Synthesis And Properties Of Azaacenes

The organic field effect transistor（OFET）is a device based on organic semiconductor materials.Due to its potential application prospects in flexible displays,organic integrated circuits,etc.,it has caused widespread research around the world.Compared with inorganic transistors,organic field-effect transistors have the advantages of simple preparation process,low cost,light weight,good flexibility,and large area processing.Organic semiconductor materials are the most important factor in determining the performance of organic field effect transistors.Hole-transporting（p-type）materials have developed rapidly in recent years,while electron-transporting（n-type）materials are relatively lagging because of their complicated synthetic methods and functional units.The preparation of stable n-type and bipolar materials in the air faces huge challenges.Azaacenes compounds have good stability and are easy to form rigid coplanar conjugate structures,leading to good film-forming properties and high carrier mobility.They are an important class of organic transistor materials.Especially in recent years,They have been widely studied as n-type and bipolar semiconductor materials.In this dissertation,a series of new small azaacenes molecular compounds and azaacenes indigo derivatives are synthesized.The chemical structures of these compounds are characterized,and their thermal stability,photo-electric properties,and the performance of Field Effect Transistor were intestigated.The main research contents are as follows:1.Design and synthesis of small azaacenes molecule compounds containing different halogen atom substituents:starting from simple and readily available raw materials,YLP3,YLP4 and YLP5 with different halogen substituents were synthesized via traditional condensation reaction.The chemical structures of the intermediate and the target products were characterized by ¹H NMR,¹³C NMR and MS.Material property studies show that the introduction of halogen substituents has a greater impact on its molecular packing,intermolecular forces,optical absorption and molecular energy levels.These small molecular materials show good device performance under atmospheric environmental conditions.Among them,YLP5 showed typical charge transfer behavior of p-type materials,with a mobility of 0.168 cm²/Vs,while YLP3 and YLP4 showed bipolar charge transfer behavior.YLP3 has an electron mobility of 0.014 cm²/Vs and a hole mobility of0.186 cm²/Vs,and YLP4 has an electron mobility of 0.021 cm²/Vs and a hole mobility of 0.121 cm²/Vs.2.Green and efficient synthetic methods were used to prepare isoindigo derivatives YLP9,YLP10 and YLP11 with larger conjugated systems than the aforementioned azaacenes.These molecules consist of twelve fused rings（including benzene ring and nitrogen-containing heterocyclic ring）.The chemical structures of intermediate and final products were characterized by ¹H NMR,¹³C NMR and MS.Material property studies showed that extended conjugated systems have a greater impact on the solubility,planar structure,electron affinity and the characteristic absorption in the visible-near infrared（NIR）region of the molecule.The maximum absorption wavelengths of YLP9,YLP10 and YLP11 in the UV-visible spectrum are 828 nm,901 nm and 837 nm.OFET device studies show that the hole mobilities of YLP9,YLP10 and YLP11 are 4.26×10^-6 cm²/Vs,1.51×10^-3 cm²/Vs and 2.70×10^-3 cm²/Vs,respectively,indicating that small indigo derivatives with large conjugated systems can also be used as excellent materials for organic field effect transistors.