High-performance flexible smart window based on copper nanowire/multi-walled carbon nanotube transparent conducting film

Flexible smart-window technology is promising in controlling the building energy in an intelligent city; however, fabricating a high-performance flexible smart windows through a simple, cost-effective, and scalable method is a challenge. Herein, we present an approach for fabricating a flexible smart window that can achieve a maximum difference of the transparency between the “ON” and “OFF” state (Δ T_ON-OFF) of 69.6% at a low applied voltage (35 V) using flexible transparent electrodes (FTEs) of copper nanowires/multi-walled carbon nanotubes (Cu NWs/MWCNTs). MWCNTs were coated on the nanowire network by spin coating to form bridges between the Cu NWs, resulting good optoelectrical properties of the FTE (a sheet resistance of 22 Ω/sq at 90% of the transmittance) and uniform electric field of the device. Moreover, MWCNTs enable excellent mechanical stability under a bending test of over 5000 cycles of the electrodes. As a result, the flexible smart window can achieve high output performance, mechanical durability, and fast response. Furthermore, our method is in the solution phase and operates at room temperature (25 °C), which indicates the suitability of flexible smart windows for commercial applications.