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Tahara H, Sakamoto M, Teranishi T, Kanemitsu Y. Coherent electronic coupling in quantum dot solids induces cooperative enhancement of nonlinear optoelectronic responses. NATURE NANOTECHNOLOGY 2024; 19:744-750. [PMID: 38297146 DOI: 10.1038/s41565-024-01601-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 01/04/2024] [Indexed: 02/02/2024]
Abstract
Synchronized dynamics of quantum dot (QD) ensembles are essential for generating ultrafast and giant optical responses beyond those of individual QDs. Increasing the strength of the direct electronic coupling between QDs is a key strategy for the realization of cooperative quantum phenomena. Here, we observe a quantum cooperative effect on nonlinear photocurrents caused by the coherent electronic coupling in semiconductor QD solids. We measure quantum interference signals cooperatively generated in QD solids. We control the inter-QD distance with atomic precision using bidentate ligands that strongly link the QDs. The harmonic quantum interference signals are strongly enhanced when shortening the molecular length of the ligand. Furthermore, we clarify that the coherence length of multiexcitons extends to neighbouring QDs. This finding is direct evidence that multiexciton coherent tunnelling assists the ultrafast exciton delocalization. Cooperative enhancement in QD solids may find application in advanced quantum optoelectronics.
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Affiliation(s)
- Hirokazu Tahara
- The Hakubi Center for Advanced Research, Kyoto University, Kyoto, Japan.
- Institute for Chemical Research, Kyoto University, Uji, Japan.
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Birhanu Hayilesilassie R, Gemta AB, Maremi FT, Getahun Kumela A, Gudishe K, Dana BD. Detection and photothermal inactivation of Gram-positive and Gram-negative bloodstream bacteria using photonic crystal biosensor and plasmonic core-shell. RSC Adv 2024; 14:11594-11603. [PMID: 38601705 PMCID: PMC11004602 DOI: 10.1039/d4ra01802h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 04/02/2024] [Indexed: 04/12/2024] Open
Abstract
Plasmonics and core-shell nanomaterials hold great potential to develop pharmaceuticals and medical equipment due to their eco-friendly and cost effective fabrication procedures. Despite these advancements, combating drug-resistant bacterial infections remains a global challenge. Therefore, this study aims to introduce a tailored theoretical framework for a one-dimensional (1D) photonic crystal biosensor (PCB) composed of (ZrO2/GaN)N/defect layer/(ZrO2/GaN)N, designed to detect Gram-positive and Gram-negative bloodstream bacteria employing the transfer matrix method (TMM). In addition, using the finite difference methods (FDM), the photothermal inactivation of bloodstream bacteria with plasmonic core-shell structures (FeO@AuBiS2) was explored using key factors such as light absorption, heat generation, and thermal diffusion. By incorporating six dielectric layers and contaminated blood into the proposed PCB, a maximum sensitivity of 562 nm per RIU was recorded, and using rod-shaped plasmonic core-shell structures, 5.8 nm-1 light absorption capacity and 152 K change in temperature were achieved. The maximum detection sensitivity, light absorption, heat conduction and heat convection capacity of the proposed 1D PCB and plasmonic core-shell show an effective approach to combating drug-resistant bacteria.
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Affiliation(s)
- Ruth Birhanu Hayilesilassie
- Department of Applied Physics, School of Applied Natural Sciences, Adama Science and Technology University P.O.Box 1888 Adama Ethiopia
| | - Abebe Belay Gemta
- Department of Applied Physics, School of Applied Natural Sciences, Adama Science and Technology University P.O.Box 1888 Adama Ethiopia
| | - Fekadu Tolessa Maremi
- Department of Applied Physics, School of Applied Natural Sciences, Adama Science and Technology University P.O.Box 1888 Adama Ethiopia
| | - Alemayehu Getahun Kumela
- Department of Applied Physics, College of Natural and Computational Sciences, Mekdela Amba University P.O.Box 032 Tullu Awulia Ethiopia
| | - Kusse Gudishe
- Department of Applied Physics, College of Natural and Computational Sciences, Jinka University Jinka Ethiopia
| | - Bereket Delga Dana
- Department of Applied Physics, College of Natural and Computational Sciences, Jinka University Jinka Ethiopia
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Shulenberger KE, Sherman SJ, Jilek MR, Keller HR, Pellows LM, Dukovic G. Exciton and biexciton transient absorption spectra of CdSe quantum dots with varying diameters. J Chem Phys 2024; 160:014708. [PMID: 38174790 DOI: 10.1063/5.0179129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 12/04/2023] [Indexed: 01/05/2024] Open
Abstract
Transient absorption (TA) spectroscopy of semiconductor nanocrystals (NCs) is often used for excited state population analysis, but recent results suggest that TA bleach signals associated with multiexcitons in NCs do not scale linearly with exciton multiplicity. In this manuscript, we probe the factors that determine the intensities and spectral positions of exciton and biexciton components in the TA spectra of CdSe quantum dots (QDs) of five diameters. We find that, in all cases, the peak intensity of the biexciton TA spectrum is less than 1.5 times that of the single exciton TA spectrum, in stark contrast to a commonly made assumption that this ratio is 2. The relative intensities of the biexciton and exciton TA signals at each wavelength are determined by at least two factors: the TA spectral intensity and the spectral offset between the two signals. We do not observe correlations between either of these factors and the particle diameter, but we find that both are strongly impacted by replacing the native organic surface-capping ligands with a hole-trapping ligand. These results suggest that surface trapping plays an important role in determining the absolute intensities of TA features for CdSe QDs and not just their decay kinetics. Our work highlights the role of spectral offsets and the importance of surface trapping in governing absolute TA intensities. It also conclusively demonstrates that the biexciton TA spectra of CdSe QDs at the band gap energy are less than twice as intense as those of the exciton.
