Showing papers on "Spontaneous emission published in 2021"
TL;DR: In this paper, a one-dopant alloying strategy was proposed to generate smaller, monodisperse colloidal particles (confining electrons and holes, and boosting radiative recombination) with fewer surface defects.
Abstract: Electroluminescence efficiencies of metal halide perovskite nanocrystals (PNCs) are limited by a lack of material strategies that can both suppress the formation of defects and enhance the charge carrier confinement. Here we report a one-dopant alloying strategy that generates smaller, monodisperse colloidal particles (confining electrons and holes, and boosting radiative recombination) with fewer surface defects (reducing non-radiative recombination). Doping of guanidinium into formamidinium lead bromide PNCs yields limited bulk solubility while creating an entropy-stabilized phase in the PNCs and leading to smaller PNCs with more carrier confinement. The extra guanidinium segregates to the surface and stabilizes the undercoordinated sites. Furthermore, a surface-stabilizing 1,3,5-tris(bromomethyl)-2,4,6-triethylbenzene was applied as a bromide vacancy healing agent. The result is highly efficient PNC-based light-emitting diodes that have current efficiency of 108 cd A−1 (external quantum efficiency of 23.4%), which rises to 205 cd A−1 (external quantum efficiency of 45.5%) with a hemispherical lens. Guanidinium doping is shown to enhance the operation of perovskite nanocrystal light-emitting diodes.
450 citations
TL;DR: In this article, the state-of-the-art in colloidal metal-halide perovskite nanocrystals (MHP NCs) is discussed, and the challenges associated with their thickness-controlled synthesis, environmental and thermal stability, and their application in making efficient LEDs are discussed.
Abstract: Colloidal metal-halide perovskite nanocrystals (MHP NCs) are gaining significant attention for a wide range of optoelectronics applications owing to their exciting properties, such as defect tolerance, near-unity photoluminescence quantum yield, and tunable emission across the entire visible wavelength range. Although the optical properties of MHP NCs are easily tunable through their halide composition, they suffer from light-induced halide phase segregation that limits their use in devices. However, MHPs can be synthesized in the form of colloidal nanoplatelets (NPls) with monolayer (ML)-level thickness control, exhibiting strong quantum confinement effects, and thus enabling tunable emission across the entire visible wavelength range by controlling the thickness of bromide or iodide-based lead-halide perovskite NPls. In addition, the NPls exhibit narrow emission peaks, have high exciton binding energies, and a higher fraction of radiative recombination compared to their bulk counterparts, making them ideal candidates for applications in light-emitting diodes (LEDs). This review discusses the state-of-the-art in colloidal MHP NPls: synthetic routes, thickness-controlled synthesis of both organic-inorganic hybrid and all-inorganic MHP NPls, their linear and nonlinear optical properties (including charge-carrier dynamics), and their performance in LEDs. Furthermore, the challenges associated with their thickness-controlled synthesis, environmental and thermal stability, and their application in making efficient LEDs are discussed. This article is protected by copyright. All rights reserved.
62 citations
TL;DR: In this article, a bound state in the continuum based on Fano interference is proposed to quench quantum fluctuations, which can effectively quench the effect of spontaneous emission in a small laser.
Abstract: It is an important challenge to reduce the power consumption and size of lasers, but progress has been impeded by quantum noise overwhelming the coherent radiation at reduced power levels. Thus, despite considerable progress in microscale and nanoscale lasers, such as photonic crystal lasers, metallic lasers and plasmonic lasers, the coherence length remains very limited. Here we show that a bound state in the continuum based on Fano interference can effectively quench quantum fluctuations. Although fragile in nature, this unusual state redistributes photons such that the effect of spontaneous emission is suppressed. Based on this concept, we experimentally demonstrate a microscopic laser with a linewidth that is more than 20 times smaller than existing microscopic lasers and show that further reduction by several orders of magnitude is feasible. These findings pave the way for numerous applications of microscopic lasers and point to new opportunities beyond photonics. Quantum noise is suppressed by a bound state in the continuum (BIC) approach, enabling a microlaser with narrow linewidth compared to other small lasers.
