Spectrally Selective PANI/ITO Nanocomposite Electrodes for Energy-Efficient Dual Band Electrochromic Windows

Glazing employing electrochromic materials can change their optical characteristics of transparency and absorption of solar radiation according to users' needs by simultaneously reducing visible light and NIR transmission through the window. However, spectral selectivity has been becoming a key requirement in smart dynamic windows as it permits maximizing both visual and thermal comfort while minimizing energy consumption for heating, cooling, and lighting. Herein, a dual band electrochromic system is presented, which consists of an engineered nanocomposite electrode capable of advantageously combining the broad band plasmonic response of nanocrystalline indium-tin-oxide with high optical contrast of polyaniline. Their synergistical spectroelectrochemical features make possible the implementation of a four-state tunable electrochromic system (here referred to as "plasmochromic"), which permits selectively regulating optical transmittance in the visible and near-infrared range and exhibits excellent spectral selectivity (the ratio between visible light transmittance (TLUM) and solar transmittance (TSOL) can be tuned from 0.67 to 1.61) across a potentials window of only 1.2 V.