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Affiliation(s)
| | - Skylar J Sherman
- Department of Chemistry, University of Colorado Boulder, 215 UCB, Boulder, Colorado 80309, USA
| | - Madison R Jilek
- Department of Chemistry, University of Colorado Boulder, 215 UCB, Boulder, Colorado 80309, USA
| | - Helena R Keller
- Materials Science and Engineering, University of Colorado Boulder, 613 UCB, Boulder, Colorado 80303, USA
| | - Lauren M Pellows
- Department of Chemistry, University of Colorado Boulder, 215 UCB, Boulder, Colorado 80309, USA
| | - Gordana Dukovic
- Department of Chemistry, University of Colorado Boulder, 215 UCB, Boulder, Colorado 80309, USA
- Materials Science and Engineering, University of Colorado Boulder, 613 UCB, Boulder, Colorado 80303, USA
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, 027 UCB, Boulder, Colorado 80309, USA
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Abstract
The microscopic origin and timescale of the fluctuations of the energies of electronic states has a significant impact on the properties of interest of electronic materials, with implication in fields ranging from photovoltaic devices to quantum information processing. Spectroscopic investigations of coherent dynamics provide a direct measurement of electronic fluctuations. Modern multidimensional spectroscopy techniques allow the mapping of coherent processes along multiple time or frequency axes and thus allow unprecedented discrimination between different sources of electronic dephasing. Exploiting modern abilities in coherence mapping in both amplitude and phase, we unravel dissipative processes of electronic coherences in the model system of CdSe quantum dots (QDs). The method allows the assignment of the nature of the observed coherence as vibrational or electronic. The expected coherence maps are obtained for the coherent longitudinal optical (LO) phonon, which serves as an internal standard and confirms the sensitivity of the technique. Fast dephasing is observed between the first two exciton states, despite their shared electron state and common environment. This result is contrary to predictions of the standard effective mass model for these materials, in which the exciton levels are strongly correlated through a common size dependence. In contrast, the experiment is in agreement with ab initio molecular dynamics of a single QD. Electronic dephasing in these materials is thus dominated by the realistic electronic structure arising from fluctuations at the atomic level rather than static size distribution. The analysis of electronic dephasing thereby uniquely enables the study of electronic fluctuations in complex materials.
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Kobiyama E, Tahara H, Sato R, Saruyama M, Teranishi T, Kanemitsu Y. Reduction of Optical Gain Threshold in CsPbI 3 Nanocrystals Achieved by Generation of Asymmetric Hot-Biexcitons. NANO LETTERS 2020; 20:3905-3910. [PMID: 32343589 DOI: 10.1021/acs.nanolett.0c01079] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Lead halide perovskite nanocrystals (NCs) are a class of promising light-emitting materials and have been considered as gain media in lasers. Strong exciton-exciton interactions in NCs cause an energy shift of the lowest optical transition and affect the optical gain threshold. Here, we clarify the dynamics of exciton-exciton interactions in highly photoexcited CsPbI3 NCs by double-pump transient absorption spectroscopy. This method provides control over the population of each excited state by varying the time interval between the two pump pulses. We find that the band-edge energy shift induced by the formation of asymmetric hot-biexcitons (comprising one ground-state exciton and one hot exciton) is smaller than that induced by hot excitons and hot biexcitons in the ensemble. We demonstrate that the generation of asymmetric hot-biexcitons reduces the optical gain threshold in the CsPbI3 NC ensemble.