56 citations
TL;DR: In this paper, a large-scale fabrication of patterned perovskite light-emitting diodes towards display panels is presented, which has been demonstrated as the most successful route for commercial organic LED displays.
Abstract: With rapid advances of perovskite light-emitting diodes (PeLEDs), the large-scale fabrication of patterned PeLEDs towards display panels is of increasing importance. However, most state-of-the-art PeLEDs are fabricated by solution-processed techniques, which are difficult to simultaneously achieve high-resolution pixels and large-scale production. To this end, we construct efficient CsPbBr3 PeLEDs employing a vacuum deposition technique, which has been demonstrated as the most successful route for commercial organic LED displays. By carefully controlling the strength of the spatial confinement in CsPbBr3 film, its radiative recombination is greatly enhanced while the nonradiative recombination is suppressed. As a result, the external quantum efficiency (EQE) of thermally evaporated PeLED reaches 8.0%, a record for vacuum processed PeLEDs. Benefitting from the excellent uniformity and scalability of the thermal evaporation, we demonstrate PeLED with a functional area up to 40.2 cm2 and a peak EQE of 7.1%, representing one of the most efficient large-area PeLEDs. We further achieve high-resolution patterned perovskite film with 100 μm pixels using fine metal masks, laying the foundation for potential display applications. We believe the strategy of confinement strength regulation in thermally evaporated perovskites provides an effective way to process high-efficiency and large-area PeLEDs towards commercial display panels. Overcoming the limitations to fabricate large-area perovskite light-emitting diodes is crucial for bringing the technology a step closer to commercialization. Here, the authors report a 40.2 cm2 large-area device with an EQE of 7.1% by using the thermal evaporation method.
53 citations
34 citations
TL;DR: In this paper, a very bright deep-blue emission in double perovskite Cs2Na0.4Ag0.6InCl6 alloyed with Bi doping was successfully achieved by pressure-driven reverse intersystem crossing (RISC), an abnormal photophysical process of energy transfer from the excited triplet state back to the singlet.
Abstract: Maximizing the regeneration of singlet excitons remains a considerable challenge in deep-blue emission systems to obtain low-cost, high-efficiency fluorescent materials. However, the formation of the long-lifetime triplet excitons generally dominates the radiative process, making it greatly difficult to harvest deep-blue emission with high color purity because of the depression of singlet excitons. Here, a very bright deep-blue emission in double perovskite Cs2Na0.4Ag0.6InCl6 alloyed with Bi doping (CNAICB) was successfully achieved by pressure-driven reverse intersystem crossing (RISC), an abnormal photophysical process of energy transfer from the excited triplet state back to the singlet. Therein, the inherently broad emission of CNAICB was associated with the self-trapped excitons (STEs) at excited triplet states, whereas the radiative recombination of STEs populated in excited singlet states was responsible for the observed deep-blue emission. Moreover, the deep-blue emission corresponds to Commission Internationale de L'Eclairage (CIE) coordinates (0.16, 0.06) at 5.01 GPa, which meets the requirement of Rec. 2020 display standards. Likewise, pressure was introduced as an efficient tool to rule out the possibility of the recombination of free excitons and clarify the long-standing conventional dispute over the origin of the low-wavelength emission of Cs2AgInCl6. Our study not only demonstrates that pressure can be a robust means to boost the deep-blue emission but also provides deep insights into the structure-property relationship of lead-free CNAICB double perovskites.
33 citations
08 Mar 2021
TL;DR: In this paper, a chiral exceptional surface was used to tune the spontaneous emission rate from a single quantum emitter inside an optical microcavity, from total suppression to a two fold enhancement compared to a similar cavity operating at a diabolic point.
Abstract: The authors show how chiral exceptional surfaces can be used to tune the spontaneous emission rate from a single quantum emitter inside an optical microcavity, from total suppression to a two fold enhancement compared to a similar cavity operating at a diabolic point.
33 citations
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TL;DR: In this article, the authors report algorithms for the digital quantum simulation of the dynamics of open quantum systems governed by a Lindblad equation using an adaptation of the quantum imaginary time evolution (QITE) algorithm.
