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Title: The influence of charge injection from intermediate connectors on the performance of tandem organic light-emitting devices

Charge generation in a typical intermediate connector, composed of “n-type doped layer/transition metal oxide (TMO)/hole transporting layer (HTL),” of a tandem organic light-emitting device (OLED) has recently been found to arise from charge transfer at the TMO/HTL interfaces. In this paper, we investigate the effect of hole injection barriers from intermediate connectors on the performance of tandem OLEDs. The hole injection barriers are caused by the offset of the highest occupied molecular orbital (HOMO) energy levels between HTLs contained in the intermediate connector and the top electroluminescence (EL) unit. We also find that although charge generation can occur at the interfaces between the TMO and a wide variety of HTLs of different HOMO values, an increase in the hole injection barrier however limits the electroluminescence efficiency of the top EL units. In the case of large hole injection barriers, significant charge accumulation in the HTLs makes the intermediate connector lose its functionality gradually over operating time, and limits device stability.
Authors:
 [1] ;  [2] ; ; ;  [3] ;  [1]
  1. Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu 215123 (China)
  2. (Canada)
  3. Department of Electrical and Computer Engineering and Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1 (Canada)
Publication Date:
OSTI Identifier:
22402770
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 22; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CONNECTORS; DOPED MATERIALS; EFFICIENCY; ELECTROLUMINESCENCE; ENERGY LEVELS; HOLES; INTERFACES; LAYERS; LIGHT EMITTING DIODES; MOLECULAR ORBITAL METHOD; PERFORMANCE; STABILITY