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Affiliation(s)
- Etsuki Kobiyama
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Hirokazu Tahara
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Ryota Sato
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Masaki Saruyama
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Toshiharu Teranishi
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Yoshihiko Kanemitsu
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
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Xu JX, Yuan Y, Liu M, Zou S, Chen O, Zhang D. Quantification of the Photon Absorption, Scattering, and On-Resonance Emission Properties of CdSe/CdS Core/Shell Quantum Dots: Effect of Shell Geometry and Volumes. Anal Chem 2020; 92:5346-5353. [PMID: 32126174 DOI: 10.1021/acs.analchem.0c00016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Reliable quantification of the optical properties of fluorescent quantum dots (QDs) is critical for their photochemical, -physical, and -biological applications. Presented herein is the experimental quantification of photon scattering, absorption, and on-resonance-fluorescence (ORF) activities of CdSe/CdS core/shell fluorescent QDs as a function of the shell sizes and geometries. Four spherical QDs (SQDs) with different diameters and four rod-like QDs (RQDs) with different aspect ratios (ARs) have been analyzed using UV-vis, fluorescence, and the recent polarized resonance synchronous spectroscopic (PRS2) methods. All quantum dots are simultaneous absorbers and scatterers in the UV-vis wavelength region, and they all exhibit strong ORF emission in the wavelength regions where the QDs both absorb and emit. The absorption and scattering cross-sections of the CdS shell are linearly and quadratically, respectively, proportional to the shell volume for both the SQDs and RQDs. However, the effects of CdS shell coating on the core optical properties are different between SQDs and RQDs. For RQDs, increasing the CdS shell volume through the length elongation has no effect on either the peak wavelength or intensity of the CdSe core UV-vis absorption and ORF, but it reduces the QD fluorescence depolarization. In contrast, increasing CdS shell volume in the SQDs induces red-shift in the CdSe core peak UV-vis absorption and ORF wavelengths, and increases their peak cross-sections, but it has no effect on the SQD fluorescence depolarization. The RQD ORF cross-sections and quantum yields are significantly higher than their respective counterparts for the SQDs with similar particle sizes (volumes). While these new insights should be significant for the QD design, characterization, and applications, the methodology presented in this work is directly applicable for quantifying the optical activities of optically complex materials where the common UV-vis spectrometry and fluorescence spectroscopy are inadequate.
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Affiliation(s)
- Joanna Xiuzhu Xu
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
| | - Yucheng Yuan
- Department of Chemistry, Brown University, 324 Brook Street, Providence, Rhode Island 02912, United States
| | - Muqiong Liu
- Department of Chemistry, University of Central Florida, Orlando, Florida 32816, United States
| | - Shengli Zou
- Department of Chemistry, University of Central Florida, Orlando, Florida 32816, United States
| | - Ou Chen
- Department of Chemistry, Brown University, 324 Brook Street, Providence, Rhode Island 02912, United States
| | - Dongmao Zhang
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
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Nakahara S, Ohara K, Tahara H, Yumoto G, Kawawaki T, Saruyama M, Sato R, Teranishi T, Kanemitsu Y. Ionization and Neutralization Dynamics of CsPbBr 3 Perovskite Nanocrystals Revealed by Double-Pump Transient Absorption Spectroscopy. J Phys Chem Lett 2019; 10:4731-4736. [PMID: 31362511 DOI: 10.1021/acs.jpclett.9b01554] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Ionization of nanocrystals (NCs) causes both photoluminescence intermittency and a reduction in luminescence quantum efficiency and thus plays a critical role in the optoelectronic performance of NC-based devices. Here, we study the ionization and neutralization processes of CsPbBr3 perovskite NCs under strong photoexcitation by means of double-pump transient absorption spectroscopy. A strong initial pulse is used to generate ionized NCs, and their optical responses are investigated by varying the excitation intensity and delay time of the second pump pulse. We find that charging can occur either via nonradiative Auger recombination of biexcitons or via any possible recombination of trions. The presence of the extra charge inside of an ionized perovskite NC significantly reduces its absorption cross section. The experiments reveal that ionized NCs exhibit two types of neutralization processes with time constants on the order of nanoseconds and microseconds. These results are useful for the optimal design of NC-based photonic devices.
