We demonstrate 120-fold photoluminescence enhancement of VB-spin defects in hBN by coupling them to nanopatch antennas. Since the laser spot is 6.25 times larger than the antenna area, the actual enhancement is 750-fold.
more » « less- Award ID(s):
- 2015025
- NSF-PAR ID:
- 10348796
- Date Published:
- Journal Name:
- CLEO: QELS_Fundamental Science 2022
- Page Range / eLocation ID:
- FF3C.3
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Recently, CuI‐ and AgI‐based halide double perovskites have been proposed as promising candidates for overcoming the toxicity and instability issues inherent within the emerging Pb‐based halide perovskite absorbers. However, up to date, only AgI‐based halide double perovskites have been experimentally synthesized; there are no reports on successful synthesis of CuI‐based analogues. Here we show that, owing to the much higher energy level for the Cu 3d10orbitals than for the Ag 4d10orbitals, CuIatoms energetically favor 4‐fold coordination, forming [CuX4] tetrahedra (X=halogen), but not 6‐fold coordination as required for [CuX6] octahedra. In contrast, AgIatoms can have both 6‐ and 4‐fold coordinations. Our density functional theory calculations reveal that the synthesis of CuIhalide double perovskites may instead lead to non‐perovskites containing [CuX4] tetrahedra, as confirmed by our material synthesis efforts.
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Abstract Recently, CuI‐ and AgI‐based halide double perovskites have been proposed as promising candidates for overcoming the toxicity and instability issues inherent within the emerging Pb‐based halide perovskite absorbers. However, up to date, only AgI‐based halide double perovskites have been experimentally synthesized; there are no reports on successful synthesis of CuI‐based analogues. Here we show that, owing to the much higher energy level for the Cu 3d10orbitals than for the Ag 4d10orbitals, CuIatoms energetically favor 4‐fold coordination, forming [CuX4] tetrahedra (X=halogen), but not 6‐fold coordination as required for [CuX6] octahedra. In contrast, AgIatoms can have both 6‐ and 4‐fold coordinations. Our density functional theory calculations reveal that the synthesis of CuIhalide double perovskites may instead lead to non‐perovskites containing [CuX4] tetrahedra, as confirmed by our material synthesis efforts.
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Abstract Spin defects in hexagonal boron nitride, and specifically the negatively charged boron vacancy (VB‐) centers, are emerging candidates for quantum sensing. However, the VB‐defects suffer from low quantum efficiency and, as a result, exhibit weak photoluminescence. In this work, a scalable approach is demonstrated to dramatically enhance the VB‐emission by coupling to a plasmonic gap cavity. The plasmonic cavity is composed of a flat gold surface and a silver cube, with few‐layer hBN flakes positioned in between. Employing these plasmonic cavities, two orders of magnitude are extracted in photoluminescence enhancement associated with a corresponding twofold enhancement in optically detected magnetic resonance contrast. The work will be pivotal to progress in quantum sensing employing 2D materials, and in realization of nanophotonic devices with spin defects in hexagonal boron nitride.
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Abstract Hyperpolarized orthohydrogen (
o ‐H2) is a frequent product of parahydrogen‐based hyperpolarization approaches like signal amplification by reversible exchange (SABRE), where the hyperpolarizedo ‐H2signal is usually absorptive. We describe a novel manifestation of this effect wherein large antiphaseo ‐H2signals are observed, with1H enhancements up to ≈500‐fold (effective polarizationP H≈1.6 %). This anomalous effect is attained only when using an intact heterogeneous catalyst constructed using a metal–organic framework (MOF) and is qualitatively independent of substrate nature. This seemingly paradoxical observation is analogous to the “partial negative line” (PNL) effect recently explained in the context of Parahydrogen Induced Polarization (PHIP) by Ivanov and co‐workers. The two‐spin order of theo ‐H2resonance is manifested by a two‐fold higher Rabi frequency, and the lifetime of the antiphase HPo ‐H2resonance is extended by several‐fold.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1364/CLEO_QELS.2022.FF3C.3
