Session: 02-07: Sustainable Buildings, Communities, and Cities

Paper Number: 130271

130271 - Luminescent Transparent Wood With Exceptional Optical Transparency and Robust Photoluminescence 

Abstract: 

Transparent wood-based functional materials have garnered significant attention across various applications due to their outstanding optical, mechanical, and thermal properties, as well as their environmentally friendly nature. Recently, luminescent transparent wood incorporating luminophores has been developed for purposes such as general lighting and optical sensing. However, the existing endeavors still have room for improvement in terms of their optical and photoluminescence properties, which are crucial for further enhancing their environmental and energy benefits in other application scenarios.

In this work, a luminescent transparent wood with exceptional optical transparency and robust photoluminescence is demonstrated. To achieve this, CdSe/ZnS quantum dots (QDs) are employed as the luminophore due to their high quantum yield (~95%) and photo-stability. Besides, thiol-ene (OSTE) is selected as the polymer matrix to develop the transparent wood template, as it offers the advantages of reducing the haze of transparent wood and enhancing the ensemble quantum yield of polymer-QD composite systems. Notably, the fabrication methods of this luminescent transparent wood are simple and scalable where the natural balsa wood undergoes a UV-assisted lignin-modification process, resulting in the optically-white and mechanically-strong wood template, which enables the subsequent polymer impregnation. The CdSe/ZnS QD is dispersed in OSTE consisting of the stoichiometric mixture of thiol and alkene monomers. The thorough impregnation of the OSTE-QD mixture into the highly porous lignin-modified wood template not only brings about effective polymer-wood bonding which leads to high optical transparency, but also enables efficient light trapping and re-emission of the QD photoluminescence. More specifically, the resultant luminescent transparent wood composite exhibits exceptional optical transparency (i.e., luminous transmittance τ_lum = 78.2%) and strong photoluminescence (i.e., relative quantum yield QY = 38.8%), manifesting its potential for advanced photoelectrical applications, such as luminescent solar concentrators (LSCs) when integrated with side-mounted solar cells for solar-harvesting and electricity-generating photovaltaic windows. Moreover, the luminescent transparent wood also demonstrates remarkable mechanical strength (i.e., tensile strength σ_tens = 40.4 MPa) and excellent thermal insulation capabilities (i.e., thermal conductivity K = 0.175 W/(m⋅K)), contributing to building energy efficiency, thermal management, and safety considerations.

In summary, the luminescent transparent wood presented in this study holds great promise as a candidate for luminescent solar-concentrating photovoltaic windows, representing a significant breakthrough in the field of sustainable building-integrated photovoltaics (BIPV) and energy-efficient windows. The material's exceptional optical transparency, robust photoluminescence, high mechanical strength, effective thermal insulation, and environmental friendliness synergistically contribute to the advancement of building energy-efficient technologies. By harnessing these properties, this innovative solution offers a promising pathway toward a sustainable future. 

Presenting Author: Yuwei Du City University of Hong Kong

Presenting Author Biography: PhD student in School of Energy and Environment, City University of Hong Kong.
MSc in Intelligent Building Technology and Management, BEng in Building Service Engineering.
Research interest in energy-efficient and sustainable smart window technologies (thermochromic, photovoltaic, and luminescent) for solar regulation and harvesting.
Previous research experiences in perovskite thermochromic smart windows, and transparent-wood for smart window applications.

Authors:

Yuwei Du City University of Hong Kong
Chi Yan TSO City University of Hong Kong
Sai Liu City University of Hong Kong