| Functional organic molecules refer to some organic molecules with important physical,chemical and biological application values or properties.Compared with traditional inorganic molecules,functional organic molecules have the advantages of light weight,clear structure,easy to modify,and low price.They can be widely used in optical sensors,organic field effect transistors(OFETs),organic photovoltaic cells(OPVs),organic light emitting diodes(OLEDs)and other fields,starting from the structure-performance of molecules to study the physical and chemical properties of materials to realize the development of new organic materials.This dissertation is to explore the relationship between structure and performance of two functional organic molecules from a microscopic point of view,and combines theoretical calculations with high-precision non-empirical optimal tuned range-separated density functional theory(TRS-DFT)to study potential charge transport.It provides theoretical support and research basis for the reasonable synthesis of high-performance semiconductor device materials and optoelectronic materials in experiments1.In the first part,based on the experimental synthesis,we systematically studied the structure-performance relationship and transmission characteristics of a series of designed diketopyrrolopyrrole-zinc porphyrin Zn P-n TDPP(n=1-4).Three non-empirical optimal tuned range-separated density functional theories(LC-w PBE,LC-BLYP,w B97XD)are used for the fully meso-substituted Zn P-4TDPP,and it is proved that w B97XD can reduce the self-interaction error to a large extent.For other oligomers,the w B97XD method is adopted to the other moleculars.The molecular geometry,electronic structure and charge transport properties were theoretically studied,and the influence of structure on performance was also explored.The combination of electron-rich zinc-porphyrin(Zn P)and electron-deficient diketopyrrolopyrrole(TDPP)forms the D-A structure with push-pull intramolecular interaction,showing good planarity and?-conjugated stacking characteristics,thus promotes charge transfer.As the number of TDPP receptors increases on the meso position of the donor zinc-porphyrin,HOMO decreases,LUMO increases,and recombination energy decreases.It has been confirmed that Zn P-4TDPP is an excellent p-type semiconductor with low recombination energy and high charge mobility.Zn P-3TDPP has been proved to be a potential p-type semiconductor material,which is worthy of synthesis and effective use.In addition,it is confirmed that TRS-DFT w B97XD effectively reduces the self-interaction error(SIE)which is existing in the traditional B3LYP functional,and provides a balance between delocalization and non-delocalization.2.In the second part,we introduced four?-conjugated groups with different electronic nature including 2-naphthalenyl,4-methoxyphenyl,4-Methyl benzoate,and 4-benzonitrile to the C~8 position of 5-phenylbenzo[b]phosphindole 5-oxide(Ph BPO)to reveal the relationship between structures and properties.The properties of phosphole-based?-conjugated compounds could be well tuned via simple chemical modification.Density functional theory(DFT)calculations were carried out to comparatively study the ground state geometries,orbital energy gaps,infrared(IR)spectra,UV-vis spectra,and fluorescence(FL)spectra of the five Ph BPO derivatives.Good correspondences between the simulated and experimental IR and UV-vis spectral properties were found,proving the feasibility of the DFT method.The IR and UV-vis spectra were assigned and explained in detail on the basis of the calculation results and the substituional effect of different substituents on the structure,besides,spectral properties was also revealed.The large FL oscillator strengths indicate these Ph BPO derivatives are good candidates for fluorescent materials.Ph BPO derivatives possess easy-to-modify sites and thus can be further utilized as functional materials. |
PDF Full Text Request