title: Diimide nanoclusters play hole trapping and electron injection roles in organic light-emitting devices.
abstract: We report thermally stable diimide nanoclusters that could potentially replace the conventional thick electron transport layer (ETL) in organic light-emitting devices (OLEDs). Bis-[1,10]phenanthrolin-5-yl-bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic diimide (Bphen-BCDI) was synthesized from the corresponding dianhydride and amine moieties, and its purified product exhibited a high glass transition temperature (232 °C) and a wide band gap (3.8 eV). The Bphen-BCDI subnanolayers deposited on substrates were found to form organic nanoclusters, not a conventional layer. The OLED made with a subnanolayer of Bphen-BCDI nanoclusters, instead of a conventional ETL, showed greatly improved efficiency (about 2-fold) compared with an OLED without the diimide nanoclusters. The role of the BPhen-BCDI nanoclusters was assigned to hole trapping and electron injection in the present OLED structure.
authors.affiliation: Organic Nanoelectronics Laboratory, Department of Chemical Engineering, Kyungpook National University, Daegu, 702-701, Republic of Korea.
authors.forename: Gwijeong
authors.initials: G
authors.lastname: Cho
authors.forename: Hyena
authors.initials: H
authors.lastname: Lee
authors.forename: Sungho
authors.initials: S
authors.lastname: Woo
authors.forename: Sungho
authors.initials: S
authors.lastname: Nam
authors.forename: Hwajeong
authors.initials: H
authors.lastname: Kim
authors.forename: Youngkyoo
authors.initials: Y
authors.lastname: Kim
mesh_terms: D004579:Electron Transport; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007094:Imides / Q000737:chemistry*; D008029:Lighting / Q000295:instrumentation*; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D009930:Organic Chemicals / Q000737:chemistry*; D010316:Particle Size; D012666:Semiconductors
chemical_list: D007094:Imides; D009930:Organic Chemicals