| Organic electroluminescent devices（OLEDs）are attracting more and more attention due to their excellent performance of self-luminous,full color display and high luminous efficiency.In device preparation,printing or inkjet printing wet process is simple,easy to achieve large-scale device preparation.So this preparation methods greatly reducing the device manufacturing costs.In general,high molecular weight materials are better suited for the wet processes due to their good moldability.However,due to polymer materials purify are difficult,molecular weight distribution is not uniform,solubility and reproducibility is poor.So it is difficult to obtain a better development in soolution-process device.Dendritic macromolecule materials are used for the fabrication of wet-process OLED devices due to it meet both the structural certainty of small-molecule materials and the excellent film-forming properties of the polymers.Thermal Activation Delayed Fluorescence（TADF）materials are the third generation of display materials following conventional fluorescent and phosphorescent materials.This new type of material does not require doping rare metals to get 100%of the internal quantum efficiency,so it got the greatly attention of scientists.Therefore,the development of a TADF dendrimer material is great importance to obtain an efficient self-host solution-processed device.In this paper,two kinds of solution self-host dendritic thermal activation delayed fluorescent materials were designed and synthesized.And from the following aspects,thermodynamic properties,photophysical properties,electrochemical properties and device performance,the properties of the luminescent materials were systematically studied.The specific work of the study is as follows,（1）A bipolar transmission dendritic thermal activation delayed fluorescent material G-CzTrz was designed and synthesized.In contrast,the luminescent core G-O molecules of the dendritic TADF material G-CzTrz were also synthesized.Thermodynamic properties,photophysical properties and electrochemical properties of the new dendritic TADF material G-CzTrz showed good thermal stability,film formation and solubility,which is suitable for the preparation of solution-processed devices.And this non-conjugate way to introduce peripheral branches,making the new material can maintain the original luminous properties unchanged.Single-carrier device research shows that the introduction of bipolar transmission group in thenew material G-CzTrz peripheral can effectively balance the exciton transport and injection,contribute to significantly improve device performance.The research on device performance shows that the maximum current efficiency of the self-host solution-processed devices based on G-CzTrz material reaches 18.4 cd A-11 and the maximum external quantum efficiency（EQE）reaches 6.7%,which is higher than that of the undoped wet-process GO device 3 times.（2）Two kinds of novel dendritic thermal activation delayed fluorescent material,4CzCN-SP and5CzCN-SP,were designed and synthesized.A series of photophysical,electrochemical and device performance tests were carried out.The results show that the new synthesized materials 4CzCN-SP and 5CzCN-SP which use 2-methoxy-9,9’-spirobi[fluorene],an electron-transporting group,as the functional dendrites keep the luminous nuclear optical properties unchanged.Meanwhile the problem of quenching the concentration of the self-host solution-processed devices and the imbalance of the light-emitting nuclear exciton are effectively suppressed.The results show that5CzCN-SP as a luminescent layer prepared from the body of the wet OLED achieved better luminescence performance-the starting voltage is only 3.8 eV,the maximum brightness of 26774cd m-2,the maximum power efficiency of 15.1 lm W-1,the maximum external quantum efficiency（EQE）reached 13.1%.This device performance is among the best reported self-host solution-processed OLEDs performance categories. |
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