Study On The Built-in Electric Field Control And Photocatalytic Performance Of Perylene Diimide-based Semiconductor

In recent years,low-cost and high-efficiency metal-free semiconductors have attracted much attention due to their advantages of tunable structure,easy preparation,and low cost.As an n-type organic semiconductor,perylene diimide(PDI)has attracted a lot of research due to its wide light absorption range,facile synthesis method,and good photothermal stability.However,the highly symmetrical structure of PDI molecules results in very small intramolecular dipole moments and weakπ-πpacking density,which greatly inhibits the migration of photogenerated carriers in PDI.Therefore,an effective method to facilitate the charge separation of PDI semiconductors is urgently needed.Studies have shown that adjusting substituent groups on the aromatic nucleus and imide position is an important method to improve the photocatalytic performance of PDI.Based on this,this work uses perylene diimide as the research object,constructs catalysts with different built-in electric field strengths to improve the photocatalytic performance of perylene diimide-based semiconductors,and systematically studies the perylene diimide-based Photocatalytic performance enhancement mechanism and reaction mechanism of semiconductors.The main research content is as follows:1.Perylene diimide(PDI)-triazine-based supramolecules were prepared by supramolecular self-assembly method.The structures of the prepared catalysts were characterized by XRD,IR,XPS and other methods.In addition,the photocatalytic ammonia synthesis rate of the catalyst was measured in the absence of cocatalyst and sacrificial agent.The experimental results demonstrate the excellent photocatalytic nitrogen fixation efficiency of PDI-triazine-based supramolecules.In addition,DFT simulation calculations show that the embedded triazine unit can not only adjust the HOMO and LOMO bands and light absorption characteristics of PDI molecules,but also greatly enhance the molecular dipole of PDI and promote carrier separation.2.PDI-based semiconductor conjugated macromolecules usually have different rotation angles,which can significantly affect the charge mobility,but the mechanism is still unclear.Here,we synthesized PDI-based polymers with molecular internal angles of 94.7~o,149.7~o,and 176.3~oto explore the role ofπ-conjugated non-planar molecules.Density functional theory(DFT)calculations and experimental results show that materials with vertical structures have antibonding interactions in anisotropic polarized monomers,resulting in larger molecular dipoles,which greatly enhance the built-in electric field of the molecule and facilitate the loading process.flow separation.And PDIMH has high photocatalytic oxidation coupling efficiency of benzylamine.