A Flexible and Infrared-Transparent Bi2Te3-Carbon Nanotube Thermoelectric Hybrid for both Active and Passive Cooling

On-demand thermal management based on the Peltier effect of thermoelectric (TE) materials has attracted great attention due to its unique advantages of a simple structure, no moving parts, quietness, compactness, and precise temperature control. However, conventional bulk TE materials are inherently rigid, and it is therefore difficult to acquire close contact with heat sources and heat sinks with complex geometries, resulting in poor heat transfer and cooling ability. In addition, they are optically opaque and dense, blocking passive heat dissipation by thermal radiation and air convection. Tailoring TE materials with mid-infrared (IR) transparency and good flexibility to achieve both active and passive cooling remains a great challenge. Here, we report a nanoporous TE hybrid composed of (000l)-textured n-type Bi2Te3 nanocrystals anchored on a single-wall carbon nanotube (SWCNT) network. It achieves an in-plane power factor of ∼265 μW m–1 K–2 and a low thermal conductivity of ∼0.34 W m–1 K–1, yielding a TE figure of merit (ZT) value of ∼0.23 in the temperature range from room temperature to ∼373 K. This hybrid has excellent flexibility and a maximum IR transparency of ∼16%. Our results open a way to develop efficient TEs with both active and passive cooling abilities.