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Richardson A, Alster J, Khoroshyy P, Psencik J, Valenta J, Tuma R, Critchley K. Direct Synthesis and Characterization of Hydrophilic Cu-Deficient Copper Indium Sulfide Quantum Dots. ACS OMEGA 2024; 9:17114-17124. [PMID: 38645370 PMCID: PMC11025077 DOI: 10.1021/acsomega.3c09531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 02/21/2024] [Accepted: 03/21/2024] [Indexed: 04/23/2024]
Abstract
Copper indium sulfide (CIS) nanocrystals constitute a promising alternative to cadmium- and lead-containing nanoparticles. We report a synthetic method that yields hydrophilic, core-only CIS quantum dots, exhibiting size-dependent, copper-deficient composition and optical properties that are suitable for direct coupling to biomolecules and nonradiative energy transfer applications. To assist such applications, we complemented previous studies covering the femtosecond-picosecond time scale with the investigation of slower radiative and nonradiative processes on the nanosecond time scale, using both time-resolved emission and transient absorption. As expected for core particles, relaxation occurs mainly nonradiatively, resulting in low, size-dependent photoluminescence quantum yield. The nonradiative relaxation from the first excited band is wavelength-dependent with lifetimes between 25 and 150 ns, reflecting the size distribution of the particles. Approximately constant lifetimes of around 65 ns were observed for nonradiative relaxation from the defect states at lower energies. The photoluminescence exhibited a large Stokes shift. The band gap emission decays on the order of 10 ns, while the defect emission is further red-shifted, and the lifetimes are on the order of 100 ns. Both sets of radiative lifetimes are wavelength-dependent, increasing toward longer wavelengths. Despite the low radiative quantum yield, the aqueous solubility and long lifetimes of the defect states are compatible with the proposed role of CIS quantum dots as excitation energy donors to biological molecules.
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Affiliation(s)
- Amanda Richardson
- Astbury
Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K.
- School
of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, U.K.
| | - Jan Alster
- Department
of Chemical Physics, Faculty of Mathematics and Physics, Charles University, Prague 121 16, Czech Republic
| | - Petro Khoroshyy
- Department
of Chemical Physics, Faculty of Mathematics and Physics, Charles University, Prague 121 16, Czech Republic
| | - Jakub Psencik
- Department
of Chemical Physics, Faculty of Mathematics and Physics, Charles University, Prague 121 16, Czech Republic
| | - Jan Valenta
- Department
of Chemical Physics, Faculty of Mathematics and Physics, Charles University, Prague 121 16, Czech Republic
| | - Roman Tuma
- Astbury
Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K.
- School
of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, U.K.
- Faculty
of Science, University of South Bohemia, Ceske Budejovice 370 05, Czech Republic
| | - Kevin Critchley
- Astbury
Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K.
- School
of Physics and Astronomy, Faculty of Engineering and Physical Sciences, University of Leeds, Leeds LS2 9JT, U.K.
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Singha PK, Kistwal T, Datta A. Single-Particle Dynamics of ZnS Shelling Induced Replenishment of Carrier Diffusion for Individual Emission Centers in CuInS 2 Quantum Dots. J Phys Chem Lett 2023; 14:4289-4296. [PMID: 37126796 DOI: 10.1021/acs.jpclett.3c00467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Insights into blinking and photoactivation of aqueous copper indium sulfide (CIS) quantum dots have been obtained using fluorescence correlation spectroscopy (FCS) and fluorescence lifetime correlation spectroscopy (FLCS). An unusual excitation wavelength-dependence of photoactivation/photocorrosion is manifested in an increase in the initial correlation amplitude G(0) for λex = 532 nm, but a decrease for λex = 405 nm. This has been rationalized in terms of different contributions from surface-assisted recombination in the two cases. Blinking times obtained from the autocorrelation functions (ACFs) of the 100-200 ns lifetime component (core Cu-mediated recombination) are almost unaffected by shelling, but those from the ACF for the 10-30 ns lifetime (surface states) increase significantly. Absence of cross-correlation between the two recombinative states of bare CIS QDs and the emergence of an anticorrelation with the introduction of the ZnS shell are observed, indicating the diffusive nature of the two states for CIS-ZnS. The diffusion is inhibited in bare CIS QDs due to the preponderance of surface states.
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Affiliation(s)
- Prajit Kumar Singha
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Tanuja Kistwal
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Anindya Datta
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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Mukherjee S, Ghosh S, Biswas D, Ghosal M, De K, Mandal PK. Transforming exciton dynamics in perovskite nanocrystal through Mn doping. NANOSCALE 2023; 15:6947-6953. [PMID: 36974486 DOI: 10.1039/d3nr00241a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Zn-alloyed CsPb(Cl/Br)3 perovskite nanocrystals (PNCs) have been synthesized and used as a model system for Mn doping in order to understand the effect of Mn doping on exciton dynamics. While keeping the PL emission maximum and PLQY of both PNC samples nearly the same, the radiative decay rate of the host band decreases ∼6.5 times and the non-radiative decay rate increases ∼2.5 times upon Mn doping. Unlike reports in the literature in which the dopant emission decreases to near-zero, in the present case we observe ∼5.5-fold enhancement of the integrated PL intensity of the dopant emission when the temperature decreases from 290 K to 190 K. Interestingly, the FWHM of the host PL emission band increases with a decrease in temperature from 290 K to 190 K. A higher value of phonon energy in PNC2 (58 ± 2 meV) in comparison to CsPbBr3 has been noted. The low magnitude of the Huang-Rhys factor indicates less electron phonon coupling for the Mn-doped PNC system. Temperature-dependent dopant PL decay exhibits biexponential decay behaviour with time constants τ1 = 450-540 μs and τ2 = 1.1-1.2 ms. With a decrease in temperature from 290 K to 190 K, the amplitude of the faster component decreases from 80% to 60%; concomitantly, the amplitude of the slower component increases from 20% to 40%. Ultrasensitive single-particle spectroscopic analyses reveal that, although the probability density distributions (PDDs) of the durations of both ON and OFF events of PNC1 could be fitted with a truncated inverse power law (TIPL), however, for PNC2, both PDDs could be fitted with an inverse power law (IPL). A comparatively lower value of the power law exponent mON indicates a higher probability of longer ON events for PNC1 than for PNC2. Truncation in the PDDs of both ON and OFF events has been observed for PNC1, but not in the PDDs of either ON or OFF events for PNC2. The presence of shallow trap states is responsible for the truncation for PNC1, whereas the presence of deep dopant states does not allow truncation in the host PL emission of PNC2. All these observations clearly demonstrate that Mn doping transforms the host PL exciton dynamics for Zn-alloyed Mn-doped CsPb(Cl/Br)3 PNCs very significantly.
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Affiliation(s)
- Soumen Mukherjee
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India
| | - Swarnali Ghosh
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India
| | - Dibyendu Biswas
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India
| | - Mainak Ghosal
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India
| | - Kheyali De
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India
| | - Prasun K Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India
- Centre for Advanced Functional Materials, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India.
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