Preparation And Magnetic And Thermoelectric Property Investigation Of Polycyclic Aromatic Imides Anion

As a material with strong interaction,fused-ring aromatic semiconductors can build effective conductive channels throughπ-πstacking between molecules,which can be used to fabricate devices with high mobility.However,due to the strongπ-πinteractions between molecules,solvation is difficult,resulting in difficulty in dissolution.The hard-to-process properties of this strong aggregation greatly limit the application of the material.For example,doped polyacetylene has a conductivity of up to 10⁵ S cm^-1,but its insoluble and non-melting properties make it difficult to process.In the first chapter of this thesis,we started from the development of organic solid materials,mainly introduced the development of the field of organic magnetism based on electron spin and the development status of the field of organic thermoelectric based on the properties of charge transport semiconductors.In the second chapter of this thesis,we started from the commercialized naphthalimide NDI-H,and first explores the method of chemical reduction of NDI-H with hydrazine hydrate.Through the analysis of UV-Vis spectra and electron spin resonance（EPR）of the solution,it was determined that the obtained solution was a dianion solution of NDI-H.However,the NDI-H anions reduced by hydrazine hydrate have poor film-forming properties and fail to prepare films of suitable size for thermoelectric applications.We developed a method of reductively doping NDI-H with phenyllithium reagent to prepare its anion radical film.By adjusting the amount of dopant added,an N-type thermoelectric material with power factor up to 18.8μW m^-1 K^-2 was obtained under the optimal doping ratio of 15 mol%,and its low in-plane thermal conductivity was tested by the 3ωmethod:0.106 W m^-1 K^-1,the figure of merit（ZT value）of0.053 at room temperature was finally obtained,which was the highest value among NDI derivatives.In the third chapter of this thesis,the hydrazine hydrate solution of NDI-H anion prepared in the second chapter was evaporated to dryness of the hydrazine hydrate solvent in a glove box,and the obtained NDI-H anion powder was dissolved in deoxygenated pure deionized water,afterwise NDI-H anions with different free radical concentrations were prepared by quantitative oxidation of H₂O₂ solution.By adjusting the amount of added H₂O₂,the controllable transition of powder magnetic properties from paramagnetic to ferromagnetic can be achieved.Finally,when the addition ratio of H₂O₂ is 50%,the relative free radical concentration is 100%,and a pure organic room temperature ferromagnets with the saturation magnetization of 1.1 emu g^-1is obtained.Through density functional theory（DFT）calculations,it is shown that the interlayer distance and the face slip distance between the NDI-H radical anions have great influence on the magnetic properties,and within a certain range,the energy of the ferromagnetic state is lower than that of the antiferromagnetic state.It is possible to obtain stable spontaneously magnetized NDI-H magnets.In the fourth chapter of this thesis,starting from the insoluble fused-ring aromatic molecules,two insoluble small molecules PBI-NH₂ and PBI-NH₂-4Cl of peryleneimide were designed firstly with two end groups substituted with amino groups.The peryleneimide molecule is reduced to its corresponding anion state solution by chemical reduction with hydrazine hydrate.In the strong polar solvent hydrazine hydrate,the concentration of the prepared solution can reach to 0.5～3 mg m L^-1,thereby simultaneously realize the dissolution of the insoluble fused-ring imide and the preparation of its anion state.The dynamic light scattering characterization of the anion solution showed that it formed a dispersion with particle size ranging from several hundred nanometers to several micrometers.Films were then prepared by drop coating.Structural analysis of the films by SEM and GIWAXS shows that the PBI-NH₂ anions are assembled into ordered nanorod structures,while the PBI-NH₂-4Cl anions are amorphous films due to disordered molecular packing and molecular configuration twist.Thermoelectric tests in a glove box show that the PBI-NH₂ anion film has an electrical conductivity of 5.0 S cm^-1,which has potential for use in thermoelectric materials.This thesis is based on the chemical reductive dissolution of fused cyclic imides,and the thermoelectromagnetic application of the anions obtained after reduction.The results show that chemical reduction is an effective method to realize the processing of fused-ring imide solution,and its anion has a high concentration of free radicals,and it has development potential in conductivity and organic magnetism,and has application value。...