Bogdan Markovich Benin


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Benin

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Bogdan Markovich

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0000-0002-6502-8237

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Publications 1 - 10 of 16
  • Microcarrier-Assisted Inorganic Shelling of Lead Halide Perovskite Nanocrystals
    Item type: Journal Article
    Dirin, Dmitry; Benin, Bogdan Markovich; Yakunin, Sergii; et al. (2019)
    ACS Nano
    The conventional strategy of synthetic colloidal chemistry for bright and stable quantum dots has been the production of epitaxially matched core/shell heterostructures to mitigate the presence of deep trap states. This mindset has been shown to be incompatible with lead halide perovskite nanocrystals (LHP NCs) due to their dynamic surface and low melting point. Nevertheless, enhancements to their chemical stability are still in great demand for the deployment of LHP NCs in light-emitting devices. Rather than contend with their attributes, we propose a method in which we can utilize their dynamic, ionic lattice and uniquely defect-tolerant band structure to prepare non-epitaxial salt-shelled heterostructures that are able to stabilize these materials against their environment, while maintaining their excellent optical properties and increasing scattering to improve out-coupling efficiency. To do so, anchored LHP NCs are first synthesized through the heterogeneous nucleation of LHPs onto the surface of microcrystalline carriers, such as alkali halides. This first step stabilizes the LHP NCs against further merging, and this allows them to be coated with an additional inorganic shell through the surface-mediated reaction of amphiphilic Na and Br precursors in apolar media. These inorganically shelled NC@carrier composites offer significantly improved chemical stability toward polar organic solvents, such as γ-butyrolactone, acetonitrile, N-methylpyrrolidone, and trimethylamine, demonstrate high thermal stability with photoluminescence intensity reversibly dropping by no more than 40% at temperatures up to 120 °C, and improve compatibility with various UV-curable resins. This mindset for LHP NCs creates opportunities for their successful integration into next-generation light-emitting devices.
  • Lone-Pair-Induced Structural Ordering in the Mixed-Valent 0D Metal-Halides Rb23BiIIIxSbIII7–xSbV2Cl54 (0 ≤ x ≤ 7)
    Item type: Journal Article
    Benin, Bogdan Markovich; Mc Call, Kyle; Wörle, Michael; et al. (2021)
    Chemistry of Materials
    Mixed-valent metal-halides containing ns2 lone pairs may exhibit intense visible absorption, while zero-dimensional (0D) ns2-based metal-chlorides are generally colorless but have demonstrated promising optoelectronic properties suitable for thermometry and radiation detection. Here, we report solvothermally synthesized mixed-valent 0D metal-halides Rb23BiIIIxSbIII7-xSbV2Cl54 (0 ≤ x ≤ 7). Rb23SbIII7SbV2Cl54 crystallizes in an orthorhombic space group (Cmcm) with a unique, layered 0D structure driven by the arrangement of the 5s2 lone pairs of the SbIIICl6 octahedra. This red material is likely the true structure of a previously reported monoclinic "Rb2.67SbCl6"phase, the structure of which was not determined. Partially or fully substituting SbIII with isoelectronic BiIII yields the series Rb23BiIIIxSbIII7-xSbV2Cl54 (0 < x ≤ 7), which exhibits a similar layered 0D structure but with additional disorder that yields a trigonal crystal system with an enantiomorphic space group (R32). Second harmonic generation of 532 nm light from a 1064 nm laser using Rb23BiIII7SbV2Cl54 powder confirms the noncentrosymmetry of this space group. As with the prototypical mixed-valent pnictogen halides, the visible absorption bands of the Rb23BiIIIxSbIII7-xSbV2Cl54 family are the result of intervalent SbIII-SbV and mixed-valent BiIII-SbV charge transfer bands (CTB), with a blueshift of the absorption edge as BiIII substitution increases. No PL is observed from this family of semiconductors, but a crystal of Rb23BiIII7SbV2Cl54 exhibits a high resistivity of 1.0 × 1010 ω·cm and X-ray photoconductivity with a promising μτ product of 8.0 × 10-5 cm2 s-1 V-1. The unique 0D layered structures of the Rb23BiIIIxSbIII7-xSbV2Cl54 family highlight the versatility of the ns2 lone pair in semiconducting metal-halides, pointing the way toward new functional 0D metal-halide compounds.
