Electrochromism of Conducting Polymer Polypyrrole Films and the Elucidation of its Deterioration Mechanism

导电聚合物如聚吡咯有望用作电致变色器件，因为它们的导电性和对光的吸收会随着离子的掺杂和非掺杂而发生变化。然而，很难使它们适合实际使用，因为这些聚合物机械上坚硬易碎，重复使用时循环寿命很短。为了克服这一困难，阐明导电聚合物电致变色的劣化机理是非常有效的。本研究通过对聚吡咯(PPy)薄膜在电解液中施加循环电压的微观观察、密度梯度离心法和原子力显微镜(AFM)的观察，研究了聚吡咯(PPy)薄膜在循环电压作用下的特性变化。(1)在循环掺杂/不掺杂的PPy薄膜中观察到针孔。(2)销孔个数和a…总数随着施加电压循环次数的增加，针孔的面积增加。(3)电解液离子循环掺杂/不掺杂后，PPy薄膜的密度增加。(4)原子力显微镜观察表面形貌表明，电解离子循环掺杂/不掺杂后，PPy薄膜的颗粒尺寸变小。(5)电沉积聚吡咯薄膜的电致变色性能恶化是由于聚吡咯薄膜在电致变色离子的循环掺杂和非掺杂过程中收缩引起的，为了克服这些缺陷并提高其实用性能，我们开发了一种新的导电聚合物薄膜的方法：聚吡咯(PPy)和聚乙烯醇(PVA)的复合膜。利用这种PPy/PVA复合材料，我们研制了一种固态电致变色显示器件。在重复和交替施加(]sy+-的直流电压下，该器件显示颜色变化(黑色和透明黄色)超过2x10；lt；@D15@&gt；d1次。[)0.9.较少

Conducting polymers such as polypyrrole are expected to utilize as electrochromic devices, because they change in their electrical conductivity and absorption of light, corresponding to doping and undoping of ions. However, it has been difficult to fit them for practical use, because these polymers are mechanically hard and brittle and they have only a short cycle-life when used repeatedly. In order to overcome the difficulty, it is very effective to clarify the deterioration mechanism of electrochromism of conducting polymers. In this study, the transition of the characteristics of polypyrrole (PPy) films while applying cyclic voltage in electrolyte solution was studied by the microscopic observation with a CCD video camera, a density gradient centrifugation method, and atomic force microscopy (AFM).From this study we conclude as follows. (1) Pin holes were observed in the PPy film with cyclic doping/undoping of electrochrolyte ions. (2) The the number of the pin holes and the total a … More rea of the pin holes were increased as the increase of the cyclic number of the voltage application. (3) The density of PPy films were increased after cyclic doping/undoping of electrochrolyte ions. (4) The surface morphology observed by AFM shows that the grain size of PPy films shrunk after cyclic doping/undoping of electrochrolyte ions. (5) The deterioration of electrochromism appeared on the electrodeposited PPy films was caused by the shrinkage of PPy films during cyclic doping and undoping of electrochrolyte ions.And also, to overcome these defects and to improve their practical performance, we developed a new method of conducting polymer films of good durability ; composite films of Polypyrrolc (PPy) and the Poly vinyl-alcohol (PVA). By using this PPy/PVA composite, we developed a solid-state device of electrochromic display. The device showed color change (black & transparent yellow) more than 2X10<@D15@>D1 times under repeated and alternate application of DC voltages of (]SY.+-。[) 0.9. Less