Stress‐Triggered Mechanoluminescence in ZnO‐Based Heterojunction for Flexible and Stretchable Mechano‐Optics

Abstract

Owing to the forthcoming global energy crisis, the search for energy‐saving materials has intensified. Over the past two decades, mechanically induced luminescent materials have received considerable attention as they can convert waste into useful components, for instance, the conversion from stress into light. However, this material features many constraints that limit its widespread application. Herein, a strategy to improve the mechanoluminescence (ML) of ZnO by embedding it in a ZnF2:Mn2+ matrix is introduced. Upon dynamic excitation via an external stress, the reddish‐yellow ML is confirmed to originate from the 4T1 (4G) → 6A1 (6S) transition of the optically active Mn2+ center. Moreover, the sample with the strongest ML contains the appropriate amount of ZnF2 (ZnF2:ZnO = 7:3). By performing density functional theory calculations, a possible ML‐enhancement mechanism is elucidated, which indicates the formation of a ZnF2/ZnO:Mn2+ heterojunction. Considering the unique characteristics of ML, its promising applications are demonstrated in various mechano‐optics scenarios, including flexible and stretchable optoelectronics, advanced self‐powered displays, e‐skins/e‐signatures, and anti‐counterfeiting, without the use of external light/electric‐incentive sources. The study significantly increases the variety of ML materials and is expected to strengthen the foundation for the future development of smart mechanically controlled devices and energy‐saving systems.

Simultaneous NIR photoluminescence and mechanoluminescence from Cr3+ activated MgGa2O4 phosphors with multifunctions for optical sensing

“…According to the data, when Dq/ B > 2.3, the main body is a strong crystal field and 2 E → 4 A 2 of Cr 3+ ions dominates. 35–37 At this point, the NIR light exhibits narrowband emission. When Dq/ B < 2.3, indicating a weak crystal field, a 4 T 2 → 4 A 2 transition occurs, leading to broadband emission.…”

Novel Red Mechanoluminescence in Mn‐Doped ZnGa2S4 Crystal Phosphors via a Molten Salt Shielding Method

“…The results indicated that the emitted light intensity and applied stress exhibited a linear relationship, implying that ZnGa 2 S 4 : Mn 2+ can be used as a stress detection sensor, robotic tactile, and intelligent anti‐counterfeiting in diverse realms. [ 2,31,6,32 ] Figure S7, Supporting Information, shows the ML intensity of ZnGa 2 S 4 : 5% Mn synthesized by molten salt shielding method and traditional solid phase method respectively, which means the molten salt method is able to enhance the ML intensity of ZnGa 2 S 4 phosphor. The ML images under different light conditions are shown in Figure S6, Supporting Information, of the supporting material.…”

Poly(vinyl alcohol)-Modified Colloidal Silicon Nanoparticles for Flexible Screen Printing Inks and Anticounterfeiting Applications

“…Usually, counterfeit goods will use inferior products or even contain toxic and harmful raw materials, which seriously jeopardize people’s health and disrupt the market order. As a result, various anticounterfeiting technologies have emerged, such as radio frequency technology, laser holograms, and watermarks. − However, most of these technologies require a high cost and complex equipment. Therefore, low-cost and easy-to-implement screen printing technology has gradually attracted people’s attention.…”