利用变温瞬态电致发光研究OLED载流子的输运机理

研究了不同温度下几种结构的有机电致发光器件(OLED)的瞬态电致发光响应特性以及电流密度-电压-亮度特性。研究发现,启亮电压随温度升高而减小的加速度在200 K时出现拐点,且这一数值主要由电子传输层Alq3的迁移率决定。当温度为200 K时,延迟时间td最重要的影响因素是Mo O3空穴注入势垒,随着温度的升高,Δtd逐渐减小,到300 K时基本消失。Vf代表光衰减时间随温度增长的平均速率。Mo O3注入层和电致发光材料Ir(ppy)3都会对载流子的堆积起促进作用。由Mo O3注入层不同引起的ΔVf是0.52μs/K,由电致发光材料Ir(ppy)3不同引起的ΔVf是0.73μs/K。

Study on Carriers Transport Mechanism in OLED by Variable Temperature Transient Electroluminescence

The transient electroluminescence response characteristics at different temperatures and the current density-voltage-luminance ( J-V-L ) characteristics of several organic light-emitting de-vices ( OLEDs) were studied. It is found that the acceleration of the turn-on voltage decreasing with the increase of temperature appears the inflection point at 200 K, and this value mainly depends on the mobility of the electron transport layer Alq3 . When the temperature is 200 K, the most important factors of delay time td is hole injection barrier MoO3 . The td decreases with the increase of tempera-ture and gradually disappears at 300 K. Vf represents the average rate of the fall time increasing with the temperature. Both MoO3 and Ir( ppy) 3 can promote the accumulation of carriers. ΔVf caused by MoO3 injection layer is 0. 52 μs/K, and that caused by the electroluminescent material Ir(ppy)3 is 0. 73 μs/K.