Synthesis And Memory Behaviors Of Polyimides Containing Porphyrin Pendant Group

With the explosive growth in the information era,traditional memory materials,such as magnetic storage,optical storage and semiconductor storage,have gradually approached their physical limit and cannot meet the demand of the storge materials characterized by ultra-large capacity,ultra-high density and ultra-fast response speed.In recent years,polymer-based storage materials have gradually become the focus of research,and are expected to be a supplement or substitute for conventional information storage materials because they have numerous advantages of low-cost potential,simplicity in device structure,three-dimensional stacking capacity,large capacity for data storage,and etc.Up to now,electric bistable and tristable phenomena have been observed in polymer-based memory materials.Among them,polyimides with the structure of electron donor-acceptor have attracted more and more attention.Frequently-used electron donors are carbazole and triphenylamine compounds.Porphyrin is a good choice for electron donor due to its easily modified chemical structure,strong coordination ability and unique electronic configuration and photoelectric properties.Based on the above background,in this paper,we report the design and synthesis of novel porphyrin-containing and zinc-porphyrin-containing diamines,named as N'-(4-aminophenyl)-N'-(4-(10,15,20-triphenylporphyrin-5-yl)phenyl)benzene-1,4-diamine(BAPAP)and N'-(4-aminophenyl)-N'-(4-(10,15,20-triphenyl-zinc-porphyrin-5-yl)phenyl)benzene-1,4-diamine(Zn-BAPAP),respectively.Four kinds of soluble polyimides with D-A structure were prepared by using BAPAP and Zn-BAPAP as electron donors,4,4'-(Hexafluoroisopropylidene)diphthalic anhydride(6FDA)and 3,3',4,4'-Diphenyl sulfone tetracarboxylicdianhydride(DSDA)as electron acceptors,separately.The products were named 6FDA/BAPAP?6FDA/Zn-BAPAP?DSDA/BAPAP and DSDA/Zn-BAPAP,whose structure are confirmed by FT-IR and 1H-NMR spectra.The optical and electrochemical properties of polyimides are characterized by UV-vis,fluorescence emission spectra and CyV sweeps.Fabricate sandwiched memory devices with the structure of ITO|polyimides thin film|Al,and test current-voltage characteristics with semiconductor parameter.The results show that:6FDA/BAPAP has Flash property and DSDA/BAPAP functions as WORM memory.6FDA/Zn-BAPAP and DSDA/Zn-BAPAP has the characteristics of multi-level,and their low-level both show DRAM property,while the behaviors of high-level are Flash and WORM respectively.The molecular configuration,orbital distribution and energy level of polyimides model compounds are calculated and analyzed by means of molecular simulation,which provides a theoretical explanation for the storage mechanism.