Abstract: Quantum simulation on emerging quantum hardware is a topic of intense interest. While many studies focus on computing ground state properties or simulating unitary dynamics of closed systems, open quantum systems are an interesting target of study owing to their ubiquity and rich physical behavior. However, their non-unitary dynamics are also not natural to simulate on near-term quantum hardware. Here, we report algorithms for the digital quantum simulation of the dynamics of open quantum systems governed by a Lindblad equation using an adaptation of the quantum imaginary time evolution (QITE) algorithm. We demonstrate the algorithms on IBM Quantum's hardware with simulations of the spontaneous emission of a two level system and the dissipative transverse field Ising model. Our work shows that the dynamics of open quantum systems can be efficiently simulated on near-term quantum hardware.
29 citations
TL;DR: In this paper, a periodic silver nanoparticle (NP) arrays were fabricated by magnetron sputtering method with anodic aluminum oxide templates to enhance the UV light emission from ZnO by the surface plasmon resonance effect.
Abstract: Periodical silver nanoparticle (NP) arrays were fabricated by magnetron sputtering method with anodic aluminum oxide templates to enhance the UV light emission from ZnO by the surface plasmon resonance effect. Theoretical simulations indicated that the surface plasmon resonance wavelength depended on the diameter and space of Ag NP arrays. By introducing Ag NP arrays with the diameter of 40 nm and space of 100 nm, the photoluminescence intensity of the near band-edge emission from ZnO was twofold enhanced. Time-resolved photoluminescence measurement and energy band analysis indicated that the UV light emission enhancement was attributed to the coupling between the surface plasmons in Ag NP arrays and the excitons in ZnO with the improved spontaneous emission rate and enhanced local electromagnetic fields.
28 citations
TL;DR: In this paper, the authors demonstrate a median Purcell factor of 15 for a small ensemble of erbium ions doped into a nanoparticle within a fiber-based microcavity.
Abstract: The interaction of single quantum emitters with an optical cavity enables the realization of efficient spin-photon interfaces, an essential resource for quantum networks. The dynamical control of the spontaneous emission rate of quantum emitters in cavities has important implications in quantum technologies, e.g., for shaping the emitted photons’ waveform or for driving coherently the optical transition while preventing photon emission. Here we demonstrate the dynamical control of the Purcell enhanced emission of a small ensemble of erbium ions doped into a nanoparticle. By embedding the nanoparticles into a fully tunable high finesse fiber based optical microcavity, we demonstrate a median Purcell factor of 15 for the ensemble of ions. We also show that we can dynamically control the Purcell enhanced emission by tuning the cavity on and out of resonance, by controlling its length with sub-nanometer precision on a time scale more than two orders of magnitude faster than the natural lifetime of the erbium ions. This capability opens prospects for the realization of efficient nanoscale quantum interfaces between solid-state spins and single telecom photons with controllable waveform, for non-destructive detection of photonic qubits, and for the realization of quantum gates between rare-earth ion qubits coupled to an optical cavity. Control of quantum emitters is needed in order to enable many applications. Here, the authors demonstrate enhancement and dynamical control of the Purcell emission from erbium ions doped in a nanoparticle within a fiber-based microcavity.
28 citations
TL;DR: In this paper, a comprehensive numerical study for the operating behavior and physical mechanism of nitride micro-light-emitting-diode (micro-LED) at low current density is presented.
