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In this paper, recent results regarding rare earth element doped with chalcogenide glasses for optical gain media such as amplifiers and lasers are reviewed. Rare earth Chalcogenide glasses are formed when chalcogen elements (S, Se, Te etc.) are mixed with new additive elements (Ge, Ga, Sb, As etc.) and also with rare earth elements (Er, Dy, Pd, Pr etc.) from periodic table and prepared by melt quench technique (MQT). Rare earth element doped with chalcogenide glasses has been emerged as a suitable candidate for applications in the numeral passive and active. Among various materials, chalcogenide glasses show significant improvement in their emission properties in the optical communication range and spectroscopic properties. Finally, rare earth doped chalcogenide and optical fibers show potential for high power mid-infrared gain medium and their spectroscopic properties as well.

Titanium dioxide (TiO2) has been extensively studied for photocatalytic water splitting applications for more than 50 years because of its advantages, such as its low cost, abundance, good chemical stability, nontoxicity, and sufficient energy potential to oxidize and reduce water molecules. On the other hand, TiO2 has its own set of limitations, namely its wide bandgap (Eg = ∼3.2 eV), which makes it less effective in sunlight. A few methods have been reported to overcome these problems, one of which is to make a heterojunction composite with other materials. The added material can inject electrons directly into the conduction band of TiO2 and provide a tiered band structure, which can reduce the occurrence of photogenerated electron and hole recombination. Currently, the research and development of heterojunctions consisting of TiO2 with chalcogenide materials has attracted the attention of many researchers. Metal chalcogenides offer a number of advantages, including absorption onset tuning, a size-dependent bandgap that can lead to high theoretical quantum efficiencies, effective charge transfer to the conduction band when TiO2 is exposed to visible light, and high photochemical stability. In this review, the performance of various TiO2/metal chalcogenide heterojunctions for photoelectrochemical water splitting is presented. The role of most common metal chalcogenides in TiO2 will be exposed. Finally, the review concludes with a summary and recommendations for further research on this hot issue.

Strain engineering is a promising method for tuning the electronic properties of two-dimensional (2D) materials, which are capable of sustaining enormous strain thanks to their atomic thinness. However, applying a large and homogeneous strain on these 2D materials, including the typical semiconductor MoS2, remains cumbersome. Here we report on a facile strategy for the fabrication of highly strained MoS2 via chalcogenide substitution reaction (CSR) of MoTe2 with lattice inheritance. The MoS2 resulting from the sulfurized MoTe2 sustains ultra large in-plane strain (approaching its strength limit ~10%) with great homogeneity. Furthermore, the strain can be deterministically and continuously tuned to ~1.5% by simply varying the processing temperature. Thanks to the fine control of our CSR process, we demonstrate a heterostructure of strained MoS2/MoTe2 with abrupt interface. Finally, we verify that such a large strain potentially allows the modulation of MoS2 bandgap over an ultra-broad range (~1 eV). Our controllable CSR strategy paves the way for the fabrication of highly strained 2D materials for applications in devices.

Sb2Se3, a quasi-1D structured binary chalcogenide, has great potential as a solar cell light absorber owing to its anisotropic carrier transport and benign grain boundaries when the absorber layer is properly aligned along the [hk1] direction perpendicular to the substrate. A growth technique with a high deposition rate, such as vapor transport deposition, is preferred to form an [hk1]-oriented Sb2Se3 film. However, the possible decomposition of Sb2Se3 during cooling after the high-temperature deposition appears to result in Se deficiency accompanied by the formation of deep-level donor-like defects, such as Se vacancies and Sb on Se antisite defects. Here, we present comprehensive passivation strategies for the rear interface of Sb2Se3 solar cells in a superstrate configuration, namely post-deposition annealing treatment (PAT) under Se, and the introduction of an electron-blocking layer between Sb2Se3 and the rear metal contact. The PAT effectively passivated the defects associated with Se deficiency and greatly improved the open-circuit voltage and fill factor of Sb2Se3 solar cells. With the further introduction of a poly(N,N-bis(4-butylphenyl)-N,N-bis(phenyl)benzidine) electron-blocking layer, the Sb2Se3 solar cell achieved an efficiency of 7.0%.

Two-dimensional (2D) crystals have renewed opportunities in design and assembly of artificial lattices without the constraints of epitaxy. However, the lack of thickness control in exfoliated van der Waals (vdW) layers prevents realization of repeat units with high fidelity. Recent availability of uniform, wafer-scale samples permits engineering of both electronic and optical dispersions in stacks of disparate 2D layers with multiple repeating units. Here we present optical dispersion engineering in a superlattice structure comprising alternating layers of 2D excitonic chalcogenides and dielectric insulators. By carefully designing the unit cell parameters, we demonstrate greater than 90% narrow band absorption in less than 4 nm of active layer excitonic absorber medium at room temperature, concurrently with enhanced photoluminescence in square-centimetre samples. These superlattices show evidence of strong light–matter coupling and exciton–polariton formation with geometry-tuneable coupling constants. Our results demonstrate proof of concept structures with engineered optical properties and pave the way for a broad class of scalable, designer optical metamaterials from atomically thin layers. Square-centimetre scale, multilayer superlattice structures based on atomically thin two-dimensional chalcogenide monolayers enable the realization of excitonic metamaterials.

A molecular crystal structure model of the lead-free halide chalcogenide semiconductor Cs2LiInX6 (X = F, Cl, and Br) was established, and its energy band, density of states, optical properties, and...

