Toward liquid cell quantum sensing: Ytterbium complexes with ultranarrow absorption.

The energetic disorder induced by fluctuating liquid environments acts in opposition to the precise control required for coherence-based sensing. Overcoming fluctuations requires a protected quantum subspace that only weakly interacts with the local environment. We report a ytterbium complex that exhibited an ultranarrow absorption linewidth in solution at room temperature with a full width at half maximum of 0.

Efficient 2D to 0D Energy Transfer in HgTe Nanoplatelet-Quantum Dot Heterostructures through High-Speed Exciton Diffusion.

Large area absorbers with localized defect emission are of interest for energy concentration via the antenna effect. Transfer between 2D and 0D quantum-confined structures is advantageous as it affords maximal lateral area antennas with continuously tunable emission. We report the quantum efficiency of energy transfer in in situ grown HgTe nanoplatelet (NPL)/quantum dot (QD) heterostructures to be near unity (>85%), while energy transfer in separately synthesized and well separated solutions of HgTe NPLs to QDs only reaches 47 ± 11% at considerably higher QD concentrations.

Maximizing light-driven CO and N fixation efficiency in quantum dot-bacteria hybrids.

Integrating light-harvesting materials with microbial biochemistry is a viable approach to produce chemicals with high efficiency from the air, water, and sunlight. Yet it remains unclear whether all absorbed photons in the materials can be transferred through the material-biology interface for solar-to-chemical production and whether the presence of materials beneficially affect the microbial metabolism. Here we report a microbe-semiconductor hybrid by interfacing CO/N-fixing bacterium with CdTe quantum dots for light-driven CO and N fixation with internal quantum efficiencies of 47.

Exploring the design of superradiant J-aggregates from amphiphilic monomer units.

Excitonic chromophore aggregates have wide-ranging applicability in fields such as imaging and energy harvesting; however their rational design requires adapting principles of self-assembly to the requirements of excited state coupling. Using the well-studied amphiphilic cyanine dye C8S3 as a template-known to assemble into tubular excitonic aggregates-we synthesize several redshifted variants and study their self-assembly and photophysics. The new pentamethine dyes retain their tubular self-assembly and demonstrate nearly identical bathochromic shifts and lineshapes well into near-infrared wavelengths.

Spectrally Selective Time-Resolved Emission through Fourier-Filtering (STEF).

We demonstrate a method for separating and resolving the dynamics of multiple emitters without the use of conventional filters. By directing the photon emission through a fixed path-length imbalanced Mach-Zehnder interferometer, we interferometrically cancel (or enhance) certain spectral signatures corresponding to one emissive species. Our approach, Spectrally selective Time-resolved Emission through Fourier-filtering (STEF), leverages the detection and subtraction of both outputs of a tuned Mach-Zehnder interferometer, which can be combined with time-correlated single photon counting (TCSPC) or confocal imaging to demix multiple emitter signatures.

Establishing design principles for emissive organic SWIR chromophores from energy gap laws.

Rational design of bright near and shortwave infrared (NIR: 700-1000 SWIR: 1000- 2000 nm) emitters remains an open question with applications spanning imaging and photonics. Combining experiment and theory, we derive an energy gap quantum yield master equation (EQME), describing the fundamental limits in SWIR quantum yields ( ) for organic chromophores. Evaluating the photophysics of 21 polymethine NIR/SWIR chromophores to parameterize the EQME, we explain the precipitous decline of past 900 nm through decreasing radiative rates and increasing nonradiative losses via high frequency vibrations relating to the energy gap.

Approaching the intrinsic exciton physics limit in two-dimensional semiconductor diodes.

Two-dimensional (2D) semiconductors have attracted intense interest for their unique photophysical properties, including large exciton binding energies and strong gate tunability, which arise from their reduced dimensionality. Despite considerable efforts, a disconnect persists between the fundamental photophysics in pristine 2D semiconductors and the practical device performances, which are often plagued by many extrinsic factors, including chemical disorder at the semiconductor-contact interface. Here, by using van der Waals contacts with minimal interfacial disorder, we suppress contact-induced Shockley-Read-Hall recombination and realize nearly intrinsic photophysics-dictated device performance in 2D semiconductor diodes.

Dielectric Screening Modulates Semiconductor Nanoplatelet Excitons.

The influence of external dielectric environments is well understood for 2D semiconductor materials but overlooked for colloidally grown II-VI nanoplatelets (NPLs). In this work, we synthesize MX (M = Cd, Hg; X = Se, Te) NPLs of varying thicknesses and apply the Elliott model to extract exciton binding energies-reporting values in good agreement with prior methods and extending to less studied cadmium telluride and mercury chalcogenide NPLs. We find that the exciton binding energy is modulated both by the relative effect of internal vs external dielectric and by the thickness of the semiconductor material.

