Solution Processing Of Crosslinked Conjugated Polymers And Their Optoelectronic Properties

Crosslinked conjugated polymers（CPs） have attracted wide attention from researchers due to their lightweight,easy functionalization,good physical and chemical stability.The ultimate goal for the design of functional materials is to realize their practical application,while exploring the types and functionalities,the processability of POPs has also become one of the most important problems in the field.Therefore,during exploring the kinds and functionalization,the crucial key of CPs is how to realize their solution processibility.Accordingly,the main task of this dissertation is taking advantage of electrostatic repulsion to explore solution-processable CPs strategies including these three followed innovative manners.At the same time,we discovered the optoelectronic properties and potential applications of solution-processable CP films.The first part in Chapter 2,ionization method to solubilize two-dimentional CP（2D-CP）.We reported a highly soluble PVCP（Pyrene and Viologen Crosslinked Polymer）with 8 mg mL^-1 by encoding pyrene unit exhibiting strongπ-πinteractions（tends to form stacks）and viologen unit with inherently high charge density（provides strong electrostatic repulsion and hampers the stacking）.We obtained soluble PVCP through controlling the interaction between the nanosheets.It was facile to dissolve in kinds of solvent to keep stable.These unique characterizations endowed PVCP solubility.We could acquire high quality and large area PVCP films.Moreover,the thickness of the PVCP films can be controlled easily which guarantees that the films can be employed on varies of electronic devices.As for the performance,PVCP film exhibited excellent anisotropy between the horizontal(conductivity:1.8×10^-10 S m^–1) and vertical(conductivity:0.4 S m^-1)because of hindering the carrier transport in laminates and facilitating in interlamination.The second part in Chapter 3,electrochemical reductive method to solubilize imine-based two-dimentional CP（2D Im-CPs）.Im-CPs were chosen to be research object.We achieved Im-CPs solutions through electrochemical exfoliation.The specific carbon-nitrogen double bond for Im-CPs can be reducted into carbon-nitrogen single bond.During the electrochemical exfoliated process,the nitrogen could be protonated which will increase the distance between the Im-CPs nanosheets and weaken its inter-layer interaction.The result demonstrate that the electrochemical exfoliated method is universal,which is benefical for the development of solution processable methods of 2D Im-CPs.The third part in Chapter 4,protonation-assisted method to solubilize three-dimentional CP（3D-CP）.Through the superiority of donor-acceptor structures,porphyrins and triazines can be induced into crosslinked conjugated polymers-TPCP（Triazine and Porphyrin Crosslinked Polymer）that are capable of switching their electronic properties between electron-rich and electron-poor states.Although the obtained conjugated polymers are almost insoluble in most solvents,a small amount of protonic acid can cause the formation of a colloidal solution of polymers.The skeleton was protonated with the adding of the protonic acid which regarded as the proton source.The porphyrin center dominates nitrogen which facilitates the process of protonation.The dissolution process is proved to be a surface charge effect induced by protonation of porphyrin units in the polymer frameworks.Because of the particular traits,we can acquire the smooth and large-area TPCP films on diverse substrates by drop-casting which benefits the TPCP compatible with many kinds of device applications.In view of the intrinsic optoelectronic properties,the thermoelectric property was measured and TPCP exhibited overstable as n-type thermoelectric materials.This work may pave the way for the design and development of solution-processed crosslinked polymer films as promising thermoelectric materials with excellent power factor 185 μW m^-1 K^-2,which exhibited the highest value among the processable N-type materials.