Low-emissivity fine-tuning of efficient VO2-based thermochromic stacks with silver nanowire networks†

Abstract

In response to the urgent need for environmentally sustainable alternatives to combat climate change, considerable attention has been directed towards the development of functional materials for energy management. Among these, thermochromic-based smart windows have emerged as a significant area of interest due to their ability to dynamically and passively regulate the amount of sunlight entering a building while maintaining consistently high visible transmittance. Additionally, low thermal emissivity is crucial for energy efficiency in cold climates. In this theoretical study, we numerically explore the application of silver nanowire networks as a low infrared emissivity coating to enhance the performance of VO₂-based thermochromic multilayer stacks. We propose a highly efficient thermochromic stack capable of achieving a luminous transmittance of 79% and a solar modulation ability of 15.7%, while simultaneously exhibiting an infrared emissivity as low as 8%. Via the addition of the Ag NW network, we show that it is also possible to reduce the emissivity of VO₂ nanoparticle-based stacks up to 20% while keeping a FOM higher than 0.01, which we show is not possible by using a Ag thin film alone.