Self-assembly Of Perylene Imides Containing Secondary Amine Groups And Photoelectric Properties

As one of the cleanest energy sources on earth,solar energy can be directly converted into electricity by the photovoltaic effect.Scientists have long been keen to find the most efficient and cheapest photoelectric devices to convert light into energy.As a new technology developed in recent decades,organic photovoltaic cell(OPV)has been constantly developed due to its advantages of wide raw materials,simple production and low price.Perylene imide,as a kind of high-performance dye was synthesized for the first time since 1910,through the ring functional group of twelve to replace to the decoration,has been made a lot of different optical electronic performance of derivatives.The organic nanomaterials of Perylene imide derivatives with different functions were continuously developed and applied.For example,the dye-sensitized battery had the airfield effect transistor(EFT),the organic light-emitting diode(OLED),the fluorescent probe laser,the carrier of dye-medicine.In order to obtain organic nanometer functional materials,the application of supramolecular self-assembly technology has attracted wide attention.As a kind of organic-conjugated molecules,Perylene imide and its derivatives were similar to the large conjugated system of graphene,which made the intermolecular interactions of perylene imide strong and easy to spontaneous molecular accumulation.It was possible for us to design reasonable molecular structures and make use of the sensitivity of supramolecular assembly to environmental factors to artificially regulate molecular aggregation behavior during self-assembly of Perylene imide derivatives,so as to obtain organic nanometer functional materials with different sizes,morphologies and photoelectric properties.At present,studies on the construction of perylene imide as the representative of-conjugated supramolecular assembly by non-covalent bond interaction are relatively common,but few reports on how to effectively design molecular structures and precisely control molecular aggregation to meet people's needs are reported.At the same time,the effects of various non-covalent bond coordination actions on the macroscopic properties and microstructure of supramolecular aggregates are still in the exploration stage.Therefore,on the basis of the previous work of the research group,three kinds of B-PDI containing secondary amine groups with different molecular terminals were synthesized and self-assembled in liquid phase by changing the composition of solvents in THF/H₂O assembly system.The reasons for the unique solution of B-PDI system turning from red to blue in the process of self-assembly were analyzed,and the photoelectric properties of three kinds of Perylene imide derivatives containing secondary amine groups were evaluated as follows:1.The molecular structures of perylene imide derivatives(B-PDI-1,B-PDI-2 and B-PDI-3)were synthesized by rational design of molecular structures and introduction of different amine side chains.The molecular structures were determined by H1 NMR and IR spectroscopy.2.The rapid solvent diffusion method was adopted to conduct self-assembly experiments by changing the composition of THF and H₂O in THF/H₂O assembly system.The optical physical properties of the assembled system in the aggregate were characterized by UV-VIS and fluorescence spectra.The morphology of B-PDI-1aggregates was observed by scanning electron microscope.Combined with X-ray powder diffraction technology and Guassian 09W program simulation,the possible accumulation model of B-PDI-1 aggregate was explored.The results show that when the solvent composition of THF/H₂O assembly system is changed,B-PDI-1 molecule in the mixed solution adopts j-shaped molecular stacking with the increase of H₂O content.The morphology of aggregates evolved from spiral nanoribbons,long oblique quadrilateral,irregular nanorods and long straight nanoribbons.In the process of molecular aggregation,a two-layer molecular model may be adopted,and the slip Angle between adjacent molecules is 45.3°.3.The CV cycle curves of the aggregate films obtained in different assembly environments were tested by the electrochemical workstation,the electronic structure of the aggregates was characterized,and the discoloration mechanism of THF/H2O solution containing B-PDI-1 was discussed.Due to the effect of the increased content of the undesirable solvent tetrahydrofuran in the THF/H2O solution system on the aggregate lattice,the interaction between molecules head and tail is enhanced.The overlapping degree of concentrated LUMO and HOMO level conjugated plane of Perylene ring was changed,which led to the difference of optical band gap of aggregate,the selective absorption of light waves by aggregate and the change of electronic structure of aggregate.4.The transient photoelectric response and J-V curve tests of three perylene imide derivatives with secondary amine groups obtained from THF/H₂O binary solvent system were performed,and the photoelectric performance of B-PDI was evaluated.By comparing the transient photoelectric responses of the three derivatives,B-PDI-1 can form a stable photogenerated current at f_THF<50%;B-PDI-3can form stable photogenerated current only when f_THF=30%and 60%;The photogenerated current of B-PDI-1 is unstable at all ratios,which is related to the electronic pathway and structural defects of the material itself.However,when f_THF=80%,B-PDI-2 has the highest monochromatic conversion efficiency of 0.74%and the lowest open circuit voltage of-0.04351v.When f_THF=60%,the conversion efficiency is 0.58%;The optimal conversion efficiency of B-PDI-1 was only 0.43%when f_THF=60%.Through the above studies have shown that contain secondary amine groups imide derivatives in THF/H₂O binary solvent system,the assembly due to its special molecular structure and physical properties of light and is able to obtain organic nano light brings great role in promoting development of functional materials,at the same time its good photoelectric performance makes it has great potential value in the field of photovoltaic applications.