Dual‐Rare‐Earth‐Doped Piezoelectric Semiconductor Gallate Solids With Spectral Tuning for Energy Conversion and Photonic Applications

ABSTRACT Mechanoluminescent materials have gained significant attention for their unique capability to convert mechanical stimuli into light without external optical or electrical excitation, holding immense promise for applications in safety monitoring, biomedicine, optical anti‐counterfeiting, and intelligent sensing. However, current mechanoluminescent materials are hindered by limitations such as a single functional mode, a restricted emission color gamut, and poor stability. To address these challenges, we report a layered piezoelectric semiconductor, (Sr, Ca)Ga 4 O 7 host doped with dual rare‐earth activators Tb 3+ and Eu 3+ , which enables unprecedented multimodal luminescence responsiveness to mechanical force, UV light, X‐rays, and temperature within a single crystalline framework. By precisely tuning the Tb 3+ /Eu 3+ doping ratio, the material achieves continuously adjustable photoluminescence, mechanoluminescence, and X‐ray‐excited photoluminescence spectra across the green‐to‐red color gamut. Notably, the material demonstrates an ultralow mechanoluminescence activation threshold (≤ 10 kPa) and exhibits millisecond‐level response kinetics. A series of potential applications, including digital information encryption, high‐precision handwriting identification, modern motion analysis, and imaging detection, are designed based on its multimodal luminescence. This work establishes a paradigm for designing multifunctional luminescent materials through piezoelectric‐semiconductor‐rare‐earth synergy.