Nanoporous thermochromic VO₂ (M) thin films: controlled porosity, largely enhanced luminous transmittance and solar modulating ability.
Vanadium dioxide is the most widely researched thermochromic material with a phase transition temperature (τ(c)) of around 68 °C, and its thermochromic performance can be enhanced by adding nanoporosity. Freeze-drying has been employed to fabricate nanostructures with different porosities from 16 to 45% by varying the prefreezing temperature and precursor concentration. The luminous transmittance (Tlum) and solar modulating ability (ΔTsol) are greatly enhanced as a result of increasing pore size and pore density. The freeze-dried sample with 7.5 mL of H2O2 precursor dip-coated at 300 mm/min gives the best combination of thermochromic properties (Tlum ≈ 50%, ΔTsol = 14.7%), which surpasses the best combined thermochromic performance reported to date that we are aware of (Tlum ≈ 41%, ΔTsol = 14.1%).
School of Materials Science and Engineering and ‡Facility for Analysis, Characterization, Testing and Simulation, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798.
Xun
X
Cao
Ning
N
Wang
Jia Yan
JY
Law
Say Chye Joachim
SC
Loo
Shlomo
S
Magdassi
Yi
Y
Long