Non-pre-irradiation multicolor mechanoluminescence in piezoelectric Ca3Ga4O9 for secure channel encryption

Mechanoluminescence (ML) materials as a special type of energy conversion medium play an important role in a wide range of fundamental applications. However, in numerous previously investigated ML host systems, effective activation of ML was typically confined to limited types of luminescent centers, seriously restricting the emission spectral diversity form a single system. Additionally, a significant proportion of the ML materials identified to date necessitate pre-irradiation with light to acquire ML capabilities. These limitations considerably restrict the practical application of ML in real-world scenarios. Herein, a mechanical-energy-driven piezoelectric gallate system (Ca 3 Ga 4 O 9 ) was identified as a promising ML matrix due to its non-pre-irradiation activation properties and excellent lanthanide ion holding capacity. Under non-pre-irradiation conditions, tunable and extended ML spectral domain from violet to near infrared was realized in the designed lanthanide ions activated Ca 3 Ga 4 O 9 (Ca 3 Ga 4 O 9 :Ln 3+ ) compounds. Through systematic experimental investigations and theoretical modeling, the underlying mechanism of the ML has been elucidated. It is revealed that the non-pre-irradiation multicolor ML phenomena fundamentally originate from the synergistic contribution of triboelectric and piezoelectric effects. These developed Ca 3 Ga 4 O 9 :Ln 3+ composites based on ML display intriguing potential application in aviation secure channel encryption, allowing security access control encryption with improved security performance.