藍色磷光材料與其主體材料在有機電激發光元件之應用

Blue Phosphorescent Emitters and Hosts and Their Application in Organic Electroluminescent Devices

施宏欣(Hung-Hsin Shih)

指導教授 ： 鄭建鴻

國立清華大學/理學院/化學系/博士(2007年)

https://doi.org/10.6843/NTHU.2007.00380

摘要

無資料

關鍵字

發光二極體 ； 有機發光二極體 ； 主體材料 ； 主層材料 ； 藍色磷光 ； 銥金屬錯合物 ； 白光 ； 碳六十 ； 藍光 ； 藍色摻雜材料 ； 三蝶烯 ； 磷光

並列摘要

Abstract

We have presented the syntheses of more deep blue iridium complexes with using the 3-phenylpyrazole ligands and new third ligands to form the typical cyclometalated (C^N) chelation and typical anionic (N^N) chelation for iridium center, respectively. According to the third ligands (N^N), they can be divided into two series: One is 2-pyridylpyrazole with five-six member rings, the other is 1-imidazolylpyrazole with five-five member rings. Physical properties, including UV-vis absorption, emission spectra in CH2Cl2 or solid crystal at room temperature, and HOMO and LUMO energy levels of these blue phosphorescent materials were checked. Most of these compounds emit room-temperature blue light and the more deep blue emission was located around 438, 464 and 496 nm. When using sean111 as dopant, the device shows emission peaks at 454, 482 nm, maximum brightness of 4299 cd/m2, maximum external quantum efficiency of 1.2 % and good CIE coordinates of (0.14, 0.17).

Heteroatom-center-arylsilane derivatives (BSi, BSiB, BSiCN and BSiPN) were synthesized as novel host materials for deep blue or greenish-blue phosphorescent dopants. These materials not only have good thermal stability (melting point and glass-transition temperature) but also high triplet-state energy level above 2.9 eV. The devices with FIrpic or (dfppy)2Ir(pytz) doped in them have high luminous efficiencies, including external quantum efficiency, current efficiency and power efficiency. The maximum external quantum efficiencies of BSi:FIrpic and BSiB:(dfppy)2Ir(pytz) devices were 9.6 % with the CIE coordinates of (0.14, 0.29) and 8.2 % with the CIE coordinates of (0.13, 0.21), respectively.

Triarylaminotriptycene derivatives were conveniently prepared as host materials for RGB phosphorescent dopants. TCTP and TPTP exhibit excellent thermal stability and a high melting point, especially TCTP (Tg = 238 ℃, Tm = 378 ℃). Both of them have high triplet-state energy level (above 2.9 eV) improved the host–guest energy transfer to blue phosphorescent materials, but TPTP with lower triplet energy of 2.94 eV also can be used as a host for green and red phosphorescent materials. The blue devices of FIrpic and (dfppy)2Ir(pytz) show maximum external quantum efficiency of 10.1 % and 7.9 %, and the CIE coordinates of (0.14, 0.36) and (0.14, 0.22), respectively. The green device of TPTP:Ir(ppy)3 exhibits maximum external quantum efficiency of 11.5 % with the CIE coordinates of (0.23, 0.66). For the red device of TPTP:Ir(DBQ)2(acac) with the CIE coordinates of (0.62, 0.38), the maximum external quantum efficiency of 9.8 % is achieved. The two emission zones for white light device by employing FIrpic and Ir(DBQ)2(acac) have the maximum external quantum efficiency of 8.5 % and the CIE coordinates of (0.32, 0.33) at 8 V.

We have demonstrated the white light-emitting devices with high brightness, and great external quantum efficiency and current efficiency from blue fluorescent (T1) or (T2) and green (Ir(ppy)3) and red (Ir(DBQ)2(acac) or Ir(MDQ)2(acac)) phosphorescent materials. The white EL spectra with the very stable three emission zones were contributed from three materials. In addition, they own very stable white CIE coordinates (0.34, 0.33) and (0.35, 0.37) and high CRI from 6 V to 15 V. The devices with the structure [NPB/CBP:Ir(DBQ)2(acac)/CBP: Ir(ppy)3/ T1 or T2 / Electron transporting materials show bright white light and good luminous efficiencies] .

C60 doping in the thin hole transport materials as a hole-injection layer of an organic electroluminescent devices can improve the luminous efficiencies, including the maximum current efficiency and power efficiency at the same voltage and current density. When the concentrations of fullerene (C60) doped in NPB (7 nm) were varied between 25%-50%, the luminescence efficiencies also increased more than 30%. In addition, application in the general devices using C545T as a green dopant emitter in Alq has the same effects under similar conditions.

並列關鍵字

OLED ； host ； guest ； blue phosphorescence ； iridium comlpex ； white light ； dopant ； Fullerene ； Organic Light-Emitting Diode ； Light-Emitting Diode ； triptycene ； arylsilane ； phosphorescence

參考文獻

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