Introducing transition metals into the intercluster linkers has been considered an important strategy for the rapid development of metal chalcogenide supertetrahedral (Tn) cluster-based open frameworks with excellent properties. However, using this strategy for achieving the structure and property tunability in the cluster-based framework of Tn (n ≥ 5) is still a great challenge. Herein, we report on three new sulfide and oxosulfide open frameworks of T5 clusters, i.e., T5-ZnMnInOS ([In30Zn5Mn4O2S58]12-), T5-MnInOS ([In34Mn5O2S58]8-), and T5-MnInS ([In28Mn6S54]12-). Interestingly, transition metals Zn and Mn are successfully introduced into T5-ZnMnInOS and T5-MnInOS via the consolidation of corner-shared Zn2OS2 and Mn2OS2 units, respectively. Under the photoexcitation of UV light, three compounds can emit bright-orange-red light closely associated with the Mn2+ ions, and the compounds containing M2OS2 units exhibit better photoluminescence (PL) lifetimes. Variable-temperature PL spectra demonstrate that the introduced M2OS2 units are favorable for weakening the deformation of the skeleton structure and decreasing the red shifts of the emission peaks at low temperatures. Moreover, the experimental results exhibit that the three compounds are wide-band-gap semiconductors and that the photogenerated electron separation efficiency can be doubly increased because the intercluster linkers are fixed by the M2OS2 units. This work paves a new way for enriching the content and distribution types of transition-metal sites in the supertetrahedral cluster-based metal chalcogenide open frameworks.

Quantum dots (QDs) are three-dimensional (3D) quantum confinement materials with confined size on the nanoscale. They are semiconductors, possessing a tunable energy gap in the range of visible light energy. In QDs, the 3D quantum confinements of excitons result in tunable fluorescence emission relying upon the QDs size and shape when excited by monochromatic light. Besides, the attempts to improve their outstanding optoelectronic properties, i.e. superior to those of bulk, thin-film semiconductor and organic dyes, many efforts have been conducted, in recent times, regarding sustainable QDs synthesis aiming at biocompatibility and cost reduction. Among the green synthesis routes of QDs there are two distinguished; namely inorganic QDs and carbon-based QDs. The first route is made of low-bandgap metal chalcogenide either extracted from a living being, e.g. earthworm, or capped with an organic ligand. While, the second route is made of carbon-core and passivating the surface with different functional groups, namely carboxyl, hydroxyl, in addition to amine. These functional groups are derived from coke or organic carbon reservoir, i.e. fruits and their juice, animal, vegetable, spice and waste paper. Numerous fundamental applications of QDs, such as biomedicine, sensing, catalysis, and solar cells, exploit the characteristic fluorescence emission of QDs, quantum yields and their modulation upon interaction with the external environment. In this review, two prototype QDs examples are used to highlight the route to sustainable QDs synthesis and solar cells implementation and some perspectives.

The continuous exploration of multinary chalcogenide semiconductors has provided a variety of new functional materials. In this paper, four new quaternary chalcogenides AHgPS4 (A+ = Na+, K+, Rb+, Cs+) have been prepared by solid-state syntheses. These findings complement the lack of research on this quaternary system. Influenced by the size effect of cations and the coordination mode of Hg, the four compounds crystallize in four different space groups [NaHgPS4, P4n2; KHgPS4, Pnn2; RbHgPS4, P21/n; CsHgPS4, P212121] and show an interesting evolution from a 3D framework structure to a 1D chain structure. Moreover, all of these compounds feature noncentrosymmetric (NCS) structures except for RbHgPS4. The materials exhibit wide band gaps of 2.7 eV < Eg < 3.0 eV. The NCS- related second-harmonic-generation (SHG) property of NaHgPS4 and KHgPS4 was also studied. They display strong powder SHG responses (3.14 × AgGaS2 for NaHgPS4; 4.15 × AgGaS2 for KHgPS4), which indicate their intriguing potential as IR nonlinear-optical materials. Moreover, first-principles theoretical calculations were performed to understand the structure-property relationships of these materials.

By controlling the amorphous-to-crystalline relative volume, chalcogenide phase-change memory materials can provide multi-level data storage (MLS), which offers great potential for high-density storage-class memory and neuro-inspired computing. However, this type of MLS system suffers from high power consumption and a severe time-dependent resistance increase (“drift”) in the amorphous phase, which limits the number of attainable storage levels. Here, we report a new type of MLS system in yttrium-doped antimony telluride, utilizing reversible multi-level phase transitions between three states, i.e., amorphous, metastable cubic and stable hexagonal crystalline phases, with ultralow power consumption (0.6–4.3 pJ) and ultralow resistance drift for the lower two states (power-law exponent

In this paper, a novel Sagnac Interferometer (SI) based chalcogenide Photonic Crystal Fiber (PCF) temperature sensor is theoretically and numerically analyzed operating in the mid infrared (MIR) region. The PCF cladding air holes are proposed to be filled with a highly temperature sensitive liquid chloroform to enhance the temperature sensitivity. The temperature sensing characteristics of three different infiltration technique is investigated theoretically and compared by Finite Element Method (FEM). Simulation results show that full infiltration performs better than partial infiltration. In the numerical analysis two sensing dips with high linearity is achieved for full infiltration which shows sensitivity of −5.77 nm/°C and 8.49 nm/°C when the temperature increases from 25 to 85 °C for the specific fiber length of 1.532 mm. The R2 values are 0.957446809 and 0.97680771 for the respective two sensing dips. The proposed highly sensitive sensor has broad detection window which can be applied in fingerprint unlocking, MIR radiation detection in human body, biomedicine applications, and environmental temperature monitoring.

