A near-infrared photoelectrochromic device with indoor thermal management for self-powered smart windows

Abstract

A photoelectrochromic device (PECD) is a combination of a dye-sensitized solar cell (DSSC) and an electrochromic device (ECD) that directly generates transmittance contrast from solar radiation without an additional power source. In terms of application, PECDs have recently been utilized as self-powered smart windows for eco-friendly green buildings. The majority of PECDs have exceptional optical performance in the visible light region, with their electrochromic property regulating the indoor luminance. Nonetheless, indoor temperature regulation is also a potential opportunity that might be examined further for PECDs. As the temperature is highly correlated with the incident flux of infrared light, this study presents a near-infrared photoelectrochromic device (NIR-PECD) with WO₃ as the electrochromic material for blocking infrared radiation, realizing indoor thermal management without external power. The NIR-PECD exhibited the ability of thermal modulation and lowered the indoor temperature with a transmittance contrast in the NIR region, demonstrating a transmittance contrast (ΔT) of 40.2% and an outstanding photocoloration efficiency (PhCE) of 55.85 cm² min⁻¹ W⁻¹ at the wavelength of 1000 nm. In addition, the NIR-PECD also displayed a 5.6 °C temperature difference between the colored and bleached states, indicating the thermal management capabilities of keeping the interior cool in the colored state by blocking the NIR. As a further application, NIR-PECDs can be used as self-powered smart windows in green buildings to achieve internal temperature control without external power.