高水平發光偶極比藍光熱激活化延遲螢光材料及發光元件之研究

Investigation on high horizontal dipole ratio blue thermally activated delayed fluorescence organic emitters and devices

劉育均(Yu-Chun Liu)

指導教授 ： 吳忠幟

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202101858

摘要

有機發光二極體(OLED)歷經長時間的發展至今已成為顯示、照明產品的重要技術之一。近年來隨著熱激活化延遲螢光(TADF)材料的發展，其低成本、高效率和易於調整分子結構的特性吸引了廣泛的注意和研究。有著TADF材料的助力，有機發光二極體的外部量子效率(EQE)屢創新高，EQE超過30%的元件也已出現。近期的研究指出，高內部量子效率(IQE)、高水平發光偶極比(Horizontal dipole ratio)是達成高EQE的關鍵因素，而此兩因素會大幅地受到分子特性所影響。
在本篇論文的第一部分，我們研究兩種新的TADF藍光材料SOBA和S2OBA的薄膜光物理特性與元件特性，並與已發表過的分子DOBA進行比較。我們的研究表明，SOBA和S2OBA的薄膜其PLQY可分別達88.5%與86.7%，水平發光偶極比可達86%與88%。在與適當的材料搭配且未使用額外的光學出光結構下，兩種分子製成的元件可分別表現出最高29.3%和17.9%的EQE (25.7%、13.1%, at 1000 cd/m2)，同時擁有更藍的光色。
本篇論文的第二部分，我們探討於SOBA的基礎上，另外設計的兩種藍光TADF材料pCzSOBA和mCzSOBA的薄膜光物理特性與元件特性。實驗中兩種分子分別表現出高達87.0%和88.7%的PLQY和86%與81%的水平發光偶極比。兩種分子製成的元件可表現出最高24.0%和24.3%的EQE (18.4%、20.6%, at 1000 cd/m2)，同時擁有與SOBA相似的光色。這些結果有助於發展一系列性能相似的分子，使日後對於TADF材料分子的研究能有更多創新的空間。

關鍵字

有機發光元件 ； 熱激活化延遲螢光 ； 水平發光偶極比

並列摘要

Organic light-emitting diodes (OLEDs) have become one of the most important technologies for display and lighting products after a long period of development since they were first published. Recently, with the development of thermally activated delayed fluorescence (TADF) materials, their low-cost, high-efficiency, and easy-to-adjust molecular structures and characteristics have attracted extensive attention and research. With the help of TADF materials, the external quantum efficiency (EQE) of organic light-emitting diodes has repeatedly reached new highs, and devices with more than 30% EQE has also been reported. Recent studies have pointed out that high internal quantum efficiency (IQE) and high level of horizontal dipole ratio are key factors for achieving high EQE. These two factors in general are greatly affected by molecular characteristics.
In the first part of this thesis, we study the thin film photophysical properties and device characteristics of two novel blue TADF materials, SOBA and S2OBA, and compare them with the published molecule DOBA. Our research shows that the PLQY of SOBA and S2OBA films can reach 88.5% and 86.7%, respectively, and the horizontal dipole ratio can reach 86% and 88%. When matched with appropriate materials, the device made of the two materials possess up to 29.3% and 17.9% EQE (25.7%, 13.1%, at 1000 cd/m2) without the use of additional optical light out-coupling structures. Both device at the same time has a bluer color than DOBA.
In the second part of this thesis, we study the thin film photophysical properties and device characteristics of two novel blue TADF materials pCzSOBA and mCzSOBA designed on the basis of SOBA. In our experiment, the two materials showed up to 87.0% and 88.7% PLQY, 86% and 81% horizontal dipole ratio respectively. The device made of the two materials can show up to 24.0% and 24.3% EQE (18.4%, 20.6%, at 1000 cd/m2), and have a color similar to SOBA. These results are believed to be of help for further development of TADF materials.

並列關鍵字

Organic light-emitting diodes ； thermally activated delayed fluorescence ； horizontal dipole ratio

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