串聯式發光元件中間層之機制

Mechanism of Interlayer in Tandem Light Emitting Device

鄭昀閩(Yun-Min Chung)

指導教授 ： 陳壽安

國立清華大學/工學院/化學工程學系/碩士(2010年)

摘要

摘要
串聯式有機發光元件 (tandem organic light-emitting device, tandem OLED) 是利用中間層將數個發光元件連接，使其效率與亮度增加。其中，中間層是由兩層所組成：一層為低功函數金屬 (low work function metal, ex: lithium) 摻雜電子傳輸材料，稱為 n型摻雜層；另一層則為強拉電子材料 (ex: 2,3,5,6-Tetrafluoro-7,7,8,8,-tetracyano-quinodimethane, F4-TCNQ) 摻雜電洞傳輸材料，稱為 p型摻雜層。
在一般文獻中認為中間層可產生額外的電荷 (非電極注入之電荷)，並注入到鄰近發光層與電極注入之電荷再結合放光，因此，中間層又稱為電荷產生層 (charge generation layer, CGL)。但於元件操作時中間層持續消耗電子與電洞，若無電荷補充則明顯不合理，且此電荷補充機制尚無人提出，故本論文首先利用時間解析螢光光譜儀 (time-resolved electroluminescence, TREL)，證明中間層所消耗之電荷需由電極注入之電荷補充，才能繼續注入電荷到發光層中，且其補充所需時間之長短也會受到由電極注入電荷數目之影響。此機理之提出可讓我們對 tandem OLED之中間層電荷產生機制有更深入的了解，並進而設計出高效率之發光元件。

關鍵字

串聯式 ； 中間層 ； 有機發光二極體

並列摘要

Abstract
Tandem organic light-emitting device (tandem OLED), in which an interlayer is used to connect several units, shows impressive device performances as compared to that in conventional OLED. In general, an interlayer is composed of two layers: one is low work function metal (ex: lithium) doping electron transport material, which is called n-doped layer; Another is acceptor (ex: 2,3,5,6-Tetrafluoro-7,7,8,8,-tetracyano-quinodimethane, F4-TCNQ) doping hole transport material, which is called p-doped layer.
It is generally believed that additional charges (the charges that are not injected from electrode) is generated in the interlayer and sequent injected into the adjacent emitting layer, in which recombination between these charges and injected charges from the electrode takes place and gives rise to light emission. Therefore, the interlayer is also called the “charge generation layer” (CGL). However, the charges in the interlayer is consumed continuously during device operation, it must be a mechanism to regenerate the charges in the interlayer, which is not reported in the literature so far. Therefore, in this thesis, we use time-resolved electroluminescence (TREL) to prove that the charges consumed in the interlayer need to be supplied by the injected charges from the electrode, and the time require for charge supplement is also influence by the number of charges injected from the electrode. The mechanism proposed here can provide insight into the charges generation mechanism in the interlayer of tandem OLED and the highly efficiency LED can be designed accordingly.

並列關鍵字

tandem ； interlayer ； OLED

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