Assembly of ITO Nanocrystals into Nanotubes Using Polycarbonate Membranes for Dual-Band Electrochromic Modulation

Assembling doped metal oxide nanocrystals (NCs) into one-dimensional (1D) structures can enhance the optical and electrochemical properties of thin films. However, achieving this assembly without damaging the NCs’ properties has been challenging. Here, we present facile method to assemble near-infrared (NIR) absorbing plasmonic indium tin oxide (ITO) NCs into 1D nanotubes (NTs) using track-etched polycarbonate (PC) membranes as templates. By infiltrating freestanding PC membranes with 3% doped ITO NCs, attaching them to an adhesive layer, and then annealing, we produce robust ITO NTs on substrates. Fabricated ITO NTs, featuring mesopores and macropores, exhibit rapid NIR modulation under electrochemical potential while maintaining static visible opacity, making them useful for privacy protection and thermal management. Incorporating NbO_x into these ITO NT films demonstrates rapid switching and electrochemically stable visible and NIR dual-band electrochromic modulation, highlighting the significance of structuring NCs.