High-performance hydrovoltaic smart window fabricated via laser-assisted printing for sustainable energy-saving buildings

Laser-assisted fabrication of a high-performance multifunctional smart window. • Smart window integrating optical modulation and energy harvesting. • Superhydrophobic surface enables self-cleaning and droplet energy conversion. Although hydrogel-based smart windows are promising energy-saving building components, they suffer from contamination-induced performance degradation and limited functionality. In this study, we report a zero-energy-consumption hydrovoltaic smart window (ZEC-HSW) that structurally combines optical regulation, self-cleaning, and droplet-induced energy harvesting. Owing to the reversible phase transition, the ZEC-HSW autonomously switches between transparent and opaque states, achieving a high visible transmittance modulation (ΔT vis  = 61.8%) and a large solar modulation ability (ΔT sol  = 46.3%). The bioinspired superhydrophobic surface (WCA ≈ 153°, WSA ≈ 3°) enables effective self-cleaning while being intrinsically coupled with raindrop-driven hydrovoltaic energy conversion, delivering an instantaneous voltage of ~30 V with stable output over 10,000 s. Thermal experiments and building simulations demonstrate a 7.5 °C reduction in indoor temperature, accompanied by average decreases of 34.66% in cooling energy consumption and 1756 kg in carbon emissions. This work establishes an integrated smart window strategy that unifies passive optical regulation, environmental self-maintenance, and droplet-enabled energy harvesting, offering a scalable strategy for sustainable buildings. Download: Download high-res image (271KB) Download: Download full-size image