Design And Synthesis Of Solution-Processible Covalent Organic Frameworks For Photoelectronic Applications

Covalent organic frameworks are well structure-designable to form ordered skeletons,providing a polymer platform for the design of optoelectronic materials and devices,which can be applied in a broad field such as catalysis,luminescence,energy storage and ion transport.However,it is a great challenge for COFs to be applied in optoelectronic thin-film devices since they are insoluble,refractory and morphology-uncontrollable.Therefore,it is of great significance to study the solutionprocessible performance and morphology controllable preparation of COFs.In this paper,based on this problem,two synthesis strategies,including post-modification and bottom-up,were selected to prepare spheroidal structures with controllable morphology and at the same time futher design and synthesis the stacked COFs,studying how interlayer-connected chemical bonds influences the micromorphology and electrical properties.The details are as follows:(1)Solution-processible anthracene-type covalent organic frameworks: design,synthesis and photoelectronic properties.A strategy for modulating the morphology of anthracene-type covalent organic frameworks including anthracene self-crosslinked after ultraviolet(UV)irradiation is proposed to enhance their solution-dispersibility and solution-solubility.According to characteristic that anthracene can self-crosslink under UV light,the controllable morphology is induced by selfcrosslinking behavior under UV light.Then,chemical bonds are formed between layers of the anthracene-type COFs,and the boundaries of microsphere about COFs can be connected to some extent after UV irradiation.Furthermore,the uniformity of the microsphere size is modulated by adjusting reaction temperature,so as to realize the controllable preparation properties and solutionprocessability of anthracene-type COFs.After mechanical grinding and ultrasonic exfoliation,this research shows that the acetone solution of COFs has the Tyndall effect,proving its good solutiondispersing properties.Therefore,anthracene-type COFs units in this chapter are solution-processible.(2)Solution-processible stacked covalent organic frameworks: design,synthesis and optoelectronic properties.In order to achieve better solution-processibility based on the last chapter and solve the difficult problem on incomplete coupling between layers,the stacked covalent organic frameworks are designed to deliver the solution-processible performance by adopting the strategy of bottom-up approach,and furthermore they are studied about their electrical properties in this part.[2,2]paracyclophane is introduced into COFs,and then the stacked covalent organic frameworks is designed by adopting the strategy of bottom-up approach.After mechanical grinding and ultrasonic exfoliation,the stacked COFs not only are well solution-dispersing,but also show uniform lamellar structure in the microscopic level,exfoliated significantly better than the similar non-stacked COFs done.Compared with the non-stacked COFs,the stacked COFs have lithium-ion mobility.Applied to lithium batterie,the lithium-ion transference number about the stacked COFs is bigger and the energy storage properties lithium-ion conductivity is better by contrast.