Study On The Realization Of Full Fluorescent White Organic Light-emitting Diodes Based On Exciplex

Organic Light-emitting Diodes(OLEDs)have become a leader in the field of lighting and display with their advantages of self-luminescence,healthy light source,and thinness.Currently,thermally activated delayed fluorescence(TADF)materials have become one of the hot research directions in the field because of their excellent performance of 100%internal quantum efficiency without heavy metal atoms.Exciplex complexes have attracted the attention of many researchers due to the intermolecular TADF effect and have shown great potential for application as the research progresses.In this paper,we propose to realize fully fluorescent white light organic electroluminescent devices using radical complex structures,and the specific work is as follows.(1)Based on the relevant studies on the exciplex complexes,this paper presents for the first time the organic hole-transporting material4,4’,4"-tris[phenyl(m-tolyl)amino]triphenylamine(m-MTDATA)and the blue TADF material 10-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-10Hspiro[acridine-9,9’-fluorene](Spiro AC-TRZ)was used as the donor and acceptor of the exciplex complex,respectively,to achieve red light emission at 604 nm.Based on the luminescence phenomenon of this red exciplex complex,we investigated its electroluminescence properties and designed a series of experiments to investigate the exciplex complex luminescence devices.We found that the exciplex complex can form exciplex complex emission at very low donor concentration and exciplex complexes can be formed at both donor and acceptor doping or interface sites.In the process of investigation,we found that the emission of blue peaks appeared in the electroluminescent device,and the source of its luminescence was explored in some way,and finally we concluded that the emission of blue peaks consisted of two parts.Next,we used the device structure to adjust the blue light emission,and finally completed a triple undoped device structure using m-MTDATA/ Spiro AC-TRZ/ 1,3,5-tris[(3-pyridyl)-3-phenyl]benzene(Tmpypb)with CIE coordinates of(0.378,0.389),full width at half maxima of 230 nm,and color rendering index(CRI)of 87,providing a new idea for white light device preparation: white light by monochromatic photoluminescence of exciplex complexes and complementary colors.(2)To address the performance of white devices,we adopt two options of using materials with high energy levels and optimizing the device structure for further investigation.We use m CP,a commonly used deep blue light body material,as a hole transport material to test the performance of blue TADF material and finally achieve the blue emission with luminous efficiencies of 35.57 cd/A and 31.92 lm/W and CIE coordinates of(0.17,0.31).At the same time,we used m CP as the hole transport layer to investigate the effect of this change on the red light emission from the red exciplex complex,and achieved the red light emission from the exciplex complex as the guest when m CP was used as the main body.On the basis of these investigation experiments,we achieved a white light device with a maximum efficiency of 28.78 cd/A(23.73 lm/W),CIE coordinates of(0.36,0.47),CRI of 72,and full width at half maxima of 184 nm using the doped structure.