Self-powered Smart Window Based on Droplet-based Electricity Generator

Abstract

The discovery of fossil fuel has made a qualitative leap in human civilization, but also brought huge danger for human future. In the past two centuries, the ever-increasing energy consumption, especially the fossil energy, has brought about series of severe climatic problems such as global warming, which has been the biggest challenge for human sustainability. Among them, around 30%~ 40% attributes to the building energy consumption and the proportion is still rising with the expanding use of heating, ventilation, and air-conditioning.

Glass windows, as the main channel for heat exchange between the indoor and outdoor, occupied more than half of the heat flow. Developing smart windows, that enables the scientific regulation of heat flow, is of great significance to reduce the building energy consumption. In this thesis, aiming at the energy-efficient smart window, we design and manufactured thermochromic smart window, and self-powered smart window, allowing for the efficient regulations for solar energy in a fully energy-efficient mode.

First, this thesis introduced four different kinds of smart windows, the underlying transformation mechanism and summarized the recent progress around smart window, especially for the self-powered smart window.

Second, aiming at thermochromic smart window based on ultra-stable vanadium oxide materials. we developed a facile one-step hydrothermal process that allows to synthesize high-purity VO₂(M/R) nanoparticles with various morphologies such as nanorods, nanogranules, nanoblocks, and nanospheres. W dopants are successfully implanted in VO₂(M/R) unit cells with high doping efficiency, which allows to regulate the size, morphology, and phase of obtained nanoparticles. The underlying regulation mechanism is presented in detail to reveal how hydrothermal products vary with W doping contents, which provides a synthetic strategy for the preparation of shape controlling VO₂(M/R) nanoparticles with high purity to satisfy different specific demands for corresponding applications in the field of thermochromic smart windows.

Third, we developed a fully self-powered CLC-SW is by leveraging droplet-based electricity generator (DEG) as a spontaneous and sustained energy reservoir, in which DEG has superior capacities to harvest ceaseless energy from ambient environment and circumvent any additional electrical power input. It is demonstrated that DEG-driven CLC-SW exhibits a rapid response and high tunability in the transformation between the transparent state and the hazy state in a wide range of solar spectrum. Moreover, both the transparent and hazy modes can be self-sustained for a long time, also be reversibly switched by the gentle mechanical pressure loading. The DEG-driven smart window developed in this work can find applications such as indoor temperature modulation and privacy information protection.

In summary, we developed a series of energy-efficient smart window that enables efficient regulation of the solar energy in a fully self-powered mode. We believe our research can inspire a new research path towards fully self-power smart window by integrating the nanogenerator and phase-change materials.

Date of Award	15 Dec 2022
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Zuankai WANG (Supervisor)