  • White CsPbBr3: Characterizing the One‐Dimensional Cesium Lead Bromide Polymorph
    Item type: Journal Article
    Aebli, Marcel; Benin, Bogdan Markovich; McCall, Kyle M.; et al. (2020)
    Helvetica Chimica Acta
    Inorganic lead halide perovskites have gained immense scientific interest for optoelectronic applications. In this work, we present a one‐dimensional polymorph of cesium lead bromide (δ‐CsPbBr3) synthesized through a simple anion‐exchange reaction, wherein distorted edge‐sharing PbBr6 octahedra form 1D chains isolated by Cs ions. δ‐CsPbBr3 was characterized by Raman spectroscopy, X‐ray diffraction, 207Pb and 133Cs solid‐state NMR, and by optical emission and absorption spectroscopies. This non‐perovskite material irreversibly transforms into the well‐known three‐dimensional perovskite phase (γ‐CsPbBr3) upon heating to above 151 °C. The indirect bandgap was determined by absorption measurements and calculation to be 2.9 eV. δ‐CsPbBr3 exhibits broadband yellow photoluminescence with a quantum yield of 3.2 %±0.2 % at room temperature and 95 %±5 % at 77 K, and this emission is attributed to the recombination of self‐trapped excitons. This study emphasizes that the metastable δ‐CsPbBr3 may be a persistent, concomitant phase in Cs−Pb‐Br‐containing materials systems, such as those used in solar cells and LEDs, and it showcases the characterization tools used for its detection.
  • Radiative lifetime-encoded unicolour security tags using perovskite nanocrystals
    Item type: Journal Article
    Yakunin, Sergii; Chaaban, Jana; Benin, Bogdan Markovich; et al. (2021)
    Nature Communications
    Traditional fluorescence-based tags, used for anticounterfeiting, rely on primitive pattern matching and visual identification; additional covert security features such as fluorescent lifetime or pattern masking are advantageous if fraud is to be deterred. Herein, we present an electrohydrodynamically printed unicolour multi-fluorescent-lifetime security tag system composed of lifetime-tunable lead-halide perovskite nanocrystals that can be deciphered with both existing time-correlated single-photon counting fluorescence-lifetime imaging microscopy and a novel time-of-flight prototype. We find that unicolour or matching emission wavelength materials can be prepared through cation-engineering with the partial substitution of formamidinium for ethylenediammonium to generate “hollow” formamidinium lead bromide perovskite nanocrystals; these materials can be successfully printed into fluorescence-lifetime-encoded-quick-read tags that are protected from conventional readers. Furthermore, we also demonstrate that a portable, cost-effective time-of-flight fluorescence-lifetime imaging prototype can also decipher these codes. A single comprehensive approach combining these innovations may be eventually deployed to protect both producers and consumers.
  • Guanidinium-Formamidinium Lead Iodide: A Layered Perovskite-Related Compound with Red Luminescence at Room Temperature
    Item type: Journal Article
    Nazarenko, Olga; Kotyrba, Martin R.; Yakunin, Sergii; et al. (2018)
    Journal of the American Chemical Society
    Two-dimensional hybrid organic–inorganic lead halides perovskite-type compounds have attracted immense scientific interest due to their remarkable optoelectronic properties and tailorable crystal structures. In this work, we present a new layered hybrid lead halide, namely [CH(NH2)2][C(NH2)3]PbI4, wherein puckered lead-iodide layers are separated by two small and stable organic cations: formamidinium, CH(NH2)2+, and guanidinium, C(NH2)3+. This perovskite is thermally stable up to 255 °C, exhibits room-temperature photoluminescence in the red region with a quantum yield of 3.5%, and is photoconductive. This study highlights a vast structural diversity that exists in the compositional space typically used in perovskite photovoltaics.
  • Lead-Free Low-Dimensional Main Group Metal Halides: New Self-Trapped Excitonic Emitters and Their Applications
    Item type: Doctoral Thesis
    Benin, Bogdan Markovich (2020)
    Metal-halide based semiconductors have been in the limelight for the past few years as a result of the outstanding performance of devices in a variety of optoelectronic applications utilizing lead-halide perovskites. Lead-free materials based on Sb, Sn, or Bi with a three-dimensional (3D) framework, on the other hand, have yet to provide a true alternative. This thesis instead explores the field of low-dimensional, specifically zero-dimensional (0D), lead-free metal-halides as luminescent materials. These 0D materials contain disconnected metal-halide octahedra, which drastically alters their optoelectronic properties compared to fully connected 3D structures and, prior to 2017, the library of such 0D metal-halides was exceedingly small. This work began with the study of the optical properties of one known yet uninvestigated incongruently melting phase — Cs4SnBr6. This material was found to exhibit broad yet efficient room temperature photoluminescence (RT PL), which occurs as a result of the recombination of self-trapped excitons (STEs). The STE emission in this phase was then found to be compositionally tunable within the Cs4-xAxSn(Br1-yIy)6 (A=Rb,K; x,y≤1) family. The discovery of this and other phases by the community prompted a closer look at the optical properties of various additional Sn-based 0D and 1D materials such as (C4H14N2I)4SnI6 and [C(CH2)3]2SnBr4. In doing so, it became evident that their PL lifetimes were extremely temperature dependent (~ 20 ns/K). This opened the door to using 0D metal-halides as remote-optical thermometric and thermographic luminophores i.e. materials which can be used to optically determine temperature. In addition to this thermal