Functional neuronal computing systems that support information diversification require high-density memory with selector devices to reduce leakage current in cross-point architectures, which drives us to develop a functional switching layer that operates as three distinct devices, namely non-volatile memory, selector, and synaptic devices, using a GeTe-based single material system. In this study, amorphous Ag-GeTe switching layers are engineered by doping with Te species to achieve either resistive switching (RS) or threshold switching properties. The Ag/Ag-GeTe/Ag memory device exhibits multilevel characteristics via a tunable compliance current approach. By comparison, Ag/Ag-GeTex/Ag selector device provides excellent selectivity (>106) with a very low OFF-current (∼10−11 A). The RS mechanism for memory and selector devices is interrogated by using conductive atomic force microscopy. Moreover, the Ag/Ag-GeTe/Ag RS device mimics a cohort of basic and complex synaptic plasticity properties, including potentiation-depression and four-spike time-dependent plasticity rules that include asymmetric Hebbian, asymmetric anti-Hebbian, symmetric Hebbian, and symmetric anti-Hebbian learning rules. The capability of the synaptic devices to detect image edges is demonstrated by using a convolution neural network. The present work showcases the multi-functionality of Ag-GeTe materials, which will likely emerge as a prominent candidate for high-density cross-point architecture-based neuromorphic computing systems.

Structures absorbing electromagnetic waves in the infrared spectral region are important optical components in key areas such as biosensors, infrared images, thermal emitters, and special attention is required for reconfigurable devices. We propose a three-dimensional metal-dielectric plasmonic absorber with a layer of PCM’s (Phase Change Materials). The phase shift effects of PCMs are numerically analyzed, and it is possible to obtain a shifting control of the resonant absorption peaks between the amorphous and crystalline states using the Lorentz–Lorenz relation. By using this empirical relation, we analyzed the peak absorption shift at intermediate phases between the amorphous and the crystalline. The geometric parameters of the structure with the PCM layer in the semi-crystalline state were adjusted to exhibit strong absorption for normal incidence. The effects of the oblique incidence on the absorption for the TM and TE polarization modes were also analyzed. Our results demonstrate that PCMs have great potential for reconfigurable nanophotonic devices.

The downscaling of nonlinear optical devices is significantly hindered by the inherently weak nonlinearity in regular materials. Here, we report a giant third-harmonic generation discovered in epitaxial thin films of V-VI chalcogenide topological insulators. Using a tailored substrate and capping layer, a single reflection from a 13 nm film can produce a nonlinear conversion efficiency of nearly 0.01%, a performance that rivals micron-scale waveguides made from conventional materials or metasurfaces with far more complex structures. Such strong nonlinear optical emission, absent from the topologically trivial member in the same compound family, is found to be generated by the same bulk band characteristics that are responsible for producing the band inversion and the nontrivial topological ordering. This finding reveals the possibility of obtaining superior optical nonlinearity by examining the large pool of newly discovered topological materials with similar band characteristics.

Perovskite-perovskite tandem solar cells have bright prospects to improve the power conversion efficiency (PCE) beyond the Shockley-Queisser (SQ) limit of single-junction solar cells. The star lead-based halide perovskites are well-recognized as suitable candidates for the front cell, thanks to their suitable band gap (∼1.8 eV), strong optical absorption, and high certified PCE. However, the toxicity of lead for the front cell and the lack of a narrow band gap (∼1.1 eV) for the rear cell seriously restrict the development of the two-junction tandem cell. To break through this bottleneck, a novel Dion-Jacobson (DJ)-type (n = 2) chalcogenide perovskite CsLaM2X7 (M = Ta, Nb; X = S, Se) has been found based on the powerful first-principles and advanced many-body perturbation GW calculations. Their excellent electronic, transport, and optical properties can be summarized as follows. (1) They are stable and environmentally friendly lead-free materials. (2) The direct band gap of CsLaTa2Se7 (0.96-1.10 eV) is much smaller than those of lead-based halide perovskites and very suitable for the rear cell in the two-junction tandem cell. (3) The carrier mobility in CsLaTa2Se7 reaches 1.6 × 103 cm2 V-1 s-1 at room temperature. (4) The absorption coefficients (3-5 × 105 cm-1) are 1 order higher than that of Si (104 cm-1). (5) The estimated PCEs of the Cs2Sb2Br8-CsLaTa2Se7 tandem cell (33.3%) and the concentrator solar cell (35.8% in 100 suns) are higher than those of the best recorded GaAs-Si tandem cell (32.8%) and the perovskite-perovskite tandem solar cell (24.8%). These energetic results strongly demonstrate that the novel lead-free chalcogenide perovskites CsLaM2X7 are good candidates for the rear cell of tandem cells.

The paper presents a study of the formation of holographic diffraction gratings in thin films of chalcogenide glassy semiconductors. The recording process of holographic gratings at the argon-laser radiation wave length 488 nm and the process of chemical etching that enables the formation of а relief holographic grating are analysed. The optimum conditions for the formation of diffraction gratings in films of arsenic sulfide As2S3 are defined. It is shown that at the 488 nm wave length of an argon laser the optimum exposure comes to ∼5–8 J/cm2. At the recording stage a quasi-phase (relief-phase) grating is formed, with the diffraction efficiency on the order of a few per cent. Etching of the exposed sample with a solution of NaOH alkali in deionised water and isopropanol makes it possible to increase considerably the relief depth and to improve the diffraction efficiency of a thin diffraction grating approximately up to 20 % for the red spectral region, and to approach the maximal value ∼34 % for the near infra-red region. The results of the study considered look promising for the creation of relief holographic gratings which are essential in present-day optical instrument building (production of spectral devices, holographic sights, and the like).

