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Cai R, Feng M, Kanwat A, Furuhashi T, Wang B, Sum TC. Floquet Engineering of Excitons in Two-Dimensional Halide Perovskites via Biexciton States. NANO LETTERS 2024; 24:3441-3447. [PMID: 38457695 DOI: 10.1021/acs.nanolett.4c00074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/10/2024]
Abstract
Layered two-dimensional halide perovskites (2DHPs) exhibit exciting non-equilibrium properties that allow the manipulation of energy levels through coherent light-matter interactions. Under the Floquet picture, novel quantum states manifest through the optical Stark effect (OSE) following intense subresonant photoexcitation. Nevertheless, a detailed understanding of the influence of strong many-body interactions between excitons on the OSE in 2DHPs remains unclear. Herein, we uncover the crucial role of biexcitons in photon-dressed states and demonstrate precise optical control of the excitonic states via the biexcitonic OSE in 2DHPs. With fine step tuning of the driven energy, we fully parametrize the evolution of exciton resonance modulation. The biexcitonic OSE enables Floquet engineering of the exciton resonance with either a blue-shift or a red-shift of the energy levels. Our findings shed new light on the intricate nature of coherent light-matter interactions in 2DHPs and extend the degree of freedom for ultrafast coherent optical control over excitonic states.
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Affiliation(s)
- Rui Cai
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Minjun Feng
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Anil Kanwat
- Energy Research Institute@NTU (ERI@N), Nanyang Technological University, 50 Nanyang Drive, Singapore 637553
| | - Tomoki Furuhashi
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Bo Wang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Tze Chien Sum
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
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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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Diroll BT. Optical stark effect on CdSe nanoplatelets with mid-infrared excitation for large amplitude ultrafast modulation. NANOTECHNOLOGY 2023; 34:245706. [PMID: 36917849 DOI: 10.1088/1361-6528/acc40c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 03/14/2023] [Indexed: 06/18/2023]
Abstract
The optical Stark effect is a universal response of the electronic structure to incident light. In semiconductors, particularly nanomaterials, the optical Stark effect achieved with sub-band gap photons can drive large, narrowband, and potentially ultrafast changes in the absorption or reflection at the band gap through excitation of virtual excitons. Rapid optical modulation using the optical Stark effect is ultimately constrained, however, by the generation of long-lived excitons through multiphoton absorption. This work compares the modulation achievable using the optical Stark effect on CdSe nanoplatelets with several different pump photon energies, from the visible to mid-infrared. Despite expected lower efficiencies for spectrally-remote pump energies, infrared pump pulses can ultimately drive larger sub-picosecond optical Stark shifts of virtual excitons without creation of real excitons. The CdSe nanoplatelets show subpicosecond shifts of the lowest excitonic resonance of up to 22 meV, resulting in change in absorption as large as 0.32 OD (49% increase in transmission), with a long-lived offset from real excitons less than 1% of the peak signal.
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Affiliation(s)
- Benjamin T Diroll
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, IL 60439, United States of America
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Lin X, Han Y, Zhu J, Wu K. Room-temperature coherent optical manipulation of hole spins in solution-grown perovskite quantum dots. NATURE NANOTECHNOLOGY 2023; 18:124-130. [PMID: 36536044 DOI: 10.1038/s41565-022-01279-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 10/27/2022] [Indexed: 06/17/2023]
Abstract
Manipulation of solid-state spin coherence is an important paradigm for quantum information processing. Current systems either operate at very low temperatures or are difficult to scale up. Developing low-cost, scalable materials whose spins can be coherently manipulated at room temperature is thus highly attractive for a sustainable future of quantum information science. Here we report ambient-condition all-optical initialization, manipulation and readout of hole spins in an ensemble of solution-grown CsPbBr3 perovskite quantum dots with a single hole in each dot. The hole spins are initialized by sub-picosecond electron scavenging following circularly polarized femtosecond-pulse excitation. A transverse magnetic field induces spin precession, and a second off-resonance femtosecond-pulse coherently rotates hole spins via strong light-matter interaction. These operations accomplish near-complete quantum-state control, with a coherent rotation angle close to the π radian, of hole spins at room temperature.
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Affiliation(s)
- Xuyang Lin
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yaoyao Han
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jingyi Zhu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, China
| | - Kaifeng Wu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, China.
- University of Chinese Academy of Sciences, Beijing, China.
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