1
|
Rana G, Das S, Singha PK, Ali F, Maji R, Datta A. The effect of Cu(I)-doping on the photoinduced electron transfer from aqueous CdS quantum dots. J Chem Phys 2024; 161:024705. [PMID: 38990118 DOI: 10.1063/5.0218548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2024] [Accepted: 06/24/2024] [Indexed: 07/12/2024] Open
Abstract
The doping of CdS quantum dots (QDs) with Cu(I) disrupts electron-hole correlation due to hole trapping by the dopant ion, post-photoexcitation. The present paper examines the effect of such disruption on the rate of photoinduced electron transfer (PET) from the QDs to methyl viologen (MV2+), with implications in their photocatalytic activity. A significantly greater efficiency of PL quenching by MV2+ is observed for the doped QDs than for the undoped ones. Interestingly, the Stern-Volmer plots constructed using PL intensities exhibit an upward curvature for both the cases, while the PL lifetimes remain unaffected. This observation is rationalized by considering the adsorption of the quencher on the surface of the QDs and ultrafast PET post-photoexcitation. Ultrafast transient absorption experiments confirm a faster electron transfer for the doped QDs. It is also realized that the transient absorption experiment yields a more accurate estimate of the binding constant of the quencher with the QDs, than the PL experiment.
Collapse
Affiliation(s)
- Gourab Rana
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Sharmistha Das
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Prajit Kumar Singha
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Fariyad Ali
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Rohan Maji
- Department of Chemistry, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India
| | - Anindya Datta
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| |
Collapse
|
2
|
Bagnall A, Eliasson N, Hansson S, Chavarot-Kerlidou M, Artero V, Tian H, Hammarström L. Ultrafast Electron Transfer from CuInS 2 Quantum Dots to a Molecular Catalyst for Hydrogen Production: Challenging Diffusion Limitations. ACS Catal 2024; 14:4186-4201. [PMID: 38510668 PMCID: PMC10949191 DOI: 10.1021/acscatal.3c06216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 02/06/2024] [Accepted: 02/16/2024] [Indexed: 03/22/2024]
Abstract
Systems integrating quantum dots with molecular catalysts are attracting ever more attention, primarily owing to their tunability and notable photocatalytic activity in the context of the hydrogen evolution reaction (HER) and CO2 reduction reaction (CO2RR). CuInS2 (CIS) quantum dots (QDs) are effective photoreductants, having relatively high-energy conduction bands, but their electronic structure and defect states often lead to poor performance, prompting many researchers to employ them with a core-shell structure. Molecular cobalt HER catalysts, on the other hand, often suffer from poor stability. Here, we have combined CIS QDs, surface-passivated with l-cysteine and iodide from a water-based synthesis, with two tetraazamacrocyclic cobalt complexes to realize systems which demonstrate high turnover numbers for the HER (up to >8000 per catalyst), using ascorbate as the sacrificial electron donor at pH = 4.5. Photoluminescence intensity and lifetime quenching data indicated a large degree of binding of the catalysts to the QDs, even with only ca. 1 μM each of QDs and catalysts, linked to an entirely static quenching mechanism. The data was fitted with a Poissonian distribution of catalyst molecules over the QDs, from which the concentration of QDs could be evaluated. No important difference in either quenching or photocatalysis was observed between catalysts with and without the carboxylate as a potential anchoring group. Femtosecond transient absorption spectroscopy confirmed ultrafast interfacial electron transfer from the QDs and the formation of the singly reduced catalyst (CoII state) for both complexes, with an average electron transfer rate constant of ≈ (10 ps)-1. These favorable results confirm that the core tetraazamacrocyclic cobalt complex is remarkably stable under photocatalytic conditions and that CIS QDs without inorganic shell structures for passivation can act as effective photosensitizers, while their smaller size makes them suitable for application in the sensitization of, inter alia, mesoporous electrodes.
