Issue 10, 2024

Why do Si quantum dots with stronger fast emission have lower external photoluminescence quantum yield?

Abstract

Silicon quantum dots (QDs) are a promising non-toxic alternative to the already well-developed platform of light-emitting semiconductor QDs based on III–V and II–VI materials. Oxidized SiQDs or those surface-terminated with long alkyl chains typically feature long-lived orange-red photoluminescence originating in quantum-confined core states. However, sometimes an additional short-lived PL band, whose mechanism is still highly debated, is reported. Here, we perform a detailed study of the room-temperature PL of SiQDs using samples covering three main fabrication techniques. We find evidence for the presence of only one set of radiative processes in addition to the typical long-lived PL. Moreover, we experimentally determine the ratio between the short- and long-lived PL component, obtaining a wide range of values (0.003 – 0.1) depending on the type of sample. In accordance with an already published report, we observe a tendency of SiQDs with stronger short-lived PL to have lower external quantum yield. We explain this trend using a model of the optical performance of an ensemble of QDs with widely varying optical characteristics through a mechanism we call selective lifetime-based quenching.

Graphical abstract: Why do Si quantum dots with stronger fast emission have lower external photoluminescence quantum yield?

Supplementary files

Article information

Article type
Paper
Submitted
21 Nov 2023
Accepted
08 Apr 2024
First published
09 Apr 2024
This article is Open Access
Creative Commons BY-NC license

Nanoscale Adv., 2024,6, 2644-2655

Why do Si quantum dots with stronger fast emission have lower external photoluminescence quantum yield?

T. Popelář, F. Matějka, J. Kopenec, G. Morselli, P. Ceroni and K. Kůsová, Nanoscale Adv., 2024, 6, 2644 DOI: 10.1039/D3NA01031G

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