以新穎含銥錯合物染料製作高效率黃光有機發光二極體

Highly Efficient Yellow Organic Light Emitting Diode with a Novel Iridium Complex Emitter

林佑星

指導教授 ： 周卓煇

國立清華大學/工學院/材料科學工程學系/碩士(2013年)

摘要

黃光可應於用高品質RGBY顯示器，同時對於生理友善的低色溫照明光源來說，黃光扮演了一個關鍵的角色。而對於有機發光二極體(Organic Light Emitting Diode, OLED)來說，如果要能通過真空熱蒸鍍的方式製作高品質元件或是利用連續滾印(Roll-to-roll)的方式製作低成本大面積元件，勢必需要具備有可乾、可濕製作的特性的發光染料。 因此，研發出一個具備有可乾、可濕製作特性的高效率的黃光發光染料便顯得重要。本研究將一具有拉電子特性的氟原子導入環金屬配位體5-methyl-5H-benzo[c][1,5]naphthyridin-6-one，並成功合成出一新穎高效率且可乾、可濕製作的銥錯合物黃磷光染料 bis[5-methyl- 7-fluoro-5H-benzo(c)(1,5)naphthyridin-6-one] iridium (picolinate)。利用濕式製程所製備的元件，在亮度為1,000 cd/m2時，其能量效率為52.3 lm/W，外部量子效率為18.5%，能量效率為濕式製作黃光OLED的最高紀錄；若改以乾式製程所製備的元件，其能量效率為75.1 lm/W，外部量子效率為22.6%，能量效率為乾式製作黃光OLED的最高紀錄。而元件的高效率主要可歸因於利用了氟原子來取代發光染料上的氫原子，而造成： 一、 改變分子間較密的堆疊方式以減少染料間的自我焠熄；二、能減少分子以非放光形式的能量損失，使得分子能具有較高的量子產率 (71%)。

關鍵字

有機發光二極體 ； 黃光 ； 銥錯合物

並列摘要

Yellow emission is crucial in RGBY display technology and in fabricating physiologically-friendly low color temperature lighting source. Emitters with both wet- and dry-process feasibility are highly desirable to fabricate, respectively, high quality devices via vapor deposition and cost effective large area-size devices via roll-to-roll fabrication. We demonstrate in this report high-efficiency organic light-emitting diodes with a novel wet- and dry-process feasible yellow emitting iridium complex, bis[5-methyl-7-fluoro-5H- benzo(c)(1,5) naphthyridin- 6-one]iridium (picolinate). By spin coating, the device shows, at 1,000 cd /m2 for example, an external quantum efficiency (EQE) of 18.5% with an efficacy of 52.3 lm/W, the highest among all reported yellow devices via wet-process, while using vapor deposition, the EQE is 22.6% with a 75.1 lm/W efficacy, the highest among all dry-processed counterparts. The high efficiency may be attributed to the replacement of the hydrogen atom with a fluorine atom on a 2-substitutional site in the emitter to prevent dense molecular packing caused self-quenching and reduce radiationless deactivation rate, leading to a high quantum yield (71%).

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