Collapse
Affiliation(s)
- Andrew
J. Bagnall
- Department
of Chemistry-Ångström Laboratory, Uppsala University, SE-75120 Uppsala, Sweden
- Univ.
Grenoble Alpes, CNRS, CEA, IRIG, Laboratoire de Chimie et Biologie
des Métaux, 17
rue des Martyrs, F-38054 Grenoble, Cedex, France
| | - Nora Eliasson
- Department
of Chemistry-Ångström Laboratory, Uppsala University, SE-75120 Uppsala, Sweden
| | - Sofie Hansson
- Department
of Chemistry-Ångström Laboratory, Uppsala University, SE-75120 Uppsala, Sweden
| | - Murielle Chavarot-Kerlidou
- Univ.
Grenoble Alpes, CNRS, CEA, IRIG, Laboratoire de Chimie et Biologie
des Métaux, 17
rue des Martyrs, F-38054 Grenoble, Cedex, France
| | - Vincent Artero
- Univ.
Grenoble Alpes, CNRS, CEA, IRIG, Laboratoire de Chimie et Biologie
des Métaux, 17
rue des Martyrs, F-38054 Grenoble, Cedex, France
| | - Haining Tian
- Department
of Chemistry-Ångström Laboratory, Uppsala University, SE-75120 Uppsala, Sweden
| | - Leif Hammarström
- Department
of Chemistry-Ångström Laboratory, Uppsala University, SE-75120 Uppsala, Sweden
| |
Collapse
|
3
|
Dzhagan V, Mazur N, Kapush O, Selyshchev O, Karnaukhov A, Yeshchenko OA, Danylenko MI, Yukhymchuk V, Zahn DRT. Core and Shell Contributions to the Phonon Spectra of CdTe/CdS Quantum Dots. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:921. [PMID: 36903799 PMCID: PMC10004847 DOI: 10.3390/nano13050921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 02/20/2023] [Accepted: 03/01/2023] [Indexed: 06/18/2023]
Abstract
The parameters of the shell and interface in semiconductor core/shell nanocrystals (NCs) are determinant for their optical properties and charge transfer but are challenging to be studied. Raman spectroscopy was shown earlier to be a suitable informative probe of the core/shell structure. Here, we report the results of a spectroscopic study of CdTe NCs synthesized by a facile route in water, using thioglycolic acid (TGA) as a stabilizer. Both core-level X-ray photoelectron (XPS) and vibrational (Raman and infrared) spectra show that using thiol during the synthesis results in the formation of a CdS shell around the CdTe core NCs. Even though the spectral positions of the optical absorption and photoluminescence bands of such NCs are determined by the CdTe core, the far-infrared absorption and resonant Raman scattering spectra are dominated by the vibrations related with the shell. The physical mechanism of the observed effect is discussed and opposed to the results reported before for thiol-free CdTe Ns as well as CdSe/CdS and CdSe/ZnS core/shell NC systems, where the core phonons were clearly detected under similar experimental conditions.
