Active and passive modulation of solar light transmittance in a uniquely multifunctional dual-band single molecule for smart window applications

Functional materials may change color by heat and electricity separately or simultaneously in smart windows. These materials have not only demonstrated remarkable potential in the modulation of solar radiation but are also leading to the development of indoor environments that are more comfortable and conducive to improving individuals' quality of life. Unfortunately, dual-responsive materials have not received ample research attention due to economic and technological challenges. As a consequence, the broader utilization of smart windows faces hindrances. To address this new generational multi-stimulus responsive chromic materials, our group has adopted a developmental strategy to create a poly(NIPAM)_n-HV as a switchable material by anchoring active viologen (HV) onto a phase-changing poly(NIPAM)_n-based smart material for better utility and activity. These constructed smart windows facilitate individualistic reversible switching, from a highly transparent state to an opaque state (thermochromic) and a red state (electrochromic), as well as facilitate a simultaneous dual-stimuli response reversible switching from a clear transparent state to a fully opaque (thermochromic) and orange (electrochromic) states. Absolute privacy can be attained in smart windows designed for exclusive settings by achieving zero transmittance. Each unique chromic mode operates independently and modulates visible and near-infrared (NIR) light in a distinct manner. Hence, these smart windows with thermal and electric dual-stimuli responsiveness demonstrate remarkable heat regulation capabilities, rendering them highly attractive for applications in building facades, energy harvesting, privacy protection, and color display.