All-Lanthanide Mechanoluminescence from Transparent Ln-doped MgF₂@Elastomer for Flexible and Stretchable Lighting and Stress Sensing

Mechanoluminescent materials have gained considerable attention over the past two decades because of their ability to convert wasted mechanical actions, such as friction and compression, into useful light energy. Despite great advances in this field, host matrices that are considered for immobilizing luminescent centers to realize mechanoluminescence are limited mainly to sulfides, oxysalts, and oxysulfides to some extent. To address this shortcoming, a new series of mechanoluminescent materials, i.e., lanthanide-doped MgF2 (Lanthanide = Yb-3+,Yb-2+, Tm3+, Dy3+, Tb3+, Eu-3+,Eu-2+, Sm3+, Ho3+, and Er3+) are presented. Upon stimulation with external mechanical stress, all the materials exhibit mechanoluminescence, covering the spectral range of 385 to 1000 nm. Based on this and transparent Ln-doped MgF2@Elastomer, the potential value of these mechanoluminescent materials in dynamic pressure visualization is expanded for certain new applications, such as bungee jumping and trampolining. These findings are expected to provide valuable information to the materials community.