Transparent and Flexible Thermal Insulation Window Material
Feng Hu, Lu An, Changning Li, Jun Liu, Guibin Ma, Yong Hu, Yulong Huang, Yuzi Liu, Thomas Thundat, Shenqiang Ren
Abstract
Transparent windows that insulate against infrared light and heat entering buildings hold the promise of reducing energy consumption. However, a long-standing challenge for energy-saving window materials is to concurrently achieve a large tuning of refractive index, broad transmission modulation, and near-room-temperature phase transition. Here, we report the insulation of heat and infrared radiation by using a functionally graded transparent nanocomposite consisting of a hollow network-nanoparticle hybrid. We demonstrate ΔT of 6.9°C by combining the light-reflectance properties of metallic nanoparticles and the thermal insulation of hollow shell networks, resulting in an equivalent cooling power of 396 W/m2 under a light intensity of 3 W/cm2. This flexible nanocomposite sheet shows a high transparency of 91.0%, low haze in the visible region, and a modulus of 160 MPa. The gradient nanocomposites combine UV light blocking, visible transparency, and infrared light shielding, potentially opening a new avenue for energy-saving building window applications.