Design,Synthesis And Electro-optical Properties Of Swivel Cruciform Structure-conjugated Organic Molecules Based On Anthracene

In recent years,the popularity of ultra-thin and large-area self-luminous flat panel display industry has made the development of organic light-emitting devices(OLEDs)a very attractive application prospect.The development of high-efficiency,high-stability organic electroluminescent materials has played a significant role in the development of electroluminescent devices(OLEDs).It has been found that some conjugated skeletal distorted fluorescent molecules are more fluorescently efficient in nanoaggregates and solid states than the typical linear planar conjugated organic fluorescent molecules.Besides,this kind of molecule is combined by the linear conjugates(branch group)and the C?C single bonds(cyclotrons)of the intermediate aromatic rings of the molecules.Thus,the molecule are in swivel-conformation structure due to the steric repulsion.This structure is very favorable for material solubility,solution film formation,morphological stability,and weak ??? interactions.By linking with different units,the composition,structure,geometry and conformation of the molecule,aggregation behavior,fluorescence color,carrier transport,and electroluminescent properties of the material can be effectively controlled.In this paper,we designed and synthetized a series of molecules with swivel cruciform based on anthracene by adjusting the type and position of the carcass,the specific research contents are as follows:1.Using bis(4-tert-butylphenyl)carbazole and bis(4-tert-butylphenyl)amine as the branch units respectively and 9,10-diphenylanthracene as the body group,we designed and synthesized two molecules BCZ-M and BDPA-M,they are both anthracene derivatives based on swivel cruciform structure.We explored the molecular properties by changing the branch unites.The branch group tert-butyl carbazole of BCZ-M is a good hole-transporting material is used to design electroluminescent materials with excellent hole-transporting properties;The tert-butyl amine of BDPA-M is one kind of strong electron donor,it is used to design D?A?D tape electroluminescent materials.Studies have shown that both BCZ-M and BDPA-M are blue-emitting materials,their photo-and electroluminescence spectra are highly compatible.Moreover,the thermal stability of BCZ-M and BDPA-M is extremely high,and no crystallization and melting peaks are found within the measurable temperature range,which is very favorable for improving the stability of the device.Compared to BCZ-M,BDPA-M has a clear solvation phenomenon from low-polarity solvents to high-polarity solvents,the red shifts was about 144 nm.Its excited state is dominated by charge transfer excitation,and its device properties are also better than BCZ-M.The un-doped device has an EQE(external quantum efficiency)of2.75% and a maximum luminescence brightness of 1112.62 cd m-2.However,the devices with the BCZ-M as the light emitting layer under the same device structure have an efficiency roll-off.2.We designed and synthesized a molecule 2CHOBDPA by using the core9,10-diphenylanthracene and the branch group aldehyde and(4-tert-butylphenyl)amine to the benzene ring at 5-position and 2-position.The sterically hindered interaction between the arylhydrazine center and the two branches of the molecule makes the molecule cross-conjugation in a spatial convolution,forming a strongly twisted weakly conjugated structure.Through testing,it was found that the maximum fluorescence emission wavelength of the molecule is 461 nm,still in the blue light emitting region,and the molecule has an obvious piezochromic behavior.From the perspective of the single crystal structure of the two molecules,2CHOBDPA is in an "E" shape and BDPA-M is in a "Z" shape.Compared with BDPA-M,the intermolecular distance of 2CHOBDPAs is increased by 4 times.