|성명||김용현 교수 (Yong-Hyun Kim, Professor)|
|주제||Quantum Simulation on Colloidal Quantum Dots|
1997. KAIST 물리학과 학사
1999. KAIST 물리학과 석사
2003. KAIST 물리학과 박사
2003-2009. 미국 National Renewable Energy Laboratory 연구원
2009-2011. KAIST 나노과학기술대학원 조교수
2011-2017. KAIST 나노과학기술대학원 부교수
2017-현재. KAIST 나노과학기술대학원/물리학과 교수
Colloidal quantum dots (CQD) have recently attracted much attention for large-scale optoelectronic applications such as light-emitting diode (LED) and solar cell.
This is mostly because there exist scalable solution-based synthetic routes for CQDs, of which size and band gap are readily controlled. Chalcogenide CQDs have been extensively tested for LED (CdSe, ZnSe) and solar cell (PbSe, PbS) applications.
However, the ligand-surface interaction in the organic-inorganic hybrid systems has not been seriously discussed although it is very important for further development and deployment of the CQD technologies.
CQDs generally consist of inorganic nanocrystal cores and surface passivating organic ligands.
Depending on the nanocrystal cores and their surface passivation, CQDs could have various shapes from cube to tetrahedral, cuboctahedral, and spherical shapes.
The stability of CQD materials and devices could thus be sensitively subjective to the surface-ligand interaction depending on type, shape, and size of CQDs.
In this talk, I will discuss our recent first-principles based understanding on how to stabilize CQDs by controlling surface chemistry, or surface-ligand interactions of IV-VI, II-VI and III-V CQDs based on results of simple electron counting rules and first-principles density-functional theory calculations. Based on these ab initio understandings, we could be able to improve photovoltaic performances of CQD solar cells, including power conversion efficiency and hysteretic behavior.