The Influence Of Ionic Liquid On The Electrochromic Performance Of Poly(4,4’,4"-tris[4-(2-Bithienyl)Phenyl]Amine) Film

As a new type of intelligent materials, Electrochromic materials(EC) have received extensive attention in recent years for various applications in electronics, energy, construction and military. Conducting polymers(CPs) have been considered to be one of the most potential EC materials owing to their excellent processibility, multicolor display property, high coloration efficiency and high optical contrast. However, the relatively slow response speed and poor long-term stability have severely limited the practical applications of the CPs-based EC materials. Therefore, how to improve the electrochemical and Electrochromic performance of CPs via various methods has become one of the key point. In this paper, the research purpose is to explore the influence of ionic liquid how to effect on the EC properties of conducting ploymer by introduction ways and different kinds of ionic liquid.For the first part, the 1-butyl-3-methylimidazolium tetrafluoroborate([BMIM]BF4) functionalized ITO substrate was successfully prepared via solution immersion method, then incorporated with poly(4,4’,4"-tris[4-(2-bithienyl)phenyl]amine)(PTBTPA) to form the PTBTPA-[BMIM]BF4 film by electrochemical polymerization, SEM, XPS, EDX, cyclic voltammetry and FT-IR spectra confirm that ionic liquids have attached to the surface of ITO and successfully incorporating with polymer PTBTPA. The PTBTPA-[BMIM]BF4 film presents good electrochemical activity and reversible multicolor changes. Interestingly, comparing with the bleached time(tb) and the colored time(tc) of the pure PTBTPA film(1.76 s and 4.51 s) at 1100 nm, and can retain 37.7% of its original electroactivity after 500 cycles, the PTBTPA-[BMIM]BF4 film exhibits shorter tb and tc(0.87 s and 2.90 s) at the same wavelength and can retain 70.4% of its original electroactivity after 500 cycles in ionic liquid solution. Therefore, these results demonstrate that the electrochromic performances of the CPs are significantly enhanced through introducing ionic liquid. Moreover, the electrochemical impedance spectra demonstrates the PTBTPA-[BMIM]BF4 film possesses much lower charge transfer resistance, which leading to the faster diffusion speed.The second part of the paper is mainly study how the ionic liquid [BMIM]BF4 affect the electrochromic performances of conducting ploymer during electrochemical polymerization medium and redox doping/dedoping process electrochemical transmission medium. SEM, cyclic voltammogram polymerization and cyclic voltammetry confirm that the introduction of the ionic liquid [BMIM]BF4 can affect the surface morphology and electrochemical properties of PTBTPA film. EDX and FT-IR spectra confirm that the anion BF4- in the electrolyte has doped into polymer film in the oxidation state. The polymer film presents good electrochemical activity and reversible multicolor changes. When the TBAP is introduced simultaneously during the electrochemical polymerization and redox doping/dedoping process, the polymer film shows the highest optical contrast of 52.3% and can retain 37.7% of its original electroactivity after 1000 cycles. However, whenthe ionic liquid is introduced simultaneously during the electrochemical polymerization and redox doping/dedoping process, the polymer film shows the highest optical contrast of 70.2% and can retain 52.5% of its original electroactivity after 1000 cycles. These results demonstrate that the electrochromic performances of the conducting polymer PTBTPA are significantly enhanced through introducing ionic liquid [BMIM]BF4.The last part of the text is mainly study the effect of different kinds of ionic liquids([BMIM]BF4, [BMIM]PF6 and [BMIM]CF3SO3) on the electrochromic performances of conducting polymer. SEM, cyclic voltammogram polymerization and cyclic voltammetry confirm that different kinds of ionic liquid affect the surface morphology, polymerization process and electrochemical property of PTBTPA film. EDX and FT-IR spectra confirm that different anions in the electrolyte have doped into polymer films in the oxidation state. The film presents good electrochemical activity and reversible multicolor changes. The [BMIM]BF4-PTBPTA film show the highest optical contrast of 70.2% and can retain 77.6% of its original electroactivity after 1000 cycles. The [BMIM]PF6-PTBPTA film show the highest optical contrast of 53.2% and can retain 51.2% of its original electroactivity after 1000 cycles. And the[BMIM]CF3SO3-PTBPTA film show the highest optical contrast of 47.1% and can retain 1.8% of its original electroactivity after 1000 cycles The results demonstrate that the electrochromic performances of PTBPTA are significantly enhanced mostly through introducing ionic liquid [BMIM]BF4.