ABSTRACT Versatile, tunable, and potentially scalable single‐photon sources are a key asset in emergent photonic quantum technologies. In this work, a single‐photon source based on WS 2 micro‐domes, created via hydrogen ion irradiation, is realized and integrated into an open, tunable optical microcavity. Single‐photon emission from the coupled emitter–cavity system is verified via the second‐order correlation measurement, revealing a value of . A detailed analysis of the spectrally selective, cavity enhanced emission features shows the impact of a pronounced acoustic phonon emission sideband, which contributes specifically to the non‐resonant emitter–cavity coupling in this system. The achieved level of cavity–emitter control highlights the potential of open‐cavity systems to tailor the emission properties of atomically thin quantum emitters, advancing their suitability for real‐world quantum technology applications.

2-(2′-hydroxyphenyl)benzothiazole (HBT) exhibits remarkable photophysical properties, in particular intense fluorescence, both in solution and in solid state. For this reason, this compound and related ones are intensely studied for a...

Versatile, tunable, and potentially scalable single-photon sources are a key asset in emergent photonic quantum technologies. In this work, a single-photon source based on WS_2 micro-domes, created via hydrogen ion irradiation, is realized and integrated into an open, tunable optical microcavity. Single-photon emission from the coupled emitter-cavity system is verified via the second-order correlation measurement, revealing a g^(2)(τ=0) value of 0.3. A detailed analysis of the spectrally selective, cavity enhanced emission features shows the impact of a pronounced acoustic phonon emission sideband, which contributes specifically to the non-resonant emitter-cavity coupling in this system. The achieved level of cavity-emitter control highlights the potential of open-cavity systems to tailor the emission properties of atomically thin quantum emitters, advancing their suitability for real-world quantum technology applications.

Two-dimensional (2D) heterostructures (HSs) offer unlimited possibilities for playing with layer number, order, and twist angle. The realization of high-performance optoelectronic devices, however, requires the achievement of specific band alignments, k-space matching between conduction and valence band extrema, and efficient charge transfer between the constituent layers. Fine-tuning mechanisms to design ideal HSs are lacking. Here, we show that layer-selective strain engineering can be exploited as an extra degree of freedom to tailor the band alignment and optical properties of 2D HSs. To that end, strain is selectively applied to MS2 (M = Mo or W) monolayers in InSe/MS2 HSs, triggering a giant photoluminescence enhancement of the highly tunable but weakly emitting InSe of up to >2 orders of magnitude. Resonant excitation measurements, supported by first-principles calculations, provide evidence of a strain-activated charge transfer from the MS2 monolayers toward InSe. The huge emission enhancement of InSe widens its range of applications for optoelectronics.

Moiré excitons (MXs) are electron-hole pairs localised by the periodic (moiré) potential forming in two-dimensional heterostructures (HSs). MXs can be exploited, e.g., for creating nanoscale-ordered quantum emitters and achieving or probing strongly correlated electronic phases at relatively high temperatures. Here, we studied the exciton properties of WSe 2 /MoSe 2 HSs from T = 6 K to room temperature using time-resolved and continuous-wave micro-photoluminescence also under a magnetic field. The exciton dynamics and emission lineshape evolution with temperature show clear signatures that MXs de-trap from the moiré potential and turn into free interlayer excitons (IXs) for temperatures above 100 K. The MX-to-IX transition is also apparent from the exciton magnetic moment reversing its sign when the moiré potential is not capable of localising excitons at elevated temperatures. Concomitantly, the exciton formation and decay times reduce drastically. Thus, our findings establish the conditions for a truly confined nature of the exciton states in a moiré superlattice with increasing temperature and photo-generated carrier density.

Semiconductor materials capable of hosting luminescent lanthanide ions (Ln3+) and sensitize their emission are scarce. Halide perovskites are prime systems for this purpose, yet they often feature toxic elements (e.g., lead) in their composition and have reduced stability. The discovery of alternative semiconductors that feature host-to-Ln3+ energy transfer mechanisms - while being more stable and environmentally benign - would thus broaden the applicability of this class of luminescent materials. Herein, we report near-infrared (NIR) emitting phosphors made of BaZrS3 chalcogenide perovskite doped with Ln3+ ions (Ln = Yb, Er, Nd). We chose BaZrS3 because it features (i) crystallographic sites that can accommodate Ln3+ ions, (ii) high light absorption coefficient in the visible, and (iii) stability. The phosphors were prepared via sulfurization of Ln3+-doped BaZrO3 microparticles obtained by a microwave-assisted procedure. The so-obtained Ln3+-doped BaZrS3 display low-temperature NIR emission characteristic of each Ln3+ ion when exciting the matrix. Following photoluminescence studies on doped and undoped BaZrS3 as a function of temperature, we propose an energy level scheme that explains the rich NIR photoluminescence displayed by these phosphors. The obtained results pave the way for the optimization of Ln3+-doped BaZrS3 for optical applications and are expected to spur the study of other ternary chalcogenides sensitization of Ln3+ luminescence.

