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Halide perovskites belong to an important family of semiconducting materials with unique electronic properties that enable a myriad of applications, especially in photovoltaics and optoelectronics. Their optical properties, including photoluminescence quantum yield, are affected and notably enhanced at crystal imperfections where the symmetry is broken and the density of states increases. These lattice distortions can be introduced through structural phase transitions, allowing charge gradients to appear near the interfaces between phase structures. In this work, we demonstrate controlled multi-phase structuring in a single perovskite crystal. The concept uses cesium lead bromine (CsPbBr3) placed on a thermoplasmonic TiN/Si metasurface and enables single, double and triple phase structures to form on demand above the room temperature. This approach opens up application horizons of dynamically controlled heterostructures with distinctive electronic and enhanced optical properties.

Detection of hazardous volatile organic and inorganic species is a crucial task for addressing human safety in the chemical industry. Among these species, there are hydrogen halides (HX, X = Cl, Br, I) vastly exploited in numerous technological processes. Therefore, the development of a cost-effective, highly sensitive detector selective to any HX gas is of particular interest. Herein, we demonstrate the optical detection of hydrogen chloride gas with solution-processed halide perovskite nanowire lasers grown on a nanostructured alumina substrate. An anion exchange reaction between a CsPbBr

Ligand-free methods for the synthesis of halide perovskite nanocrystals are of great interest because of their excellent performance in optoelectronics and photonics.

Cyclometallated platinum(ii) species with ancillary acyclic diaminocarbene ligands work as efficient green emitting components of OLED devices.

Future technologies underpinning multifunctional physical and chemical systems and compact biological sensors will rely on densely packed transformative and tunable circuitry employinginanophotonics/i. For many years, plasmonics was considered as the only available platform for subwavelength optics, but the recently emerged field of resonant metaphotonics may provide a versatile practical platform for nanoscale science by employing resonances in high-index dielectric nanoparticles and metasurfaces. Here, we discuss the recently emerged field of metaphotonics and describe its connection to material science and chemistry. For tunabilty, metaphotonics employs a variety of the recently highlighted materials such as polymers, perovskites, transition metal dichalcogenides, and phase change materials. This allows to achieve diverse functionalities of metasystems and metasurfaces for efficient spatial and temporal control of light by employing multipolar resonances and the physics of bound states in the continuum. We anticipate expanding applications of these concepts in nanolasers, tunable metadevices, metachemistry, as well as a design of a new generation of chemical and biological ultracompact sensing devices.

The architecture of transparent contacts is of utmost importance for creation of efficient flexible light-emitting devices (LEDs) and other deformable electronic devices. We successfully combined the newly synthesized transparent and durable silicone rubbers and the semiconductor materials with original fabrication methods to design LEDs and demonstrate their significant flexibility. We developed electrodes based on a composite GaP nanowire-phenylethyl-functionalized silicone rubber membrane, improved with single-walled carbon nanotube films for a hybrid poly(ethylene oxide)-metal-halide perovskite (CsPbBr3) flexible green LED. The proposed approach provides a novel platform for fabrication of flexible hybrid optoelectronic devices.

Multiphoton absorption and luminescence are fundamentally important nonlinear processes for utilizing efficient light-matter interaction. Resonant enhancement of nonlinear processes has been demonstrated for many nanostructures; however, it is believed that all higher-order processes are always much weaker than their corresponding linear processes. Here, we study multiphoton luminescence from structured surfaces and, combining multiple advantages of perovskites with the concept of metasurfaces, we demonstrate that the efficiency of nonlinear multiphoton processes can become comparable to the efficiency of the linear process. We reveal that the perovskite metasurface can enhance substantially two-photon stimulated emission with the threshold being comparable with that of the one-photon process. Our modeling of free-carrier dynamics and exciton recombination upon nonlinear photoexcitation uncovers that this effect can be attributed to the local field enhancement in structured media, a substantial increase of the mode overlap, and the selection rules of two-photon absorption in perovskites.

We study active dielectric metasurfaces composed of two-dimensional arrays of split-nanodisk resonators fabricated in InGaAsP membranes with embedded quantum wells. Depending on the geometric parameters, such split-nanodisk resonators can operate in the optical anapole regime originating from an overlap of the electric dipole and toroidal dipole Mie-resonant optical modes, thus supporting strongly localized fields and high-Q resonances. We demonstrate room-temperature lasing from the anapole lattices of engineered active metasurfaces with low threshold and high coherence.