Abstract: Here we report a comprehensive numerical study for the operating behavior and physical mechanism of nitride micro-light-emitting-diode (micro-LED) at low current density. Analysis for the polarization effect shows that micro-LED suffers a severer quantum-confined Stark effect at low current density, which poses challenges for improving efficiency and realizing stable full-color emission. Carrier transport and matching are analyzed to determine the best operating conditions and optimize the structure design of micro-LED at low current density. It is shown that less quantum well number in the active region enhances carrier matching and radiative recombination rate, leading to higher quantum efficiency and output power. Effectiveness of the electron blocking layer (EBL) for micro-LED is discussed. By removing the EBL, the electron confinement and hole injection are found to be improved simultaneously, hence the emission of micro-LED is enhanced significantly at low current density. The recombination processes regarding Auger and Shockley–Read–Hall are investigated, and the sensitivity to defect is highlighted for micro-LED at low current density. Synopsis: The polarization-induced QCSE, the carrier transport and matching, and recombination processes of InGaN micro-LEDs operating at low current density are numerically investigated. Based on the understanding of these device behaviors and mechanisms, specifically designed epitaxial structures including two QWs, highly doped or without EBL and p-GaN with high hole concentration for the efficient micro-LED emissive display are proposed. The sensitivity to defect density is also highlighted for micro-LED.
TL;DR: In this article, a deterministic Purcell-enhanced single photon source is realized by integrating an atomically thin WSe2 layer with a circular Bragg grating cavity, which significantly enhances the photoluminescence from the thin layer and supports single photon generation with g(2)(0) < 0.25.
Abstract: We demonstrate a deterministic Purcell-enhanced single photon source realized by integrating an atomically thin WSe2 layer with a circular Bragg grating cavity. The cavity significantly enhances the photoluminescence from the atomically thin layer and supports single photon generation with g(2)(0) < 0.25. We observe a consistent increase of the spontaneous emission rate for WSe2 emitters located in the center of the Bragg grating cavity. These WSe2 emitters are self-aligned and deterministically coupled to such a broadband cavity, configuring a new generation of deterministic single photon sources, characterized by their simple and low-cost production and intrinsic scalability.
TL;DR: In this paper, a fundamental breakdown of the photonic spontaneous emission (SE) formula derived from Fermi's golden rule was demonstrated for a quantum two-level system, where the SE rate scales with the local photon density of states.
Abstract: We demonstrate a fundamental breakdown of the photonic spontaneous emission (SE) formula derived from Fermi's golden rule, in absorptive and amplifying media, where one assumes the SE rate scales with the local photon density of states, an approach often used in more complex, semiclassical nanophotonics simulations. Using a rigorous quantization of the macroscopic Maxwell equations in the presence of arbitrary linear media, we derive a corrected Fermi's golden rule and master equation for a quantum two-level system (TLS) that yields a quantum pumping term and a modified decay rate that is net positive. We show rigorous numerical results of the temporal dynamics of the TLS for an example of two coupled microdisk resonators, forming a gain-loss medium, and demonstrate the clear failure of the commonly adopted formulas based solely on the local density of states.
TL;DR: In this paper, two-dimensional metasurface axicons and lenses that emit collimated and focused beams, respectively, were proposed to redirect surface-guided waves that dominate the natural emission pattern of quantum wells.
Abstract: Phased-array metasurfaces have been extensively used for wavefront shaping of coherent incident light. Due to the incoherent nature of spontaneous emission, the ability to similarly tailor photoluminescence remains largely unexplored. Recently, unidirectional photoluminescence from InGaN/GaN quantum-well metasurfaces incorporating one-dimensional phase profiles has been shown. However, the possibility of generating arbitrary two-dimensional waveforms-such as focused beams-is not yet realized. Here, we demonstrate two-dimensional metasurface axicons and lenses that emit collimated and focused beams, respectively. First, we develop off-axis meta-axicon/metalens equations designed to redirect surface-guided waves that dominate the natural emission pattern of quantum wells. Next, we show that photoluminescence properties are well predicted by passive transmission results using suitably engineered incident light sources. Finally, we compare collimating and focusing performances across a variety of different light-emitting metasurface axicons and lenses. These generated two-dimensional phased-array photoluminescence waveforms facilitate future development of light sources with arbitrary functionalities.
TL;DR: In this article, a monolithically integrated ultraviolet (UV) light emitting diodes (LEDs) and visible-blind UV photodetectors (PDs) employing the same p-GaN/AlGaN-/GaN epi-structures grown on Si.