sensitivity, this emission process was found to be intrinsic and incredibly robust with no changes to the PL lifetime observed between synthetic batches or after partial degradation or partial oxidation. These two factors together allowed for a thermometric precision of ±13 mK. Although this was quite impressive, the fact of the matter remained that these are still tin-based materials and they will, inevitably, fully oxidize. This inspired the dimensional reduction of the pnictogen halides to discover new, oxidatively stable 0D materials for remote-optical thermometry. This resulted in the Rb7Bi3-3xSb3xCl16 (x≤1) family of materials, which also exhibit STE PL with a similar thermal sensitivity as the tin-based materials. Furthermore, these structures contain edge-shared octahedral dimers, which were determined to be the source of RT PL and the luminescent properties of structures containing them have not been previously investigated. This work also led to the discovery of a new set of mixed-valent materials with the composition Rb23MIII7SbV2Cl54 (MIII = Bi, Sb). These 0D structures contain octahedra of with xi various oxidation states (3+ and 5+) and exhibit intense colors as a result of intervalent/mixed-valent charge transfer. While non-luminescent even at 12 K, these materials do exhibit relatively high mobility-lifetime products under X-ray illumination, suggesting that the site-to-site tunneling through this structure may provide a potentially useful tool for new X-ray and hard-radiation detector materials. In summary, the work presented here has resulted in several, substantial contributions to the low-dimensional metal-halide community, which include the synthesis and characterization of several new materials as well as the identification and successful demonstration of remote-optical thermometry/thermography as a new application for this class of materials. This dissertation serves as an effective foundation for further research in the field by giving other researchers an overview of the field as well as insights into potentially interesting avenues for investigation, both for materials as well as possible applications.
  • Efficient Lone-Pair-Driven Luminescence: Structure–Property Relationships in Emissive 5s2 Metal Halides
    Item type: Review Article
    McCall, Kyle M.; Morad, Viktoriia; Benin, Bogdan Markovich; et al. (2020)
    ACS Materials Letters
    Low-dimensional metal halides have been the focus of intense investigations in recent years following the success of hybrid lead halide perovskites as optoelectronic materials. In particular, the light emission of low-dimensional halides based on the 5s2 cations Sn2+ and Sb3+ has found utility in a variety of applications complementary to those of the three-dimensional halide perovskites because of its unusual properties such as broadband character and highly temperature-dependent lifetime. These properties derive from the exceptional chemistry of the 5s2 lone pair, but the terminology and explanations given for such emission vary widely, hampering efforts to build a cohesive understanding of these materials that would lead to the development of efficient optoelectronic devices. In this Perspective, we provide a structural overview of these materials with a focus on the dynamics driven by the stereoactivity of the 5s2 lone pair to identify the structural features that enable strong emission. We unite the different theoretical models that have been able to explain the success of these bright 5s2 emission centers into a cohesive framework, which is then applied to the array of compounds recently developed by our group and other researchers, demonstrating its utility and generating a holistic picture of the field from the point of view of a materials chemist. We highlight those state-of-the-art materials and applications that demonstrate the unique capabilities of these versatile emissive centers and identify promising future directions in the field of low-dimensional 5s2 metal halides.
  • The Rb7Bi3−3xSb3xCl16 Family: A Fully Inorganic Solid Solution with Room‐Temperature Luminescent Members
    Item type: Journal Article
    Benin, Bogdan Markovich; Mc Call, Kyle; Wörle, Michael; et al. (2020)
    Angewandte Chemie. International Edition
    Low‐dimensional ns2‐metal halide compounds have received immense attention for applications in solid‐state lighting, optical thermometry and thermography, and scintillation. However, these are based primarily on the combination of organic cations with toxic Pb2+ or unstable Sn2+, and a stable inorganic luminescent material has yet to be found. Here, the zero‐dimensional Rb7Sb3Cl16 phase, comprised of isolated [SbCl6]3− octahedra and edge‐sharing [Sb2Cl10]4− dimers, shows room‐temperature photoluminescence (RT PL) centered at 560 nm with a quantum yield of 3.8±0.2 % at 296 K (99.4 % at 77 K). The temperature‐dependent PL lifetime rivals that of previous low‐dimensional materials with a specific temperature sensitivity above 0.06 K−1 at RT, making it an excellent thermometric material. Utilizing both DFT and chemical substitution with Bi3+ in the Rb7Bi3−3x Sb3x Cl16 (x ≤1) family, we present the edge‐shared [Sb2Cl10]4− dimer as a design principle for Sb‐based luminescent materials.
  • High-resolution remote thermometry and thermography using luminescent low-dimensional tin-halide perovskites
    Item type: Journal Article
    Yakunin, Sergii; Benin, Bogdan Markovich; Shynkarenko, Yevhen; et al. (2019)
    Nature Materials
  • Highly Emissive Self-Trapped Excitons in Fully Inorganic Zero-Dimensional Tin Halides
    Item type: Journal Article
    Benin, Bogdan Markovich; Dirin, Dmitry; Morad, Viktoriia; et al. (2018)
    Angewandte Chemie. International Edition
Publications 1 - 10 of 16