Mechanoluminescence in Sr 3 P 4 O 13 Enabled by Contact Electrification‐Induced Energy Transfer

ABSTRACT Mechanoluminescence (ML) materials, capable of converting mechanical action into light emissions, hold great promise for stress‐sensing applications. However, the lack of general design principles for developing efficient and self‐powered ML materials has significantly impeded progress in this field. Herein, we report a novel class of self‐powered Sr 3 P 4 O 13 (SPO) ML materials enabled by energy transfer from electron‐hole pair recombination induced by contact electrification. Through combined analyses using piezoresponse force microscopy (PFM), thermoluminescence (TL) spectroscopy, triboelectric potential measurements, temperature‐dependent ML spectra, and density functional theory (DFT) calculations of charge density difference, the underlying ML mechanism is elucidated as contact electrification‐induced energy transfer. Systematic investigation of SPO:Bi and a series of SPO:RE (RE = Eu, Tb, Dy, Sm, Er, Tm) phosphors reveals that activator ions possessing spin‐allowed broadband absorption are favorable for achieving efficient ML, a correlation that extends consistently to radioluminescence (RL) and cathodoluminescence (CL) behaviors. Leveraging the favorable luminescence performance, we demonstrate proof‐of‐concept applications in a single material platform that integrates handwritten signature authentication, structural health monitoring, X‐ray imaging, optical temperature sensing, and multi‐stimulus information encryption. This work provides fundamental insights into contact electrification‐induced ML and establishes important design guidelines for developing efficient ML materials and their versatile applications.