Chalcogenide photonics offers unique solutions for a broad range of applications from mid-infrared sensing to integrated, ultrafast, ultrahigh-bandwidth signal processing. However, to date its usage has been limited to the infrared part of the electromagnetic spectrum, thus avoiding ultraviolet and visible ranges due to absorption of chalcogenide glasses. Here, we experimentally demonstrate and report near-infrared to ultraviolet frequency conversion in an As2S3-based metasurface, enabled by a phase locking mechanism between the pump and the inhomogeneous portion of the third harmonic signal. Due to the phase locking, the inhomogeneous component co-propagates with the pump pulse and encounters the same effective dispersion as the infrared pump, and thus experiences little or no absorption, consequently opening previously unexploited spectral range for chalcogenide glass science and applications, despite the presence of strong material absorption in this range., The use of chalcogenide glass in optical science and applications at the UV frequencies has been so far hindered by its absorption in this spectral region. Here the authors demonstrate that a nanostructured chalcogenide glass can efficiently generate third harmonic radiation, leading to a strong UV light source at the nanoscale.

Investigating the promising chalcogenide materials for the development of memory and advanced neuromorphic computing applications is a critical step in realizing electronic memory and synaptic devices that can efficiently emulate biological synaptic functions. However, the assessment of monochalcogenide materials for the fabrication of highly scalable memory and electronic synaptic devices that can accurately mimic synaptic functions remain limited. In the present study, we investigated the thickness-dependent resistive switching (RS) behavior of conductive bridge random access memory (CBRAM) based on a monochalcogenide GeSe switching medium for its possible application in high-performance memory and electronic synapses. GeSe thin films of different thicknesses (6, 13, 24, 35, 47, and 56 nm) were deposited via sputtering to fabricate CBRAM devices with a stacking sequence of Ag/GeSe/Pt/Ti/SiO2. The devices exhibited compliance current (CC)-free and electroforming-free RS with highly stable endurance and retention characteristics with no major degradation. All devices with a thickness of 6 nm had a low-resistance state (LRS), which required an initial reset to ensure reliable switching cycles. The devices with a thickness of 47 nm and above exhibited the co-existence of unipolar resistive switching (U-RS) and bipolar resistive switching (B-RS) with the CC-controlled transition between the two switching behaviors. Multilevel resistance states in the 24-nm device between a highresistance state (HRS) and an LRS were achieved by controlling the set-CC (from 5 mA to CC-free) and the reset stop voltage (from −0.5 to −1.0 V) during the set and reset processes, respectively. The analog RS behavior of the device was further investigated with appropriate pulse measurements to emulate vital synaptic functions, including long-term potentiation (LTP), long-term depression (LTD), spike-rate-dependent plasticity (SRDP), spike-timing-dependent plasticity (STDP), paired-pulse facilitation (PPF), paired-pulse depression (PPD) and post-tetanic potentiation (PTP). Overall, the detailed investigation of thickness-dependent GeSe monochalcogenide material indicates that it is a highly suitable candidate for use in highly scalable memory devices and electronic synapses for neuromorphic computing applications.

In recent years, the penternary nanocrystals synthesized as an alternative to Pt in dye-sensitized solar cells have attracted the attention of researchers due to their many important properties such as low-cost elemental component, high absorption coefficient, optimal optical band gap, high efficiency and environmental stability. Because of these attractive features, a new penternary chalcogenide semiconductor, namely Cu2CoSn(SSe)4 (CCTSSe), have been synthesized by hot-injection technique and its structural, dielectrical and optical dispersion characteristics have been reported. CCTSSe nanostructure films were produced by spin-coating method onto glass substrates. The optical, morphological, compositional and structural properties of this penternary chalcogenide semiconductor was characterized by ultraviolet–visible-near (UV–VIS-NIR) spectroscopy, energy-dispersive spectrometer (EDS), Raman spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The CCTSSe penternary nanostructure has a band gap energy of 1.186 eV, single crystalline, adequate stoichiometric ratio, kesterite phase and 10–20 nm particle sizes which are forming nanospheres. The optical dispersion and dielectric characteristics were investigated based on the reflectance and transmittance spectra measured by spectrophotometer between 200 and 2000 nm. The value of extinction coefficient and refractive index were estimated, and a relation between the optical band gap values and the refractive index values was debated. The values of oscillator energy and dispersion energy were determined by the single oscillator of the Wemple–DiDomenico method. The loss tangent and the dielectric constants were evaluated. The obtained results report the capability of the high-efficiency and low-cost CCTSSe thin films in photonic and photovoltaic applications, especially in dye-sensitized solar cells.

Chalcogenide perovskites have emerged as a new class of electronic materials, but fundamental properties and applications of chalcogenide perovskites remain limited by the lack of high quality epitaxial thin films. We report epitaxial thin film growth of BaZrS3, a prototypical chalcogenide, by pulsed laser deposition. X-ray diffraction studies show that the films are strongly textured out of plane and have a clear in-plane epitaxial relationship with the substrate. Electron microscopy studies confirm the presence of epitaxy for the first few layers of the film at the interface, even though away from the interface the films are polycrystalline with a large number of extended defects suggesting the potential for further improvement in growth. X-Ray reflectivity and atomic force microscopy show smooth film surfaces and interfaces between the substrate and the film. The films show strong light absorption near the band edge and photoluminescence in the visible region. The photodetector devices show fast and efficient photo response with the highest ON/OFF ratio reported for BaZrS3 films thus far. Our study opens up opportunities to realize epitaxial thin films, heterostructures, and superlattices of chalcogenide perovskites to probe fundamental physical phenomena and the resultant electronic and photonic device technologies.

