(373i) Enhanced Electrical Switching and Electrochromic Properties of Poly(p-phenylenebenzobisthiazole) Thin Films Embedded with Nano-WO3

The electrical switching and electrochromic phenomena of nanocomposites comprising poly(p-phenylenebenzobisthiazole) (PBZT) and tungsten oxide (WO3) nanoparticles have been investigated as a function of the nanoparticle loading. Both dissolving PBZT and doping PBZT backbone structure with acid are achieved by one simple step. Chlorosulfonic acid (CSA) is used as a solvent and spontaneously transformed to sulfuric acid upon exposure to moisture. The formed sulfuric acid serves as doping agent to improve the electrical conductivity of PBZT. The most significant enhancement of electrical switching is observed in the nanocomposites with low weight fraction (5%). The electrical conductivity of 5% WO3/PBZT nanocomposite thin film is increased by about 200 times and 2 times, respectively, as compared to those of the as-received PBZT and PBZT/CSA thin films within the scanning voltage range from -1.0 V to -0.5 V. As the nanoparticle loading increases to 20% and 30%, the nanocomposites follow ohmic conduction mechanism. Stable electrical conductivity switching has been observed before and after applying a bias on the pristine PBZT and WO3/PBZT nanocomposite thin films. Electrochromic phenomena of both pristine PBZT and WO3/PBZT nanocomposite thin films with high contrast ratio have been observed after applying a bias (3 V). The mechanisms of the nanoparticles in enhancing the electrical switching and electrochromic properties are proposed in this work.

References:

1)J Zhu; S Wei; M Jr. Alexander; D Cocke; TC Ho; Z Guo; "Electrical Conductivity Manipulation and Switching Phenomena of Poly(p-phenylenebenzobisthiazole) Thin Film by Doping Process" Journal of Materials Chemistry. 2010, 20, 568.

2)J Zhu, S Wei, M Jr Alexander, T D Dang, TC Ho, Z Guo; "Enhanced Electrical Switching and Electrochromic Properties of Poly(p-phenylenebenzobisthiazole) Thin Films Embedded with Nano-WO3"Advanced Functional Materials,2010, 18, 3076-3084.