Abstract: In this letter, we report the first demonstration of monolithically integrated ultraviolet (UV) light emitting diodes (LEDs) and visible-blind UV photodetectors (PDs) employing the same p-GaN/AlGaN/GaN epi-structures grown on Si. Due to the radiative recombination of holes from the p-GaN layer with electrons from the 2-D electron gas (2DEG) accumulating at the AlGaN/GaN heterointerface, the forward biased LED with p-GaN/AlGaN/GaN junction exhibits uniform light emission at 360 nm. Facilitated by the high-mobility 2DEG channel governed by a p-GaN optical gate, the visible-blind phototransistor-type PDs show a low dark current of ∼10-7 mA/mm and a high responsivity of 3.5×105 A/W. Consequently, high-sensitivity photo response with a large photo-to-dark current ratio of over 106 and a response time less than 0.5 s is achieved in the PD under the UV illumination from the on-chip adjacent LED. The demonstrated simple integration scheme of high-performance UV PDs and LEDs shows great potential for various applications such as compact opto-isolators.
TL;DR: In this article, temperature-dependent measurements and single-dot spectroscopy reveal that up-conversion photoluminescence and conventional down-concussion share the same electron-phonon coupled electronic states.
Abstract: Phonon-assisted up-conversion photoluminescence can boost energy of an emission photon to be higher than that of the excitation photon by absorbing vibration energy (or phonons) of the emitter. Here, up-conversion photoluminescence power-conversion efficiency (power ratio between the emission and excitation photons) for CdSe/CdS core/shell quantum dots is observed to be beyond unity. Instead of commonly known defect-assisted up-conversion photoluminescence for colloidal quantum dots, temperature-dependent measurements and single-dot spectroscopy reveal the up-conversion photoluminescence and conventional down-conversion photoluminescence share the same electron-phonon coupled electronic states. Ultrafast spectroscopy results imply the thermalized excitons for up-conversion photoluminescence form within 200 fs, which is 100,000 times faster than the radiative recombination rate of the exciton. Results suggest that colloidal quantum dots can be exploited as efficient, stable, and cost-effective emitters for up-conversion photoluminescence in various applications. Up-conversion photoluminescence in colloidal quantum dots is generally believed to be mediated by thermal activation from defect states. Here, the authors reveal that highly-efficient up-conversion photoluminescence instead is related to electron-phonon coupling.
TL;DR: In this article, the authors demonstrate cascaded energy transfer and exciton recycling at nanoassembly level for luminous solar concentrators (LSCs) for efficient solar energy harvesting.
Abstract: Luminescent solar concentrators (LSC) absorb large-area solar radiation and guide down-converted emission to solar cells for electricity production. Quantum dots (QDs) have been widely engineered at device and quantum dot levels for LSCs. Here, we demonstrate cascaded energy transfer and exciton recycling at nanoassembly level for LSCs. The graded structure composed of different sized toxic-heavy-metal-free InP/ZnS core/shell QDs incorporated on copper doped InP QDs, facilitating exciton routing toward narrow band gap QDs at a high nonradiative energy transfer efficiency of 66%. At the final stage of non-radiative energy transfer, the photogenerated holes make ultrafast electronic transitions to copper-induced mid-gap states for radiative recombination in the near-infrared. The exciton recycling facilitates a photoluminescence quantum yield increase of 34% and 61% in comparison with semi-graded and ungraded energy profiles, respectively. Thanks to the suppressed reabsorption and enhanced photoluminescence quantum yield, the graded LSC achieved an optical quantum efficiency of 22.2%. Hence, engineering at nanoassembly level combined with nonradiative energy transfer and exciton funneling offer promise for efficient solar energy harvesting.
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TL;DR: Dicke superradiance in the emission of an almost fully inverted system as a function of the atom number is investigated and is in qualitative agreement with ab-initio, beyond-mean-field calculations.
Abstract: We report the experimental observation of superradiant emission emanating from an elongated dense ensemble of laser cooled two-level atoms, with a radial extent smaller than the transition wavelength. In the presence of a strong driving laser, we observe that the system is superradiant along its symmmetry axis. This occurs even though the driving laser is orthogonal to the superradiance direction. This superradiance modifies the spontaneous emission, and, resultantly, the Rabi oscillations. We also investigate Dicke superradiance in the emission of an almost fully-inverted system as a function of atom numnber. The experimental results are in qualitative agreement with ab-initio, beyond-mean-field calculations.
