Research On High Performance Organic Light-emitting Diodes

Organic light-emitting diodes(OLEDs) have attracted much attention due to their great potentials as high quality flat panel displays and for solid-state lighting. Researchers have got some achievements from the composition of organic materials, device structure optimization and device physics, which result in a stable improvement in the luminous efficiency and lifetime of WOLEDs, the quality of colour and other key performance. Carrier injection and transport in OLEDs as the most basic physical processes can influence the light-emitting properties of the device. Due to the structural disorder and the diverse material of organic semiconductor film, the physical process of carriers is complex. In this paper, the effect of CuI film on the hole-injection properties of OLEDs were investigated by inserting CuI film into the anode side or doping CuI into hole-injection/transport materials. In addition, we studied the carrier transfer and luminescence characteristics of 8-hydroxyquinoline metal complexes, which will benefit to the preparation of high-performance WOLEDs device.We fabricated OLEDs with the structure of ITO/m-MTDATA: xCuI/m-MTDATA /NPB/Alq3:C545T/Alq3/LiF/Al, in which the transition metal compound-CuI was doped into the hole-injecting material m-MTDATA with different proportions. The effect of the proportions of m-MTDATA: CuI on the OLED performance was investigated. Doping CuI into m-MTDATA can improve the injection and transption of carrieres in the OLEDs, which resulted in reduce the operation voltage and enhance the power efficiency. The maximum luminance of the devices is 44760 cd/m2. When the operation voltage is 5.5 V, the maximum power efficiency is 6.6 lm/W.We doped CuI into the hole-transport material NPB that produced a set of organic fluorescent devicess and structured as ITO/NPB:(x wt.%)CuI/NPB/ Alq3/ LiF/Al. Drop CuI into the hole-transport material NPB can promote the hole injection and transption performance, reduce the opration voltage and enhance the power efficiency. Produced a set of the organic phosphorescence devicess with the hole injection layer with CuI and NPB:CuI, respectively. When the opration voltage is 10 V, the doped device is more than ten times for the undoped device. Indicated that, no mather the CuI thin or doped CuI layer can reduce the opration voltage and enhance the luminance. When the current density exceed 5mA/cm2, at the same current density, the device with 10 wt.% NPB: CuI achieved the higher current efficiency, the maximum current efficiency is 12.3 cd/A. The doped devices with the maximum power efficiency is 9.8 lm/W, more than two times for the without CuI device.8-hydroxyquinoline aluminum(Alq3) is a comprehensive performance excellent electron transport material and luminescent materials. A carbazole derivatives was synthesized and lead into Znq2 at C-2 of 8-hydroxyquinolinenamed(E)-2-(2-(9-ptoly1- 9H-carbazo1-3-y1)viny1)quinolin-Zinc(MCzHqZn). We use MCzHqZn as a yellow material.Preparation of a set of structure ITO/2T-NATA/NPB:2wt.%MCzHqZn/ BCP/ Alq3/LiF/Al. The Commission Internationale del’Eclairage(CIE) coordinates is fairly close to the white-light equi-energy point, high color rendering index, chromaticity coordinates stable white device. The maximum current efficiency of 2.3 cd/A with the coordinates of(0.320, 0.347), corresponding CRI of 78–81.The CIE coordinates correspond to CCT is 5914 K at 8532 cd/m2.From the brightness at 1000 to 5000 cd/m2, the roll-off current efficiency is 9.0%.