Design,Synthesis And Properties Of Nonplanar Fluorene Based Delayed Fluorescence Materials

In recent years,with the OLED(Organic Light-Emitting Diode,organic light-emitting diode)to accelerate the pace of industrialization,panel companies have laid OLED production line,the relevant research,especially in the upper reaches of the industry chain research has become the focus of research and development.Among them,the TADF(Thermally Activated Delayed Fluorescence)material,which is the next generation luminescent layer material,is an important part of the study with its easy preparation,low cost and high luminous performance.As the intermolecular TADF material system,the radical complex type delayed fluorescence system is more and more easy to achieve smaller singlet and triplet energy level difference is getting more and more scientific research workers attention,our research group found in the study,with The thermophilic delayed fluorescence emission of the excited group complex can be achieved by the addition of 4,4',4''-tris(carbazole-9-yl)triphenylamine(TCTA)to the SFX-based materials with symmetric cyano-substituted.At the same time,we also note that SFX derivatives have been applied and reported in optoelectronic devices and delayed fluorescent devices.In this paper,we based on keeping the symmetry characteristics of cyano substituted fluorene skeleton,through the transformation of the steric configuration of groups and other factors,study the structure-activity relationship between the materials based on non planar fluorene with symmetrical cyano substitution and realization of TADF of exciplex.First of all,we have prepared a series of sterically hindered fluorene based compounds with the characteristics of symmetric cyano group by changing the different steric hindrance units on the 9 position of fluorene.We systematically studied the photophysical properties of these mixing films of these compounds with TCTA by half-and-half.It is found that different kinds of steric hindrance elements have a certain influence on the exciplex-TADF.Secondly,we further change the structure of the molecular skeleton and design three "H-shaped" molecules.In contrast,we designed and prepared a single arm substituted contrast molecule to further demonstrate the effect of the molecular skeleton("H-shaped")on the delayed fluorescence properties.Finally,considering the process problems from doping and host-guest system during preparing organic light emitting devices(OLEDs)with the intramolecular TADF emitters and intermolecular TADF materials,we hope to design and build an integrated of host and guest delayed fluorescent molecule from the point of view of the donor and acceptor materials using in exciplex-TADF.