The Reseach Of Blue Phosphorescent Organic Light-emitting Devices Based On Firpic

Organic Light-emitting Diodes(OLEDs)are known as the most promising new generation of solid-state lighting and flat panel display technology because of their high efficiency,fast response,self-luminous,it has made great progress in all aspects after nearly two decades of development.Blue organic electroluminescence is an important part of full color display,but relative to the red and green light,the performance and the practical application of Blue Organic Light-emitting Diodes(BOLED)has a certain gap.The research of BOLED has been relatively backward in the state to a certain extent,and thus restricts the development of full-color OLED display.Therefore,the primary task of developing the blue phosphorescent OLED is to study the high-performance blue phosphorescent material and the reasonable device structure,which will improve efficiency and improve color of the devices.In this paper,we fabricated highly efficient double-emitting layer and ultra-thin non-doped blue organic electroluminescent devices.We has studied the physical properties of the device and the physical process in the device preliminarily.The research work has deepened our understanding of the physical processes in organic electroluminescent devices,and the research results have some reference value for the development of new and efficient devices and the development of their applications.The main contents are as follows:1.Research on High Efficiency Blue Phosphorescent Devices.In this chapter,a typical blue organic phosphorescent material FIrpic is used as the luminescent material,and the electron transport layer TmPyPb and the hole transport layer TCTA are doped as the dual emission layer of the device.And its photoelectric properties were studied.It was found that the maximum luminous efficiency of the device exceeded 20.5 cd/A,far exceeding the single-layer device prepared under the same conditions.2.Research on ultra-thin non-doped Blue Phosphorescent Devices.Firstly,we studied the single-layer ultra-thin non-doped blue OLEDs devices,the experimental results show that as the FIrpic thickness increases,the emission peak gradually blue shift,appear FIrpic luminous peak and increased gradually.Furthermore,with the yellow light component gradually decreased and the spectrum narrowed gradually,a typical blue light emission formed.But the efficiency is not high,we haveanalysis that there are two main reasons for the efficiency is not high of the devices.First,the light emitting area is too narrow,the difference between the HOMO level and the LUMO level between TPBi and TCTA is 0.4eV.Electrons and holes can produce complex excitons by overcoming a large energy barrier,so a large amount of carrier accumulation occurs at the TPBi/TCTA interface and thus Internal quantum efficiency is low.Second,with the increase in FIrpic thickness,the equivalent of FIrpic concentration is increasing.And there has been a lot of concentration quenching center because of a large concentration of quenching occurs.Secondly,we have studied the performance of the multi-layer ultra-thin non-doped organic electromechanical devices.In which the hole and electron transport material are in a symmetrical position between FIrpic layers.It was found that when FIrpic layers were three layers,with each layer FIrpic thickness of 1nm,the body thickness of 5nm,best performance of the device is shown,up to maximum efficiency 9.86cd/A,maximum efficiency than single increased by eighty percent,comparable to the performance of the same layer doping.Ultra-thin doping avoids precise concentration control and simplifies the process.