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Affiliation(s)
- Satoshi Nakahara
- Institute for Chemical Research , Kyoto University , Uji , Kyoto 611-0011 , Japan
| | - Keiichi Ohara
- Institute for Chemical Research , Kyoto University , Uji , Kyoto 611-0011 , Japan
| | - Hirokazu Tahara
- Institute for Chemical Research , Kyoto University , Uji , Kyoto 611-0011 , Japan
| | - Go Yumoto
- Institute for Chemical Research , Kyoto University , Uji , Kyoto 611-0011 , Japan
| | - Tokuhisa Kawawaki
- Institute for Chemical Research , Kyoto University , Uji , Kyoto 611-0011 , Japan
| | - Masaki Saruyama
- Institute for Chemical Research , Kyoto University , Uji , Kyoto 611-0011 , Japan
| | - Ryota Sato
- Institute for Chemical Research , Kyoto University , Uji , Kyoto 611-0011 , Japan
| | - Toshiharu Teranishi
- Institute for Chemical Research , Kyoto University , Uji , Kyoto 611-0011 , Japan
| | - Yoshihiko Kanemitsu
- Institute for Chemical Research , Kyoto University , Uji , Kyoto 611-0011 , Japan
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Fu S, Zhang S, Li J, Bai Z, Wu T, Man Z. Passively Q-switched Nd-doped fiber laser based on PbS/CdS core/shell quantum dots as a saturable absorber. APPLIED OPTICS 2019; 58:3036-3041. [PMID: 31044909 DOI: 10.1364/ao.58.003036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 03/20/2019] [Indexed: 06/09/2023]
Abstract
In our work, PbS/CdS core/shell quantum dots with an absorption peak of 1043 nm were successfully employed as a modulator for achieving a passively Q-switched Nd-doped fiber laser. The saturation intensity and modulation depth of the film-type modulator were 7.6 MW/cm2 and 4.1%, respectively. Due to the protection of the CdS shell, the PbS core exhibited good photo-chemical stability, which led to the generation of stable passively Q-switched operation. The maximum average output power was 7.88 mW with a minimum pulse width of 235.7 ns. To our knowledge, this was the first demonstration focusing on the combination of quantum dot and Nd-doped fiber laser; in addition, 235.7 ns was the narrowest pulse width of a passively Q-switched Nd-doped fiber laser. Our results highlighted the excellent nonlinear absorption properties of PbS/CdS core/shell quantum dots and give significant guidance for future optical applications of quantum dots and demonstrations of pulsed Nd-doped fiber lasers.
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Nakazawa N, Zhang Y, Liu F, Ding C, Hori K, Toyoda T, Yao Y, Zhou Y, Hayase S, Wang R, Zou Z, Shen Q. The interparticle distance limit for multiple exciton dissociation in PbS quantum dot solid films. NANOSCALE HORIZONS 2019; 4:445-451. [PMID: 32254096 DOI: 10.1039/c8nh00341f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Understanding the behaviour of multiple exciton dissociation in quantum dot (QD) solid films is of fundamental interest and paramount importance for improving the performance of quantum dot solar cells (QDSCs). Unfortunately, the charge transfer behaviour of photogenerated multiple exciton in QD solid films is not clear to date. Herein, we systematically investigate the multiple exciton charge transfer behaviour in PbS QD solid films by using ultrafast transient absorption spectroscopy. We observe that the multiple exciton charge transfer rate within QD ensembles is exponentially enhanced as the interparticle distance between the QDs decreases. Biexciton and triexciton dissociation between adjacent QDs occurs via a charge transfer tunneling effect just like single exciton, and the charge tunneling constants of the single exciton (β1: 0.67 ± 0.02 nm-1), biexciton (β2: 0.68 ± 0.05 nm-1) and triexciton (β3: 0.71 ± 0.01 nm-1) are obtained. More importantly, for the first time, the interparticle distance limit (≤4.3 nm) for multiple exciton charge transfer between adjacent QDs is found for the extraction of multiple excitons rapidly before the occurrence of Auger recombination. This result points out a vital and necessary condition for the use of multiple excitons produced in PbS QD films, especially for their applications in QDSCs.
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Affiliation(s)
- Naoki Nakazawa
- Faculty of Informatics and Engineering, The University of Electro-Communications, Tokyo 182-8585, Japan.
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Lian Z, Sakamoto M, Vequizo JJM, Ranasinghe CSK, Yamakata A, Nagai T, Kimoto K, Kobayashi Y, Tamai N, Teranishi T. Plasmonic p–n Junction for Infrared Light to Chemical Energy Conversion. J Am Chem Soc 2018; 141:2446-2450. [DOI: 10.1021/jacs.8b11544] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Zichao Lian
- Department of Chemistry, Graduate School of Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Masanori Sakamoto
- Institute for Chemical Research, Kyoto University, Gokasho,
Uji, Kyoto 611-0011, Japan
| | - Junie J. M. Vequizo
- Graduate School of Engineering, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya 468-8511, Japan
| | - C. S. Kumara Ranasinghe
- Graduate School of Engineering, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya 468-8511, Japan
| | - Akira Yamakata
- Graduate School of Engineering, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya 468-8511, Japan
| | - Takuro Nagai
- National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Koji Kimoto
- National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Yoichi Kobayashi
- Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan
| | - Naoto Tamai
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Toshiharu Teranishi
- Institute for Chemical Research, Kyoto University, Gokasho,
Uji, Kyoto 611-0011, Japan
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