Molten Salt Shielded Synthesis of Monodisperse Layered CaZnOS-Based Semiconductors for Piezophotonic and X-Ray Detection Applications.

CaZnOS-based semiconductors are the only series of material system discovered that can simultaneously realize a large number of dopant elements to directly fulfill the highly efficient full-spectrum functionality from ultraviolet to near-infrared under the same force/pressure. Nevertheless, owing to the high agglomeration of the high temperature solid phase manufacturing process, which is unable to control the crystal morphology, the application progress is limited. Here, the authors report first that CaZnOS-based fine monodisperse semiconductor crystals with various doping ions are successfully synthesized by a molten salt shielded method in an air environment. This method does not require inert gas ventilation, and therefore can greatly reduce the synthesis cost and more importantly improve the fine control of the crystal morphology, along with the crystals' dispersibility and stability. These doped semiconductors can not only realize different colors of mechanical-to-optical energy conversion, but also can achieve multicolor luminescence under low-dose X-ray irradiation, moreover their intensities are comparable to the commercial NaI:Tl. They can pave the way to the new fields of advanced optoelectronic applications, such as piezophotonic systems, mechanical energy conversion and harvesting devices, intelligent sensors, and artificial skin as well as X-ray applications.

Bright Circularly Polarized Mechanoluminescence from 0D Hybrid Manganese Halides.

Hybrid metal halides (HMHs) with efficient circularly polarized luminescence (CPL) have application prospects in many fields, due to their abundant host-guest structures and high photoluminescence quantum yield (PLQY). However, CPLs in HMHs are predominantly excited by light or electricity, limiting their use in multivariate environments. It is necessary to explore a novel excitation method to extend the application of chiral HMHs as smart stimuli-responsive optical materials. In this work, an enantiomeric pair of 0D hybrid manganese bromides, [H2(2R,4R)-(+)/(2S,4S)-(-)-2,4-bis(diphenylphosphino)pentane]MnBr4 [(R/S)-1] is presented, which exhibits efficient CPL emissions with near-unity PLQYs and high dissymmetry factors of ± 2.0 × 10-3. Notably, (R/S)-1 compounds exhibit unprecedented and bright circularly polarized mechanoluminescence (CPML) emissions under mechanical stimulation. Moreover, (R/S)-1 possess high mechanical force sensitivities with mechanoluminescence (ML) emissions detectable under 0.1 N force stimulation. Furthermore, this ML emission exhibits an extraordinary antithermal quenching effect in the temperature range of 300-380 K, which is revealed to originate from a thermal activation energy compensation mechanism from trap levels to Mn(II) 4T1 level. Based on their intriguing optical properties, these compounds as chiral force-responsive materials are demonstrated in multilevel confidential information encryption.

Modulating Smart Mechanoluminescent Phosphors for Multistimuli Responsive Optical Wood.

Mechanoluminescence is a smart light-emitting phenomenon in which applied mechanical energy is directly converted into photon emissions. In particular, mechanoluminescent materials have shown considerable potential for applications in the fields of energy and sensing. This study thoroughly investigates the mechanoluminescence and long afterglow properties of singly doped and codoped Sr2 MgSi2 O7 (SMSO) with varying concentrations of Eu2+ and Dy3+ ions. Subsequently, a comprehensive analysis of its multimode luminescence properties, including photoluminescence, mechanoluminescence, long afterglow, and X-ray-induced luminescence, is conducted. In addition, the density of states mapping is acquired through first-principles calculations, confirming that the enhanced mechanoluminescence properties of SMSO primarily stem from the deep trap introduced by Dy3+ . In contrast to traditional mixing with Polydimethylsiloxane, in this study, the powders are incorporated into optically transparent wood to produce a multiresponse with mechanoluminescence, long afterglow, and X-ray-excited luminescence. This structure is achieved by pretreating natural wood, eliminating lignin, and subsequently modifying the wood to overall modification using various smart phosphors and epoxy resin composites. After natural drying, a multifunctional composite wood structure with diverse luminescence properties is obtained. Owing to its environmental friendliness, sustainability, self-power, and cost-effectiveness, this smart mechanoluminescence wood is anticipated to find extensive applications in construction materials and energy-efficient displays.

Smart Mechanoluminescent Phosphors: A Review of Strontium-Aluminate-Based Materials, Properties, and Their Advanced Application Technologies.

Mechanoluminescence, a smart luminescence phenomenon in which light energy is directly produced by a mechanical force, has recently received significant attention because of its important applications in fields such as visible strain sensing and structural health monitoring. Up to present, hundreds of inorganic and organic mechanoluminescent smart materials have been discovered and studied. Among them, strontium-aluminate-based materials are an important class of inorganic mechanoluminescent materials for fundamental research and practical applications attributed to their extremely low force/pressure threshold of mechanoluminescence, efficient photoluminescence, persistent afterglow, and a relatively low synthesis cost. This paper presents a systematic and comprehensive review of strontium-aluminate-based luminescent materials' mechanoluminescence phenomena, mechanisms, material synthesis techniques, and related applications. Besides of summarizing the early and the latest research on this material system, an outlook is provided on its environmental, energy issue and future applications in smart wearable devices, advanced energy-saving lighting and displays.

MgF2:Mn2+: novel material with mechanically-induced luminescence.

Mechanoluminescent (ML) materials can directly convert external mechanical stimulation into light without the need for excitation from other forms of energy, such as light or electricity. This alluring characteristic makes ML materials potentially applicable in a wide range of areas, including dynamic imaging of force, advanced displays, information code, storage, and anti-counterfeiting encryption. However, current reproducible ML materials are restricted to sulfide- and oxide-based materials. In addition, most of the reported ML materials require pre-irradiation with ultraviolet (UV) lamps or other light sources, which seriously hinders their practical applications. Here, we report a novel ML material, MgF2:Mn2+, which emits bright red light under an external dynamic force without the need for pre-charging with UV light. The luminescence properties were systematically studied, and the piezophotonic application was demonstrated. More interestingly, unlike the well-known zinc sulfide ML complexes reported previously, a highly transparent ML film was successfully fabricated by incorporating MgF2:Mn2+ into polydimethylsiloxane (PDMS) matrices. This film is expected to find applications in advanced flexible optoelectronics such as integrated piezophotonics, artificial skin, athletic analytics in sports science, among others.