Enhanced electrochromic switching speed and electrochemical stability of conducting polymer film on an ionic liquid functionalized ITO electrode

Abstract

The 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF 4 ) functionalized ITO substrate was successfully prepared via a solution immersion method and then incorporated with poly(4,4 0 ,4 00 -tris[4-(2-bithienyl)phenyl]amine) (PTBTPA) to form the PTBTPA-[BMIM]BF 4 film by electrochemical polymerization, which presents reversible multicolor changes from orange, olive green to dark gray. Interestingly, compared with the bleaching time (t b ) and the coloring time (t c ) of the pure PTBTPA film (1.76 s and 4.51 s) at 1100 nm, the PTBTPA-[BMIM]BF 4 film exhibits shorter t b and t c (0.87 s and 2.90 s) at the same wavelength. Obviously, the switching speed of the PTBTPA-[BMIM]BF 4 film has been improved significantly, and it is further supported by the electrochemical impedance spectra which demonstrate that the PTBTPA-[BMIM]BF 4 film possesses much lower charge transfer resistance. The reduction of charge transfer resistance could be attributed to (1) the private channel provided by the ionic liquid [BMIM]BF 4 as a linker between the polymer and the electrode; (2) the ability of the simultaneous doping and dedoping of ClO 4 À in the electrolyte and BF 4 À ions of the ionic liquid. Moreover, the cyclic stability studies reveal that the PTBTPA-[BMIM]BF 4 film exhibits better durability and retains 70.4% of its original electroactivity after 500 cycles in ionic liquid solution. The results demonstrate that the electrochemical and the electrochromic performances could be significantly enhanced through incorporating PTBTPA with the ionic liquid ([BMIM]BF 4 ).

Label-free optical detection of bioelectric potentials using electrochromic thin films

“…The temporal response of the film must be sufficiently fast in order to capture cellular electric potentials on the order of 1 ms. However, the long response time of macroscopic electrochromic coatings, typically on the order of seconds (38,39), is too slow for capturing millisecond neuroelectric activities. We hypothesize that the temporal response is determined by charging of the active electrode area and the bulk diffusion of the counterions necessary for charge stabilization (40).…”

Label-free optical detection of bioelectric potentials using electrochromic thin films

“…The temporal response of the film must be sufficiently fast in order to capture cellular electric potentials in the order of 1 ms. However, the long response time of macroscopic electrochromic coatings, typically on the order of seconds (38,39), is too slow for capturing millisecond neuroelectric activities. We hypothesize that the temporal response is determined by charging of the active electrode area and the bulk diffusion of the counter ions necessary for charge stabilization (40).…”

A Transparent Multidimensional Electrode with Indium Tin Oxide Nanofibers and Gold Nanoparticles for Bistable Electrochromic Devices

“…Except for developing novel high-performance EC materials as previously reported, fabricating suitable electrodes is another important strategy to improve the performance of electrochromic devices (ECDs). − For organic bistable electrochromic devices (BECDs), the responsiveness is dependent on the rate of ion transport in the EC film and the rate of heterogeneous electron transfer between the conductive electrode and EC materials. − In addition, the maintaining ability of their colored states is closely related to the stability of materials and the diffusion of EC molecules, which is an important influence factor of the self-erasing phenomenon in the devices. − Herein, a multidimensional indium tin oxide (ITO)-Au conductive network deposited tightly on a two-dimensional (2D) fluorine-doped tin oxide (FTO) electrode was prepared by a facile electrospinning and applied efficiently for BECDs. The highly conductive ITO-Au network could improve the electron transfer rate and reduce the distance of electron transfer, which was beneficial for the response rate of devices.…”