Piezoelectrically induced electron detrapping model for mechanoluminescent semiconductors: A unified theoretical and experimental perspective

Mechanoluminescence (ML) in semiconductors originates from the coupled interaction between mechanical stress, internal polarization fields, and trapped charge carriers. Rather than proposing a new mechanism, this perspective synthesizes and critically examines the existing theoretical and experimental studies that attribute stress-induced light emission to piezoelectrically assisted electron detrapping in semiconducting and phosphor materials. Emphasis is placed on frameworks developed for systems such as ZnS:Mn and ZnO, where mechanically generated piezoelectric potentials modulate trap depths, facilitate carrier release, and enable radiative recombination. By revisiting established formulations and extending their discussion to include non-uniform field distributions, multi-level trap states, and realistic defect landscapes, this perspective highlights how piezoelectric field effects can coexist with, complement, or dominate over thermal and triboelectric contributions depending on material chemistry, defect structure, temperature, and loading conditions. Comparative analysis underscores that piezoelectric assisted detrapping is particularly effective under dynamic stress and low-temperature regimes, while thermally activated processes remain robust and reliable in other contexts. Together, these insights provide a balanced interpretative framework for understanding ML across material classes and offer guiding principles for the rational design of self-powered mechanoluminescent and piezophotonic systems for stress sensing, structural health monitoring, and energy-autonomous optoelectronic applications and to identify key directions for future research.