Spectral Properties Of Aggregation Induced Luminescent Material CzCNDSB Under High Pressure

Aggregation induced emission(AIE)effect refers to the phenomenon that the emission of molecules is hard to be observed under low concentration of solution.However,when the concentration of solution increases,in which the molecules get aggregated,the molecules emit rather strong fluorescence.This phenomenon relates to the space distance between molecules.Pressure is an effective physical means to change the distance of molecules or atoms.By compressing the distance between molecules or atoms,pressure can promote the interaction between adjacent electron orbitals and thus the chemical bond length,crystal structure and electronic structure of matter.New material configurations and chemical or physical phenomena have been observed under high pressure condition.In this paper,the high-pressure technology is applied to molecules with AIE effect,in order to explore the influence of pressure on the steady-state and transient-state optical properties of the materials,and preliminarily understand the optical properties of AIE materials under the extreme conditions.In this paper,CzCNDSB is selected as the research object.Experimental results show that the absorption peak of CzCNDSB has obvious red shift and broadening with pressure increasing.Emission wavelength of CzCNDSB has red shift with pressure increasing and can completely recovers to the initial position after pressure relief.The results show that the emission spectrum has a good linear relationship with the external pressure,which is very beneficial to the potential application of pressure sensor.The effect of pressure on the excited state dynamics of CzCNDSB is further investigated by transient absorption experiments under high pressure.Transient absorption results indicate that transition between local excited state and self-trapping sates have pressure dependent behavior.Since they have contrary shift tendency with pressure increasing,the transfer rate shows wave-like tendency.As a result of enhanced electron-phonon interaction,possibility of decay from self-trapping state gets faster and induced fluorescence is quenched.