Halide perovskite nanocrystals are a family of nanomaterials with a high prospect for use in light-emitting devices, lasers, and quantum optics, which makes their integration into photonic circuits...

Chemically synthesized inorganic lead halide perovskite lasers based on nanostructures, generating coherent light at room temperature, and having a low threshold, have become powerful tools for var...

The rational combination of plasmonic and all-dielectric concepts within hybrid nanomaterials provides a promising route toward devices with ultimate performance and extended modalities. Spectral matching of plasmonic and Mie-type resonances for such nanostructures can only be achieved for their dissimilar characteristic sizes, thus making the resulting hybrid nanostructure geometry complex for practical realization and large-scale replication. Here, we produced amorphous TiO2 nanospheres decorated and doped with Au nanoclusters via single-step nanosecond-laser irradiation of commercially available TiO2 nanopowders dispersed in aqueous HAuCl4. Fabricated hybrids demonstrate remarkable light-absorbing properties (averaged value ≈96%) in the visible and near-IR spectral range mediated by bandgap reduction of the laser-processed amorphous TiO2 as well as plasmon resonances of the decorating Au nanoclusters. The findings are supported by optical spectroscopy, electron energy loss spectroscopy, transmission electron microscopy, and electromagnetic modeling. Light-absorbing and plasmonic properties of the produced hybrids were implemented to demonstrate catalytically passive SERS biosensor for identification of analytes at trace concentrations and solar steam generator that permitted to increase water evaporation rate by 2.5 times compared with that of pure water under identical 1 sun irradiation conditions.

Resonant dielectric structures have emerged recently as a new platform for subwavelength nonplasmonic photonics. It was suggested and demonstrated that magnetic and electric Mie resonances can enhance substantially many effects at the nanoscale including spontaneous Raman scattering. Here, we demonstrate stimulated Raman scattering (SRS) for isolated crystalline silicon (c-Si) nanoparticles and observe experimentally a transition from spontaneous to stimulated scattering manifested in a nonlinear growth of the signal intensity above a certain pump threshold. At the Mie resonance, the light gets confined into a low volume of the resonant mode with enhanced electromagnetic fields inside the c-Si nanoparticle due to its high refractive index, which leads to an overall strong SRS signal at low pump intensities. Our finding paves the way for the development of efficient Raman nanolasers for multifunctional photonic metadevices.

The ability of light manipulation at a sub-wavelength scale of metal halide perovskite-based nanostructures through nanophotonic design were employed for advanced optical and optoelectronic applications. While these nanostructures could be efficiently tuned in the visible spectral range, their operation at infrared wavelengths is still challenging. Herein, we illustrate that islandlike films of lead-free CH3NH3SnI3 can generate strong and tunable Mie-type resonances in the near-infrared spectral range. Two critical factors contribute to the Mie resonance properties-the microscale geometry is crucial for the initiation of Mie resonances in the particles, while the concentration of free holes formed via the oxidation of Sn2+ to Sn4+ modulates the spectral position of Mie resonances. Moreover, coupling the Mie resonances to the photoluminescence peak wavelength results in the enhancement of the photoluminescence intensity. This study offers a platform for the implementation of optically resonant perovskite nanostructures as tunable light emitters for infrared photonics and optoelectronics.

Last decade, halide perovskites demonstrate high potential for efficient, tunable, and cheap photonic sources. Recently, single-particle perovskite lasers of various compositions and shapes with all dimensions close or smaller than the emitted wavelengths were demonstrated experimentally in a broad range of temperatures. In this review, we aim to cover not only the recent progress in the single-particle perovskite lasers but also provide a comprehensive analysis on strategies to achieve the most compact perovskite lasers with the best working parameters.

Ionic migration plays an important role in the operation of perovskite-based solar cells and light-emitting diodes. Although ionic migration is a reversible process, it often leads to worsening of the perovskite-based device performance and hysteresis in current–voltage characteristics; the phase segregation in mixed halide perovskites is the most harmful effect. The reason lies in the dynamical band structure changes, one of the biggest challenges in the development of light-emitting solar cells, which can be solved through controllable engineering. Herein, we demonstrate the controllable band structure bending due to ion migration under an applied voltage in mixed halide perovskite devices. The band structure rearrangement is demonstrated in light-emitting solar cells based on the perovskite with organic cations methylammonium (MA+) and formamidinium (FA+), and with PEDOT:PSS and C60 transport layers having a high barrier of 0.8 eV for charge injection. The devices based on MAPbBr2I and FAPbBr2I demonstrate different threshold voltages of 1.7 and 2.6 V, respectively, in the LED regime after device pre-biasing, whereas the device with the monohalide perovskite MAPbBr3 does not demonstrate such behavior. We assume that this arises from the different dipole moments of the organic cation molecules, MA+ and FA+, possessing non-zero dipole moments of 2.29 Debye and 0.21 Debye, respectively. Our hypothesis is that under the applied voltage, perovskite cations and anions move towards the perovskite/transport layer interfaces and form accumulation layers. Moreover, the organic accumulation layer at the perovskite/electron transport layer interface additionally bends the device band structure and lowers the LED threshold voltage due to its dipole nature. This ability to change the device band structure in situ opens the way for the development of dual functional devices based on a simple design. In addition, it makes the mixed halide perovskite more flexible than monohalide ones for the creation of different optoelectronic devices without the use of special types of transport materials.

