Energy-Saving VO2 Bilayer Films with Self-Cleaning and Self-Healing for Smart Windows

Thermochromic VO2 has garnered widespread attention with unique optical regulation in the fields of smart windows. However, VO2 windows with persistent stability and optical tunability in an outdoor environment are still a challenge. This study presents a multifunctional VO2 film, including a thermochromic VO2/polymer layer with VO2 particles dispersed in a urea-polydimethylsiloxane (uPDMS) matrix and a smooth liquid-infused porous surface (SLIPS) layer with silicone oil filling in porous structures. Entrapping VO2 particles within the urea-polydimethylsiloxane net ensures thermochromic stability. The extensive hydrogen bonds between urea groups and highly mobile polydimethylsiloxane chains ensure the self-healing performance, while the upper SLIPS layer offers the self-cleaning performance. This bilayer composite film demonstrates excellent solar modulation ability (ΔTsol = 20.25%), adequate visible light transmittance (Tlum,c = 47.78%), a remarkable self-cleaning performance (RA = 8.9°), and notable self-healing abilities (healing rate = 88.48%). The research herein offers a reliable approach for fabricating stable smart energy-saving window films.