Synthesis And Photoelectric Properties Of Novel Heteroacenes Materials

Due to their high charge carrier mobility,acenes have been widely used in organic electronic devices,such as organic field effect transistors?OFETs?,organic light emitting diodes?OLEDs?,organic solar cells?OPVs?,nonlinear optics,etc.However,acenes with six or even more fused benzene rings are very unstable.Insertion of heteroatoms into the skeletons of acenes is an exciting method to enhance their stability,except the Insertion of electronegative heteroatoms or side groups.The nitrogen atom doping can not only improve the stability of acenes,but also can adjust the acene's charge transfer properties,from P-type to bipolar or even N-type,to a large extent,expand the scope of application of acenes materials.Azaacenes can usually be obtained by condensation reaction and oxidative coupling reaction.The building blocks for the construction of azaacenes are the different kinds of ortho-diamines?or tetraamines?,ortho-dichloro and their analogues and ortho-diketones?or tetraketones?,respectively.Diamines?or tetraamines?are generally more readily adjustable in their structures and much more easily synthesized than diketones or dichloro aromatics.The combination of different building blocks may construct different length of azaacenes.Thus,the development of novel building blocks is very important and highly desirable.In this thesis,recent progress in the field of azaacene including the synthetic methods and applications has been reviewed firstly,and then three types of benzothiadiazole derivatives?stable diamine precursors?were designed for the construction of novel building blocks.Based on those modules,several novel azaacenes were constructed and their optoelectronic properties were studied.The research contents are as follows:Benzothiadiazole derivatives BTH-N and BTH-DN containing pyrazine and pyridineheterocycles,bromobenzothiadiazole derivatives BTH-BrN and BTH-Br,BTH-DBr with and without pyridine heterocycles and benzothiadiazole derivatives BTH-O and BTH-S containing O?S?heteroatoms in the main skeleton have been designed.Their structures were characterized by ¹H NMR,¹³C NMR and MS.Their basic photoelectric properties were fully characterized.The bromine-substituted compound BTH-Br has a low energy level and a narrow bandgap?1.76 eV?.However,BTH-O containing O-heterocycle showed strong fluorescence.Non-centrosymmetrically heterohexacenes DAOH and DATH were obtained by the condensation reaction between pyrene diketone and diamine,and their structures were fully characterized by¹H NMR,¹³C NMR and MS.Single-crystal X-ray analysis showed that the compound DAOH had a planar structure with interplanar distances of 3.54?and3.55?,respectively,indicating the presence of?-?stacking.The fibrous microcrystals of the compound DATH were obtained by reprecipitation at a rotation rate of 300 r/min and3 mg/ml,while the compound DAOH cuboid crystallites were determined by a solvent evaporation method at 3 mg/ml and 20°C.Centrosymmetrically heterodecaacenes TAOD and TATD were obtained by the condensation reaction of the pyrene tetraketone and diamine,and their structures were characterized by ¹H NMR,¹³C NMR and MS.Single crystal X-ray analysis showed that the compound TAOD had a planar structure,while the compound TATD had a twisted structure,and the dithiol group was folded out of the center pyrene plane with a dihedral angle of 55.77°.In addition,the microcrystals of compounds TAOD and TATD were obtained by reprecipitation at 400 r/min,6 mg/ml,25°C and 300 r/min,5 mg/ml,10°C,respectively.The third-order nonlinear optical properties of the two compounds have been studied in solid based on their microcrystals.