Our research interests span the fields of solid-state electronics, photonics and optoelectronics, and nanomanufacturing. Our team explores novel nanomaterials for next-generation optical and electronic applications, including integrated optical devices, sensors and actuators, and energy harvesting. Below are some research highlights.
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Mechanically Flexible Mid-Infrared Imagers
Demonstrated mechanically flexible mid-infrared images using 2D ink films (Nat. Commun., 2025). We present flexible MWIR imagers consisting of photodiodes fabricated on thin plastic substrates using BP ink films. We demonstrate mechanically robust responsivity up to 2.5-mm bending radii and after 5000 bending cycles. Leveraging this flexibility, we achieve full-azimuthal imaging, detecting directional light sources with precision.
Invisible Bright Emission: Mid-Infrared LEDs Based on 2D Materials
Discovered anomalous thickness-dependence of photoluminescence quantum yield in 2D black phosphorus, transitioning from free-carrier to excitonic system (Nature Nanotechnology, 2023). Demonstrated optoelectronic device applications based on black phosphorus, which have shown promising performance: a room-temperature operational lifetime of black phosphorus LEDs up to ~ 15,000 h via packaging technology (Nature Communications, 2023). Toward practical device applications, we have developed scalable thin film processing from chip to wafer scale (Science Advances 2024; Advanced Materials 2024; Nano Letters 2024).
Perfectly Bright 2D Semiconductors
Developed an approach to overcome a bottleneck in the light-emission efficiency of light-emitting devices that uses strain engineering to achieve near 100% luminescence efficiency at all brightness levels (Science, 2021; Nano Letter, 2022). Demonstrated that the application of mechanical strain on a thin semiconductor film changes its electronic structure to reduce the instances of nonradiative recombination and thus improve light-emission efficiency. This work provides guidance for the design of mobile devices and lighting applications with enhanced energy efficiency.
Extremely Thin Ferroelectric Memories and Energy Harvesters
Discovered in-plane ferroelectricity in an atomically thin (<1 nm) semiconductor tin sulfide (Nat. Commun., 2020). Developed a growth technique to synthesize high-quality crystals using by physical vapor deposition (PVD). Its in-plane ferroelectricity has an advantage in confining ferroelectric polarization even below 1 nm thickness, which can be applied to memory and nano power generators with an ease of miniaturization.
Germanium Laser for Silicon Photonics
Developed UHV-CVD growth technique for n+-Ge on Si and improvement of direct gap photoluminescence from Ge for application to near-infrared light sources in Si photonics. Bandgap engineering was explored by utilizing strain and doping, to convert Ge into an optical gain material. Ge-based light source could be used to boost the amount of data that can be transmitted with chip-based optical computing and communication (Opt. Express, 2017; Sci. Rep., 2022).
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