In situ growth of PEDOT/graphene oxide nanostructures with enhanced electrochromic performance

Designed Growth of Covalently Bonded WO3/PEDOT Hybrid Nanorods Array with Enhanced Electrochromic Performance

A covalently bonded WO3/PEDOT hybrid nanorods array has been prepared through solvothermal, oil bath, and electrochemical deposition methods using KH57 as a coupling agent. The obtained WO3/PEDOT shows substantially increased electrochromic performance with an increased response speed (3.4 s for coloring and 1.2 s for bleaching), excellent optical modulation (86.7% at 633 nm), high coloration efficiency (122.0 cm2/C at 633 nm), and distinguished cyclic stability. It was found that the covalent bond interaction between WO3 and PEDOT plays an essential role in property enhancement. The covalently bonded inorganic/organic hybrid nanorods array may promise great potential in developing smart-display and energy-efficient materials and devices featuring low energy consumption, cost effectiveness, and environmental protection.

Electrodeposited Gold Nanostructures for the Enhancement of Electrochromic Properties of PANI-PEDOT Film Deposited on Transparent Electrode

Conjugated polymers (CPs) are attractive materials for use in different areas; nevertheless, the enhancement of electrochromic stability and switching time is still necessary to expand the commercialization of electrochromic devices. To our best knowledge, this is the first study demonstrating the employment of electrodeposited gold nanostructures (AuNS) for the enhancement of CPs' electrochromic properties when a transparent electrode is used as a substrate. Polyaniline-poly(3,4-ethylenedioxythiophene) (PANI-PEDOT) films were electrodeposited on a transparent indium tin oxide glass electrode, which was pre-modified by two different methods. AuNS were electrodeposited at -0.2 V constant potential for 60 s using both the 1st method (synthesis solution consisted of 3 mM HAuCl4 and 0.1 M H2SO4) and 2nd method (15 mM HAuCl4 and 1 M KNO3) resulting in an improvement of optical contrast by 3% and 22%, respectively. Additionally, when using the 1st method, the coloration efficiency was improved by 50% while the switching time was reduced by 17%. Furthermore, in both cases, the employment of AuNS resulted in an enhancement of the electrochromic stability of the CPs layer. A further selection of AuNS pre-modification conditions with the aim to control their morphology and size can be a possible stepping stone for the further improvement of CPs electrochromic properties.

Rational Design of Oxygen Deficiency-Controlled Tungsten Oxide Electrochromic Films with an Exceptional Memory Effect

Owing to their nonemissive characteristics, electrochromic materials promise distinct advantages in developing next-generation eye-friendly information displays. Yet, it remains a challenge to manipulate the structure of the materials to achieve a strong memory effect with high optical contrast, which is of importance for displaying images with essentially zero energy consumption. Here, we design a mixed crystalline WO_x thin film implanted with massive oxygen deficiencies based on a conventional reactive magnetron sputtering process. The obtained WO_x film exhibits high dual-band optical modulation in both visible (VIS, 99.0% in 633 nm) and near-infrared (NIR, 94.2% in 1300 nm) regions as well as an exceptional memory effect (the colored transmittance increases only by 0.04% at 633 nm after 50 days). The enhanced electrochromic performance can be attributed to dense Li⁺-ion binding sites as well as the trapping effect provided by the massive internal oxygen deficiencies. The strategy in this work bestows the WO_x thin film a promising candidate for developing electrochromic information displays and other energy-efficient devices as well.

A facile approach to prepare porous polyamide films with enhanced electrochromic performance

Novel electroactive triphenylamine-based polyamide (PA) films with a purposeful porous structure have been designed and prepared by a simple route. Polymer thin films containing well dispersed electrolyte salts were prepared first, then channels of pores could be generated within the polymer film by washing the salts out. With the help of the porous channels, the diffusion rate between electroactive species and the electrolyte during the electrochemical process could be effectively increased. Consequently, the driving potential and electrochromic response time can be efficiently improved through this approach. Novel porous PA films with optimal results both in optical transparency and electrochemical properties could be readily obtained by choosing a commonly used supporting electrolyte TBABF4 as a salt in this study. When the PA films containing un-washed TBABF4 salt were further assembled into electrochromic devices (ECDs), the salt could then be leached out during the electrochemical redox switching process to form a porous film structure and also serves as a supporting electrolyte in ECDs simultaneously. Therefore, EC performance such as the driving potential and response time could be enhanced obviously by this simplified fabrication procedure of ECDs.