DGIST Scholar: Diimide nanoclusters play hole trapping and electron injection roles in organic light-emitting devices

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Diimide nanoclusters play hole trapping and electron injection roles in organic light-emitting devices

Title: Diimide nanoclusters play hole trapping and electron injection roles in organic light-emitting devices

Author(s): Cho, Gwijeong ; Lee, Hyena ; Woo, Sungho ; Nam, Sungho ; Kim, Hwajeong ; Kim, Youngkyoo

Subject: Amine Moieties ; Chemistry ; Current Density ; Diimide ; Electron Injection ; Electron Transport ; Electron Transport Layers ; Equipment ; Equipment Design ; Equipment Failure Analysis ; Glass Transition ; Glass Transition Temperature ; Hole Trapping ; Hole Traps ; Illumination ; Imide ; Imides ; Instrumentation ; Light Emission ; Lighting ; Materials Testing ; Nano-Structures ; Nanoclusters ; Nanomaterial ; Organic Chemicals ; Organic Compound ; Organic Light-Emitting Devices ; Particle Size ; Semiconductor ; Semiconductors ; Thermally Stable ; Ultrastructure ; Wide Band Gap

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. © 2011 The Royal Society of Chemistry.