Exciton-polaritons offer a versatile platform for realization of all-optical integrated logic gates due to the strong effective optical nonlinearity resulting from the exciton-exciton interactions. In most of the current excitonic materials there exists a direct connection between the exciton robustness to thermal fluctuations and the strength of exciton-exciton interaction, making materials with highest levels of exciton nonlinearity applicable at cryogenic temperatures only. Here, we show that strong polaronic effects, characteristic for perovskite materials, allow to overcome this limitation. Namely, we demonstrate the record-high value of the nonlinear optical response in nanostructured organic-inorganic halide perovskite MAPbI$_3$, experimentally detected as 19.7 meV blueshift of the polariton branch under femtosecond laser irradiation. This is substantially higher than characteristic values for the samples based on conventional semiconductors and monolayers of transition metal dichalcogenides. The observed strong polaron-enhanced nonlinearity exists for both tetragonal and orthorombic phases of MAPbI$_3$, and remains stable at elevated temperatures.

Lead halide perovskites were known to be a prospective family of materials for terahertz (THz) generation. On the other hand, perovskite nanostructures, nanoantennas, and metasurfaces allow tailoring perovskites optical characteristics, resulting in more efficient interaction with incident or emitted light. Moreover, the perovskites are robust materials against formation of defects caused by mechanical deformations and can be efficiently nanostructured by various high throughput methods. In this work, we have enhanced THz emission from MAPbI3 perovskite upon femtosecond laser irradiation using nanoimprint lithography. The formed nanostructures not only improve absorption of the incident laser pulses, but also lead to a non-symmetric near-field distribution. As a result, we have enhanced the efficiency of THz emission from the nanostructured perovskite by 3.5 times as compared with a smooth perovskite film. Our results paved the way for a new application of large-scale perovskite nanostructuring, making halide perovskites competitive with more expensive conventional semiconductors for THz generation.

Nanoscale periodical chemical composition modification of different two-component compound materials GaAs, CdTe, W0.5C and TiC was realized for the first time through multi-shot femtosecond laser irradiation of their surfaces. The resulting surface modification represents periodical nanoscale ripples with different chemical composition in valleys and ridges. The underlying mechanism is related to a sequence of elementary processes, such as laser excitation surface plasmon-polariton, their interference with the incident laser radiation, inhomogeneous surface heating and incongruent cavitation-like material removal. The latter mechanism is responsible for higher evaporation rate of the components with higher volatility, resulting in growth of surface concentration of low-volatility components.

The architecture of transparent contacts is of utmost importance for creation of efficient flexible light-emitting devices (LEDs) and other deformable electronic devices. We successfully combined the newly synthesized transparent and durable silicone rubbers and the semiconductor materials with original fabrication methods to design LEDs and demonstrate their significant flexibility. We developed electrodes based on a composite GaP nanowire-phenylethyl-functionalized silicone rubber membrane, improved with single-walled carbon nanotube films for a hybrid poly(ethylene oxide)-metal-halide perovskite (CsPbBr

We demonstrate optically tunable control of second-harmonic generation in all dielectric nano-antennas: by using a control beam which is absorbed by the nano-resonator, we thermo-optically change the refractive index of the radiating element to modulate amplitude and phase of the second-harmonic signal. For a moderate temperature increase, sizeable modulation is demonstrated; the large tunability of the single meta-atom response paves the way to exciting avenues for reconfigurable homogeneous and heterogeneous metasurfaces.