Collapse
Affiliation(s)
- Volodymyr Dzhagan
- V. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, 03028 Kyiv, Ukraine
- Physics Department, Taras Shevchenko National University of Kyiv, 01601 Kyiv, Ukraine
| | - Nazar Mazur
- V. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, 03028 Kyiv, Ukraine
| | - Olga Kapush
- V. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, 03028 Kyiv, Ukraine
| | - Oleksandr Selyshchev
- Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany
- Center for Materials, Architectures, and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, D-09107 Chemnitz, Germany
| | - Anatolii Karnaukhov
- V. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, 03028 Kyiv, Ukraine
| | - Oleg A. Yeshchenko
- Physics Department, Taras Shevchenko National University of Kyiv, 01601 Kyiv, Ukraine
| | - Mykola I. Danylenko
- Frantsevich Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 03142 Kyiv, Ukraine
| | - Volodymyr Yukhymchuk
- V. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, 03028 Kyiv, Ukraine
| | - Dietrich R. T. Zahn
- Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany
- Center for Materials, Architectures, and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, D-09107 Chemnitz, Germany
| |
Collapse
|
4
|
Nagelj N, Brumberg A, Peifer S, Schaller RD, Olshansky JH. Compositionally Tuning Electron Transfer from Photoexcited Core/Shell Quantum Dots via Cation Exchange. J Phys Chem Lett 2022; 13:3209-3216. [PMID: 35377650 DOI: 10.1021/acs.jpclett.2c00333] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
It is critical to find methods to control the thermodynamic driving force for photoexcited charge transfer from quantum dots (QDs) and explore how this affects charge transfer rates, since the efficiency of QD-based photovoltaic and photocatalysis technologies depends on both this rate and the associated energetic losses. In this work, we introduce a single-pot shell growth and Cu-catalyzed cation exchange method to synthesize CdxZn1-xSe/CdyZn1-yS QDs with tunable driving forces for electron transfer. Functionalizing them with two molecular electron acceptors─naphthalenediimide (NDI) and anthraquinone (AQ)─allowed us to probe nearly 1 eV of driving forces. For AQ, at lower driving forces, we find that higher Zn content results in a 130-fold increase of electron transfer rate constants. However, at higher driving forces electron transfer dynamics are unaltered. The data are understood using an Auger-assisted electron transfer model and analyzed with computational work to determine approximate binding geometries of these electron acceptors. Our work provides a method to tune QD reducing power and produces useful metrics for optimizing QD charge transfer systems that maximize rates of electron transfer while minimizing energetic losses.
Collapse
Affiliation(s)
- Nejc Nagelj
- Department of Chemistry, Amherst College, Amherst, Massachusetts 01002, United States
| | - Alexandra Brumberg
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Shoshanna Peifer
- Department of Chemistry, Amherst College, Amherst, Massachusetts 01002, United States
| | - Richard D Schaller
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Jacob H Olshansky
- Department of Chemistry, Amherst College, Amherst, Massachusetts 01002, United States
| |
Collapse
|
5
|
Roy D, De CK, Ghosh S, Mukherjee S, Mandal S, Mandal PK. Ultrafast dynamics and ultrasensitive single particle spectroscopy of optically robust core/alloy shell semiconductor quantum dots. Phys Chem Chem Phys 2022; 24:8578-8590. [PMID: 35355030 DOI: 10.1039/d1cp05780d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A "one-pot one-step" synthesis method of Core/Alloy Shell (CAS) quantum dots (QDs) offers the scope of large scale synthesis in a less time consuming, more economical, highly reproducible and high-throughput manner in comparison to "multi-pot multi-step" synthesis for Core/Shell (CS) QDs. Rapid initial nucleation, and smooth & uniform shell growth lead to the formation of a compositionally-gradient alloyed hetero-structure with very significantly reduced interfacial trap density in CAS QDs. Thus, interfacial strain gets reduced in a much smoother manner leading to enhanced confinement for the photo-generated charge carriers in CAS QDs. Convincing proof of alloy-shelling for a CAS QD has been provided from HRTEM images at the single particle level. The band gap could be tuned as a function of composition, temperature, reactivity difference of precursors, etc. and a high PLQY and improved photochemical stability could be achieved for a small sized CAS QD. From the ultrafast exciton dynamics in CdSe and InP CAS QDs, it has been shown that (a) the hot exciton thermalization/relaxation happens in <500 fs, (b) hot electron trapping dynamics occurs within a ∼1 ps time scale, (c) band edge exciton trapping occurs within a 10-25 ps timescale and (d) for CdSe CAS QDs the hot hole gets trapped in about 35 ps. From fast PL decay dynamics, it has been shown that the amplitude of the intermediate time constant can be correlated with the PLQY. A model has been provided to understand these ultrafast to fast exciton dynamical processes. At the ultrasensitive single particle level, unlike CS QDs, CdSe CAS QDs have been shown to exhibit (a) constancy of PLmax (i.e. no bluing) and (b) constancy of PL intensity (i.e. no bleaching) of the single CAS QDs for continuous irradiation for one hour under an air atmosphere. Thus, CAS QDs hold the promise of being a superior optical probe in comparison to CS QDs both at the ensemble and at the single particle level, leading to enhanced flexibility of the CAS QDs towards designing and developing next generation application devices.
