Metallic Degenerately Doped Free-Electron-Confined Plasmonic Nanocrystal and Infrared Extinction Response

Abstract

In this paper, synthetically scaled-up degenerately n-type doped indium tin oxide (Sn:In2O3) nanocrystals are described as highly transparent conductive materials possessing both optoelectronic and crystalline properties. With tin dopants serving as n-type semiconductor materials, they can generate free-electron carriers. These free electrons, vibrating in resonance with infrared radiation, induce strong localized surface plasmon resonance (LSPR), resulting in efficient infrared absorption. To commercialize products featuring Sn:In2O3 with localized surface plasmon resonance, a scaled-up synthetic process is essential. To reduce the cost of raw materials during synthesis, we aim to proceed with synthesis in a large reactor using industrial raw materials. Sn:In2O3 can be formulated into ink dispersed in solvents. Infrared-absorbing ink formulations can capitalize on their infrared absorption properties to render opaque in the infrared spectrum while remaining transparent in the visible light spectrum. The ink can serve as a security ink material visible only through infrared cameras and as a paint absorbing infrared light. We verified the transparency and infrared absorption properties of the ink produced in this study, demonstrating consistent characteristics in scaled-up synthesis. Due to potential applications requiring infrared absorption properties, it holds significant promise as a robust platform material in various fields.