Pressure- and Rate-Dependent Mechanoluminescence with Maximized Efficiency and Tunable Wavelength in ZnS: Mn<sup>2+</sup>, Eu<sup>3+</sup>
Hao Wang, Xiaohui Chen, Junlong Li, Mei Li, Ke Liu, Dongliang Yang, Shang Peng, Tingting Zhao, Bohao Zhao, Yanchun Li, Yonggang Wang, Chuanlong Lin, Wenge Yang
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 rate-dependent 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 rate-dependent 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.