Seminar & Colloquium
[세미나: 8월 20일(화), 오전 10시 30분] Prof. Robert L. Z. Hoye, University of Oxford
Title
Halide Perovskite Nanocrystals: Polarised Light Emission and Defect Tolerance in Hot Carriers
Speaker
Prof. Robert L. Z. Hoye, Associate Professor, Inorganic Chemistry Laboratory, University of Oxford
* Education
- 2015 – 2016 Postdoctoral Research Associate from Massachusetts Institute of Technology, USA
Advisor: Prof. Tonio Buonassisi
- 2012 – 2015 Doctor of Philosophy in Department of Materials Science and Metallurgy, University of Cambridge, UK
Supervisor: Prof. Judith Driscoll
Thesis title: “Tuning metal oxides for solar cells and light emitting diodes”
- 2009 – 2011 Bachelor of Engineering with First Class Honours in Department of Chemical and Materials Engineering, University of Auckland, New Zealand
* Professional Experience
- Oct. 2022 – present Associate Professor of Inorganic Chemistry, and Fellow of St. John’s College, Royal Academy of Engineering (RAEng) Senior Research Fellow, University of Oxford
- Jan. 2020 – Sept. 2022 Senior Lecturer and RAEng Research Fellow, Imperial College London
- 2019 – 2020 Kim and Juliana Silverman Research Fellow, Downing College
- 2018 – 2019 Royal Academy of Engineering Research Fellow, University of Cambridge
- 2016 – 2019 Thomas Nevile Junior Research Fellow, Magdalene College
| Date | Tuesday, August 20th , 2024
| Time | 10:30 ~
| Venue | 33동 125호(WCU 다목적실)
[Abstract]
Metal-halide perovskites exhibit bright and sharp luminescence, with properties that can be tuned over a wide range through solution processing. The first half of this talk examines realising polarised luminescence. Here, CsPbI3 nanoplatelets are self-assembled into an edge-up orientation. Through strong dielectric and quantum confinement, there is a large exciton fine structure splitting. As a result, we achieve strong emission from out-of-plane dipoles for the optically bright excitons in these superlattices. In light-emitting diodes, this leads to a high degree of polarisation of 74.4% in electroluminescence, without requiring any photonic structures [1].
The second half of this talk makes use of the versatility of metal-halide perovskites to examine hot carrier cooling. In particular, although defect tolerance has been widely quoted as a key enabling properties of band-edge (cold) carriers, it is unknown whether this can be extended to hot carriers [2]. Through interband and intraband femtosecond spectroscopy, along with excitation-energy-dependent photoluminescence quantum efficiency measurements and kinetic modelling, we show that hot carriers are not universally defect tolerant, but depend on the energy of the traps. The trap density in CsPbX3 (X is Br, I or both) is intentionally tuned by washing the surface with polar antisolvents [3], and we show that hot carriers are directly trapped by defects, without going through a cold carrier intermediate. By showing how defects affect hot carriers, this work leads to design principles that could be used to realise hot carrier solar cells.
[1] Ye, …, Hoye, Nature Photonics, 18, 586 (2024).
[2] Ye, …, Hoye, Nature Communications (2024). Accepted In Principle.
[3] Ye, …, Hoye, J. Am. Chem. Soc., 144, 12102 (2022).
| Host | 강기훈 교수(02-880-7189)