Improved Optical and Electrochromic Properties of NiOx Films by Low-Temperature Spin-Coating Method Based on NiOx Nanoparticles

Abstract

Solution approaches to NiOx films for electrochromic applications are problematic due to the need of an additional high-temperature annealing treatment step in inert gas. In this study, nanostructured NiOx powder with grain size of about 10.1 nm was synthesized for fabrication of NiOx films for electrochromic application. Non-toxic dispersants of isopropanol and deionized water were used and the whole process was carried out in air. The effects of the number of spin-coating layers, annealing temperature, and the volume ratios of isopropanol to deionized water were systematically investigated. Large transmittance change of 62.3% at 550 nm, high coloration efficiency (42.8 cm2/C), rapid switching time (coloring time is 4 s, bleaching time is 3 s), and good stability were achieved in the optimized NiOx film. The optimized process only required a low processing temperature of 150 °C in air with spin-coating three times and 1:2 volume ratio of isopropanol to deionized water. Finally, good cycle durability of up to 2000 cycles without obvious degradation was demonstrated by cyclic voltammetry tests in a LiClO4/propylene carbonate electrolyte. This study provides a simple and effective approach for fabrication of NiOx films at low temperature in air, which is attractive for further commercialization of electrochromic devices.

Flexible Transparent Symmetric Solid-State Supercapacitors Based on NiO-Decorated Nanofiber-Based Composite Electrodes with Excellent Mechanical Flexibility and Cyclability

“…32 The NFC electrode confirmed the presence of AgNWs, showing the two crystal peaks, which are located at diffraction angles 2θ = 38.2°(111) and 44.8°(200). 33 The NiO@NFC electrodes also clearly showed the typical crystal peaks for the NiO nanoparticles at the same diffraction angles, 30 indicating the successful incorporation of NiO nanoparticles. CV curves (a, b) of the NiO@ITO//NiO@ITO and NiO@NFC//NiO@NFC symmetric devices at various scan rates ranging from 10 to 100 mV s −1 (inset: simple schematic diagram of the flexible and transparent sandwich-type symmetric device based on the NFC electrodes decorated with NiO nanoparticles).…”

“…The detailed descriptions were also well explained in our previous report. 4 For the anode and cathode materials, the NFC electrode was further decorated with NiO nanoparticles via a spin-coating method 30 to produce the flexible and transparent NiO-decorated NFC (NiO@ NFC) supercapacitor electrodes. As a comparison, the conventional ITO film electrode was also utilized instead of a NFC electrode.…”

Electrodeposited Copolymers Based on 9,9′-(5-Bromo-1,3-phenylene)biscarbazole and Dithiophene Derivatives for High-Performance Electrochromic Devices

“…Another crucial criterion of electrochromism is the coloration efficiency ( η ), which can be calculated from the following equation [ 61 ]: where Q d stands for the injected/ejected charge as a function of electrode active area. As presented in Table 3 , the η of PBPBC, P(BPBC- co -BT), P(BPBC- co -CDT), and P(BPBC- co -CDTK) films were evaluated to be 140.3 cm 2 C −1 at 1040 nm, 130.0 cm 2 C −1 at 1030 nm, 121.7 cm 2 C −1 at 1050 nm, and 283.7 cm 2 C −1 at 1070 nm, respectively.…”

Quasi-Solid-State Electrochromic Cells with Energy Storage Properties Made with Inkjet Printing

“…Anodic EC materials can be colored by electrochemical oxidation and are usually employed as counter electrodes (CE). The most popular anodic EC material is nickel oxide (NiO), whereas iridium dioxide (IrO 2 ), vanadium pentoxide (V 2 O 5 ), and organic-, metallo-organic or polymeric complexes have also been used [ 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. The electrochemical reaction of NiO coloration in alkaline aqueous solution can be described as: …”