the samples showed identical fluorescence in the solution and solid states, and the efficiency was maintained at a high level (approximately 0.50) because of the bulky substituents between the boron atom and the benzimidazole unit, which can effectively separate the flat luminescent units. In addition, neat thin films composed of 1 or 2 exhibited high electron and hole mobility in the same order of magnitude 10(-4), as determined by time-of-flight. The fabricated electroluminescent devices that employed 1 or 2 as emitting materials showed high-performance deep-blue emissions with Commission Internationale de L'Eclairage (CIE) coordinates of (X = 0.15, Y = 0.09) and (X = 0.16, Y = 0.08), respectively. Thus, the synthesized boron-containing materials are ideal candidates for fabricating high-performance deep-blue organic light-emitting diodes.
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, International Joint Research Laboratory of Nano-Micro Architecture Chemistry, College of Chemistry, Jilin University , Changchun 130012, P. R. China.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Zhang
authors.forename: Houyu
authors.initials: H
authors.lastname: Zhang
authors.forename: Chuanjun
authors.initials: C
authors.lastname: Jiao
authors.forename: Kaiqi
authors.initials: K
authors.lastname: Ye
authors.forename: Hongyu
authors.initials: H
authors.lastname: Zhang
authors.forename: Jingying
authors.initials: J
authors.lastname: Zhang
authors.forename: Yue
authors.initials: Y
authors.lastname: Wang
mesh_terms: D001562:Benzimidazoles / Q000737:chemistry*; D001895:Boron / Q000737:chemistry*; D018360:Crystallography, X-Ray; D055615:Electrical Equipment and Supplies; D004563:Electrochemistry; D008024:Ligands; D049449:Luminescence; D008958:Models, Molecular; D008968:Molecular Conformation; D055620:Optical Phenomena; D013696:Temperature
chemical_list: D001562:Benzimidazoles; D008024:Ligands; C031000:benzimidazole; D001895:Boron