Research Progress on VO2-Based Smart Windows: From Phase Transition Mechanisms to Performance Regulation

Vanadium dioxide (VO2), a typical thermochromic material, undergoes a metal–semiconductor transition (MST) near 68 °C, accompanied by lattice distortion and band structure reconstruction, making it an ideal material for smart window applications. However, VO2 faces several bottlenecks that limit its engineering applications, including a relatively high phase transition temperature, poor color comfort, trade-offs between visible light transmittance and solar modulation efficiency, and inadequate long-term stability. This paper first discusses the structural evolution and mechanisms of the VO2 phase transition. It then focuses on the three core performance aspects of VO2-based smart windows: phase transition temperature regulation, color regulation, and optical performance regulation. Furthermore, it systematically reviews the latest research advancements in key technologies, including elemental doping, interfacial strain engineering, micro- and nanostructure engineering, multilayer film design, and inorganic–organic composite modification. Finally, the paper analyzes current challenges in terms of long-term stability, low-temperature flexible fabrication, skin comfort, and environmental friendliness, and discusses optimization pathways and future prospects for the practical application of VO2-based smart windows.