中国物理B ›› 2003, Vol. 12 ›› Issue (7): 796-802.doi: 10.1088/1009-1963/12/7/318

• GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS • 上一篇    下一篇

Numerical investigations on the current conduction in bilayer organic light-emitting devices with ohmic injection of charge carriers

彭应全, 张福甲, 宋长安   

  1. School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China
  • 收稿日期:2003-01-08 修回日期:2003-02-18 出版日期:2005-03-16 发布日期:2005-03-16
  • 基金资助:
    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).

Numerical investigations on the current conduction in bilayer organic light-emitting devices with ohmic injection of charge carriers

Peng Ying-Quan (彭应全), Zhang Fu-Jia (张福甲), Song Chang-An (宋长安)   

  1. School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China
  • Received:2003-01-08 Revised:2003-02-18 Online:2005-03-16 Published:2005-03-16
  • Supported by:
    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).

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摘要： 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.

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.

Key words: numerical simulation, organic light-emitting diodes, current conduction

中图分类号:  (Numerical simulation; solution of equations)

  • 02.60.Cb
85.60.Jb (Light-emitting devices) 73.40.-c (Electronic transport in interface structures) 72.80.Le (Polymers; organic compounds (including organic semiconductors)) 73.21.Ac (Multilayers) 78.60.Fi (Electroluminescence) 72.20.Jv (Charge carriers: generation, recombination, lifetime, and trapping)