Abstract A numerical model for bilayer organic light-emitting diodes (OLEDs) has been developed on the basis of trapped charge limited conduction. The dependences of the current density on the operation voltage, the thickness and trap properties of the hole transport layer (HTL) and emission layer (EML) in bilayer OLEDs of the structure anode/HTL/EML/cathode have been numerically investigated. It has been found that, for given values of reduced trap depth, total trap density, and carrier mobility of HTL and EML, there exists an optimum thickness ratio of HTL to the sum of HTL and EML, by which a maximal current density, and hence maximal quantum efficiency and luminance, can be achieved. The current density decreases quickly with the mean trap density, and decreases nearly exponentially with the mean reduced trap depth.
Received: 08 January 2003
Revised: 18 February 2003
Accepted manuscript online:
(Charge carriers: generation, recombination, lifetime, and trapping)
Fund: Project supported by the National Natural science Foundation of China (Grant No. 60076023) and The Natural Science Foundation of Gansu Province (Grant No. ZS021-A25-003-Z).
Cite this article:
Peng Ying-Quan (彭应全), Zhang Fu-Jia (张福甲), Song Chang-An (宋长安) Numerical investigations on the current conduction in bilayer organic light-emitting devices with ohmic injection of charge carriers 2003 Chinese Physics 12 796
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