Solar-powered Ba₅(PO₄)₃F:Mn⁵⁺ phosphors for passive satellite positioning and temperature sensing

As satellite computing capabilities and satellite-ground communications advance, on-orbit power supply shortages are increasingly a limiting factor, making passive devices a key aerospace research direction. Herein, we report a solar-powered near-infrared (NIR) phosphor compatible with Starlink, Qianfan, and other satellite constellations. This phosphor could achieve autonomous NIR emission with zero-power operation on satellites and serve as an optical beacon to support passive NIR positioning, eliminating exclusive reliance on BeiDou and GPS and providing an innovative technical alternative for satellite navigation. Specifically, the Ba₅(PO₄)₃F:Mn⁵⁺ phosphor shows a broad absorption band in the 500-900 nm range, well matched to the solar spectrum. Under sunlight excitation, it exhibits a narrow NIR emission band centered at 1174 nm with an FWHM of 9.5 nm. Based on the temperature-dependent intensity ratio of the dual emissions at 1174 nm and 1228 nm, we fabricated a solar-powered passive luminescent thermometer, achieving a maximum relative sensitivity of 0.83% K^-1 at 429 K. This study opens a new route for passive satellite positioning and temperature monitoring, holding great significance for advancing passive device innovation in the aerospace field.