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.

透明的窗户可以隔绝进入建筑物的红外线和热量，因此有望减少能耗。但是，节能窗材料的长期挑战是同时实现大的折射率调整，宽的透射调制和接近室温的相变。在这里，我们通过使用功能梯度透明纳米复合材料（由中空网络-纳米粒子杂化物组成）报告了热量和红外辐射的隔热情况。我们通过结合金属纳米粒子的光反射特性和中空壳网络的隔热性能，证明了6.9°C的ΔT，在3 W / cm ²的光强度下产生了396 W / m ²的等效冷却功率。该柔性纳米复合材料片材显示出91.0％的高透明度，可见光区域的低雾度以及160MPa的模量。梯度纳米复合材料结合了紫外线阻隔，可见光透明和红外遮光功能，为节能建筑窗应用开辟了新途径。