Study On The Performance Of Platinum-based Green Phosphorescent Organic Light-Emitting Diode

Phosphorescent organic electroluminescent devices(PhOLEDs)can break the spin-forbidden by increasing the heavy metal composition of the frontier orbit,and promote the exciton radiation transition to achieve 100%internal quantum efficiency.However,researches phosphorescent material of the device is focused on iridium complexes,platinum complexes few studies on the phosphorescent materials and devices.In this thesis,the electrochemical and photophysical properties of novel platinum metal complex phosphorescent materials and their luminescence mechanisms in different host-guest structures are studied.The main research contents are as follows:Firstly,the thesis studies the electrochemical properties,photo and electroluminescence properties and thermal stability of the new platinum metal complexes Pt0 and Pt4,and discusses the different doping device performance of two new phosphorescent materials.The electroluminescent wavelengths of the materials Pt0 and Pt4 are both 520 nm.At the current density of 20 mA/cm2,we found that the device voltage of doped PtO is 7.16 V,the current efficiency is 19.19 cd/A,the voltage of the device doped with Pt4 is 6.84 V,and the current efficiency is 32.64 cd/A.Pt4 is an excellent monochromatic green OLED guest material,and under high concentration conditions,Pt0 forms an excimer at a wavelength of 648 nm in the light-emitting layer of the device.If it is mixed with a short-wavelength blue light material,it has the potential of a white device.Secondly,we have made the new material Pt4 doped with three different host materials TCTA,E228 and E258 to form the light-emitting layer,and we studied the effects of host material,transport layer material and thickness on the performance of OLEDs based on platinum metal complex Pt4.By analyzing the data of its spectrum,efficiency and stability,we found that the material E258 has the best overall performance when the doping concentration is 15 wt%and the thickness of the luminescent layer is 15 nm.At a current density of 20 mA/cm2,the device voltage is 5.6 V,the current efficiency is 50.65 cd/A,and the luminance is 10010 cd/m2.Finally,we studied the effects of different host-guest doping and functional layers on device stability.We have found that the device material energy level adaptability,the carrier transport balance,and the distance between the luminescent layer and the electrode all have a large effect on the lifetime of the device.