TL;DR: In this article, the authors carried out a comparative analysis of planar metallic, high refractive index dielectric, and hybrid nanoantennas considering three different parameters: the Purcell factor enhancement, radiation efficiency, and directionality properties.
Abstract: The confinement of electromagnetic energy to subwavelength volumes through nanoscale antennas can be used to enhance the spontaneous emission of quantum emitters. With this aim, different configurations of metallic and high refractive index dielectric nanoparticles have been explored. Here, we carry out a comparative analysis of planar metallic, high refractive index dielectric, and hybrid nanoantennas considering three different parameters: the Purcell factor enhancement, radiation efficiency, and directionality properties. We focus our study on different geometries and material combinations of a dimer of cylinders. A dimer made of two gold nanocylinders is the most promising candidate for improving the spontaneous emission. While most previous works have paid attention to the redirection of the scattered emission in the nanoparticle plane, our proposed nanostructure of two large gold cylinders ( R = λ / 4 ) emits most of the radiation upwards. This effect is due to the strong quadrupolar electric contribution to the resonant mode. With the aim to further improve the directionality properties, additional silicon nanocylinders are used as directors of the scattered radiation, increasing the directivity by a factor of 2.4 with respect to the gold dimer without directors. All in all, a hybrid structure composed of a gold dimer and silicon nanoparticles is proposed to enhance the spontaneous emission of a single quantum dot and to govern its emission pattern. The results shown in this work could be useful in fluorescence enhancement or in quantum photonics. They are particularly interesting for the development of single-photon sources based on quantum dots and other nanoscale emitters.
TL;DR: In this article, plasmonic nanoantennas, optical cavities, and their hybrids that can be integrated with multilayer bP to enhance its light absorption is explored.
Abstract: Black phosphorus (bP), a two-dimensional (2D) layered material, has shown great potential for infrared (IR) optoelectronics owing to the narrow and direct bandgap it exhibits when in multilayer form However, its thinness and optical anisotropy lead to weak light absorption, which limits the performance of bP-based photodetectors In this work, we explore plasmonic nanoantennas, optical cavities, and their hybrids that can be integrated with multilayer bP to enhance its light absorption This is achieved by near-field light intensity enhancement and polarization conversion In addition, we demonstrate that these nanostructures can boost the spontaneous emission from bP Light absorption enhancements of up to 185 and 16 times are obtained for linearly polarized and unpolarized IR light, respectively, in comparison with a commonly used device architecture (bP on SiO2/Si) Moreover, IR light emission enhancements of up to 18 times are achieved The optical nanostructures presented here can be exploited for enhancing the detectivity of photodetectors and electroluminescence efficiency of light-emitting diodes based on bP and other 2D materials
TL;DR: In this paper, color-saturated CsPbBr3−xIx (x = 0 − 3)/ZnO heterojunctions based white light emitting diodes (LEDs) on a flexible platform were presented.
TL;DR: In this article, the authors proposed the edge state-led mode coupling under topological protection, i.e., localized surface plasmons almost do not have any influence on the edge states, while the edge-state greatly changes the local field distribution of surface plasms.
Abstract: We propose the mechanism of edge state-led mode coupling under topological protection; i.e., localized surface plasmons almost do not have any influence on the edge state, while the edge state greatly changes the local field distribution of surface plasmons. Based on this mechanism, in the well-designed topological photonic structure containing a resonant plasmon nanoantenna, an obvious absorption reduction in the spontaneous emission spectra appears due to the near-field deformation around the antenna induced by the edge state. Because a plasmon antenna with ultrasmall mode volume provides large Purcell enhancement and simultaneously the photonic crystal guides almost all scattering light into its edge state, the rate of nonscattering single photons reaches more than 10^{4}γ_{0}. This topological state-led mode coupling mechanism and induced absorption reduction, which are based on topological protection, will have a profound effect on the study of composite topological photonic structures and related micro- and nanoscale cavity quantum electrodynamics. Also, nonscattering large Purcell enhancement will provide practical use for on-chip quantum light sources, such as single-photon sources and nanolasers.
