Controlled Synthesis of Colloidal Nanocrystals
Designed synthesis of nanomaterials is of key importance to fully exploit their unique properties for various applications. However, the previous works on nanocrystals synthesis are usually based on trial-and-error approaches and the formation mechanism of colloidal nanocrystals has not been fully understood yet. We will develop rational synthetic methods of various nanomaterials (e.g., colloidal quantum dots (QDs)). To gain better understanding on these nanoscale dynamic processes, we are using the state-of-the-art characterization methods including in-situ/ex-situ spectroscopy and in-situ liquid phase electron microscopy.
Quantum Dot Displays
In the future, our daily life will be surrounded by advanced technologies such as IoT and ubiquitous computing. To realize these technologies, electronic devices need to become wearable/deformable forms. All the electronics require display components to visualize information. Previously, research on quantum dot light-emitting diodes (QLEDs) simply focused on the improvement of their performance to take advantages of vivid color of QDs. We highlight QLEDs as next-generation wearable/deformable displays by utilizing unnoticed features of QLEDs such as ultrathin thickness of the active layers and the high brightness at low driving voltage. We will realize efficient wearable QD displays using structure engineering of nanocrystal QDs.
Quantum Dots for Solar Energy Conversion
Semiconductor nanocrystal QDs have unique properties that are suitable for solar energy conversion. Their band structure can be precisely tunable by the quantum confinement effect and they can effectively absorb a wide range of visible light of the solar spectrum. Importantly, quantized energy levels of QDs can produce multiple charge carriers from the absorption of a single photon, or can enhance lifetime of hot electrons. We are developing highly efficient QD-solar cells/QD-photoelectrochemical cells/QD-photocatalysts through the materials design of nanocrystal QDs.
In-Situ Transmission Electron Microscopy
Among various of the characterization methods, transmission electron microscopy (TEM) provides direct visualization of the materials shape and crystal structure with high spatial resolution. The recent development of liquid-phase TEM provides new opportunities to see the liquid samples with high spatial and temporal resolution, which can not be achieved by other characterization methods. We are currently working on the direct real-time observation on nanoscale dynamic processes using in-situ liquid phase TEM. A better understanding of the nanoscale processes will allow us to develop novel functional materials and to address fundamental issues in a broad range of applications (e.g. catalysis, batteries, optoelectronic devices).