A Low-Voltage Multi-Band Tunable Smart Window for Self-Adaptive Thermoregulation

As a crucial smart window technology, polymer-dispersed liquid crystal (PDLC) faces two major performance limitations in applications: high driving voltage and limited spectral regulation. Herein, we develop a PDLC-based smart window that operates at low voltage and enables multi-band modulation. By incorporating p-n heterojunction nanoparticles, the electro-optical performance of the PDLC film is significantly enhanced. Specifically, a 35.1% reduction in saturation voltage (to 16.3 V) and an increased contrast ratio of 130 were achieved at a film thickness of 20 µm. Subsequent integration of W-VO₂/PMMA resulted in a V-PDLC smart window. The resulting device demonstrates switchable long-wave infrared emissivity (ε_LWIR = 0.75 at high temperature; ε_LWIR = 0.41 at low temperature), enabling passive radiative cooling while maintaining high visible light transmittance and efficient near-infrared modulation. Field test and energy simulations confirmed that the system not only provides effective temperature regulation (approximately 8°C cooling during the day and 2°C insulation at night) but also demonstrates significant energy-saving potential across various climatic zones. This research offers valuable insights for developing smart windows with adaptive and on-demand adjustment capabilities.