Study On Electrical Bistablity And Charege Transfer Characterics Of Polynaphthalimide Containing Fluorene And Triphenylamine Groups

Many years passing by, with so much progress achieved from electractive polymer memory devices applied into industry, it’s no doubt that this industry of organic memory device will acquire a wider and further concentration to meet the tremendous demands from technical needs. Totally unlike the traditional memory cell based on Si or Ge storing data by encoding "0" and "1" states, the data storage of the polymer memory devices can be realized by the bistability states (high-conductivity states and low-conductivity states) under an applied voltage, which makes it promising for the memory devices owing to its high memory storage density, fast response to the applied voltage and good electric stability. The researches about the polyimide memory device usually enclose the design of the molecular structure, especially the design of donors and acceptors at first. Besides, the side groups in donors and acceptors are benefit for the additional functions. At present, the polyimide (dual constitutional units) memory devices with linear structure have appeared in many reports. But a few of the polyimide (ternary or even more constitutional units) memory devices come out. Neither did the relationship between the composition of the multi-components and memory property. But only a few reports of the literature about storage performance of polyimide (ternary or even more structural units) and the relative contents of components to polymer for the performance of the memory device come out, and it lacks of the discussion about solvents on solubility of ternary system.A novel soluble polynaphthalimide containing fluorene and triphenylamine moieties has been synthesized in our present work,with the function of the4,4’-diaminotriphenylamine (DATPA) units served as the electron-donating moieties,1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) and9,9’-bis (4-aminophenyl) fluorene (BAPF) units served as the electron-accepting species. The purpose of adding BAPF to the polymer is not only used to improve the solubility of the mixture of the polynaphthalimide, but also to enhance the with-drawing of the electrons from the donors. The current-voltage (Ⅰ-Ⅴ) characteristics of the devices indicate that different contents of the DATPA in the polymer show a different type of memory behavior. In Au/PNI/ITO devices, the Ⅰ-Ⅴ shows a "WORM" property with the diversity of the hopping position and hopping height. And it was exhibited an excellent long-term stability with the ON/OFF current ratio up to103. Meanwhile, the Al/PNI/ITO display a series of performance, ranging from DRAM, SRAM, WORM properties. This type of device with Al as the top electrode all own good stability under applied voltage. Besides, the theoretical method of molecular simulation compared with the experimental methods of cyclic voltammetry (CyV) and ultraviolet/visible (UV/vis) are employed to interpret the conduction mechanism. And the curve fitting are of great value to determine the types of conduction mechanism:Ohmic and Tunnel or field emission are used for the interface conduction, and Space-charge-limited-current is for the bulk of the material (including the hopping process and high conduction process).