TL;DR: In this paper, the authors investigated the impact of spontaneous coupling coefficient β on lasing properties in the class-A limit by extending the well-known Scully-Lamb master equation.
Abstract: Nanocavity lasers are commonly characterized by the spontaneous coupling coefficient β that represents the fraction of photons emitted into the lasing mode. While β is conventionally discussed in semiconductor lasers where the photon lifetime is much shorter than the carrier lifetime (class-B lasers), little is known about β in atomic lasers where the photon lifetime is much longer than the other lifetimes and only the photon degree of freedom exists (class-A lasers). We investigate the impact of the spontaneous coupling coefficient β on lasing properties in the class-A limit by extending the well-known Scully–Lamb master equation. We demonstrate that in the class-A limit all the photon statistics are uniquely characterized by β and that the laser phase transition-like analogy becomes transparent. In fact, β perfectly represents the “system size” in phase transition. Finally, we investigate the laser-phase transition analogy from the standpoint of a quantum dissipative system. Calculating a Liouvillian gap, we clarify the relation between β and the continuous phase symmetry breaking.
TL;DR: In this article, the authors optimized the composition of lead-free double perovskite Cs2AgIn1-xBixCl6 nanocrystals via an antisolvent recrystallization method at room-temperature.
TL;DR: The inherent instability severely limits the applications of cesium lead halide (CsPbX3) perovskite quantum dots (PQDs) as discussed by the authors, and therefore, the authors of this paper introduce these CsPb X3 PQDs into all-inorganic amorphous solid matrices.
Abstract: The inherent instability severely limits the applications of cesium lead halide (CsPbX3) perovskite quantum dots (PQDs). Herein, introducing these CsPbX3 PQDs into all-inorganic amorphous solid mat...
TL;DR: In this article, the authors demonstrate long-range dipole-dipole interactions mediated by surface lattice resonances in a plasmonic nanoparticle lattice using angle-resolved spectral measurements and fluorescence lifetime studies.
Abstract: Spontaneous emission of quantum emitters can be enhanced by increasing the local density of optical states, whereas engineering dipole-dipole interactions requires modifying the two-point spectral density function. Here, we experimentally demonstrate long-range dipole-dipole interactions (DDIs) mediated by surface lattice resonances in a plasmonic nanoparticle lattice. Using angle-resolved spectral measurements and fluorescence lifetime studies, we show that unique nanophotonic modes mediate long-range DDI between donor and acceptor molecules. We observe significant and persistent DDI strengths for a range of densities that map to ∼800 nm mean nearest-neighbor separation distance between donor and acceptor dipoles, a factor of ∼100 larger than free space. Our results pave the way to engineer and control long-range DDIs between an ensemble of emitters at room temperature.
TL;DR: In this paper, the authors demonstrate sub-micrometer-sized, plasmonic lasers using cesium-lead-bromide perovskite (CsPbBr3) crystals, as small as 0.58 μm by 0.56 μm.
Abstract: Plasmonic lasers attracted interest for their ability to generate coherent light in mode volume smaller than the diffraction limit of photonic lasers. While nanoscale devices in one or two dimensions were demonstrated, it has been difficult to achieve plasmonic lasing with submicrometer cavities in all three dimensions. Here, we demonstrate submicrometer-sized, plasmonic lasers using cesium-lead-bromide perovskite (CsPbBr3) crystals, as small as 0.58 μm by 0.56 μm by 0.32 μm (cuboid) and 0.79 μm by 0.66 μm by 0.18 μm (plate), on polymer-coated gold substrates at room temperature. Our experimental and simulation data obtained from more than 100 plasmonic and photonic devices showed that enhanced optical gain by the Purcell effect, large spontaneous emission factor, and high group index are key elements to efficient plasmonic lasing. The results shed light on the three-dimensional miniaturization of plasmonic lasers.
