Excited States and Their Dynamics in CdSe Quantum Dots Studied by Two-Color 2D Spectroscopy

Summary, in English

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.

• Author: Zhengjun Wang; Nils Lenngren; Edoardo Amarotti; Albin Hedse; Karel Žídek; Kaibo Zheng; Donatas Zigmantas; Tõnu Pullerits
• Department/s: NanoLund: Centre for Nanoscience; Chemical Physics
• Publishing year: 2022-02-10
• Language: English
• Pages: 1266-1271
• Publication/Series: Journal of Physical Chemistry Letters
• Volume: 13
• Issue: 5
• Links: http://dx.doi.org/10.1021/acs.jpclett.1c04110
• Document type: Journal article
• Publisher: The American Chemical Society (ACS)
• Topic: Physical Chemistry (including Surface- and Colloid Chemistry); Nano-technology; Other Physics Topics
• Status: Published
• ISBN/ISSN/Other: ISSN: 1948-7185