This paper is focused on optical nonlinearity in CdS nanostructured thin films, which was reviewed comprehensively and discussed in detail along with future perspective. Due to third harmonic generation in CdS materials on exposed to highly intense light that is significant feature to develop modern photonics devices. CdS chalcogenide semiconductor binary compound is one of the most particularly promising candidate for nonlinear optical applications due to their enhanced nonlinear optical properties in thin films. CdS nanostructured thin films have been shown exceptional third order nonlinear optical (TONLO) behavior near the sub band gap energy region. This review will be based on TONLO properties of CdS nanostructured thin films, which will focus on the tailoring of TONLO properties as a function of particle size, dopant and CdS polymer nanocomposite. Doping and size effect in CdS system is the important opportunity to develop it with excellent TONLO properties. This review paper will give an open area of research possibilities to search the efficient nonlinear optical CdS nanostructured thin films for advanced modern photonics applications and also will provide an idea to develop efficient materials with exceptional TONLO properties.

Ag2Te is one of the most promising semiconductors with a narrow band gap and low toxicity; however, it remains a challenge to tune the emission of Ag2Te quantum dots (QDs) precisely and continuously in a wide range. Herein, Ag2Te QDs emitting from 950 to 2100 nm have been synthesized via trialkylphosphine-controlled growth. Trialkylphosphine has been found to induce the dissolution of small-sized Ag2Te QDs due to its stronger ability to coordinate to the Ag ion than that of 1-octanethiol, predicated by the density functional theory. By controlling this dissolution effect, the monomer supply kinetics can be regulated, achieving precise size control of Ag2Te QDs. This synthetic strategy results in state-of-the-art silver-based QDs with emission tunability. Only by taking advantage of such an ultrawide emission has the sizing curve of Ag2Te been obtained. Moreover, the absolute photoluminescence quantum yield of Ag2Te QDs can reach 12.0% due to their well-passivated Ag-enriched surface with a density of 5.0 ligands/nm2, facilitating noninvasive in vivo fluorescence imaging. The high brightness in the long-wavelength near-infrared (NIR) region makes the cerebral vasculature and the tiny vessel with a width of only 60 μm clearly discriminable. This work reveals a nonclassical growth mechanism of Ag2Te QDs, providing new insight into precisely controlling the size and corresponding photoluminescence properties of semiconductor nanocrystals. The ultrasmall, low-toxicity, emission-tunable, and bright NIR-II Ag2Te QDs synthesized in this work offer a tremendous promise for multicolor and deep-tissue in vivo fluorescence imaging.

The development of new infrared (IR) nonlinear optical (NLO) materials with strong second-harmonic generation (SHG) responses and high laser-induced damage thresholds (LIDTs) is urgent but challenging. Herein, the defective diamond-like chalcogenide Hg3P2S8 (HPS) was rationally designed and fabricated by a flexible and rigid tetrahedral motif combined strategy. HPS exhibits a phase-matching SHG response of similar to 3.6 x AGS (the largest one in the reported ternary sulfides), high LIDT (similar to 3 x AGS), wide IR transparent region (0.43-16.3 mu m), moderate birefringence (0.043 at 1064 nm), and good physicochemical stability and crystal growth habits. Theoretical analyses confirm that the large SHG effect originates from the synergistic effects between distorted HgS4, PS4, and vacancy-induced nonbonding electrons. The results indicate that HPS is a promising NLO candidate for high-power, high-efficiency laser output in the mid-IR region, which provides an insight into the exploration of new IR NLO materials.

In this work, we report experimental characterizations of stimulated Brillouin scattering (SBS) in low-loss Ge25Sb10S65 (GeSbS) chalcogenide waveguides. A 7-cm-long spiral waveguide with a propagation loss as low as 0.2 dB/cm and a microring resonator with a high loaded quality factor of 1.34×106 are demonstrated. In addition, we use a high-resolution pump-probe measurement technique to investigate the SBS characteristics in the GeSbS waveguide. The measured Brillouin frequency shift and the intrinsic Brillouin linewidth are 7.443 GHz and 47.8 MHz, respectively. A Brillouin-gain coefficient of 338 m−1W−1 is obtained, which corresponds to an intrinsic Brillouin gain of 0.524×10-9 m/W, comparable to that of As2S3 chalcogenide. Moreover, a 17.6-dB probe gain is achieved with a continuous-wave pump of 200 mW, while nonlinear losses are not observed. The large Brillouin gain, together with the low linear propagation loss and the negligible nonlinear loss, make the GeSbS chalcogenide waveguides become a very promising arsenic-free integrated platform for on-chip Brillouin applications.

Nanoinks composed of quantum dots (QDs) are applied in light-receiving devices and light-emitting devices such as solar cells and displays. However, since the most widely used QDs, PbS and CdS, are toxic and environmentally concerning, alternative materials need to be developed. We synthesized and analyzed Ag chalcogenide nanoparticles, including AgBiS2 and Ag2S nanoparticles, which are eco-friendly materials. AgBiS2 and Ag2S QD films were prepared by spin-coating nanoparticle solutions and subsequent heat treatment. The effects of the heat treatment on residual ligands and photoluminescence were determined by surface analysis. The photocurrent response of the AgBiS2 and Ag2S QD films was measured in the near-infrared region, and the effect of the heat treatment temperature was investigated. The results indicate that AgBiS2 and Ag2S are prospective materials for near-infrared photodetectors.

