| Novel materials are the bases of New Scientific & Technical Revolution in matters. With the rapid developments of organic optoelectronic devices, such as organic solar cells, organic light-emitting diodes (OLEDs) and organic field-effect transistors (OFETs), et al., organic n-type materials with high mobility, good stability and facile processability are in dire need.Thereby, basing on molecule & material designs, multiple strong electron-withdrawing F atoms were introduced in the molecular structure of a kind of traditional organic n-type material, perylene diimide. The effects of the fluorination on energy levels, aggregate structure, solubility and stability of perylene diimide were studied. The modes and mechanisms to induce the changes of optoelectronic properties were also investigated.In this dissertation, first of all, two fluorinated perylene diimides were synthesized through the nucleophilic reactions between 3,4,9,10-perylenetetracarboxylic dianhydride (PCDA) and fluorinated amines, one was fluorinated aryl substituted perylene diimide: N,N'-diperfluorophenyl-3,4,9,10-perylenetetracarboxylic diimide (DFPP), another was fluorinated alkyl substituted perylene diimide: N,N'-di(lH, lH-perfluorooctyl)-3,4,9,10-perylenetetracarboxylic diimide (DFOP). Their molecular structures were characterized by elemental analyses, FTIR and NMR measurements. Cyclic voltammetry (CV) measurements were performed to get the LUMO energy levels of DFPP and DFOP as -4.37 and -4.26 eV, respectively, which were 0.14 and 0.07 lower than those of the corresponding non-fluorinated perylene diimides, respectively. It was noticeable that the half-wave reduction potentials of DFPP and DFOP were both more positive than that of O2, suggesting that both of them were air-stable organic electron acceptors. In addition, due to its much lower LUMO energy level, in the solution in DMF, the excited DFPP could obtain an electron from the weak electron donor such as DMF to form radical anion, which wasalso air-stable. Furthermore, the fluorination changed the polarity of perylene diimides, resulting in impressive improvements of the solubilities of DFPP and DFOP, therein, the maximum solubility of DFPP in common solvents, such as chloroform and toluene, was several thousandth (wt%).The influences of the fluorination on the aggregate structure of perylene diimides films were studied through UV-Vis absorption and fluorescence spectra, the simulation of the molecular conformation, CV, AFM, SEM and XRD measurements. It was found that the fluorination induced the change of the molecular conformation of DFPP, i.e. the angle between the perylene ring and the phenyl ring was -70 degrees, the planarity of perylene diimide molecule was disrupted, and the strong electronegative F atoms in near end groups were electrostatically repulsive from each other in the film. It meant that DFPP molecules could not stack to crystallize by overlapping of neighbouring perylene rings, as a result, on the substrate at room temperature, DFPP molecules stacked randomly to give an amorphous film. However, a crystalline DFPP thin film could be prepared by elevating the temperature of the substrate to 200 癈, where a unique aggregate structure might be formed: DFPP molecules stacked with the perfluorinated phenyl groups straightly over or below the perylene cores of the adjacent DFPP molecules. For DFOP, its fluorinated terminal substituent was zigzag alkyl chain which steric hindrance was small, so that DFOP molecules could form a crystalline film through π-π interactions of successive perylene rings, but its crystallinity reduced because of the electrostatic repulsion between perfluorinated terminal substituents.The electron mobilities of DFPP and DFOP films prepared by spin coating and vacuum deposition were measured through space-charge-limited current (SCLC), quasi-steady-injection-time-of-flight (QTOF) and organic field-effect transistors (OFETs). It was observed that the electron mobilities of both pristine DFPP and DFOP films were at the level of 10-...
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