Excited states and their dynamics in CdSe quantum dots studied by two-color 2D spectroscopy

0557509 - FZÚ 2023 RIV US eng J - Journal Article
Wang, Z. - Lenngren, Nils - Amarotti, E. - Hedse, A. - Žídek, Karel - Zheng, K. - Zigmantas, D. - Pullerits, T.
Excited states and their dynamics in CdSe quantum dots studied by two-color 2D spectroscopy.
Journal of Physical Chemistry Letters. Roč. 13, č. 5 (2022), s. 1266-1271. ISSN 1948-7185
R&D Projects: GA MŠMT EF16_019/0000789
Grant - others:OP VVV - ADONIS(XE) CZ.02.1.01/0.0/0.0/16_019/0000789
Institutional support: RVO:68378271 ; RVO:61389021
Keywords : energy-transfer * nanocrystals * electron * photogeneration * recombination * coherence
OECD category: Physical chemistry; 2.11 Other engineering and technologies (UFP-V)
Impact factor: 5.7, year: 2022
Method of publishing: Open access

Quantum dots (QDs) form a promising family of nanomaterials for various applications in optoelectronics. Understanding the details of the excited-state dynamics in QDs is vital for optimizing their function. We apply two-color 2D electronic spectroscopy to investigate CdSe QDs at 77 K within a broad spectral range. Analysis of the electronic dynamics during the population time allows us to identify the details of the excitation pathways. The initially excited high-energy electrons relax with the time constant of 100 fs. Simultaneously, the states at the band edge rise within 700 fs. Remarkably, the excited-state absorption is rising with a very similar time constant of 700 fs. This makes us reconsider the earlier interpretation of the excited-state absorption as the signature of a long-lived trap state. Instead, we propose that this signal originates from the excitation of the electrons that have arrived in the conduction-band edge.
Permanent Link: http://hdl.handle.net/11104/0331478