Sebastian Volk


Last Name

Volk

First Name

Sebastian

ORCID

0000-0002-1915-1373

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2013 - 201992020 - 20244
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Publications1 - 10 of 13
  • Size, Ligand, and Defect-Dependent Electron-Phonon Coupling in Chalcogenide and Perovskite Nanocrystals and Its Impact on Luminescence Line Widths
    Item type: Journal Article
    Yazdani, Nuri; Volk, Sebastian; Yarema, Olesya; et al. (2020)
    ACS Photonics
  • Nanocrystal superlattices as phonon-engineered solids and acoustic metamaterials
    Item type: Journal Article
    Yazdani, Nuri; Jansen, Maximilian; Bozyigit, Deniz; et al. (2019)
    Nature Communications
    Phonon engineering of solids enables the creation of materials with tailored heat-transfer properties, controlled elastic and acoustic vibration propagation, and custom phonon–electron and phonon–photon interactions. These can be leveraged for energy transport, harvesting, or isolation applications and in the creation of novel phonon-based devices, including photoacoustic systems and phonon-communication networks. Here we introduce nanocrystal superlattices as a platform for phonon engineering. Using a combination of inelastic neutron scattering and modeling, we characterize superlattice-phonons in assemblies of colloidal nanocrystals and demonstrate that they can be systematically engineered by tailoring the constituent nanocrystals, their surfaces, and the topology of superlattice. This highlights that phonon engineering can be effectively carried out within nanocrystal-based devices to enhance functionality, and that solution processed nanocrystal assemblies hold promise not only as engineered electronic and optical materials, but also as functional metamaterials with phonon energy and length scales that are unreachable by traditional architectures.
  • Structural Ordering in Ultrasmall Multicomponent Chalcogenides: The Case of Quaternary Cu-Zn-In-Se Nanocrystals
    Item type: Journal Article
    Yarema, Maksym; Yazdani, Nuri; Yarema, Olesya; et al. (2024)
    Advanced Materials
    The compositional tunability of non-isovalent multicomponent chalcogenide thin films and the extent of atomic ordering of their crystal structure is key to the performance of many modern technologies. In contrast, the effects of ordering are rarely studied for quantum-confined materials, such as colloidal nanocrystals. In this paper, the possibilities around composition tunability and atomic ordering are explored in ultrasmall ternary and quaternary quantum dots, taking I-III-VI-group Cu-Zn-In-Se semiconductor as a case study. A quantitative synthesis for 3.3 nm quaternary chalcogenide nanocrystals is developed and shown that cation and cationic vacancy ordering can be achieved in these systems consisting of only 100s of atoms. Combining experiment and theoretical calculations, the relationship between structural ordering and optical properties of the materials are demonstrated. It is found that the arrangement and ordering of cationic sublattice plays an important role in the luminescent efficiency. Specifically, the concentration of Cu-vacancy couples in the nanocrystal correlates with luminescence quantum yield, while structure ordering increases the occurrence of such optically active Cu-vacancy units. On the flip side, the detrimental impact of cationic site disorder in I-III-VI nanocrystals can be mitigated by introducing a cation of intermediate valence, such as Zn (II).
  • Upscaling Colloidal Nanocrystal Hot-Injection Syntheses via Reactor Underpressure
    Item type: Journal Article
    Yarema, Maksym; Yarema, Olesya; Lin, Weyde; et al. (2017)
    Chemistry of Materials
  • Measuring the Electronic Structure of Nanocrystal Thin Films Using Energy-Resolved Electrochemical Impedance Spectroscopy
    Item type: Journal Article
    Volk, Sebastian; Yazdani, Nuri; Sanusoglu, Emir; et al. (2018)
    The Journal of Physical Chemistry Letters
  • In Situ Measurement and Control of the Fermi Level in Colloidal Nanocrystal Thin Films during Their Fabrication
    Item type: Journal Article
    Volk, Sebastian; Yazdani, Nuri; Yarema, Olesya; et al. (2018)
    The Journal of Physical Chemistry Letters
  • Dopants and Traps in Nanocrystal-Based Semiconductor Thin Films: Origins and Measurement of Electronic Midgap States
    Item type: Journal Article
    Volk, Sebastian; Yazdani, Nuri; Yarema, Olesya; et al. (2020)
    ACS Applied Electronic Materials
  • Soft surfaces of nanomaterials enable strong phonon interactions
    Item type: Journal Article
    Bozyigit, Deniz; Yazdani, Nuri; Yarema, Maksym; et al. (2016)
    Nature
  • Compact Mid-Infrared Gas Sensing Enabled by an All-Metamaterial Design
    Item type: Journal Article
    Lochbaum, Alexander; Dorodnyy, Alexander; Koch, Ueli; et al. (2020)
    Nano Letters
    The miniaturization of mid-infrared optical gas sensors has great potential to make the “fingerprint region” between 2 and 10 μm accessible to a variety of cost-sensitive applications ranging from medical technology to atmospheric sensing. Here we demonstrate a gas sensor concept that achieves a 30-fold reduction in absorption volume compared to conventional gas sensors by using plasmonic metamaterials as on-chip optical filters. Integrating metamaterials into both the emitter and the detector cascades their individual filter functions, yielding a narrowband spectral response tailored to the absorption band of interest, here CO2. Simultaneously, the metamaterials’ angle-independence is maintained, enabling an optically efficient, millimeter-scale cavity. With a CO2 sensitivity of 22.4 ± 0.5 ppm·Hz–0.5, the electrically driven prototype already performs at par with much larger commercial devices while consuming 80% less energy per measurement. The all-metamaterial sensing concept offers a path toward more compact and energy-efficient mid-infrared gas sensors without trade-offs in sensitivity or robustness.
Publications1 - 10 of 13