有機半導體材料電子結構分析與倒置式下發光有機電激發光元件之研究

Abstract

本論文研究分二部份，其一是藉由密度泛函理論為基礎之第一原理計算研究有機半導體材料之電子結構，包括有機半導體分子結構、分子軌域電子結構以及能階與能隙與材料特性之關係，我們計算有機半導體材料紅外光振動光譜、單重態與三重態能隙、斯托克位移等都與實驗數據有一致性的結果，不僅如此，我們更藉由計算結果解釋相關的物理機制，研究結果有助於新型有機半導體材料之設計與發展。 另一方面為倒置式下發光型有機發光二極體的研究，其元件可搭配非晶矽薄膜電晶體製作大尺寸主動驅動有機發光顯示器，本論文開發的倒置式下發光型有機發光元件綠光螢光效率高達 22 cd/A，並且光色不會隨視角改變，相較典型元件結構的效率高了二倍。我們也開發出高效率(13 cd/A、10.6 lm/W)及高穩定性的白光有機發光二極體，元件初始亮度 400 cd/m2 時操作壽命可達 34000小時，並且光色不會隨著操作時間而有改變。 有機半導體材料之電子結構分析，不僅可應用於有機發光二極體之研究，也有助於有機薄膜電晶體、有機太陽能電池等研究之發展。倒置式有機發光二極體之研究除了可製作全彩有機發光顯示器，亦可發展為省電照明之用途，具有相當大的產業價值。

This research is divided into two parts: [1]Electronic structure of organic semiconductor materials – Study of electronic structure of organic semiconductor materials is based on the density functional theory calculations, which includes organic molecular structure, electronic structure of molecular orbital and energy levels and energy gap. The calculated of IR spectra, singlet and triplet gaps and stokes shift of selected materials are found to be in good agreement with the experimental data. This study contributed to the understanding the characteristics of organic semiconductor and the designing of new materials. [2]Inverted bottom-emission OLED (IBOLED) development - Inverted OLED is best suited for the large n-channel TFT active matrix OLED display technology. We have developed one of the most efficient (22 cd/A) green fluorescent IBOLED which is more efficient than that of the conventional OLED. The efficiency levels of the white OLED achieved 13.0 cd/A and 10.6 lm/W. The projected half-lifetime under an initial luminance of 400 cd/m2 is projected to be over 34,000 hours and the Commission International de l’Eclairage (CIE) coordinates are not affected by aging. The development of IBOLED is useful in fabricating AMOLED with high power efficiency and long device stability and is also expected to impact on the future development of low power solid-state lighting.