Design Of Thiophene-containing Imide Polymer/porphyrin Organic Composite Materials And Study Of Their Charge Transport Properties

Compared with inorganic semiconductors,organic semiconductors have the advantages of wide development space,low cost,and abundant chemical modification sites.In recent years,organic semiconductors have been widely used in devices such as organic field effect transistors(OFETs)and organic photovoltaic solar cells(OPVs).The level of carrier mobility has a great influence on the performance of electronic devices,and the carrier mobility is closely related to factors such as the internal accumulation of organic semiconductor material molecules.Therefore,studying the charge transfer performance from a microscopic point of view is of great significance for improving the performance of such electronic devices.In addition,theoretically modifying and designing organic material molecules with excellent properties but difficult to synthesize and studying their charge transport properties can greatly reduce experimental costs.Based on the research status of organic semiconductors in recent years,this thesis selected thiazolyl imide polymers with strong electron-withdrawing ability containing thiophene units and porphyrin organic composite materials containing thiophene units for a series of chemical modifications and designs.From the geometric structures,frontier molecular orbitals,ionization potentials(IP),electron affinities(EA),reorganization energies(?),charge transfer integrals(V),crystal packing models,and charge transfer mobilities and anisotropic mobilities by useing the density functional theory(DFT)with a high calculation accuracy explore the charge delocalization behavior and charge transport properties,which provide theoretical guidance for the experimental technicians to synthesize organic semiconductor materials with high carrier mobilities.After short review on organic semiconductor and theoretical methods in chapters1 and 2,in chapter 3,we studied three series of oligomers containing thiophene bisthiazolyl imides,namely the all acceptor PBTz In(n=1-8),and its acceptor-donor combined PBTz I3Tm(m=1-4)and PBTz I3T-2Fm(m=1-4)derivatives to clarify the length of oligomers,the role of thiophene donors,and the effect of fluorine substitution on charge transfer performance.We used density functional theory(DFT)and Marcus theory to systematically study the charge transfer properties of the thiazolyl oligomers of these imides.It is found that PBTz I8 has a high and balanced hole/electron mobility of 1.089/0.249 cm²V^-1s^-1,so it is a good ambipolar semiconductor.The three thiophene rings introduced in PBTz I3Tm enhance the planarity of the backbone,the replacement of thiophene H atom with F further enhances the non-covalent bond N...S and S...F interaction,thereby increasing the molecular flatness,thus making PBTz I3T-2Fm(m=1-4)a better semiconductor.PBTz I3T3 is a ambipolar organic semiconductor with a hole/electron mobility of11.760/1.396 cm²V^-1s^-1,PBTz I3T-2F3 and PBTz I3T-2F4 have better ambipolar organic semiconductor performance,and their hole/electron mobility are 16.325/3.674 cm²V^-1s^-1 and 60.019/5.086 cm²V^-1s^-1.On the basis of the study of bisthiazolyl imide series oligomers in Chapter 3,we replaced the thiazole on one side with thiophene in Chapter 4,and designed and studied the thiophene one-sided thiazolyl three series of oligomers——all-acceptor PDTz TIn(n=1-4)and donor-acceptor-acceptor-bound PDTz TITm(m=1-4)and PDTz TITm-2F(m=1-4)series derivatives.Studies have shown that the introduction of a thiophene ring can reduce the ionization energy and the hole injection barrier,enhance the accumulation of molecules in the crystal,thereby increasing the charge transfer integrals,making PDTz TITm a good p-type semiconductor.Fluorine substitution increases flatness and ensures better molecular packing in the crystal,making PDTz TIT-2Fm a better p-type semiconductor.The maximum hole/electron mobility of acceptor-acceptor PDTz TI4 is 4.450/3.514 cm²V^-1s^-1,while the hole/electron mobility of PDTz TIT4 and PPDTz TIT-2F4 are 10.567/0.182 cm²V^-1s^-1and 10.225/1.838 cm²V^-1s^-1,which provides further theoretical support for the synthesis of organic semiconductor molecules containing thiophene thiazolyl imide oligomers.Based on the fact that porphyrin can be used as a good donor unit and the important role of the thiophene ring in Chapters 3 and 4,we designed a series of Zn BTEZPn(n=1-6)molecules in Chapter 5 and calculated their charge transfer properties by DFT.The results of the study clearly reveal that the length of the thiophene-containing unit of the side chain of the porphyrin-containing composite materials will increase the conjugation structure,the HOMO and EA will increase,the LUMO and IP will decrease,and the reorganization energy will decrease.The charge transfer integral and charge transfer mobility are affected by the length of the thiophene unit and are more complicated.Zn BTEZPn(n=1-6)is a good ambipolar or p-type organic semiconductor.The hole/electron transport mobility of Zn BTEZP6 is as high as 76.161/9.395 cm²V^-1s^-1,respectively.To a certain extent,it provides a direction for future experimenters to synthesize organic composite molecules containing thiophene porphyrins.