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TL;DR: In this paper, the authors showed that perovskite LEDs can transmit data efficiently to a silicon detector at 1V, a voltage below the silicon bandgap, revealing a universal origin of ultralow-voltage device operation.
Abstract: The radiative recombination of injected charge carriers gives rise to electroluminescence (EL), a central process for light-emitting diode (LED) operation. It is often presumed in some emerging fields of optoelectronics, including perovskite and organic LEDs, that the minimum voltage required for light emission is the semiconductor bandgap divided by the elementary charge. Here we show for many classes of LEDs, including those based on metal halide perovskite, organic, chalcogenide quantum-dot and commercial III-V semiconductors, photon emission can be generally observed at record-low driving voltages of 36%-60% of their bandgaps, corresponding to a large apparent energy gain of 0.6-1.4 eV per emitted photon. Importantly, for various classes of LEDs with very different modes of charge injection and recombination (dark saturation current densities ranging from ~10^-35 to ~10^-21 mA/cm2), their EL intensity-voltage curves under low voltages exhibit similar behaviors, revealing a universal origin of ultralow-voltage device operation. Finally, we demonstrate as a proof-of-concept that perovskite LEDs can transmit data efficiently to a silicon detector at 1V, a voltage below the silicon bandgap. Our work provides a fresh insight into the operational limits of electroluminescent diodes, highlighting the significant potential of integrating low-voltage LEDs with silicon electronics for next-generation communications and computational applications.
TL;DR: In this article, the authors investigate the different photon emission regimes created by a pre-excited and collimated atomic beam passing through a single mode of an optical cavity and find that the atoms undergo super-radiant emission when the collective linewidth exceeds the transit-time broadening.
Abstract: We investigate the different photon emission regimes created by a pre-excited and collimated atomic beam passing through a single mode of an optical cavity. In the regime where the cavity degrees of freedom can be adiabatically eliminated, we find that the atoms undergo superradiant emission when the collective linewidth exceeds the transit-time broadening. We analyze the case where the atomic beam direction is slanted with respect to the cavity axis. For this situation, we find that a phase of continuous light emission similar to steady-state superradiance is established providing the tilt of the atomic beam is sufficiently small. However, if the atoms travel more than half a wavelength along the cavity axis during one transit time we predict a dynamical phase transition to a bistable superradiant regime. In this phase the atoms undergo collective spontaneous emission with a frequency that can be either blue or red detuned from the free-space atomic resonance. We analyze the different superradiant regimes and the quantum critical crossover boundaries. In particular we find the spectrum of the emitted light and show that the linewidth exhibits features of a critical scaling close to the phase boundaries.
TL;DR: In this paper, the authors used the exfoliated (PEA)2PbI4 thin flake as the gain medium to construct a vertical-cavity surface-emitting laser (VCSEL), showing robust single-mode CW lasing operation with an ultra low threshold of 5.7 W cm−2 at room temperature, attributed to strong optical confinement in the high-Q cavity.
Abstract: Two-dimensional (2D) layered lead halide perovskites with large exciton binding energies, efficient radiative recombination, and outstanding environmental stability are regarded as supreme candidates for realizing highly compact and ultralow threshold lasers. However, continuous-wave (CW) pumped lasing of 2D lead halide perovskites, as the precondition for the electrically pumped lasing, is still challenging. Here, we tackled this challenge by demonstrating lasing emission in phenylethylammonium lead iodide [(PEA)2PbI4] embedded in a vertical microcavity under continuous pumping at room temperature. The millimeter-sized (PEA)2PbI4 single crystal was obtained from a two-step seed-growth method, showing high crystallization, excellent thermal stability, and outstanding optical properties. We used the exfoliated (PEA)2PbI4 thin flake as the gain medium to construct a vertical-cavity surface-emitting laser (VCSEL), showing robust single-mode CW lasing operation with an ultra-low threshold of 5.7 W cm−2 at room temperature, attributed to strong optical confinement in the high-Q cavity. Our findings provide a strategy to design and fabricate solution-based 2D perovskite VCSELs and mark a significant step toward the next-generation of coherent light sources.