Bright Chromenylium Polymethine Dyes Enable Fast, Four-Color Imaging with Shortwave Infrared Detection.

Optical imaging within the shortwave infrared (SWIR, 1000-2000 nm) region of the electromagnetic spectrum has enabled high-resolution and high-contrast imaging in mice, non-invasively. Polymethine dyes, with their narrow absorption spectra and high absorption coefficients, are optimal probes for fast and multiplexed SWIR imaging. Here, we expand upon the multiplexing capabilities in SWIR imaging by obtaining brighter polymethine dyes with varied excitation wavelengths spaced throughout the near-infrared (700-1000 nm) region.

Large-Area Synthesis and Patterning of All-Inorganic Lead Halide Perovskite Thin Films and Heterostructures.

All-inorganic lead halide perovskites have attracted tremendous interest for their excellent stability when compared with hybrid perovskites. Here we report a large-area growth of monocrystalline all-inorganic perovskite thin films and further patterning them into heterostructure arrays. We show that highly oriented CsPbBr microcrystal domains can be readily grown on muscovite mica substrates with a well-defined epitaxial relationship, which can further expand and eventually merge into large-area monocrystalline CsPbBr thin films with an excellent optical quality.

Surface chemical trapping of optical cycling centers.

Quantum information processors based on trapped atoms utilize laser-induced optical cycling transitions for state preparation and measurement. These transitions consist of an electronic excitation from the ground to an excited state and a decay back to the initial ground state, associated with a photon emission. While this technique has been used primarily with atoms, it has also recently been shown to work for some divalent metal hydroxides (e.

Silicon incorporation in polymethine dyes.

Methods to red-shift fluorophores have garnered considerable interest due to the broad utility of low energy light. The incorporation of silicon into xanthene and coumarin scaffolds has resulted in an array of visible and near-infrared fluorophores. Here, we extend this approach to polymethine dyes, another popular fluorophore class, performing experimental and computational analyses.

Mercury Chalcogenide Nanoplatelet-Quantum Dot Heterostructures as a New Class of Continuously Tunable Bright Shortwave Infrared Emitters.

Despite broad applications in imaging, energy conversion, and telecommunications, few nanoscale moieties emit light efficiently in the shortwave infrared (SWIR, 1000-2000 nm or 1.24-0.62 eV).

Decay-Associated Fourier Spectroscopy: Visible to Shortwave Infrared Time-Resolved Photoluminescence Spectra.

We describe and implement an interferometric approach to decay-associated photoluminescence spectroscopy, which we term decay-associated Fourier spectroscopy (DAFS). In DAFS, the emitted photon stream from a substrate passes through a variable path length Mach-Zehnder interferometer prior to detection and timing. The interferometer encodes spectral information in the intensity measured at each detector enabling simultaneous spectral and temporal resolution.

Single-crystal-to-single-crystal intercalation of a low-bandgap superatomic crystal.

The controlled introduction of impurities into the crystal lattice of solid-state compounds is a cornerstone of materials science. Intercalation, the insertion of guest atoms, ions or molecules between the atomic layers of a host structure, can produce novel electronic, magnetic and optical properties in many materials. Here we describe an intercalation compound in which the host [CoTe(PPr)][C], formed from the binary assembly of atomically precise molecular clusters, is a superatomic analogue of traditional layered atomic compounds.

Lead halide perovskites: Crystal-liquid duality, phonon glass electron crystals, and large polaron formation.

Lead halide perovskites have been demonstrated as high performance materials in solar cells and light-emitting devices. These materials are characterized by coherent band transport expected from crystalline semiconductors, but dielectric responses and phonon dynamics typical of liquids. This "crystal-liquid" duality implies that lead halide perovskites belong to phonon glass electron crystals, a class of materials believed to make the most efficient thermoelectrics.

Charge Saturation and Intrinsic Doping in Electrolyte-Gated Organic Semiconductors.

Electrolyte gating enables low voltage operation of organic thin film transistors, but little is known about the nature of the electrolyte/organic interface. Here we apply charge-modulation Fourier transform infrared spectroscopy, in conjunction with electrical measurements, on a model electrolyte gated organic semiconductor interface: single crystal rubrene/ion-gel. We provide spectroscopic signature for free-hole like carriers in the organic semiconductor and unambiguously show the presence of a high density of intrinsic doping of the free holes upon formation of the rubrene/ion-gel interface, without gate bias (Vg = 0 V).