Hot electron and hole dynamics in thiol-capped CdSe quantum dots revealed by 2D electronic spectroscopy

Summary, in English

Colloidal quantum dots (QDs) have attracted interest as materials for opto-electronic applications, wherein their efficient energy use requires the understanding of carrier relaxation. In QDs capped by bifunctional thiols, used to attach the QDs to a surface, the relaxation is complicated by carrier traps. Using 2D spectroscopy at 77 K, we follow excitations in thiol-capped CdSe QDs with state specificity and high time resolution. We unambiguously identify the lowest state as an optically allowed hole trap, and identify an electron trap with excited-state absorption. The presence of traps changes the initial dynamics entirely by offering a different relaxation channel. 2D electronic spectroscopy enables us to pinpoint correlations between states and to easily separate relaxation from different starting states. We observe the direct rapid trapping of 1S_3/2, 2S_3/2, and 1S_1/2 holes, and several competing electron relaxation processes from the 1P_e state.

• Author: Nils Lenngren; Mohamed A. Abdellah; Kaibo Zheng; Mohammed J. Al-Marri; Donatas Zigmantas; Karel Zidek; Tõnu Pullerits
• Department/s: Chemical Physics; NanoLund: Centre for Nanoscience
• Publishing year: 2016
• Language: English
• Pages: 26199-26204
• Publication/Series: Physical Chemistry Chemical Physics
• Volume: 18
• Issue: 37
• Links: http://dx.doi.org/10.1039/c6cp04190f
• Document type: Journal article
• Publisher: Royal Society of Chemistry
• Topic: Physical Chemistry (including Surface- and Colloid Chemistry); Condensed Matter Physics (including Material Physics, Nano Physics)
• Status: Published
• ISBN/ISSN/Other: ISSN: 1463-9076