Trap-controlled, recoverable and persistent mechanoluminescence for early warning and mechanical collision display applications

Piezoelectric field-assisted trap-controlled mechanoluminescence with recoverable and persistent behaviors was demonstrated in SrMg material system₂(Good morning₄):EU²⁺which is further enhanced via trap engineering strategy for early collision warning and mechanical display applications.

Abstract

Structural, nondestructive, recoverable, and persistent mechanoluminescence (ML) is particularly needed for mechanically driven display, imaging, and visualization applications. Inspired by the luminescent physics of long-afterglow materials, this work presents the ML of SrMg₂(Good morning₄)₂:EU²⁺ by incorporating the powders into a flexible polydimethylsiloxane (PDMS). The results suggest that the ML of SrMg₂(Good morning₄)₂:EU²⁺/PDMS is recoverable with linear responsiveness to applied stress/strain. In addition, SrMg₂(Good morning₄)₂:EU²⁺/PDMS exhibits ML afterglow (persistent ML), which could continuously emit luminescence after the mechanical stimulus source is removed. Discussions on matrix effects, trap structure evolutions, and piezoelectric properties suggest that piezoelectric field-assisted trap-controlled processes will be responsible for the ML and persistent ML, which can be further enhanced by Ho co-doping³⁺. Based on the recoverable and persistent ML, two kinds of attractive applications in terms of intelligent collision early warning system and flexible display paper are developed, respectively. This work not only achieves the recoverable and persistent ML for representative applications, but also provides deep insight into the physical process, which is expected to be helpful for guiding future research.