Journal
JOURNAL OF PHYSICAL CHEMISTRY C
Volume 126, Issue 45, Pages 19229-19239Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.jpcc.2c05348
Keywords
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Funding
- Hong Kong Research Grants Council
- Russian Science Foundation
- [CRF C7035-20G]
- [21-79-10197]
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We investigated the charge carrier dynamics in HgTe quantum dots emitting in the second near-infrared window and found that the exchange of ligands significantly affects the Auger recombination rate and the performance of HgTe-based thin film photodetectors.
We investigate the charge carrier dynamics in HgTe quantum dots emitting in the second near-infrared window (1000-2500 nm). To provide a link between fundamental physics and practical application, we made consistent studies of the charge carrier dynamics evolution for quantum dots in different states: colloidal solutions of quantum dots capped with a long-chain ligand; thin films made from them; and finally, exchanged to short-chain ligand films suitable for field effect transistor based devices. Ultrafast transient absorption spectroscopy reveals an ultralow Auger-related nonradiative relaxation threshold at 0.1 exciton per quantum dot, both in colloidal solutions and solid films, with a rate of 30 ns-1. The exchange from long-to short-chain ligands causing closer packing of the HgTe quantum dots leads to a strong increase of the Auger recombination rate of up to 100 ns-1. The competition between the Auger process and excitonic recombination significantly affects the performance of HgTe-based thin film photodetectors operating at room temperature, resulting in a 2 orders of magnitude drop in responsivity when the excitation flux was increased from 0.01 to 5 W center dot cm-2.
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