Synthesis And Properties Of Organic Room Temperature Phosphorescent Materials Based On Phenothiazine And Carbazole

With the continuous progress of science and technology society,people's increasing material and cultural needs play an increasingly important role in contemporary society.Among them,phosphorescent materials have many applications in optoelectronic information,sensing,biological imaging,and anti-counterfeiting due to their unique luminescence properties.In the past few decades,heavy metal complexes have been used as phosphorescent materials,but organometallic complexes have the disadvantages of high toxicity,shortage of resources and high cost.At this stage,due to environmental pollution and destruction,the application of traditional metal-containing luminescent materials is limited.Pure organic luminescent materials have come into everyone's field of vision.Because of their low cost,diversified molecular design,strong processability,strong biocompatibility,and low toxicity,they have broad application prospects.This subject aims to design and synthesize organic room temperature phosphorescent materials with high efficiency,long life,low price and environmentally friendly.First of all,this topic selects phenothiazine as the donor,introduces Br atoms to improve the spin-orbit coupling,thereby breaking the transition forbidden between singlet and triplet states,and synthesizing p-PTZ-Br.On this basis,the sulfur atom in p-PTZ-Br was oxidized to a sulfone group to limit the conformational isomerization of phenothiazine,so as to explore the influence of molecular stacking on molecular photophysical properties.In addition,in order to explore the difference in the photophysical properties of p-Cs-Br in different states,this topic prepared p-Cs-Br in two states,a"crystal"state and a prepared state.The experimental results show that the S atom in phenothiazine can be oxidized to limit the conformational isomerization of its derivatives and increase the phosphorescence lifetime.In addition,the crystal state of p-Cs-Br will also have a certain impact on the luminescence performance.The more regular the molecular arrangement,the longer the phosphorescence lifetime.In addition,this topic selects carbazole as the donor,introduces boronic ester group and Br atoms,designs and synthesizes two molecules with D-A-D structure2Cz-BOC and 2Cz-Br.The influence of borate ester group on photophysical properties was studied.The spin-orbit coupling is enhanced by the introduction of heavy atom Br,which increases the probability of leaping between S₁ and T₁ systems.Experimental results show that 2Cz-Br is better than 2Cz-BOC in terms of quantum yield and lifetime.Through theoretical calculation and analysis,the energy difference between the S₁ energy level and T₆ in 2Cz-BOC is much higher than the energy difference between S₁ and T₈ in 2Cz-Br,which will lead to the intersystem jump of2Cz-BOC compared to 2Cz-Br is more difficult to occur,resulting in a decrease in the quantum yield of phosphorescence?_p.In addition,the introduction of boronic ester group may change the way the molecules are stacked,leading to an increase in the rate of non-radiative transitions and a decrease in lifespan.In summary,this project designed and synthesized four molecules p-PTZ-Br,p-Cs-Br,2Cz-BOC,2Cz-Br based on phenothiazine and carbazole,and carried out structural characterization,theoretical calculation,Photophysical performance test and electrochemical test,systematically analyzed the influence of the introduction of different groups on the luminescence performance,and provided a reference for the design of organic room temperature phosphorescent small molecules.