Unraveling Mechanoluminescent Mechanisms in Doped CaZnOS Materials: Co-Mediation of Trap-Controlled and Non-Trap-Controlled Processes

Doped CaZnOS materials show great potential for mechanoluminescence (ML) applications spanning the ultraviolet-visible-near infrared (UV–vis–NIR) range. However, conflicting reports regarding the generation and reproducibility of ML hinder the understanding and practical utilization of these materials. To address this issue, a comprehensive characterization strategy combining NIR laser-assisted de-trapping, UV irradiation-induced trap-filling, in situ mechanical stimulation, and continuous ML recording is proposed. Herein, the ML behaviors of four representative doped CaZnOS materials (Mn²⁺, Bi³⁺, Er³⁺, and Ce³⁺) are investigated using this approach. The results reveal that de-trapped materials exhibit non-trap-controlled ML, wherein ML intensity gradually weakens under successive mechanical stimuli without self-recovery. In contrast, trap-filled materials demonstrate both trap-controlled ML and non-trap-controlled ML, with the former predominantly contributing to the overall ML intensity. Notably, trap-controlled ML shows only partial recovery after trap filling. The non-trap-controlled ML is attributed to plastic ML and destructive ML phenomena, while explaining trap-controlled ML through the carrier de-trapping model. These results not only clarify conflicting reports but also provide clear insights into the ML properties and mechanisms of CaZnOS-based materials, facilitating advancements in practical applications. Furthermore, the developed characterization strategy is expected to serve as a valuable reference for establishing standardized protocols to evaluate ML performance.