Synthesis, Aggregated Structure And Optoelectronic Properties Of Novel Perylene Diimide Derivatives

Perylene diimide?PDI?derivatives have attracted extensive attention due to their outstanding chemical and photochemical stabilities,high fluorescence quantum yields and high extinction coefficients from visible region to infrared region.Such dyes have found wide applications as fluorescent sensors,photovoltaic devices,organic field effect transistors,light emitting diodes and other organic electronic devices.Driven by the demands of PDI materials with novel photophysical properties,the modification on molecular structure of PDI aimed at changing the self-assembly behavior and aggregated structure was regarded as one of most important methods.The dissertation focuses on the modification of molecules by efficient synthesis based on PDI molecules:on the one hand,we studied self-assembly,aggeregates states and photoelectric properties of PDI derivatives;on the other hand,we made a research on the internal relations between aggregated structure and optoelectronic properites of PDI materials.These studies could provide theoretical and experimental basis on the research of special supramolecular structure and novel optoelectronic materials.The main contents are as follows:In chapter 1:The research of synthesis,properties and various applications of perylene and its derivatives are reviewed,then the modification of molecule structure and the exploration of optoelectronic applications as the research topics are put forward.In chapter 2:Using accessible 1,6,7,12-tetrachloroperylene tetracarboxylic acid dianhydride,we effectively synthesized S-heterocyclic annulated perylene diimide?SPDI?by palladium-catalyzed coupled reaction.Besides,we introduced branched alkyl chains to the imide position symmetrically of SPDI molecules.The influences of the length and kinds of alkyl chains on the phase behavior and aggregated structure are studied.Moreover,the carrier mobilities are characterized by time-of-flight method.The results reveal that the carrier mobilities values are3.5×10^-3 cm²v^-1s^-1 for the SPDI molecule substituted with fan-shaped alkyl chains.Therefore,the S-annulation PDI molecular systems have wide applications in the electronics fields as a novel electron transport material.In chapter 3:Strong interactions exist between SPDI molecules,which induce the obvious aggregates and fluorescence quenching,especially in concentrated solution and solid state.In this chapter,a novel SPDI molecule equipped with POSS nanoparticles has been designed and synthesized.The bulky effect of POSS group has been proved to inhibit the assembly between SPDI molecules and improve the fluorescent quantum yields.Moreover,the molecule can be self-assembled into crystalline microbelts with length of several hundred micrometers and the discrete dimer packing arrangement enables POSS-SPDI-POSS to exhibit enhanced photoluminescent properties which can be used in the organic photoelectric devices.Furthermore,the combined dual mechanisms of electron transfer and Si-O cleavage make POSS-SPDI-POSS a novel colorimetric and ratiometric fluorescent F^-sensor with high selectivity,good sensitivity,and rapid response.In chapter 4:PDI fluorophore incorporated with a commercially available polymer PMMA were successfully synthesized by dispersion polymerization to produce mono-disperse,high emission,easy-dispersed POSS-PDI-PMMA microbeads against photobleaching.The incorporation of PDI molecules with PMMA backbone reduces the?-?stacking between PDI molecules and increases the quantum yields in solid state.More importantly,the introduction of POSS groups to the microspheres can further inhibit the self-assembly of PDI dyes,especially when the contents of PDI molecules increased in the microspheres system.As a consequence,the solid-state quantum yields of the PDI-PMMA microbeads can be improved to 68%,which is the highest value as reported based on the PDI microspheres.