Unusual Spectral Diffusion of Single CuInS<sub>2</sub> Quantum Dots Sheds Light on the Mechanism of Radiative Decay.
basic_science · Level V
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- Record sourced from PubMed, PMID 33395305.
- Also identified by DOI 10.1021/acs.nanolett.0c04239 and PMC identifier 7809691.
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Abstract
The luminescence of CuInS<sub>2</sub> quantum dots (QDs) is slower and spectrally broader than that of many other types of QDs. The origin of this anomalous behavior is still under debate. Single-QD experiments could help settle this debate, but studies by different groups have yielded conflicting results. Here, we study the photophysics of single core-only CuInS<sub>2</sub> and core/shell CuInS<sub>2</sub>/CdS QDs. Both types of single QDs exhibit broad PL spectra with fluctuating peak position and single-exponential photoluminescence decay with a slow but fluctuating lifetime. Spectral diffusion of CuInS<sub>2</sub>-based QDs is qualitatively and quantitatively different from CdSe-based QDs. The differences reflect the dipole moment of the CuInS<sub>2</sub> excited state and hole localization on a preferred site in the QD. Our results unravel the highly dynamic photophysics of CuInS<sub>2</sub> QDs and highlight the power of the analysis of single-QD property fluctuations.