DFT Calculations Of Structures,Solvent Effects And Opto-electrical Properties On Rubrene And Its Derivatives

As a popular organic molecule,rubrene(5,6,11,12-tetraphenyl tetracene)is widely used in research and manufacture of various functional materials and devices.However,rubrene also has some drawbacks,for example,it is sensitive to light and oxygen.Accordingly,in recent years,it has been the hot spot of present research design and develop rubrene derivatives with excellent properties by introducing different substituents.After introducing the substituents,the electronic donor of HOMO orbital and the electron acceptor of LUMO orbital changes with the change of the molecular structure,which leads to the change of the energy gap.Moreover,structure changes not only change the optical properties of molecules,but also change the extent of intramolecular charge transfer.In this paper,we studied the structural changes,spectral shifts and opto-electric properties of rubrene and its derivatives in different environments.The main contents are as follows:First of all,this paper introduces the organic electroluminescent materials,photovoltaic materials,organic electronic materials,as well as the study of the rubrene system and the background of calculation.The density functional theory is a method to solve the Schr?dinger equation by using the functional theory,since the calculation speed is fast and the result is accurate,it is suitable for the system.On this basis,the solvent theory,the excited state theory and the electron transport theory were used for system calculations.And then,the infrared spectrums of rubrene and its three derivatives in twelve solvents were calculated.The infrared spectrums of four kinds of molecules in different solvents were obtained by adding the Polarization Continuous Model(PCM).The effect of solvents were determined by analyzing the movements and intensities of the characteristic peaks.The displacement of rubrene and its derivatives in the hydrogen proton solvents are obvious,the band shift in the polar functional group solvents are relatively obvious,and the displacement in the alcoholic solvents and the inert solvents are small,as a result of the strong hydrogen bond force between solutemolecules and hydrogen proton solvents,and the strong induction between solute molecules and the solvents containing polar functional group.At the same time,the solvent electrons acceptor AN,the solvent electrons giver DN,Dimroth solvent parameter ET(30)and Brownstein solvent parameter S were analyzed the correlation with the vibrational frequency of the C-F bond of(5,12-difluorophenyl-6,11-diphenylmethoxy)naphthacene.The correlation sequence is S>ET(30)>AN>DN.Meanwhile there is a system theoretical calculation research to the optical properties of rubrene and its derivatives,the geometries electronic structures,ionization potentials,affinities and the influence of the absorption and emission spectrums of rubrene and its derivatives were studied.The results show that the introduction of alkanes substituents,the absorption peak and fluorescence emission peak of rubrene and its derivatives molecules occur blue shift,while red shift occurs when aromatic substituents were introduced.The molecular absorption spectrums of the aromatic substituted molecular(R-Cp)have strong absorption peaks at 500-700 nm and 300-500 nm,which is more favorable for the absorption of visible light and is suitable for photovoltaic power generation materials such as solar cells.Lastly,the electric properties of rubrene and its derivatives were studied.Analysis of the front orbital and energy gaps found that it is easier to form excitons by introducing aromatic ring substituents.The introduction of substituents on the main chain favors the enhancement of the ? conjugation,whereas the introduction on the branch is opposite,indicating that the HOMO-LUMO energy gap of the molecule can be reduced by introducing stronger conjugate substituents in the main chain to get better optoelectronic performance materials.Analysis of ionization potentials,electron affinities and reorganizations can be found that the oxygen-aromatic substituted molecular(R-Furan),aromatic substituted molecular(R-Cp)and one of methoxy substituted molecular(R-OMe3)are suitable for hole-forming semiconductor materials,and Fluorine substituted molecular(R-F),two of methoxy substituted moleculars(R-OMe2,R-OMe1)are more suitable for electron transport materials,while the electron and hole reorganizations of one of methoxy substituted molecular(R-OMe4)and methyl substituted molecular(R-Me)are less different andare suitable as emissive materials in organic semiconductor transistors.