Preparation,properties And Applications Of Aggregation Induced Emission Enhancement Materials

Aggregation Induced Emission Enhancement(AIEE)materials are a kind of special molecular materials.When they are in the solution state,their fluorescence is very weak,but they can show strong fluorescence in the aggregation state.Up to date,the luminescence bands of AIEE materials are located in region of the visible light,but the aggregation induced ultraviolet emission enhancement(AIUVE)materials have not been reported yet,let alone the reports of up-conversion-AIEE(AIUCE)materials.AIUCE materials have attractive application value in the field of new solar energy,and AIUVE materials have broad application prospects in medical sterilization and water quality cleansing.It is of great significance to study AIUVE materials and AIUCE materials.In this paper,we focus on the study of AIUVE and AIUCE materials.The main research contents are as follows:?.Preparation and Structure Characterization of Molecular MaterialsDesired to obtain ultraviolet emission,a series of phenanthrene derivatives(Compd.1-8)were designed,since their conjugation effect would be reduced by phenanthrene' skeleton structure.In this paper,eight phenanthrene derivatives were prepared by Suzuki reaction and characterized by 1H NMR,mass spectra(ESI-MS),infrared spectroscopy and thermogravimetry(TG).Among the samples,Compd.3-8 have not been reported in the literature,and Compd.3,6,9 obtains a crystal and measures its crystal structure through X-ray.A new structure of tetrastyrene-rhodamine was prepared by the introduction of tetrastyrene group into the structure of xanthene,and characterized by NMR,mass spectrometry(ESI-MS)and infrared spectroscopy.?.Aggregation-induced ultraviolet fluorescence enhancement(AIUVE)performance and device researchIn this paper,the structure-activity relationship of the absorption effect and luminescent properties of the 9,(10)-substituent of phenanthrene were studied.The results show that the planarity of single-substituted phenanthrene derivatives(e.g.Compd.1)are better than double substituted phenanthrene derivatives(e.g.Compd.2),and because the ground state polarity of the single-substituted phenanthrene derivative is less than the excited state of that,the fluorescence peak position of the single-substituted phenanthrene derivative is red-shifted as the polarity of the solvent becomes larger,and the fluorescence intensity is decreased,while the spectrum of the double-substituted phenanthrene shows the opposite behavior.This paper focuses on the effect law of substituent effect on the luminescent properties of the molecular aggregation state.We found that Compd.1-7 all exhibit aggregation-induced enhanced emission(AIEE),in which the double-substituted phenanthrenes(Compd.2 and Compd.4)have poor planarity,the properties of AIEE is not obvious,and their AIEE fluorescence increased by about twice as much;In addition,the study found that the effects of ortho substituents is better than meta substituents,due to the substituents located in the meta position,Compd.5?Compd.6,Compd.7 have weak substituent effect,so their AIEE fluorescence is similar to that of Compd.1,both increased by about 2 times;besides Compd.3 has strong ortho substituent effect,and its ICT absorption band is red-shifted and produces strong AIEE fluorescence,its intensity is increased by 5 times;but Compd.8 contains sulphur atoms in the ortho position and has strong ortho-atomic effect,which makes the aggregation fluorescence intensity of the compound decrease.The crystal structure shows that the reason why phenanthrene derivatives have AIEE effect,mainly because weak ?-?stacking interactions and the suppression of the intermolecular ?-? gathering result in the efficient AIEE.Two organic electroluminescent devices(OLED 1 and OLED 2)were prepared with Compd.3 and Compd.6 as emitting layer.The device structure is:ITO(anode)/NPB(hole transport layer,30 nm)/phenanthrene derivative emitting layer(30 nm)/BCP(electron transport layer,30 nm)/LiQ(electron injection layer,2 nm)/Al(cathode).The electroluminescent(EL)peaks of devices 1 and 2 are approximately 450 nm(blue light).Compared with the molecular photoluminescence(PL)spectrum,the EL emission of device 1 and device 2 is derived from the base excited emission.Instead of NPB,CPB is used as the hole transport layer,the rest of the semiconductor film is not changed to make OLED 3,and the device structure consists of ITO(anode)/CBP(hole transport layer,30 nm)/Compd.6 emitting layer(20 nm)/BCP(electron transport layer,30 nm)/LiQ(electron injection layer)/Al(cathode).The EL peak of device 3 is located at 383 nm(purple fluorescence),it is indicated that the emission band of this OLED device matches the TiO2 energy level(3.2 eV forbidden bandwidth and 380 nm for the absorption peak),and it has potential application value.An invention patent(application number CN 201810045951.9)and an English article have been completed according those results.?.the Aggregation induced up-conversion enhancement(AIUCE):The UV-Vis absorption spectra and fluorescence spectra of tetrastyrene-rhodamine(RhT)in the as-synthesized state were tested.Decipherment the underlying mechanisms for the AIE phenomena at 385 nm excitation light source were studied.Researches have shown that with the increase in the content of poor solvents,the tetrastyryl group can transfer energy to the xanthene fluorescence,so that the fluorescence intensity of the RhT molecule becomes stronger,exhibiting aggregation-induced fluorescence enhancement effect,therefore its energy transfer structure is intramolecular energy transfer.By testing the upconversion spectra of RhT and RhB in the aggregated state,the AIUCE phenomenon was studied.Studies have shown that when the poor solvent reaches a certain level,the fluorescence intensity of up-conversion of RhT has increased by 4 times,showing the effect of aggregation-enhanced fluorescence(AIEE),while the contrast samples of RhB in the system of poor solvent increased,while up-conversion fluorescence intensity gradually decreased,no aggregation-induced fluorescence enhancement was observed,and the diametrically opposite spectral behavior was observed with RhT.Therefore,introducing the AIEE group into the xanthene matrix can effectively increase its up-conversion efficiency and achieve a good up-conversion-AIEE characteristic.