Quaternary chalcogenide materials have long been a source of semiconductors for optoelectronic applications. Recent studies on I2-II-IV-X4 (I = Ag, Cu, Li; II = Ba, Sr, Eu, Pb; IV = Si, Ge, Sn; X = S, Se) materials have shown particular versatility and promise among these compounds. These semiconductors take advantage of a diverse bonding scheme and chemical differences among cations to target a degree of antisite defect resistance. Within this set of compounds, the materials containing both Ag and Sr have not been experimentally studied and leave a gap in the full understanding of the family. Here, we have synthesized powders and single crystals of two Ag- and Sr-containing compounds, Ag2SrSiS4 and Ag2SrGeS4, each found to form in the tetragonal I42m structure of Ag2BaGeS4. During the synthesis targeting the title compounds, two additional materials, Ag2Sr3Si2S8 and Ag2Sr3Ge2S8, have also been identified. These cubic compounds represent impurity phases during the synthesis of Ag2SrSiS4 and Ag2SrGeS4. We show through hybrid density functional theory calculations that Ag2SrSiS4 and Ag2SrGeS4 have highly dispersive band-edge states and indirect band gaps, experimentally measured as 2.08(1) and 1.73(2) eV, respectively. Second-harmonic generation measurements on Ag2SrSiS4 and Ag2SrGeS4 powders show frequency-doubling capabilities in the near-infrared range.

Nanoscale miniaturization of chalcogenide semiconductors such as lead sulfide (galena) can generate interesting quantum confinement effects in the field of optoelectronic applications. In this work, we developed a process in order to obtain SiO2 nanospheres coated with Galena, as the denominated core–shell system; this process is based on Stober’s method, where the magnetic stirring was replaced by an ultrasonic bath to achieve well rounded and highly stable silica nanoparticles with diameters average of 70 nm. The PbS shell cover presents a thickness of 10 nm around. The nanostructures’ chemical composition, morphology, and optical properties were determined by transmission electron microscopy and UV–Vis spectroscopy. As a result, the nanoshells correspond to cubic PbS, presenting some interplanar distances of 2.95 A and 3.41 A; this nanoshell also shown an optical spectrum shift toward blue and a remarkable increase of 3.75 eV in its band gap, compared with the PbS bulk value. The chemical composition is studied by energy scattering spectroscopy and X-ray photoelectron spectroscopy analysis.

As power-conversion devices, flexible thermoelectrics that enable conformal contact with heat sources of arbitrary shape are attractive. However, the low performance of flexible thermoelectric materials, which does not exceed those of brittle inorganic counterparts, hampers their practical applications. Herein, we propose inorganic chalcogenide-nanostructured carbon nanotube (CNT) yarns with outstanding power factor at a low temperature using electrochemical deposition. The inorganic chalcogenide-nanostructured CNT yarns exhibit the power factors of 3425 and 2730 μW/(m·K2) at 298 K for the p- and n-type, respectively, which is higher than those of previously reported flexible TE materials. On the basis of excellent performance and geometry advantage of the nanostructured CNT yarn for modular design, all-CNT based thermoelectric generators have been easily fabricated, showing the maximum power densities of 24 and 380 mW/m2 at ΔT = 5 and 20 K, respectively. These results provide a promising strategy for the realization of high-performance flexible thermoelectric materials and devices for flexible/or wearable self-powering systems.

Spatially controlled preparation of heterostructures composed of layered materials is important in achieving interesting properties. Although vapor-phased deposition methods can prepare vertical and lateral heterostructures, liquid-phased methods, which can enable scalable production and further solution processes, have shown limited controllability. Herein, we demonstrate by using wet chemical methods that metallic Sn0.5Mo0.5S2 nanosheets can be deposited epitaxially on the edges of semiconducting SnS2 nanoplates to form SnS2/Sn0.5Mo0.5S2 lateral heterostructures or coated on both the edges and basal surfaces of SnS2 to give SnS2@Sn0.5Mo0.5S2 core@shell heterostructures. They also showed good light-to-heat conversion ability due to the metallic property of Sn0.5Mo0.5S2. In particular, the core@shell heterostructure showed a higher photothermal conversion efficiency than the lateral counterpart, largely due to its randomly oriented and polycrystalline Sn0.5Mo0.5S2 layers with larger interfacing area for multiple internal light scattering.

The extension of plasmonics to materials beyond the conventional noble metals opens up a novel and exciting regime after the inspiring discovery of characteristic localized surface plasmon resonances (LSPRs) in doped semiconductor nanocrystals originating from the collective oscillations of free holes in the valence band. We herein prepare colloidal monodisperse eccentric dual plasmonic noble metal-nonstoichiometric copper chalcogenide (Au@Cu2−xSe) hybrid hetero-nanostructures with precisely controlled semiconductor shell size and two tunable LSPRs in both visible (VIS) and near-infrared (NIR) regions associated with Au and Cu2−xSe, respectively. Through systematic evaluations of the photocatalytic performance of Au@Cu2−xSe upon sole NIR and dual VIS + NIR simultaneous excitations, we are capable of unambiguously elucidating the role of plasmonic coupling between two dissimilar building blocks on the accelerated photocatalytic reactions with greater rate constants from both experimental and computational perspectives. The significantly enhanced strength of the electromagnetic field arising from efficient plasmonic coupling under the excitation of two LSPRs results in the superior activities of dual plasmonic Au@Cu2−xSe in photocatalysis. The new physical and chemical insights gained from this work provide the keystone for the rational design and construction of high-quality dual- or even multi-plasmonic nano-systems with optimized properties for widespread applications ranging from photocatalysis to molecular spectroscopies.

