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

• 来源期刊: 中国物理(英文版)
• 关键词: numerical simulation organic light-emitting diodes current conduction
• 年，卷（期）: 2003,（7）
• 页码范围: 796-802
• 页数: 7页
• 语种: 英文

摘要

A numerical model for bilayer organic light-emitting diodes (OLEDs) has been developed on the basis of trappedcharge limited conduction. The dependences of the current density on the operation voltage, the thickness andtrap properties of the hole transport layer (HTL) and emission layer (EML) in bilayer OLEDs of the structure an-ode/HTL/EML/cathode have been numerically investigated. It has been found that, for given values of reduced trapdepth, total trap density, and carrier mobility of HTL and EML, there exists an optimum thickness ratio of HTL tothe 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 exponentiallywith the mean reduced trap depth.