Man-Chung Wong

Magnetic‐Induced Luminescence from Flexible Composite Laminates by Coupling Magnetic Field to Piezophotonic Effect

Magnetic-induced luminescence (MIL) is realized via a strain-mediated coupling strategy. MIL composite laminates composed of magnetic actuator and phosphor phases are developed. The MIL performance is tested under low magnetic fields at room temperature. The results provide a novel type of promising luminescent and magnetic material for developing some new concept devices.

Magnetic-Assisted Noncontact Triboelectric Nanogenerator Converting Mechanical Energy into Electricity and Light Emissions.

A magnetic-assisted noncontact triboelectric nanogenerator (TENG) is developed by combining a magnetic responsive layer with a TENG. The novel TENG device is applied to harvest mechanical energy which can be converted into electricity and light emissions. This work has potential for energy harvesting, magnetic sensors, self-powered electronics and optoelectronics applications.

Temporal and Remote Tuning of Piezophotonic‐Effect‐Induced Luminescence and Color Gamut via Modulating Magnetic Field

Light-emitting materials have been extensively investigated because of their widespread applications in solid-state lighting, displays, sensors, and bioimaging. In these applications, it is highly desirable to achieve tunable luminescence in terms of luminescent intensity and wavelength. Here, a convenient physical approach of temporal and remote tuning of light-emitting wavelength and color is demonstrated, which is greatly different from conventional methods. It is shown that by modulating the frequency of magnetic-field excitation at room temperature, luminescence from the flexible composites of ZnS:Al, Cu phosphors induced by the piezophotonic effect can be tuned in real time and in situ. The mechanistic investigation suggests that the observed tunable piezophotonic emission is ascribed to the tilting band structure of the ZnS phosphor induced by magnetostrictive strain under a high frequency of magnetic-field excitation. Furthermore, some proof-of concept devices, including red-green-blue full-color displays and tunable white-light sources are demonstrated simply by frequency modulation. A new understanding of the fundamentals of both luminescence and magnetic-optics coupling is thus provided, while offering opportunities in magnetic-optical sensing, piezophotonics, energy harvesting, novel light sources, and displays.

Enhanced output power of a freestanding ball-based triboelectric generator through the electrophorus effect

The recent development of the Internet of Things and related sensor technologies has greatly impacted logistics tracking, structural health monitoring, environmental analysis, and data extraction. It is highly imperative to develop a technology to allow the sensor node to operate independently, sustainably, and in a maintenance-free way by harvesting energy from the ambient environment. Here we demonstrate a triboelectric device as a highly efficient and durable kinetic energy harvester from ubiquitous mechanical vibrations. We construct a cylinder coated with polytetrafluoroethylene (PTFE), and place a number of metal balls inside the cylinder. This ball-based triboelectric generator (B-TEG) converts the mechanical shaking into electricity. By grounding the metal-freestanding-layer, we form a new configuration (B-GTEG). The output power of B-GTEG shows an 8 fold improvement through the electrophorus effect compared with B-TEG, providing the potential for supplying sustainable power to wireless sensor nodes.

Triboelectric Nanogenerators: Magnetic-Assisted Noncontact Triboelectric Nanogenerator Converting Mechanical Energy into Electricity and Light Emissions (Adv. Mater. 14/2016).

A novel magnetic-assisted noncontact triboelectric nanogenerator (TENG) is proposed by J. H. Hao and co-workers on page 2744. By combining a magnetic-responsive layer, the TENG is remotely operated and controlled with noncontact mechanical motions that can be converted into electricity and light emissions. This work has potential for energy harvesting, magnetic sensors, self-powered electronics, and optoelectronics applications.

Magnetic-Induced Luminescence: Magnetic-Induced Luminescence from Flexible Composite Laminates by Coupling Magnetic Field to Piezophotonic Effect (Adv. Mater. 30/2015)

On page 4488, J. Hao and co-workers propose a practical approach to design and synthesize flexible polymer composites composed of a magnetic actuator and phosphor. Magnetic-induced luminescence (MIL) is shown via strain-mediated coupling, which can be modulated under a time-varying low magnetic field at room temperature. A magnetically driven light-emission pattern and a white-light source are demonstrated.