Contact electrification induced mechanoluminescence

Mechanoluminescence (ML) is a luminescence response to mechanical stimuli that shows a variety of significant applications. It is generally believed that ML is due to piezoluminescence in asymmetric piezoelectric materials, but this model encounters difficulties in explaining the ML for centrosymmetric nonpiezoelectric materials, especially the Lu3Al5O12: Ce3+/PDMS elastomer with ultrastrong nonpreirradiation ML. This theoretical problem has become the prominent dark cloud in the sky of the ML field. This work reveals for the first time that the ML for the centrosymmetric Lu3Al5O12: Ce3+/PDMS elastomer is essentially induced by contact electrification. According to contact electrification, an electron-cloud model of contact electrification is successfully established to understand the ML mechanism for the elastomer. This demonstrates that contact electrification arising from the interaction of two dissimilar surfaces creates a broadband excitation energy, which directly excites the luminescence levels to emit ML. Accordingly, the unique ML properties of the centrosymmetric Lu3Al5O12: Ce3+/ PDMS elastomer that cannot be explained by piezoelectricity can be well understood by contact electrification. Particularly, these results also inspire us to have reasonable new insight into the trap-dependent piezoluminescence mechanism for typical SrAl2O4: Eu2+ and ZnS: Cu/Mn2+ materials.

Automated summary

Mechanoluminescence (ML) is a luminescence response to mechanical stimuli with significant applications. This study reveals that ML in centrosymmetric elastomers is essentially induced by contact electrification. Contact electrification creates a broadband excitation energy, which directly excites luminescence levels to emit ML. These findings also provide new insight into the piezoluminescence mechanism in materials like SrAl2O4: Eu2+ and ZnS: Cu/Mn2+.