Abstract

A great deal of attention has been given to reducing the levels of infrared (IR) light entering automobiles and buildings in relation to energy-saving technology. The present use of thermal-shielding methods cuts IR radiation not by absorption, but through reflection in an effort to decrease re-radiation of heat indoors. Recent demands for thermal-shielding materials require visible and microwave transmissions with high heat-ray reflections. However, these films are unable to fully transmit electromagnetic waves in the microwave range, which are currently difficult to employ in window applications. Recently, IR plasmonic excitations on film surfaces have been observed on transparent oxide semiconductors. The sub-wavelength nanostructures are capable of supporting local surface plasmon resonances, which provide a novel concept of thermal-shielding. In this presentation, we employ experimental and theoretical approaches to report on the plasmonic properties of assembled films of ITO NPs. We show that the selective light reflections in the IR range are based on plasmon hybridizations due to field interactions induced at inter-nanoparticle gaps, and which are demonstrated by changes in the structural size of the NPs. We also focus our attention on the field interactions of .E-fields along the in-plane and out-of-plane directions in an effort to account for the matter by which the assembled films facilitate high IR reflectance. This study provides new insights for the enhancement of heat-insulating capability.

© 2017 Japan Society of Applied Physics, Optical Society of America