Collapse
Affiliation(s)
- Debjit Roy
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India.
| | - Chayan K De
- 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.
| | - Soumen Mukherjee
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India.
| | - Saptarshi Mandal
- 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
| |
Collapse
|
6
|
He S, Li Q, Jin T, Lian TT. Contributions of exciton fine structure and hole trapping on the hole state filling effect in the transient absorption spectra of CdSe quantum dots. J Chem Phys 2022; 156:054704. [DOI: 10.1063/5.0081192] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Sheng He
- Chemistry, Emory University, United States of America
| | - Qiuyang Li
- Physics, University of Michigan, United States of America
| | - Tao Jin
- Chemistry Department, Emory University, United States of America
| | | |
Collapse
|
7
|
Schleusener A, Micheel M, Benndorf S, Rettenmayr M, Weigand W, Wächtler M. Ultrafast Electron Transfer from CdSe Quantum Dots to an [FeFe]-Hydrogenase Mimic. J Phys Chem Lett 2021; 12:4385-4391. [PMID: 33939438 DOI: 10.1021/acs.jpclett.1c01028] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The combination of CdSe nanoparticles as photosensitizers with [FeFe]-hydrogenase mimics is known to result in efficient systems for light-driven hydrogen generation with reported turnover numbers in the order of 104-106. Nevertheless, little is known about the details of the light-induced charge-transfer processes. Here, we investigate the time scale of light-induced electron transfer kinetics for a simple model system consisting of CdSe quantum dots (QDs) of 2.0 nm diameter and a simple [FeFe]-hydrogenase mimic adsorbed to the QD surface under noncatalytic conditions. Our (time-resolved) spectroscopic investigation shows that both hot electron transfer on a sub-ps time scale and band-edge electron transfer on a sub-10 ps time scale from photoexcited QDs to adsorbed [FeFe]-hydrogenase mimics occur. Fast recombination via back electron transfer is observed in the absence of a sacrificial agent or protons which, under real catalytic conditions, would quench remaining holes or could stabilize the charge separation, respectively.
Collapse
Affiliation(s)
- Alexander Schleusener
- Department Functional Interfaces, Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745 Jena, Germany
- Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
| | - Mathias Micheel
- Department Functional Interfaces, Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745 Jena, Germany
| | - Stefan Benndorf
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstraße 8, 07743 Jena, Germany
| | - Markus Rettenmayr
- Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany
| | - Wolfgang Weigand
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstraße 8, 07743 Jena, Germany
| | - Maria Wächtler
- Department Functional Interfaces, Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745 Jena, Germany
- Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
- Abbe Center of Photonics, Friedrich Schiller University Jena, Albert-Einstein-Str. 6, 07745 Jena, Germany
| |
Collapse
|
8
|
Olshansky JH, Harvey SM, Pennel ML, Krzyaniak MD, Schaller RD, Wasielewski MR. Using Photoexcited Core/Shell Quantum Dots To Spin Polarize Appended Radical Qubits. J Am Chem Soc 2020; 142:13590-13597. [DOI: 10.1021/jacs.0c06073] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Jacob H. Olshansky
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Samantha M. Harvey
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Makenna L. Pennel
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Matthew D. Krzyaniak
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Richard D. Schaller
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, United States
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Michael R. Wasielewski
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, United States
| |
Collapse
|
9
|
Boldt K, Bartlett S, Kirkwood N, Johannessen B. Quantification of Material Gradients in Core/Shell Nanocrystals Using EXAFS Spectroscopy. NANO LETTERS 2020; 20:1009-1017. [PMID: 31960678 DOI: 10.1021/acs.nanolett.9b04143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Core/shell nanocrystals with a graded interface between core and shell exhibit improved optoelectronic properties compared with particles with an abrupt, sharp interface. Material gradients mitigate interfacial defects and define the shape of the confinement potential. So far, few works exist that allow to quantify the width of the gradient. In this study, ZnSe/CdS nanocrystals with graded shells made at different temperatures are characterized using extended X-ray absorption fine structure (EXAFS) and Raman spectroscopies. The average coordination number of the probed element with respect to the two possible counterions is fit to a simple, geometric model. It is shown that at the lower temperature limit for shell growth (260 °C), substantial interfacial alloying can be attributed mainly to cation migration. At higher temperature (290 °C), strain minimization leads to atomic ordering of the metal ions and an anomalously low degree of phase mixing.
