title: Design of efficient ambipolar host materials for organic blue electrophosphorescence: theoretical characterization of hosts based on carbazole derivatives.
abstract: Density functional theory calculations were carried out to investigate the electronic structures of representative ambipolar hosts for blue electroluminescence, based on two carbazole end groups and meta-terphenyl (mTP)-like bridges. The bridge molecular segments include mTP, 2,6-bisphenylpyridine, 3,5-bisphenylpyridine, and 2,6-bisphenylpyrimidine. While the ionization potentials and electron affinities of these molecules are mainly determined by their hole- and electron-transport subunits, respectively, each subunit impacts the electronic properties of the other upon their binding, mainly in an inductive way. Importantly, the lowest triplet state of the hosts is determined to be confined into the mTP-like bridges since these are the subunits with lowest individual triplet energy. Extension of the phenyl-based π-conjugated system via meta linkages is found to be effective in modulating the electron affinity value while maintaining a high triplet energy.
authors.affiliation: School of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States. dongwook-kim@kgu.ac.kr
authors.forename: Dongwook
authors.initials: D
authors.lastname: Kim
authors.forename: Veaceslav
authors.initials: V
authors.lastname: Coropceanu
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Brédas
mesh_terms: D002227:Carbazoles / Q000737:chemistry*; D049408:Luminescent Agents / Q000737:chemistry*; D008163:Luminescent Measurements; D015394:Molecular Structure; D011789:Quantum Theory
chemical_list: D002227:Carbazoles; D049408:Luminescent Agents; C041514:carbazole