Polymer−Nanoparticle Electrochromic Materials that Selectively Modulate Visible and Near-Infrared Light

In this manuscript, we describe a class of hybrid electrochromic materials utilizing polythiophenes and tin-doped indium oxide (ITO) nanoparticles that independently modulate visible and near-infrared (NIR) light. By altering the voltage applied across electrodes modified with these composite materials, the electrodes can be repeatedly switched between three distinct modes of operation. These “bright and warm”, “bright and cool”, and “dark and cool” modes vary in their visible and NIR transmission properties and are targeted toward the development of smart windows that can control both solar lighting and heating fluxes. Electrodes containing the composite films, which are fabricated by electropolymerizing polythiophenes on transparent electrodes coated with ITO nanoparticles, possess fast switching times (<90 s), moderate durability, and contrast ratios similar to those of the individual composite components. The maximum contrast ratios of the composite systems are 47% at 700 nm and 39% at 1250 nm. After 200 switching cycles, these contrast ratios degrade by 15−20%. The composite materials developed here represent a new direction of research aimed at modulating light and heat flux in smart windows.