Collapse
Affiliation(s)
- Klaus Boldt
- Department of Chemistry & Zukunftskolleg, Box 710 , University of Konstanz , 78457 Konstanz , Germany
| | - Stuart Bartlett
- Diamond Light Source , Diamond House, Harwell Science and Innovation Campus , Didcot , Oxfordshire OX11 0DE , United Kingdom
| | - Nicholas Kirkwood
- ARC Centre in Exciton Science, School of Chemistry , The University of Melbourne , Parkville , Victoria 3010 , Australia
| | - Bernt Johannessen
- ANSTO Australian Synchrotron , 800 Blackburn Rd , Clayton , Victoria 3168 , Australia
| |
Collapse
|
10
|
Enders F, Budweg A, Zeng P, Lauth J, Smith TA, Brida D, Boldt K. Switchable dissociation of excitons bound at strained CdTe/CdS interfaces. NANOSCALE 2018; 10:22362-22373. [PMID: 30474672 DOI: 10.1039/c8nr07973k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Charge carrier dynamics of semiconductor nano-heterostructures are determined by band alignment and lattice mismatch of the adjacent materials. However, quantum efficiencies for the separation of excited charge carriers at such an interface are hard to predict and cannot yet be easily controlled. In this work we examine nanorods with a severely strained, axial CdTe/CdS interface using femtosecond transient absorption spectroscopy. We show that charge separation is mitigated by equal contributions of valence band distortion and formation of coulomb pairs across the interface. Left undisturbed such localised excitons relax rapidly via non-radiative recombination channels. By adding a competitive hole acceptor that disrupts the coulomb interaction we overcome the synergetic co-localisation of the carriers and realise charge separation. The thus created long-lived state can be exploited for a broad range of applications such as photocatalysis, water splitting, and switchable nanodevices.
Collapse
Affiliation(s)
- Florian Enders
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany.
