Temperature Dependent Carrier Dynamics in Ga-Alloyed CdSe/ZnS Core–Shell Quantum Dots

• Published in: Journal of physical chemistry. C Vol. 128; no. 9; pp. 3815 - 3823
• Main Authors: Sárosi, Krisztina, Tuinenga, Christopher, Samu, Gergely F., Mogyorósi, Károly, Dudás, Júlia, Tóth, Bálint, Jójárt, Péter, Gilicze, Barnabás, Seres, Imre, Bengery, Zsolt, Janáky, Csaba, Chikán, Viktor
• Format: Journal Article
• Language: English
• Published: American Chemical Society 07-03-2024
• Subjects: C: Spectroscopy and Dynamics of Nano, Hybrid, and Low-Dimensional Materials
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.3c04689

In this work, temperature dependent transient absorption spectroscopy measurements are presented on gallium-alloyed CdSe/ZnS core–shell nanoparticles between 30 and 130 °C. To our knowledge, temperature dependent measurements in these systems have been reported only in a few papers, although all processes related to carrier recombination are affected by temperature. For these experiments, gallium-alloyed CdSe/ZnS QD samples were used with nominal doping percentages of 2.5%, 7.5%, 15%. The experimental results show that the transient absorption decay is faster for the pristine CdSe/ZnS samples than in the gallium-alloyed samples at all temperatures. It is assumed that Ga-alloying promotes the formation of trions in the samples by introducing occupied impurity levels within the bandgap of CdSe. The resulting Coulomb blockade will, in turn, prolong the hot-electron relaxation process. By variation of the temperature, the distribution of charge carriers in the different recombination channels can be altered to accelerate recombination in the Ga-alloyed samples at higher temperatures. These measurements demonstrated their usefulness for observing the redistribution of charge carriers among different relaxation pathways.