Hydrothermal Synthesis of VO₂ Polymorphs: Advantages, Challenges and Prospects for the Application of Energy Efficient Smart Windows

Abstract

Vanadium dioxide (VO ) is a widely studied inorganic phase change material, which has a reversible phase transition from semiconducting monoclinic to metallic rutile phase at a critical temperature of τ ≈ 68 °C. The abrupt decrease of infrared transmittance in the metallic phase makes VO a potential candidate for thermochromic energy efficient windows to cut down building energy consumption. However, there are three long-standing issues that hindered its application in energy efficient windows: high τ , low luminous transmittance (T ), and undesirable solar modulation ability (ΔT ). Many approaches, including nano-thermochromism, porous films, biomimetic surface reconstruction, gridded structures, antireflective overcoatings, etc, have been proposed to tackle these issues. The first approach-nano-thermochromism-which is to integrate VO nanoparticles in a transparent matrix, outperforms the rest; while the thermochromic performance is determined by particle size, stoichiometry, and crystallinity. A hydrothermal method is the most common method to fabricate high-quality VO nanoparticles, and has its own advantages of large-scale synthesis and precise phase control of VO . This Review focuses on hydrothermal synthesis, physical properties of VO polymorphs, and their transformation to thermochromic VO (M), and discusses the advantages, challenges, and prospects of VO (M) in energy-efficient smart windows application.

Development of VO2‐Nanoparticle‐Based Metal–Insulator Transition Electronic Ink

“…Vanadium oxide is among these smart materials which can tune its electrical and optical properties by applying external stimuli, such as heat or pressure. [5] In particular, VO 2 is an insulator at room temperature, but it undergoes a phase transition to a metallic state when heated to its www.advelectronicmat.de printing can be very beneficial. [4] Among these oxides, vanadium dioxide (VO 2 ) has received increased attention because it exhibits metal-insulator transition (MIT) in a reversible fashion at relatively lower temperature.…”

“…[22,23] Due to the exciting applications mentioned above, considerable effort has been devoted to producing VO 2 (M) in the form of a thin film, primarily with a dry vapor process using chemical vapor deposition, [24] sputtering, [25] metalorganic molecular beam epitaxy deposition, [26] pulsed laser deposition, [27,28] e-beam evaporation, [29] and by electric field inducing ions migration. [5] The only disadvantage of hydrothermal synthesis is the longer reaction time required, up to 2-4 d, to achieve pure VO 2 (M). The VO 2 thin-film deposition techniques using dry vapor processes require an ultrahigh level of vacuum conditions (10 −6 Torr) and sometimes very high processing temperatures (400-600 °C).…”

Vanadium Dioxide: The Multistimuli Responsive Material and Its Applications

“…Manipulating the MIT of VO 2 by external stimuli is an active research area, making VO 2 a material of great interest for novel electronic and optical devices. For example, the thermally induced MIT has been extensively studied for electro/thermal‐chromic, actuators, and thermoelectricity applications, while electrical field manipulation can be used for memory devices and Mott field effect transistor (FET) to circumvent the fundamental limits encountered in Si‐based electronics . It has been shown that VO 2 based photodetectors can respond to optical stimulation over a broad spectral range from terahertz to ultraviolet (UV), and the time‐resolved optical pump‐probe techniques provide an effective means to study the phase transition dynamics in VO 2 .…”

Review on thermochromic vanadium dioxide based smart coatings: from lab to commercial application

“…However, obstacles in (ii)-(iv) have not been solved. Although several reviews about VO 2 coatings have been reported [32,33,59,60], most of them are still in lab scale and few prospects of commercial applications are available.…”