Photoluminescence of polysiloxane-immobilized lignin-modified wood toward color-tunable and ultraviolet protective smart window

Abstract

Smart windows can benefit from the use of photochromic wooden materials. In the current study, we report the preparation of fluorescent wood that can switch color under visible and ultraviolet lighting conditions. In order to develop a transparent wood that is both fluorescent and photochromic, a mixture of europium and dysprosium activated strontium aluminum oxide (EDSA) nanoparticles (NPs; 8–13 nm) and room-temperature vulcanizing (RTV) silicone rubber (Polysiloxane) was integrated into a delignified wood. EDSA is known for its excellent photostability and thermal stability. The EDSA phosphor has to be efficiently dispersed in RTV to avoid the formation of aggregates, allowing for a better fabrication of colorless wood. The coloration findings from the CIE Lab parameters displayed that when illuminated with ultraviolet rays, this colorless wooden substrate turned green. Using a transmission electron microscope (TEM), the morphological properties of the synthesized EDSA NPs were examined. Various analysis techniques, including elemental mapping, energy-dispersive X-ray (EDX), X-ray fluorescence spectroscopic analyzer (WDXRF), scanning electron microscope (SEM), hardness testing, and photoluminescence spectra, were employed to study the photochromic woods. An absorption band (365 nm) and two emission bands (436 nm and 518 nm) were determined for the prepared photoluminescent woods. When increasing the EDSA content, the results showed that the produced EDSA-infiltrated wood was more water-resistant and highly protective against UV radiation. Reversible photochromic responsiveness to UV light was observed for the prepared transparent luminous wood without fatigue.