| | | | | | | | | | | | | |
Collapse
|
11
|
Cherepanov DA, Gostev FE, Shelaev IV, Denisov NN, Nadtochenko VA. Monitoring the electric field in CdSe quantum dots under ultrafast interfacial electron transfer via coherent phonon dynamics. NANOSCALE 2018; 10:22409-22419. [PMID: 30475371 DOI: 10.1039/c8nr07644h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Coherent phonon dynamics in CdSe quantum dots (QD) under an ultrafast electron transfer (ET) reaction of the (1Se-1S3/2) exciton quenched by methyl viologen (MV2+) adsorbed onto the QD surface was studied by ultrafast pump-probe spectroscopy. Frequency and amplitude modulations (FM, AM) of the transient absorption ΔA(ωprobe,t) in the pure CdSe and coupled CdSe/MV2+ QDs were identified in the bleach band dynamics of the red-edge exciton. The fast Fourier transform (FFT) and continuous wavelet transform analysis of the FM and AM oscillations revealed peaks at 0.51-0.58 THz (17-19 cm-1) and 6.06-6.27 THz (202-209 cm-1) attributed to the longitudinal acoustic (LA) and longitudinal optical (LO) phonons, respectively. The electron transfer to MV2+ proceeded non-exponentially with effective time constants of 164 fs (∼30%) and 540 fs (∼70%). The quantum yield of MV˙+ radical formation was 40 ± 5%. It implies a fast route for the electron-hole pair [h+…MV˙+] recombination that can be rationalized in accordance with the adiabatic ET mechanism at the semiconductor surface. In the coupled CdSe/MV2+ QDs, the amplitude of the FM oscillations rose considerably with time despite the natural attenuation of the phonon amplitude due to decoherence processes. A kinetic model explaining the increase of FM oscillations is proposed. The surprising growth of FM oscillations is elucidated by the kinetic model taking into account the relatively slow damping of LO phonon oscillations (∼1.5 ps), the ultrafast ET to MV2+, and the quantum yield of charge separation [h+…MV˙+] (∼40%). The fast formation of the charge-separated pair [h+…MV˙+] suggests the appearance of an electric field F with a strength of ∼3 × 106 V cm-1. The MV2+ reduction substantially increased the magnitude of LA phonon oscillations. Since the ET time is shorter than the period of LA phonon oscillations (∼1.8 ps), the MV2+ reduction substantially increased the magnitude of LA phonon oscillations due to the inverse piezoelectric effect. The CdSe nanocrystals exposed to the electric field F exhibit the quantum-confined Stark and Franz-Keldysh electro-absorption effects. The proposed kinetic model gives consideration to the dynamic Stark shift of the red-edge exciton and to the increased amplitude of LO phonon oscillations in the bleach band dynamics.
Collapse
Affiliation(s)
- Dmitry A Cherepanov
- N.Semenov Institute of Chemical Physics Russian Academy of Sciences, Kosigin str.4, Moscow, 119991, Russia.
| | | | | | | | | |
Collapse
|
12
|
Dworak L, Roth S, Scheffer MP, Frangakis AS, Wachtveitl J. A thin CdSe shell boosts the electron transfer from CdTe quantum dots to methylene blue. NANOSCALE 2018; 10:2162-2169. [PMID: 29327031 DOI: 10.1039/c7nr08287h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
CdTe core and CdTe/CdSe core/shell quantum dots (QD) are investigated with steady state and time-resolved spectroscopic methods. The coating of the CdTe core with a 0.7 nm thick CdSe shell shifts the lowest exciton absorption band to the red by more than 70 nm making the CdTe/CdSe QD an interesting candidate for application in solar energy conversion. Femtosecond transient absorption measurements are applied to study the photoinduced electron transfer (ET) to the molecular acceptor methylene blue (MB). ET times after single excitation of the QD are determined for different MB : QD ratios. The ET reaction is significantly faster in the case of the MB-CdTe/CdSe QD complexes, indicative of an altered charge distribution in the photoexcited heterostructure with a higher electron density in the CdSe shell. As a result of the efficient absorption of incoming light and the faster ET reaction, the amount of reduced MB in the time resolved experiments is higher for CdTe/CdSe QD compared to CdTe QD.
Collapse
Affiliation(s)
- L Dworak
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Max-von-Laue-Str. 7, D-60438 Frankfurt am Main, Germany.
