Stress-to-Light Conversion in an Earth-Abundant Oxide Semiconductor

Stress-to-light conversion in solids represents a unique photonic functionality, yet it has never been realized in a chemically simple and sustainable material. Zinc oxide (ZnO) is an earth-abundant compound widely used in cosmetics, food supplements, paints, and medicinal products since prehistoric times. It is also a promising semiconductor for electronics and photonics owing to its high transparency, high electron mobility, and wide bandgap, more than three times that of silicon. Here, we show that the sustainable semiconductor ZnO exhibits strong near-infrared (NIR) luminescence under elastic stress when defect-engineered to stabilize a p-type state. This transformation overcomes the intrinsic n-type character of ZnO through the partial substitution of Zn²⁺ with Li⁺ or Na⁺, introducing deep-level defects that enable stress-driven NIR emission and ferroelectricity. These coupled electronic and structural effects reveal a previously unknown light-emitting function in a simple oxide lattice. Our findings establish a rare-earth-free, self-powered platform for NIR photonics, offering scalable opportunities for biophotonic signaling and infrastructure health monitoring.