Synthesis And Properties Of Triphenyl Dioxazine Diimide Derivatives

Triphenyl dioxazine（TPDO）derivatives have been applied in the field of organic dyes because of their strong absorption in the visible light region,outstanding fluorescence characteristics,high thermal stability and chemical stability.However,there is few reports about the application of organic optoelectronics.The main reasons are as follows:First,because of its large conjugated plane,TPDO exhibits a strong tendency of intermolecular self-aggregation,which results in poor solubility in common organic solvents.Second,the strong aggregation always makes the solid to form large phase separation,which is easily formed exciton trap,and therefore the charge cannot be effectively separated.To solve these problems,we uses the following two strategies in this project:（1）Introducing substituents or substituent groups at the active site of triphenyl dioxazine diimides（TPDODI）to control the absorption spectra,electron energy levels and solubility;（2）Introducing distortion strategy to reduce the aggregation of triphenyl dioxazine molecular structure,and designing 3D molecular structure to make sure the high solubility and suitable phase separation scales.As a result,a series of TPDODI derivatives were designed and synthesized,and their photoelectric properties were also investigated.1.Designed and synthesized four TPDODI derivatives,2F-TPDODI,2Cl-TPDODI,2Br-TPDODI and 2I-TPDODI that are consisted of different halogen elements at the active sites.Because negative halogen elements could reduce the lowest unoccupied molecular orbital（LUMO）levels,compared with TPDODI,the LUMO energy levels of these four molecules are more negative（about-4.00 e V）and are similar with that of the classical electron acceptor material PCBM.The introduction of strong electronegative elements such as fluorine atom not only could reduce the LUMO levels and therefore making the n-typed device more stable but also may also improve the electron mobility.2.Designed and synthesized a series of different aromatic/heterocyclic substituted TPDODI derivatives.By introducing a benzene ring and other substituent groups into the active position of TPDODI,The steric hindrance between the substituted group and TPDODI can make the TPDODI skeleton form certain torsion angles with the substituted groups and inhibit the molecular aggregation of triphenyl dioxazine.The results demonstrate that these aromatic/heterocyclic substituent groups could change the light absorption,LUMO energy levels,miscibility between acceptor and donor materials,electron transport and other properties,which makes TPDODI more suitable as the electron acceptor materials.3.A twisted TPDODI diploid（2TPDODI）with 3D molecular configuration was designed and synthesized.The new compound exhibits increased the maximum molar extinction coefficient from 92 700 L·mol^-1cm^-1 of TPDODI to 126 000 L·mol^-1cm^-1 of 2TPDODI.The LUMO energy levels are-3.82 e V and-3.86 e V for TPDODI and 2TPDODI,respectively.The enhanced visible light absorption capacity and the matched energy levels mean that 2TPDODI could be used as electron acceptor materials.Besides,2TPDODI adopts a single-bond direct connection,which not only realizes the molecular space distortion,but also ensures the planar structure of the monomer TPDODI.This concept realizes that inhibiting molecular aggregation could ensure the high charge transporting,making 2TPDODI possess potential application in organic solar cells.