Synthesis And Properties Characterization Of Novel Organic Electroluminescent Materials Based On 1,5-diazarcarbazole

Organic lighting emitting diode(OLED) is regarded as “fantasy flat-panel display” and the next generation solid-lighting technology, because of its ultrathin, active emitting, flexibility and advantages of large-area film. In the past decade, much effort has been devoted for the scientists and the OLED has also made a rapidly developed. In order to improve the efficiency, host-gust system is usually used in design and facture the OLED devices to avoid the effect of triplet-triplet annihilation(TTA) and concentration quenching. Meanwhile, more and more high-thermal stability and bipolar host materials have been developed. In this paper, we designed a series of high efficient host materials based on 1, 5-diazarcarbazole and the details are as follows:Chapter 1: Briefly introduced the basic knowledge of organic electroluminescent devices, its development process, and the current industry environment in our country. Pyridoindole(carboline) derivatives and their application in OLED were reviewed. And the research projects in this paper were described.Chapter 2: A series of blue phosphorescent host materials based on 1, 5-diazarcarbazole were synthesized. Low-temperature PL spectra shows that the materials have high triplet energy level(2.85 eV), which is high enough to applicate in blue phosphorescent OLED; Cyclic voltammetry(CV), theory calculation and single carrier device indicate that the 1, 5-diazarcarbazole can effectively tone the energy level and the electron transporting features. The blue PhOLED using these host materials shown basic Firpic emitting peaks and achieved the highest external quantum efficiency(EQE) of 24.0%, the highest current efficiency(CE) of 47.8 cd/A and the highest power efficiency(PE) of 45.6 lm/W. All results illustrate that the 1, 5-diazarcarbazole group plays a key role on tone the energy level and the electron transporting features of host materials, because of the two electron-deficient C=N double-bonds were introduced.Chapter 3: In order to resolve the low Tg shown in preceding chapter, the rigid spacer, 9-phenyl-9H, 9'H-3,3'-bicarbazole, was introduced. A series of host materials were synthesized through the 1, 5-diazarcarbazole and 9-phenyl-9H,9'H-3,3'-bicarbazole substituted at benzene and pyridine. All hosts shown high Td(>420?) and high Tg(>140?) and the blue PhOLED using these hosts shown EQE of 20.2%, CE of 41.4 cd/A and 33.1 lm/W. It s worth noting that at the higf brightness of 1000 cd/m2, the device also shown the EQE of 20.0%, only 1.0% efficiency roll-off. Even in the ultral high brightness of 10000 cd/m2, the efficiency roll-off device is still under 20%.Chapter 4: Two multifunctional materials were synthesized because of the high ET of 1, 5-diazarcarbazole and high blue fluorescence emitting and high thermal stability group, phenanthroimidazole. The materials shown high Td( 413 and 411?) and Tg( 191 and 130?). The nondoped blue fluorescence OLED device achieved the highest EQE 2.59% and 2.88%, respectively. And the CIE is(0.15, 0.08) showing a deep blue emitting. The green and red PhOLED based on Ir(ppy)3 and Ir(DMQ)2(acac) shown the highest EQE are 21.0% and 18.4% of Green devices and 19.3% and 16.3% of Red devices, respectively.