Halide perovskite nanomaterials are widely used in optoelectronics and photonics due to their outstanding luminescent properties, whereas their strong multiphoton absorption makes them prospective for bioimaging. Nonetheless, instability of perovskites in aqueous solutions is an important limitation that prevents their application in biology and medicine. Here, we demonstrate fluorescence and upconversion imaging in living cells by employing CsPbBr3 nanocrystals (NCs) that show an improved water-resistance (at least for 24 h) after their coating as individual particles with various silica-based shells. The obtained phTEOS-TMOS@CsPbBr3 NCs possess high quality, which we confirm with high-resolution transmission and scanning transmission electron microscopy, X-ray diffraction analysis, Fourier-transform infrared and energy-dispersive X-ray spectroscopies, as well as with fluorescence optical microscopy. The developed platform can make the halide perovskite NCs suitable for various bioimaging applications.

Metasurfaces have recently enabled a further miniaturization of many optical components which are typically bulky and made of different materials. Notably, nonlinear optics in dielectric metasurfaces has been investigated achieving significant Second Harmonic (SH) generation efficiency in χ (2) materials [1] , [2] . In this work, we use a symmetry broken meta-atom shaped as an AlGaAs "nano-chair", obtained by removing one quarter of the volume from a nanocylinder with elliptic base, see Fig. 1(a) . The proposed geometry is promising for technological applications, because capable of emitting the SH light along the vertical direction ( z axis) [3] . We thus propose to use such structures in a metasurface that is concurrently excited by a Fundamental Frequency (FF) pump in the infrared region (1.55 μm) and by a Continuous Wave (CW) beam in the visible (550 nm). By varying the CW intensity, it is possible to control the temperature inside the meta-atom. The temperature increasing is responsible for a modification in the AlGaAs refractive index. Thus, by varying the CW light intensity, I 0 , we can optimize the temperature profile so as to change the refractive index of the meta-atom, achieving in such manner the tuning of the linear resonant response and consequently obtaining a detectable variation in the SH light. In Fig. 1(b) we elucidate that is possible to create a look-up table for the emitted SH magnitude and phase coming from the meta-atom as a function of I 0 . We verify that for the studied CW intensity range, the SH emission pattern preserves a main lobe ( y -polarized) towards the vertical direction with small amplitude alterations.

Bound states in the continuum (BICs) are lossless states predicted in quantum mechanics in 1929, and for the last decade, received special attention in optics and photonics as a versatile tool to achieve giant quality factors (Q factors) [1] . For ordered arrays of subwavelength meta-atoms, metasurfaces, with broken in-plane symmetry, it was shown that Q factor of quasi-BICs can be unambiguously controlled by variation of the unit cell asymmetry parameter [2] .

Organic-inorganic halide perovskites recently have emerged as a promising material for highly effective light-emitting diodes (LEDs) and solar cells (SCs). Despite efficiencies of both perovskite SCs and LEDs are already among the best, the development of a perovskite dual functional device that is capable of working in these two regimes with high efficiencies is still challenging. Here we demonstrate that the dual functional device based on mixed halide perovskite CH3NH3PbBr2I can be switched from SC to LED with low threshold voltage Vth

The experimental study of the single-shot 1030-nm femtosecond laser ablation of bulk silicon and silver in air and liquid media (deionized water, isopropyl alcohol) is reported. The main laser ablation mechanisms were studied via analysis of the resulting microcrater surface morphology and elemental composition in single- and multi-shot (number of pulses N = 10, 100) regimes by scanning electron microscopy with a built-in module for energy-dispersive X-ray spectroscopy. It was concluded, that multi-shot ablation in liquids leads to the lesser extent of the processed surface oxidation, than in dry conditions. The monitoring of the ablative plumes dynamics was implemented with the use of time-resolved emission spectroscopy in the non-filamentation regime, corresponding to the formation of nanoparticles without fragmentation of the ablation products. It was demonstrated, that the lifetime of the plume emission in liquid is significantly shorter, than in air: 5 and 15 ns, correspondingly, for silicon, and 10 and 30 ns for silver.

Tunable light-emitting nanostructures are prospective for reconfigurable compact optoelectronic devices. In this regard, halide perovskites are one of the most efficient class of materials, because of their outstanding electronic and optical properties as well as low cost of fabrication and nanostructuring. Here, we study the temperature-tunable reconfiguration of photonic modes in periodically nanostructured perovskite (MAPbI3) film probed by enhanced photoluminescence. We achieved the quality factors of resonances around 500 at wavelengths 750–760 nm. The experimental results are in well agreement with theoretical simulations. Our study reveals the origin of the emission enhancement from such kind of perovskite nanostructures and paves the way to highly directional, efficient, and tunable narowband emission from optoelectronic devices.