Pressure- and Rate-Dependent Mechanoluminescence with Maximized Efficiency and Tunable Wavelength in ZnS: Mn²⁺, Eu³⁺

Abstract

Mechanoluminescence (ML) has received widespread attention because of potential application in stress sensors and imaging. However, pursuing highly efficient ML remains a challenge due to multifactorial limitations such as pressure and loading rate. Here, we systematically investigate pressure-and ratedependent ML in Mn 2+ and Eu 3+ co-doped ZnS in a gigapascal pressure range by using a high-pressure dynamic diamond anvil cell and microsecond time-resolved fluorescent methods and demonstrate the giant tunability in both ML efficiency and wavelength. Compressed from ambient pressure to 11 GPa at different compression rates, ZnS: Mn 2+ , Eu 3+ exhibits a volcano shape in ML emission efficiency with an optimum at ∼3.5 GPa and ∼211.1 GPa/s, at least 1000-fold higher than that measured in the MPa range. The pressure-dependent ML is accompanied with a tunable yellow-to-red emission color change. A combination of high-pressure X-ray diffraction and photoluminescence measurements reveals that the pressure-and ratedependent ML behavior derives from pressure-induced strengthening of the crystal piezoelectric field and enhanced interaction between the host lattice and doped ions with a significant change of the energy level of the Mn ion. Significantly, the highly efficient ML of ZnS: Mn 2+ , Eu 3+ at the GPa level is reproducible under a compression-decompression process and can be manipulated on a micron scale, implying great potential in mechanical-optical energy conversion and application in dynamic pressure imaging, stress sensors, and multicolor displays.

Temperature and pressure dependent luminescence mechanism of a zinc blende structured ZnS:Mn nanophosphor under UV excitation

“…The sample retained its initial bright orange luminescence after the complete release of pressure, compared to the irreversible phase transition of the ZnS:Mn 2+ phosphor with a wurtzite structure. 49,63 The milliseconds decay times also confirm the perfect incorporation of Mn 2+ ions inside the host lattice and show that the multi-exponential Mn 2+ decay time is influenced by both pressure and temperature.…”

Tunable broadband near-infrared luminescence from Cr3+-doped gallium oxide-based phosphors for advanced sensing and LED applications

“…In this mechanism, the degenerate level splits, while the other energy levels exhibit greater splitting by the addition of [Zn 2+ –Ge 4+ ] unit substitution (negligible center-of-mass shift). 35 This splitting allows the excited electron to relax to a lower energy level, which produces a red-shifted emission spectrum and frequency band spreading, but the excitation energy nearly keeps constant. 36…”

Color-resolved mechanoluminescence of Eu and Mn co-doped SrMg2(PO4)2

“…15,16 In addition, the variation of ratiometric ML intensity could lead to a change in ML color, which makes stress sensing more intuitive and visually appealing. 17,18 For instance, Guo et al achieved a stress-induced ML color change from cyan to orange in MgF 2 :Yb 2+ ,Mn 2+ as a means of monitoring the structural safety. 19 Similarly, Wu et al reported a Lu 3 Al 2 Ga 3 O 12 :Tb 3+ ML material, where the electron transition of the Tb 3+ ion from 5 D 3 → 7 F 6-4 and 5 D 4 → 7 F 6-0 contributed two different emission bands respectively, and the ML color varied with the applied stress.…”