Active and passive modulation of solar light transmittance in a hybrid thermochromic soft-matter system for energy-saving smart window applications

Abstract

Thermochromic systems are promising candidates for energy-saving smart window applications. However, these passively responsive optical materials are subject to limitations such as a lack of active optical control, poor solar modulation (ΔT_sol) ability, and rather inconvenient switching-temperature tunability. Herein, we present a simply processed hybrid thermochromic soft-matter material sandwiched between two transparent graphene sheets, where the intermediate material possesses a phase-separated polymer framework containing liquid-crystalline micro-domains with sematic A (SmA) to chiral nematic (N*) phase change behavior and tungsten doped vanadium dioxide (W–VO₂) nanocrystals (NCs). This hybrid organic/inorganic thermochromic system not only features high mechanical strength, excellent flexibility and large-area processibility, but also possesses a dual-active/passive optical modulation mode, controllable visible and near infrared light transmittance, a tunable switching-temperature and a high ΔT_sol of 40.9%. This work not only enriches the family of thermochromic materials, embracing broad practical applications in buildings and automobiles, but also gives new insights into the next generation of smart window technologies.