Synthesis And Properties Of Triarylborane-pyrrolo[3,2-b]pyrrole Compound With AIE Properties

OLED has attractive features such as beauty,thinness,flexibility,low power consumption and high contrast.It is considered to be the next-generation new display flat panel technology and is now widely used in the display screens of smart phones and televisions.As the light-emitting layer of the core of the OLED,the small organic compound has the advantages of easy structure modification,easy synthesis and easy purification.However,most of them have the problem of aggregation-induced quenching（ACQ）in the solid state.On the contrary,the luminous efficiency of aggregation-induced emission（AIE）materials in the aggregated state is higher,and the emergence of AIE breaks through the plight of OLED development.Pyrrolo[3,2-b]pyrrole and its derivatives are a new kind of organic light-emitting materials.Its structure is composed of two pyrrole rings,which have large planar rigid conjugated structure.What’s more,there are 10 π electrons separated from each other,which makes it have strong electron-donating ability.Thus,it is an important unit for the synthesis of various small molecules and polymers.In triarylborane,the boron atom has an empty p-orbital,and it has a strong electron-deficient property when it is connected to an aromatic compound.Therefore,triarylborane is often used as a strong electron acceptor.Based on this,the compound DMBPDPP containing pyrrolo[3,2-b]pyrrole-triarylborane was designed and synthesized,and the structure of the compound was systematically characterized.The thermal stability,photophysics and electrochemical properties of the compound were also studied.What’s more,the characteristics of doped and non-doped OLEDs manufactured using the compound as a light emitting layer are also studied in detail.The main contents are as follows:（1）The development and mechanism of OLED,the AIE phenomenon and current progress,pyrrolo[3,2-b]pyrrole compounds and triarylborane compounds are introduced.（2）A new material DMBPDPP with aggregation-induced emission properties was designed and synthesized by combining triarylborane units with pyrrole[3,2-b]pyrrole skeleton,and the structure of the compound was characterized.The thermal stability,photophysical properties,electrochemical properties and AIE properties of DMBPDPP were studied.The results show that the Td of DMBPDPP is 347℃,which indicates that it has good thermal stability.The HOMO / LUMO orbital electron cloud arrangement and energy level were calculated through DFT.The results show that DMBPDPP has a distorted conformation,which can reduce the π-π interaction and produce AIE characteristics.The AIE characteristics of DMBPDPP were confirmed by spectroscopic studies of THF-H2 O solvents in different proportions.The cyclic voltammetry method was used to test the electrochemical performance.The results showed that the electrochemical performance was stable,and the HOMO / LUMO energy level was further verified experimentally.（3）Non-doped and doped OLEDs was constructed with DMBPDPP as the light-emitting layer,and its electroluminescence properties were systematically tested.The results show that the compound is a good green light material.The maximum current efficiency of the non-doped device A based on DMBPDPP is 5.90 cd A^-1,the turn-on voltage is 3.3 V,the maximum brightness is 4158 cd m-2,the maximum external quantum efficiency is 0.61%.The turn-on voltage of the 3% doped device B is 3.3V,the maximum current efficiency is 7.90 cd A^-1,the maximum brightness is 13340 cd m-2,the maximum external quantum efficiency is0.79%,and the maximum power efficiency of 7.52 lm W^-1.The turn-on voltage of the 5% doped device C is 3.0 V,the maximum power efficiency of 8.40 lm W^-1,the maximum brightness is 13500 cd m-2,the maximum current efficiency is 8.6 cd A^-1,and the maximum externalquantum efficiency is 0.77%.The maximum current efficiency of the 8%doped device D is 8.9 cd A^-1,turn-on voltage of is 3.0 V,the maximum current efficiencyis 8.9 cd A^-1,the maximum brightness is 13400 cd m-2,the maximum power efficiency of 9.01 lm W^-1,and the maximum external quantum efficiency is 0.87%.