Made available in DSpace on 2022-04-28T17:20:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-07-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) CeRTEV Tellurite glasses are considered a potential alternative for applications not achieved by SiO2-based glasses, presenting interesting optical properties, such as high linear and nonlinear refractive indexes, extended optical window, being also suitable for metallic nanoparticle growth, like Te-0. When doped with sulfide species, it can benefit the reduction of Te4+ to Te-0, which can be advantageous to synthesize in-situ chalcogenide nanoparticles and quantum dots. This work presents investigations on the reduction of Te4+ to Te-0 in tellurite glasses doped with PbS and PbO/ZnS, and aims to control this redox process through the processing with pulsed fs-laser. Tellurite glass samples were synthesized by melt-quenching technique and the thermal and structural properties were explored by different techniques, such as DSC, Raman scattering spectroscopy and mapping experiment, TEM and SAED. Reduction of tellurium to Te-0 nanocrystals into tellurite glass after laser irradiation was studied in detail and confirmed by the presence of bands at similar to 120 and 140 cm(-1) in Raman spectroscopy and mapping, assigned to the Te-Te vibrational modes, which suggest that S2- induces in-situ Te4+ reduction. Moreover, quasi spherical tellurium nanoparticles were observed through TEM and confirmed their chemical nature and crystallization by SAED. The study of tellurium reduction in the vitreous matrix becomes particularly important and promising for some applications, since its reduction generates changes in the refractive index by precipitation of Te-0 nanoparticles, allowing the fabrication of waveguides and as photosensitive material for tridimensional data storage. (C) 2021 Published by Elsevier B.V. Univ Sao Paulo, Sao Carlos Inst Chem IQSC, Sao Carlos, SP, Brazil Univ Sao Paulo, Sao Carlos Inst Phys IFSC, Sao Carlos, SP, Brazil Univ Sao Paulo, Sao Carlos Sch Engn EESC, Sao Carlos, SP, Brazil Sao Paulo State Univ, Inst Chem, Araraquara, SP, Brazil Univ Fed Alfenas, Grp Quim Mat, Pocos De Caldas, MG, Brazil Sao Paulo State Univ, Inst Chem, Araraquara, SP, Brazil FAPESP: 2018/164076 FAPESP: 2018/11283-7 FAPESP: 2018/16126-7 CeRTEV: 2013/077936

Background: Refractive index determination of biological tissues is a challenging issue. Many biological species also show vibrational signature in the infrared domain. The chalcogenidebased glasses can be used to make the fibree optic evanescent wave sensors for the detection of the analyte. Objectives: The primary objective is to study the effect of various parameters on the sensitivity of chalcogenide glass-based evanescent-wave sensor for biological tissue detection. Methods: An evanescent wave sensor has been proposed with collimated source illumination and uniform tapering. The chalcogenide materials are chosen such that the weakly guiding approximation could be followed. Complex refractive indices of liver tissue samples have been taken for the analysis of sensitivity via the method of the evanescent absorption coefficient. Equations for sensitivity have been solved analytically using MATLAB software. Results: The simplification of the formula for sensitivity leads to the inference that the sensitivity is a function of core radius, refractive indices of sample tissues and wavelength used. Moreover, since the refractive indices of the materials are also a function of temperature, therefore a change in temperature results in a change in the profile of guiding mode. Hence, the effect of temperature must also be observed. The initial simulation parameters are taken; core radius 100 μm, sensing length 4 cm and wavelength 1.0 μm. In the NIR region, we have a better sensitivity of detection for all the tissue samples and the risk of photodamage of the bio-samples is reduced to a good extent. It has been found that sensitivity decreases with wavelength and core radius, whereas increases with temperature. It has also been shown that sensitivity is found to be better with collimated in comparison with the diffused source. Conclusion: The comparative study results that one should operate at a shorter NIR region of wavelength for higher sensitivity. The collimated source illumination should be preferred over diffused one for launching the light within the fibree to have high sensitivity. Further, the length of the sensing region should be larger, but the fibree core radius should be smaller. The proposed biosensor is robust and can also be used many times if the probe (sensing region) is cleaned properly. Moreover, a small amount of analyte is enough for detection. Thus, the proposed sensor is very useful for biomedical applications with its high performance, accuracy and robustness.

Solar energy is an ideal energy source for solving energy shortages and serious environmental problems. In the past few decades, photocatalytic technology which uses solar energy to deal with the above problems has caused great interest. ZnIn2S4, as a layered ternary metal chalcogenide compound, has a series of advantages such as the wide light absorption range and adjustable bandgap. It has been applied in the different fields of photocatalysis in recent years. This review introduced the crystal structures and growth mechanism of ZnIn2S4 and summarized the preparation methods of ZnIn2S4. Also, the promoted strategies of ZnIn2S4 based photocatalytic system and their applications in the pollutant removal, hydrogen evolution, reduction of CO2, nitrogen fixation, and chemical synthesis was summarized. Furthermore, the challenges and development directions of the current ZnIn2S4 based photocatalytic system were proposed. It is hoped that this review will help researchers design a better ZnIn2S4 based photocatalytic system.

Transition metal chalcogenide quantum dots (TMCs QDs) constitute a crucial sector of semiconductors on account of large absorption coefficient for light harvesting, peculiar quantum confinement effect, and abundant active sites stemming from ultra-small size. However, elaborate and tunable modulation of anisotropic photoinduced charge carriers over TMCs QDs represents an enduring challenge in terms of sluggish charge transfer kinetic and ultra-short charge lifetime compared with nanoparticulate counterparts, thereby rendering maneuvering charge transfer of TMCs QDs a tough issue. We herein conceptually unlock the unanticipated charge transport capability of solid-state non-conductive poly(diallyl dimethylammonium chloride) (PDDA) for constructing cascade charge transfer pathway over self-assembled wide bandgap semiconductors (WBS)/PDDA/TMCs QDs multilayered heterostructures, by which unidirectional and accelerated electron transfer from TMCs QDs to WBS support mediums was spontaneously activated, markedly boosting the charge separation/migration efficiency. The integrated roles of such ultrathin insulating PDDA intermediate layer as simultaneous surface charge modifying agent and interfacial charge transfer mediator have been evidenced to be universal. The unexpected electron-withdrawing capability of ultrathin PDDA layer endows WBS (SnO 2, TiO2)@PDDA@TMCs (CdSe, CdS) QDs heterostructures with significantly enhanced net efficiency of photoactivities toward selective anaerobic reduction of nitroaromatics to amino derivatives under visible light irradiation. Our work would feature a promising scope for rational design of multifarious novel insulating polymers-based photosystems for solar energy conversion.

