Phase-change VO2-based thermochromic smart windows

• Published in: Light, science & applications science & applications, 2024-09, Vol.13 (1), p.255-22, Article 255
• Main Authors: Jiang, Cancheng, He, Lanyue, Xuan, Qingdong, Liao, Yuan, Dai, Jian-Guo, Lei, Dangyuan
• Format: Article
• Language: English
• Subjects: 639/624/399/354; 639/766/1130/2799; Adaptive radiation; Energy consumption; Energy efficiency; Lasers; Microwaves; Optical and Electronic Materials; Optical Devices; Optical properties; Optics; Photonics; Physics; Physics and Astronomy; Review; Review Article; Reviews; RF and Optical Engineering; Silicon dioxide; Vanadium
• ISSN: 2047-7538; 2095-5545; 2047-7538
• DOI: 10.1038/s41377-024-01560-9

Thermochromic coatings hold promise in reducing building energy consumption by dynamically regulating the heat gain of windows, which are often regarded as less energy-efficient components, across different seasons. Vanadium dioxide (VO 2 ) stands out as a versatile thermochromic material for smart windows owing to its reversible metal-to-insulator transition (MIT) alongside correlated structural and optical properties. In this review, we delve into recent advancements in the phase-change VO 2 -based thermochromic coatings for smart windows, spanning from the macroscopic crystal level to the microscopic structural level (including elemental doping and micro/nano-engineering), as well as advances in controllable fabrication. It is notable that hybridizing functional elements/materials (e.g., W, Mo/SiO 2 , TiN) with VO 2 in delicate structural designs (e.g., core-shell, optical cavity) brings new degrees of freedom for controlling the thermochromic properties, including the MIT temperature, luminous transmittance, solar-energy modulation ability and building-relevant multi-functionality. Additionally, we provide an overview of alternative chromogenic materials that could potentially complement or surpass the intrinsic limitations of VO 2 . By examining the landscape of emerging materials, we aim to broaden the scope of possibilities for smart window technologies. We also offer insights into the current challenges and prospects of VO 2 -based thermochromic smart windows, presenting a roadmap for advancing this field towards enhanced energy efficiency and sustainable building design. In summary, this review innovatively categorizes doping strategies and corresponding effects of VO 2 , underscores their crucial NIR-energy modulation ability for smart windows, pioneers a theoretical analysis of inverse core-shell structures, prioritizes practical engineering strategies for solar modulation in VO 2 films, and summarizes complementary chromogenic materials, thus ultimately advancing VO 2 -based smart window technologies with a fresh perspective. This review encapsulates the attributes of phase-change-VO 2 -based smart windows, highlighting their adaptive radiative cooling mechanisms, large modulation of both solar energy and thermal radiation, and methods for controlling phase-transition temperatures.