Research
Nanophotonics and nanoimaging for optoelectronics, electronics, and biological cellular structures
When photons and electrons are managed in concert at the nanoscale, numerous optoelectronic applications can be achieved with advanced functionality going beyond conventional electronics. My research experience and interests are driven by combining the field of optics, electronics, electromagnetics, semiconductor physics, nanoscale science and technology, and materials science.
Nanophotonic engineering for low-cost & high-efficiency solar energy conversion devices
Traditional light management techniques for photovoltaics have some shortcomings, such as expensive fabrication processes, wavelength and incident angle dependent behaviors, and loss of photovoltage due to the increased surface recombination. To address these shortcomings, I develop new classes of low-cost, high-efficient nanophotonic light management techniques using earth abundant, renewable micro-/nanomaterials that can increase the total power conversion efficiency of a photovoltaic device.
Bio-inspired photonics for new emerging optoelectronics
Most of the visible colors found in nature creatures rely on periodic arrangement of lattice or scattering elements on their integumentary systems. Understanding of the interplay between morphology, composition, and optical response of such elaborate integumentary nanostructures inspires the development of novel photonic materials that enable the controllable, innovative light management. In this regard, bio-inspired nanophotonics will offer expansive research opportunities to develop novel high-efficiency optoelectronic applications (e.g., solar energy devices, image detectors, sensors, display applications, etc.) and military stealth systems.
High-throughput & high-speed multi-functional nanoscale imaging systems
New optoelectronic materials such as perovskites have attracted significant attention due to the potential for low-cost, high-efficiency solar energy conversion or light emitting display devices. However, these materials suffer from various instability and degradation issues, some of which are still of unknown origin. Also, some operational principles have not been clearly established. In this regard, detailed studies should be made at the nanoscale, where photo-excited electron-hole pair generations and collections actually take place. I develop a novel high-throughput, high-speed multi-functional nanoscale imaging system based on scanning probe microscopy techniques to image nanoscale optical, electrical, and material phenomena of new emerging optoelectronic devices.
Real-time optical examination of the operation of integrated electronic circuits and biological cellular structures
An infrared detector that senses thermal radiation of objects is one of the most widely used temperature-imaging devices. However, such devices suffer from various factors that limit the spatial resolution of acquired images. Therefore, such devices are not applicable to examine the operation of many objects that have nanoscale spatial temperature variations with fast transition time, such as integrated semiconductor electronic circuits, memristor-based neuromorphic computing chips, biological samples (e.g., mitochondria), and others. My technique, a novel wide-field super-resolution opto-thermal microscopy system, has sufficient spatial resolution to detect these thermal changes.