# Longwave-transparent low-emissivity material

## TL;DR

A new all-dielectric material allows for energy savings while enabling wireless communication and thermal insulation, supporting sustainable and smart applications.

## Contribution

The introduction of a scalable, all-dielectric longwave-transparent low-e material with ultra-broadband transmittance and multiple functionalities.

## Key findings

- The material achieves 41.1% energy savings over commercial white paint.
- It enables high-speed wireless communication and noninvasive terahertz screening.
- The material supports wireless energy transfer with thermal insulation.

## Abstract

Low-emissivity (low-e) materials are crucial for conserving thermal energy in buildings, cold chain logistics, and transportation by minimizing unwanted radiative heat loss or gain. However, their metallic nature intrinsically causes severe longwave attenuation, hindering their broad applications. Here, we introduce an all-dielectric longwave-transparent low-e material (LLM) with ultra-broadband, high transmittance spanning nine orders of magnitude, from terahertz to kilohertz frequencies. This meter-scale LLM not only achieves energy savings of up to 41.1% over commercial white paint and 10.2% over traditional low-e materials but also unlocks various previously unattainable capabilities including high-speed wireless communication in energy-efficient buildings, wireless energy transfer with radiative thermal insulation, as well as noninvasive terahertz security screening and radio frequency identification in cold chain logistics. Our approach represents a photonic solution toward carbon neutrality and smart city development, paving the way for a more sustainable and interconnected future.

A scalable all-dielectric low-emissivity longwave-transparent material enables synergetic thermal and information management.