Research Topics

Hydrogen formation from water splitting is very essential to support sustinable and clean energy for the future. Ideally, hydrogen fuel could be achieved by direct decomposition of water without appliced bias using the energy of solar-light. As overall water splitting efficiency is decided from both of photocathode (H2) and photoanode (O2), development of high efficient system is essential.

The bottleneck of the technology is low efficiency of photoelectrode system.  Amazingly, the plasmonic system is known as they could overcome the theoretical (Schockley-Quisser, SQ) limit, because plasmonic systems provide additional exication states to the system. 

As there are many mechanisms exist (for example: hot electron/hole injection, hot carrier tunneling, resonant energy transfer, interfacial charge-transfer, electric field enhancement, plasmonic scattering, ..... ) highly-efficient system overcoming the SQ limit has not been achived yet. 

Incident solar light through atmosphere to ground is called optical window (300 to 2500 nm) (for the emission, it is called atmoepheric window). The control of solar light and heating/cooling saving through windows is an important strategy to provide visual astethic & energy saving function to the buildings, mobility, and so on, 

As PLDC system (type III) and Metal-oxide system (Type II) is relatively simple system, they cannot provide completely black-coloration with high transparency. In addition to that, they needs over the micron-meter thick  active layer to achieve privacy state, which means more budget in fabrication.

Metals generally have a larger imaginary part of their refractive index (k) across the infrared, visible, and ultraviolet portions of the electromagnetic spectrum,  A thin film of metal can effectively block light even at thicknesses of less than hundred nm scale. As plasmonic property arises in nanosized system, metal based smart window is more promising. This technology is newly arising area in China and America. 

Plasmonic resonance has been considered fixed and immutable. However, it is possible to controlling the resonance by applying various stimuli. There are many candidate stimulies such as, chemical, optical, thermal, electrical, magnetic, and/or combinations, so on. Resonance of plasmonic nanostructure could be tuned by changing the condition of (1) surrounding medium, (2) basis system, and (3) geometry.  

It is referred to as switchable if it can change between two states, continuously tunable if it can have multiple states, and freely tunable if it can be freely changed. The aim of the development could be varied according to targetted the application.

As plasmonic systems are very sensitive the change from (1) to (3), plasmonic nanostructure could be used as a effective & sensitive sensing flatform. Application could be broaden by combining with many optical systems.