Alloying has been a powerful and practical strategy to widen the palette of physical properties available to semiconductor materials. Thanks to recent advances in the synthesis of van der Waals semiconductors, this strategy can be extended to monolayers (MLs) of transition metal dichalcogenides (TMDs). Due to their extraordinary flexibility and robustness, strain is another powerful means to engineer the electronic properties of two-dimensional (2D) TMDs. In this article, we combine these two approaches in an exemplary metal dichalcogenide chalcogen-alloy, WSSe. Highly strained WSSe MLs are obtained through the formation of micro-domes filled with high-pressure hydrogen. Such structures are achieved by hydrogen-ion irradiation of the bulk material, a technique successfully employed in TMDs and h-BN. Atomic force microscopy studies of the WSSe ML domes show that the dome morphology can be reproduced in terms of the average of the elastic parameters and adhesion energy of the end compounds WSe2 and WS2. Micro-photoluminescence measurements of the WSSe domes demonstrate that the exceedingly high strains (ε∼4%) achieved in the domes trigger a direct-to-indirect exciton transition, similarly to WSe2 and WS2. Our findings heighten the prospects of 2D alloys as strain- and composition-engineerable materials for flexible optoelectronics.

Moiré excitons (MXs) are electron-hole pairs localised by the periodic (moiré) potential forming in two-dimensional heterostructures (HSs). MXs can be exploited, $e.g.$, for creating nanoscale-ordered quantum emitters and achieving or probing strongly correlated electronic phases at relatively high temperatures. Here, we studied the exciton properties of a WSe$_2$/MoSe$_2$ HS from $T$=6 K to room temperature using time-resolved and continuous-wave micro-photoluminescence, also under magnetic field. The exciton dynamics and emission lineshape evolution with temperature show clear signatures that MXs de-trap from the moiré potential and turn into free interlayer excitons (IXs) at $T\gtrsim$120 K. The MX-to-IX transition is also apparent from the exciton magnetic moment reversing its sign when the moiré potential is not capable to localise excitons at elevated temperatures. Concomitantly, the exciton formation and decay times reduce drastically. Thus, our findings establish the conditions for a truly confined nature of the exciton states in a moiré superlattice with increasing temperature.

Monolayers (MLs) of transition‐metal dichalcogenides host efficient single‐photon emitters (SPEs) usually associated to the presence of nanoscale mechanical deformations or strain. Large‐scale spatial control of strain would enhance the scalability of such SPEs and allow for their incorporation into photonic structures. Here, the formation of regular arrays of strained hydrogen‐filled one‐layer‐thick micro‐domes obtained by H‐ion irradiation and lithography‐based approaches is reported. Typically, the H 2 liquefaction for temperatures T <32 K causes the disappearance of the domes preventing their use as potential SPEs. Here, it is shown that the dome deflation can be overcome by hBN heterostructuring, that is by depositing thin hBN flakes on the domes. This leads to the preservation of the dome structure at all temperatures, as found by micro‐Raman and micro‐photoluminescence (µ‐PL) studies. Eventually, spatially controlled hBN‐capped WS 2 domes show the appearance, at 5 K, of intense emission lines originating from localized excitons, which are shown to behave as quantum emitters here. The electronic properties of the emitters are addressed by time‐resolved µ‐PL yielding time decays of 1–10 ns, and by magneto‐µ‐PL measurements. The latter provide an exciton magnetic moment a factor of two larger than the value observed in planar strain‐free MLs.

Moiré excitons (MXs) are electron-hole pairs localised by the periodic (moiré) potential forming in two-dimensional heterostructures (HSs). MXs can be exploited, e.g., for creating nanoscale-ordered quantum emitters and achieving or probing strongly correlated electronic phases at relatively high temperatures. Here, we studied the exciton properties of a WSe_2/MoSe_2 HS from T=6 K to room temperature using time-resolved and continuous-wave micro-photoluminescence, also under magnetic field. The exciton dynamics and emission lineshape evolution with temperature show clear signatures that MXs de-trap from the moiré potential and turn into free interlayer excitons (IXs) at T≳120 K. The MX-to-IX transition is also apparent from the exciton magnetic moment reversing its sign when the moiré potential is not capable to localise excitons at elevated temperatures. Concomitantly, the exciton formation and decay times reduce drastically. Thus, our findings establish the conditions for a truly confined nature of the exciton states in a moiré superlattice with increasing temperature.