Ultrastable Silica-Confined CsSnI₃ Perovskite Nanocrystals for Noncontact Near-Infrared Light Communication and Sunlight–Thermal–Electric Conversion

Conventional infrared photothermal materials (IR-PTMs) face significant challenges regarding environmental stability and complex synthesis, limiting their practical applications. In this work, we report silica-confined CsSnI₃ perovskite nanocrystals (CsSnI₃@silica NCs) via a simple solid-state calcination method. The silica-confined structure endows CsSnI₃@silica NCs with a high near-infrared (NIR) photothermal performance and environmental stability. Accelerated aging tests under high humidity, high temperature, and intense NIR irradiation demonstrate the better stability of CsSnI₃@silica NCs compared to unconfined CsSnI₃ powders and commercial graphene IR-PTM. A noncontact NIR light communication system is designed by combining CsSnI₃@silica NC-based photothermal imaging with machine learning. This system achieves 99.7% accuracy in recognizing symbol (letters and numbers) images written by NIR light and enables robotic arm manipulation for noncontact human-robot interaction. Furthermore, incorporating these CsSnI₃@silica NCs as a light-absorption layer in a sunlight-thermal-electric conversion system can enhance the output voltage by over 350% throughout a continuous six-month outdoor exposure period.