Mechanoluminescent Aluminum Nitride Crystal for Super-Sensitive Optical Manometry, Thermometry and Force Sensing.

AlN is a core material widely used as a substrate and heat sink in various electronic and optoelectronic devices. Introducing luminescent properties into intrinsic AIN opens new opportunities for next-generation intelligent sensors, self-powered displays, and wearable electronics. In this study, the first evidence is presented of AlN crystals exhibiting satisfactory mechanoluminescence (ML), photoluminescence (PL), and afterglow performance, demonstrating their potential as novel multifunctional optical sensors. A series of undoped AlN crystals (ranging from µm to mm scale) is successfully synthesized on tungsten substrates via physical vapor transport. A multimodal optical sensing platform is developed, showing afterglow and PL for temperature and pressure sensing, and ML for force detection. Despite minimal structural deformation under extreme conditions, attributed to the high bulk modulus of AIN, the optical sensors, driven by intrinsic defect-related emissions, exhibited excellent sensitivity to temperature and pressure. Notably, significant and previously unreported differences in the PL and ML spectra are observed in response to light and mechanical stimuli, respectively. These spectral variations are attributed to the activation of distinct defect states during PL and ML processes. This proof-of-concept study represents a significant step forward in the development of optical sensing technologies for extreme environments and force detection applications.