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 the energy consumption for heating, cooling and lighting. A dual band electrochromic system is herein presented, which consists of an engineered nanocomposite electrode capable of advantageously combining the broad band plasmonic response of nanocrystalline indium-tin-oxide with the high optical contrast of polyaniline. Their synergistical spectroelectrochemical features make possible the implementation of a four-state tunable electrochromic system (here referred as “plasmochromic”), which permits to selectively regulate the optical transmittance in the visible and in the near-infrared range and exhibits an excellent spectral selectivity over a narrow bias potential window: the ratio between visible light transmittance (TLUM) and solar transmittance (TSOL) can be tuned from 0.67 to 1.61 across a potential window of 1.2V.