Synthesis And Optoelectronic Properties Of Thioxanthene Derivates Small Molecular Light Emitting Organic Materials

With the development of the technology,organic light-emitting diodes（OLEDs）have reached the stage of commercialization,which were attributed to intense efforts to use them in various applications such as small-and medium-sized mobile devices,illumination equipment and large TV screens.It is obvious significance to develop the material for blue,green,orange and red emitters.Thus,this paper focuses on the synthesis and performance of materials contain the thioxanthene derivative for the use as universe host,traditional blue fluorescent materials and blue thermally activated delayed fluorescence（TADF）material.A series of host materials incorporating 9,9-diphenyl-9H-thioxanthene or spiro[fluorene-9,9′-thioxanthene]as the core and carbazole as the arms were designed and synthesized.Notably,a maximal power efficiency of 69.7 lm W^-1and extemal quantum efficiencyof 29.0%were achieved for an optimal device based on m-DCz-S as host for FIrpic.And phosphorescent WOLED using Firpic as the blue emitter and PO-01 as the yellow emitter acquires a maximum CE of 74.3 cd A^-1,a maximum PE of 82.7 lm W^-1 and a maximum EQE of 26.4%.Using the Cz-F-S as host for orange TADF,a maximal current efficiency of 66.7 cd/A,power efficiency of 52.46 lm W^-1and extemal quantum efficiencyof 21.8%were achieved.And using the Cz-F-S as host for green TADF 4CzIPN,a maximal current efficiency of 84.2 cd/A,power efficiency of 74.1 lm W^-1and extemal quantum efficiencyof 26.4%were achieved.Using the Cz-F-S and TmTyPZ as PN host for orange TADF,a maximal power efficiency of 69.3 lm W^-1 was achieved and for green TADF,a maximal power efficiency of 85.3 lm W^-1 was achieved.A series of TADF materials were designed and synthesized incorporating phenoxathiine10,10-dioxide as acceptor core and 9,9-dimethyl-9H-acridine（ACR）and phenoxazine（PXZ）units as donor.Effect of phenyl-bridgebetweendonor-acceptor units on photophysical properties and electroluminescence performances for highlyefficient blue and green thermally activated delayed fluorescence materials was thoroughly investigated.For blue TADF material POSO2-Ph-ACR,a maximal EQE of 19.3%was obtained and for green TADF material POSO2-Ph-PXZ,a maximal EQE of 21.0%was obtained.A series of TADF materials were designed and synthesized incorporating phenoxathiine10,10-dioxide as acceptor core and 9,9-dimethyl-9H-acridine（ACR）as donor.Effect of the ACRdonor position on photophysical properties and electroluminescence performances for highlyefficient blue TADF materials was thoroughly investigated.For blue TADF material 3,7-DACR-POSO2,a maximal EQE of 19.7%was obtained and for material 2,7-DACR-POSO2,a maximal power efficiency of 44.8 lm W^-1and extemal quantum efficiencyof 23.4%were achieved.A series of blue materials were developed incorporating spirobi[thioxanthene]10,10,10’,10’-tetraoxide as acceptor core but different donors such as 9,9-dimethyl-9H-acridine（ACR）and diphenylamine（DBP）units.For DTPA-DSO2 as blue traditional fluorescent,a maximal current efficiency of 9.7 cd/A,power efficiency of 10.6 lm W^-1and extemal quantum efficiencyof 6.2%were achieved.For DAc-DSO2 as blue TADF fluorescent,a maximal current efficiency of 53.2 cd/A,power efficiency of 48.3 lm W^-1and extemal quantum efficiency of25.4%were achieved in doped device and a maximal current efficiency of 42.5 cd/A,power efficiency of 32.7 lm W^-1and extemal quantum efficiencyof 18.2%were obtained in non-doped device.A series of blue materials were developed incorporating spiro[thioxanthene]10,10,10’,10’-tetraoxide as acceptor core but different spiro-structure while using 9,9-dimethyl-9H-acridine（ACR）as donor unit.Comparing to the TADF material DMAc-DPS,the matrials ACR-DPTX show not only the better device performance with higher EQE but also the better CIE value with（0.14,0.18）.For ACR-DPTX as blue TADF fluorescent,a maximal current efficiency of40.2 cd/A,power efficiency of 43.5 lm W^-1and extemal quantum efficiency of 28.5%were achieved in doped device.This work gives a new route to further improve the performance of deep blue TADF-OLEDs with high EQE.