| | | | | | | | | |
Collapse
|
13
|
Tkachenko NV. Photoinduced Charge Separation in Semiconductor-Quantum-Dot/Organic-Molecule Hybrids. CHEMPHOTOCHEM 2017. [DOI: 10.1002/cptc.201700161] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Nikolai V. Tkachenko
- Laboratory of Chemistry and Bioengineering; Tampere University of Technology; P.O.Box 541 33101 Tampere Finland
| |
Collapse
|
14
|
Grenland JJ, Maddux CJA, Kelley DF, Kelley AM. Charge Trapping versus Exciton Delocalization in CdSe Quantum Dots. J Phys Chem Lett 2017; 8:5113-5118. [PMID: 28972776 DOI: 10.1021/acs.jpclett.7b02242] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The spectroscopic and photophysical similarities and differences between charge trapping by surface ligands on CdSe quantum dots and charge delocalization into the shell in excited CdSe core/shell nanocrystals are discussed. Optical absorption and resonance Raman spectroscopies are used to study small CdSe quantum dots coated with organic ligands that accept electrons (methyl viologen) or holes (phenothiazine, 4-methylbenzenethiol), as well as with semiconductor shells that delocalize electrons (CdS) or holes (CdTe). The organic ligands have only a small effect on the optical absorption spectrum and contribute negligibly to the resonance Raman spectra, indicating little participation of ligand orbitals in the initial excitation. The semiconductor shells more strongly red-shift the absorption spectrum by delocalizing the electron and/or hole into the shell, and vibrations of the shell appear in the resonance Raman spectrum, showing that the shell is involved in the vertical excitation. The qualitative differences between ligand and semiconductor shells are discussed in terms of the energetics and coupling strengths.
Collapse
Affiliation(s)
- Jamie J Grenland
- Chemistry and Chemical Biology, University of California, Merced , 5200 North Lake Road, Merced, California 95343, United States
| | - Cassandra J A Maddux
- Chemistry and Chemical Biology, University of California, Merced , 5200 North Lake Road, Merced, California 95343, United States
| | - David F Kelley
- Chemistry and Chemical Biology, University of California, Merced , 5200 North Lake Road, Merced, California 95343, United States
| | - Anne Myers Kelley
- Chemistry and Chemical Biology, University of California, Merced , 5200 North Lake Road, Merced, California 95343, United States
| |
Collapse
|
15
|
Ponseca CS, Chábera P, Uhlig J, Persson P, Sundström V. Ultrafast Electron Dynamics in Solar Energy Conversion. Chem Rev 2017; 117:10940-11024. [DOI: 10.1021/acs.chemrev.6b00807] [Citation(s) in RCA: 211] [Impact Index Per Article: 30.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Carlito S. Ponseca
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Pavel Chábera
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Jens Uhlig
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Petter Persson
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Villy Sundström
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
| |
Collapse
|
16
|
Silvi S, Baroncini M, La Rosa M, Credi A. Interfacing Luminescent Quantum Dots with Functional Molecules for Optical Sensing Applications. Top Curr Chem (Cham) 2016; 374:65. [PMID: 27580893 DOI: 10.1007/s41061-016-0066-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 08/17/2016] [Indexed: 12/30/2022]
Abstract
Semiconductor quantum dots possess unique size-dependent electronic properties and are of high potential interest for the construction of functional nanodevices. Photoinduced electron- and energy-transfer processes between quantum dots and surface-bound molecular species open up attractive routes to implement chemical switching of luminescence, which is at the basis of luminescence sensing. In this article, we discuss the general principles underlying the rational design of this kind of multicomponent species. Successively, we illustrate a few prominent examples, taken from the recent literature, of luminescent chemosensors constructed by attaching molecular species to the surface of quantum dots.
Collapse
Affiliation(s)
- Serena Silvi
- Dipartimento di Chimica "G. Ciamician", Università di Bologna, via Selmi 2, 40126, Bologna, Italy.
| | - Massimo Baroncini
- Dipartimento di Chimica "G. Ciamician", Università di Bologna, via Selmi 2, 40126, Bologna, Italy
| | - Marcello La Rosa
- Dipartimento di Chimica "G. Ciamician", Università di Bologna, via Selmi 2, 40126, Bologna, Italy
| | - Alberto Credi
- Dipartimento di Scienze e Tecnologie Agro-alimentari, Università di Bologna, viale Fanin 44, 40129, Bologna, Italy.
| |
Collapse
|