有機發光二極體暫態電激發光現象

Abstract

本論文著重探討有機發光二極體（OLEDs）中載子傳輸的特性研究。我們藉由改變元件尺寸和外加電壓來觀察對應的暫態電激發光現象（Transient electroluminescence）。因為電容效應，元件尺寸會影響暫態電激發光結果。為了簡化問題，我們採用簡化過的式子來近似整體電激發光延遲時間（EL delay time），將延遲時間分為載子注入和載子傳輸時間。根據這個式子，我們推算出Alq3中的電子移動率，並且發現載子注入時間在整體延遲時間中佔有很大比例，同時元件尺寸也和延遲時間息息相關。

This thesis focuses on the transient electroluminescence (TREL) behavior of carriers transport in organic light emitting diodes (OLEDs) by varying the device size and observing the corresponding voltage and current magnitude evolution. The EL response is fundamentally governed by the device area, i.e., the capacitance of the device. For the sake of simplicity in the EL delay time, we use an approximate model by assuming Eth << E0 and ttrans << RC to describe it. The model divides the delay time into two parts, the charge injection delay and the charge transport delay. According to the formulation, we estimate electron mobility in Alq3 under fast-pulse excitation. In this study, we conclude that the charge injection process greatly contributes to EL delay, and the delay time correlates closely with the device area.