Using an Atmospheric Pressure Chemical Vapor Deposition Process for the Development of V2O5 as an Electrochromic Material

Abstract

Vanadium pentoxide coatings were grown by atmospheric pressure chemical vapor deposition varying the gas precursor ratio (vanadium (IV) chloride:water) and the substrate temperature. All samples were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, cyclic voltammetry, and transmittance measurements. The water flow rate was found to affect the crystallinity and the morphological characteristics of vanadium pentoxide. Dense stacks of long grains of crystalline oxide are formed at the highest amount of water utilized for a substrate temperature of 450 • C. Accordingly, it was indicated that for higher temperatures and a constant gas precursor ratio of 1:7, the surface morphology becomes flattened, and columnar grains of uniform size and shape are indicated, keeping the high crystalline quality of the material. Hence, it was possible to define a frame of operating parameters wherein single-phase vanadium pentoxide may be reliably expected, including a gas precursor ratio of 1:7 with a substrate temperature of >450 • C. The as-grown vanadium pentoxide at 550 • C for a gas precursor ratio of 1:7 presented the best electrochemical performance, including a diffusion coefficient of 9.19 × 10 −11 cm 2 ·s −1 , a charge density of 3.1 mC·cm −2 , and a coloration efficiency of 336 cm 2 ·C −1 . One may then say that this route can be important for the growth of large-scale electrodes with good performance for electrochromic devices.

Growth without Postannealing of Monoclinic VO2 Thin Film by Atomic Layer Deposition Using VCl4 as Precursor

“…Moreover, it can be reasonably imagined that the VCl 4 can be used not only to grow crystalline VO 2 films, but also to grow other different vanadium oxides (VO x , x = 2) by controlling the ALD-process parameters (such as process temperature, VCl 4 /H 2 O ratio, and so forth). It is just like this that the VCl 4 had been used as a precursor for atmospheric pressure CVD to grow different vanadium oxides (VO 2 and V 2 O 5 ) by controlling process parameters of temperature and VCl 4 /H 2 O ratio [30][31][32]. We anticipate this work to be a starting point for using VCl 4 as a precursor to grow various directly crystallized vanadium oxides by ALD without any postannealing process.…”

“…Various techniques had been employed for preparing VO 2 films, including the sol-gel method [22,23], electron-beam evaporation [25,26], sputtering [5,17], pulsed laser deposition (PLD) [27,28], molecular beam epitaxy (MBE) [16,29], chemical vapor deposition (CVD) [30][31][32][33][34], and atomic layer deposition (ALD) [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]. Among them, ALD is an excellent technique which has drawn much attention due to its many advantages, including preparation of the highly conformal thin films with almost 100% step coverage, accurate control of film thickness at the atomic scale, low growth temperature, and wide-area uniformity.…”

“…This work reports that a directly crystalline VO 2 film has been successfully grown by ALD using vanadium tetrachloride (VCl 4 ) and H 2 O as precursors at a reaction temperature of 350 • C without any postannealing process. It is noticed that the inorganic VCl 4 is used as an ALD precursor for the first time, although a few papers reported that the VCl 4 had been used in traditional chemical vapor deposition (CVD) techniques [30][31][32]. The VO 2 film has a significant SMT behavior with a VO 2 (M)-to-VO 2 (R) phase-transition temperature of about 61 ± 1 • C, which is verified from temperature-dependent Raman spectra and sheet-resistance variations of VO 2 film.…”

Electrochromic materials and devices for energy efficiency and human comfort in buildings: A critical review

“…Oxides based on W, Mo, Ti and Nb are cathodic while oxides based on Ni and Ir are anodic [1,31]. An intermediate situation prevails for V 2 O 5 which exhibits anodic and cathodic features in different wavelength ranges [82][83][84]. Oxides based on Cr, Mn, Fe, Co, Cu, Rh and Ta can display some electrochromism but are unable to reach a fully bleached state and/or have weak electrochromism and therefore are largely irrelevant for practical applications.…”

Optoelectronic Properties of Ti-doped SnO2 Thin Films Processed under Different Annealing Temperatures

“…Transparent conductive oxide (TCO) thin films possess excellent conductivity and optical transmittance in the visible and near-infrared regions, and are thus applied in many photoelectric components nowadays, including solar cells [1,2], organic light-emitting diodes [3,4], thin-film transistors [5,6], photovoltaic batteries [7][8][9], electrochromic devices [10][11][12], and tablet displays [13][14][15][16]. Metallic films are generally opaque in the visible light range.…”