Enhanced Thermochromic Properties of Vanadium Dioxide (VO2)/Glass Heterostructure by Inserting a Zr-Based Thin Film Metallic Glasses (Cu50Zr50) Buffer Layer

Abstract

Vanadium dioxide (VO2) with reversible metal–insulator transition (MIT) is one of the most promising energy-efficient materials. Especially for VO2-based smart windows, the visible transmittance and solar modulation ability are the most critical parameters. However, VO2 thin films that are directly deposited onto glass substrates are of poor crystallinity and MIT performance, limiting the practical applications of VO2/glass heterostructures. In this paper, a buffer layer of Cu50Zr50 was introduced to build a novel Zr-based thin film metallic glass (VO2/Cu50Zr50/glass) with multilayer structures for thermochromic applications. It is observed that the insertion of a Cu50Zr50 buffer layer with appropriate thickness results in a clear enhancement of crystalline quality and MIT performance in the VO2/Cu50Zr50/glass thin films, compared with the single-layer VO2/glass thin films. Moreover, the VO2/Cu50Zr50/glass bi-layer films exhibit better optical performance with enhanced solar modulation ability (ΔTsol = 14.3%) and a high visible transmittance (Tvis = 52.3%), which represents a good balance between ΔTsol and Tvis for smart window applications.

Thermochromic Behavior of VO2/Polymer Nanocomposites for Energy Saving Coatings

“…'Smart' windows are able to intelligently self-regulate the amount of transmitted heat, while keeping the visible transmission mainly unchanged. Vanadium dioxide (VO 2 ) is one of the most promising solid-sate materials for smart windows due to its unique optical properties related to its inherent and ultrafast reversible structural (phase-change) transition from a monoclinic VO 2 (M) to tetragonal rutile VO 2 (R) structure at a critical transition temperature of T C = 68 • C, for pure monocrystalline material [8][9][10].Conventionally, 'smart' thermochromic windows are fabricated by vapor phase deposition techniques such as sputtering [11][12][13][14], chemical vapor deposition (CVD) [15][16][17], and pulsed laser deposition (PLD) [18]. However, all these techniques are restricted by the cost and scale of vacuum systems.…”

“…However, all these techniques are restricted by the cost and scale of vacuum systems. Moreover, most of these growth techniques, although they are of high fidelity and can produce good quality thermochromic VO 2 films, demand high deposition temperatures (>400 • C) [11,[14][15][16][17][18], with very few employing sputtering techniques between 250 and 300 • C [12,13,[19][20][21], making it impossible to utilize flexible (polymeric) substrates.Another approach, called the ex-situ approach [22], to the fabrication of VO 2 thermochromic films is to first synthesize the desired material as a powder and then to deposit the material as a film onto the desired surface. Thermochromic VO 2 in the form of powders have been synthesized by various methods, such as thermolysis [23,24], rapid thermal annealing [25], pyrolysis [26], and, the most utilized method, hydrothermal (solvothermal) synthesis [27][28][29][30][31].…”

“…Conventionally, 'smart' thermochromic windows are fabricated by vapor phase deposition techniques such as sputtering [11][12][13][14], chemical vapor deposition (CVD) [15][16][17], and pulsed laser deposition (PLD) [18]. However, all these techniques are restricted by the cost and scale of vacuum systems.…”

“…However, all these techniques are restricted by the cost and scale of vacuum systems. Moreover, most of these growth techniques, although they are of high fidelity and can produce good quality thermochromic VO 2 films, demand high deposition temperatures (>400 • C) [11,[14][15][16][17][18], with very few employing sputtering techniques between 250 and 300 • C [12,13,[19][20][21], making it impossible to utilize flexible (polymeric) substrates.…”

Enhanced Phase Transition Properties of VO2 Thin Films on 6H-SiC (0001) Substrate Prepared by Pulsed Laser Deposition

“…As a result, the high quality VO 2 film preparation is still a focusing point and essential issue. Many previous experiments have been reported about the VO 2 epitaxial film growth on various substrates such as c-plane sapphire [7,8,9], TiO 2 [10,11], GaN [12] and ordinary quartz glass [13], directly or with a buffer layer [14,15], For instance, Wang et al deposited VO 2 film on p-GaN/Al 2 O 3 (0001) substrate and explored the heterojunction devices. The growth of VO 2 films on the ZnO/glass substrate provided a new research direction for the application of electronically controlled smart windows [16].…”