An Assisting Contact Electrification Strategy for Achieving Self-Recoverable Mechanoluminescence

Self-recoverable mechanoluminescence (ML) is a unique property of materials that can stably emit light under repeated stress, enabling new applications in smart sensing, displays, and wearable devices. However, self-recoverable ML is very rare and only observed in a few active phosphors excited by piezoelectricity or contact electrification. Herein, we present an assisting contact electrification strategy that can enable inactive phosphors inherently lacking ML to achieve self-recoverable ML. A typical illustration demonstrates that commercially available LaPO₄: Tb³⁺, Ce³⁺ phosphor lacks piezoelectrically excited ML. No ML of Tb³⁺ is excited in polydimethylsiloxane (PDMS), apart from the ML of LaPO₄ host. Accordingly, we introduce strongly electrifiable fluoride into PDMS to induce contact electrification, thereby successfully assisting in the excitation of self-recoverable ML of Tb³⁺ from the inactive LaPO₄: Tb³⁺, Ce³⁺. This case illustrates that, based on the assisting contact electrification strategy, the originally rare self-recoverable ML may become a universal property of all phosphors.