GCN Seminar: Photoluminescence
We are pleased to invite you to a seminar in the Greater Copenhagen Nanoscience (GCN) series with the aim to increase awareness about mutual capabilities of the three nanoscience hubs in the Copenhagen-Lund area and to inspire collaborations. The topic of this Greater-Copenhagen Nanoscience Seminar will be "Photoluminescence". This comprises new materials, imaging techniques, method development, and applications.
There will be three speakers, one from each hub (University of Copenhagen, DTU and NanoLund).
Date: 26 November 2021 from 15:15 to 16:30
Zoom: Please contact Gerda Rentschler firstname.lastname@example.org
Speakers and preliminary titles
• Tom Vosch (KU): Lanthanide up-conversion nanoparticles
• Donatas Zigmantas (NanoLund): Understanding plexcitons in hybrid nanoparticles using multidimensional electronic spectroscopy
• Nicolas Stenger (DTU): Photoluminescence of defects in 2D materials
The format will be 15 + 5 for three speakers and then a general panel discussion.
More information will come. For the moment, please block the date.
Nicolas Stenger bio and abstract:
Nicolas Stenger obtained his PhD in 2008 from the University of Strasbourg in condensed matter physics. He did his postdoc at the Karlsruhe Institute of Technology on optical and mechanical metamaterials. He moved to DTU in 2012 to work on quantum related effects in the optical response of small metallic nanoparticles. He became Associate Professor at DTU in 2017 and works currently on the design and fabrications and optical characterization of functional photonic devices for future information processing technologies. His main focus is on strong light-matter interactions between nanophotonics cavities and two-dimensional materials as well as the characterization of these effects in the near-field.
The recent discovery of quantum emitters at room temperature in the two-dimensional material hexagonal Boron Nitride  has triggered a large number of research work. However, the generation of these ultrabright quantum emitters is mostly uncontrolled and their microscopic origin remains elusive. Here, we present a novel generation process to create luminescent centres in hBN by irradiation engineering . We systematically study the density of luminescent centres at different irradiation energies and irradiation fluences (defined as the number of oxygen atoms per area). Increasing the irradiation fluence by ten results in a five-fold enhancement of the density. In combination with molecular dynamics simulations we clarify the generation mechanism, for the first time to the best of our knowledge. Furthermore, we infer that two defects are most likely generated, namely VNCB and VB-. Ab initio calculations of these defects show excellent agreement with experimental photoluminescence line shapes. The generation of quantum emitters by irradiation engineering is a step towards the controlled generation of quantum emitters in hBN. Furthermore, the presented irradiation engineering is wafer-scalable and could be adapted to other irradiating atoms or ions as well as other gapped 2D materials.
 T. T. Tran et al. Quantum emission from hexagonal boron nitride monolayers, Nature Nanotechnology 11, 37 (2016).
 M. Fischer et al. Controlled generation of luminescent centres in hexagonal boron nitride by irradiation engineering, Science Advances 7, eabe7138 (2021).