| Organic light-emitting molecules have a wide range of applications in optoelectronic devices,chemical sensors,life sciences and other fields due to their advantages such as wide variety,easy modification and formation.Traditional organic light-emitting materials generally have high luminous efficiency in dilute solution,but in concentrated solution or aggregated state,the luminous efficiency often decreases or even does not emit light(aggregation-induced quenching,ACQ).However,most of the organic light-emitting materials exist in the form of films or aggregates in practical applications.Undoubtedly,ACQ effect greatly limited the application of luminescent materials in the above fields.Aggregation-induced emission(AIE)and aggregation-induced emission enhancement(AIEE)successfully has solved the bottleneck problem of ACQ,and provided a new way to construct high efficiency solid-state luminescent materials.At present,as a new kind of luminescent materials,AIE materials show great application potential.Therefore,the research and development of new AIE materials is of great significance to enrich the AIE system and expand its application scope.Based on the previous research of our research group,a series of new anthracene,carbazole and pyridine derivatives,as well as the corresponding conjugated polymers with AIE effect have been developed by integrating anthracene,carbazole,pyridine and fluorene into organic light-emitting molecules.Their structure,thermal,optical and electrical properties were characterized.The results further enrich the content of AIE materials,and provide the theoretical basis and experimental basis for their potential application.The work of this article is as follows:In the first chapter,the concept and mechanism,the molecular system,the application and progress of AIE were introduced,and the work ideas and research contents of this paper were proposed in combination with literature and our previous work.In the second chapter,five new 9-aryl-10-aryloxyanthracene derivatives were successfully synthesized from anthrone and characterized.It was found that these new luminescent molecules showed typical AIE features,and some of them exhibited good thermal stability with 5%weight loss temperature up to 357°C in nitrogen,absolute photoluminescence quantum yield and photoluminescence lifetime as high as 93.2%and 140.25 ns in solid powders.The new anthracene derivatives could emit bright fluorescence under 365 nm ultraviolet lamp,and the fluorescence of one of them was located in the blue region.In addition,the HOMO and LUMO energy levels of the synthesized compounds were obtained by theoretical calculation,and their structure-property relationship,solvatochromism were also studied.In the third chapter,seven kinds of diketocarbazole derivatives with D-?-A-?-D bipolar structure,such as 1,4-bis[4-(9H-carbazole-9-yl)benzoyl]benzene and4,4'-bis[4-(9H-carbazol-9-yl)benzoyl]biphenyl were prepared through substitution reaction of 1,4-bis(4-fluorobenzoyl)benzene,1,3-bis(4-fluorobenzoyl)benzene and4,4'-bis(4-fluorobenzoyl)biphenyl with carbazole and 3,6-di-tert-butylcarbazole,respectively.The results showed that these new compounds had typical AIEE properties and excellent thermal stability.Their maximum emission wavelengths were red shifted with the increase of solvent polarity.The decomposition temperature of 5%weight loss in nitrogen is as high as 471 ~oC.In dilute DMF solution,their quantum yields were 52.1,48.4,95.9,68,90.7,78.7 and 90.8%respectively,which were higher than those in corresponding solid state.The longest fluorescence lifetime in the solid state is in the range of 8.57-34.86 ns.These new prepared compounds were white,light yellow or yellow solid under natural light,and could emit light yellow,blue-green,light blue or blue fluorescence under 365 nm ultraviolet lamp excitation.In the fourth chapter,four new carbazole derivatives containing sulfide sulfoxide and sulfone groups with D-?-A-?-D bipolar structure AIEE effect,such as4,4'-bis[4-(9H-carbazole-9-yl)benzoyl]diphenylsulfide,4,4'-bis[4-(3,6-di-tert-butyl-9H-carbazole-9-yl)benzoyl]diphenylsulfide,1,3-bis[4-(3,6-di-tert-butyl-9H-carbazole-9-yl)benzoyl]diphenyl sulfoxide and1,3-bis[4-(3,6-di-tert-butyl-9H-carbazole-9-yl)benzoyl]diphenyl sulfone were prepared through substitution reaction of 4,4'-(4-fluorobenzoyl)diphenyl sulfide,3,3'-bis(4-fluorobenzoyl)diphenyl sulfoxide and 3,3'-bis(4-fluorobenzoyl)diphenyl sulfone with carbazole and 3,6-di(tert-butyl)carbazole,respectively.The results showed that all four compounds had typical AIEE properties and outstanding thermal stability with the decomposition temperature of 5%weight loss in the 225-455 ~oC range in nitrogen.AIEE effect could enhance the fluorescence emission intensity greatly,and their maximum fluorescence emission wavelength in the solution were blue shifted.The quantum yield and fluorescence lifetime of the them were low in solid state,but they could emit nearly blue fluorescence under 365 nm ultraviolet light.In the fifth chapter,Chichibabin reaction of benzaldehyde with different substituents,ammonium acetate and 4-bromoacetophenone was carried out to form eight 2,6-bis(4-bromophenyl)-4-arylpyridine monomers,which were used to generate a series of conjugated polymers containing 2,6-diphenyl-4-arylpyridine and9,9-di(n-octyl)fluorene units with a number average molecular weight of 1.14×10~4?3.03×10~4 and a distribution index of 2.47?3.69 by Suzuki coupling polymerization ofthemwith2,7-bis(4,4',5,5'-tetramethyl-1,3,2-dioxaborolan-2-yl)-9,9-dioctylfluorene,respectively.The results showed that these new polymer had high thermal stability with 5%weight loss thermal decomposition temperature above 202 ~oC,up to 428 ~oC in nitrogen.They were soluble in THF,toluene,acetonitrile and other common organic solvents at room temperature,and had good film-forming performance.In addition,the polarity of the solvents had little effect on their UV-vis and PL spectra.All the polymer solutions could emit fluorescence under 365 nm ultraviolet light,indicating their AIEE phenomenon,and the polymer films could emit bright light blue to dark blue fluorescence under the excitation of 365 nm ultraviolet light.In the sixth chapter,on the basis of chapter 5,a series of conjugated copolymers containing 2,6-diphenyl-4-(4-cyanophenyl)pyridine moieties were prepared by Suzuki coupling polycondensation of 2,6-bis(4-bromophenyl)-4-(4-cyanophenyl)pyridine,2,7-bis(4,4',5,5'-tetramethyl-1,3,2-dioxaborolan-2-yl)-9,9-dioctylfluorene,9,9-di(n-oc tyl)-2,7-dibromofluorene and 3,7-dibromodibenzo[b,d]thiophene 5,5-dioxide.The effects of 2,6-diphenyl-4-(4-cyanophenyl)pyridine and S,S-dioxo-dibenzothiophene units on the properties of the resulting conjugated polymers were studied.The results showed that all the synthesized polymers had outstanding thermal stability,and the 5%weight loss thermal decomposition temperature is above 406 ~oC in nitrogen.In addition,2,6-diphenyl-4-(4-cyanophenyl)pyridine structure had little effect on the absorption wavelength of UV-vis and the emission wavelength of PL spectra,and the increase of the content of S,S-dioxo-dibenzothiophene unit was beneficial to the blue fluorescence of the copolymers. |
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