A surface-enhanced infrared absorption spectroscopic chalcogenide waveguide sensor based on the silver island film was proposed for the first time to enhance the sensing performance in both liquid and gas phases. The chalcogenide waveguide sensor was fabricated by the lift-off and oblique angle deposition methods. The surface morphology of the silver island film with different thicknesses was characterized. The absorption of ethanol (liquid) at a wavelength of 1654 nm and that of methane (gas) at 3291 nm were measured using the fabricated chalcogenide waveguide sensor. The chalcogenide waveguide sensor integrated with the 1.8 nm-thick silver island film revealed the best sensing performance. With an acceptable increased waveguide loss resulting from the fabrication of the film, the absorbance enhancement factors for ethanol and methane were experimentally obtained to be >1.5 and >2.3, respectively. The 1σ limit of detection of methane for the sensor integrated with the 1.8 nm-thick silver island film was ∼4.11% for an averaging time of 0.2 s. The mathematic relation between the absorbance enhancement factor and the waveguide loss was derived for sensing performance improvement. Also, the proposed rectangular waveguide sensor provides an idea for the design of a sensor-on-a-chip instead of other waveguide sensors with a high requirement of fabrication accuracy, for example, a slot waveguide or a photonic crystal waveguide.

Chalcogenide perovskites (CPs) exhibiting lower band gaps than oxide perovskites and higher stability than halide perovskites are promising materials for photovoltaic and optoelectronic applications. For such applications, the absence of deep defect levels serving as recombination centers (dubbed defect tolerance) is a highly desirable property. Here, using density functional theory (DFT) calculations, we study the intrinsic defects in BaZrS3, a representative CP material. We compare Hubbard-U and hybrid functional methods, both of which have been widely used in addressing the band gap problem of semi-local functionals in DFT. We find that tuning the U value to obtain experimental bulk band gap and then using the obtained U value for defect calculations may result in over-localization of defect states. In the hybrid functional calculation, the band gap of BaZrS3 can be accurately obtained. We observe the formation of small S-atom clusters in both methods, which tend to self-passivate the defects from forming mid-gap levels. Even though in the hybrid functional calculations several relatively deep defects are observed, all of them exhibit too high formation energy to play a significant role if the materials are prepared under thermal equilibrium. BaZrS3 is thus expected to exhibit sufficient defect tolerance promising for photovoltaic and optoelectronic applications.

We present the design, preparation, and performance optimization of strip waveguide in chalcogenide glass (ChG) for broadband supercontinuum (SC) generation. Ternary Ge-Sb-S systems possess large band-gap, high refractive index, and strong laser damage resistance. The characterization of strip waveguide in Ge-Sb-S glass for SC source generation with 1300 nm bandwidth is experimentally demonstrated. Sensing capability of the device is validated for optical absorption of β-phenylethylamine solutions near 1551 nm in various concentrations, revealing the repeatability and consistency of the generated SC spectrum in test. The advantages of high specificity detection scheme, scalable integration and ease of miniaturization might make the device a promising platform for biochemical monitoring.

Germanium telluride (GeTe) is a phase-change material (PCM) from chalcogenide family, which undergoes reversible transition between amorphous and crystalline phase when subjected to optical or electrical pulse. The fast structural reversibility poses GeTe as an ideal material for data storage devices. GeTe is one of the best candidates for non-volatile memory technologies because of its high speed, low power consumption, scalability, data retention, and storage capacity. In this review, we discuss the developments in GeTe PCM, and their working and effect of interface and doping to upgrade their performance for various technological applications.

We report high quality (Q) photonic crystal (PhC) nanobeam cavities in the chalcogenide glass Ge28Sb12Se60 near 1550 nm wavelength. By optimizing the structure of the PhC cavity, an ultra-high Q factor as large as $5\times 10^{6}$ is predicted by simulation, and up to $1.2\times 10^{4}$ is measured in the experiment. Such high-Q cavities in this strongly nonlinear material create an attractive platform for compact, ultrafast all-optical switches.

Ge2Sb2Te5 is the most widely utilized chalcogenide phase-change material for non-volatile photonic applications, which undergoes amorphous-cubic and cubic-hexagonal phase transition under external excitations. However, the cubic-hexagonal optical contrast is negligible, only the amorphous-cubic phase transition of Ge2Sb2Te5 is available. This limits the optical switching states of traditional active displays and absorbers to two. We find that increasing structural disorder difference of cubic-hexagonal can increase optical contrast close to the level of amorphous-cubic. Therefore, an amorphous-cubic-hexagonal phase transition with high optical contrast is realized. Using this phase transition, we have developed display and absorber with three distinct switching states, improving the switching performance by 50 %. Through the combination of first-principle calculations and experiments, we reveal that the key to increasing structural disorder difference of amorphous, cubic and hexagonal phases is to introduce small interstitial impurities (like N) in Ge2Sb2Te5, rather than large substitutional impurities (like Ag) previously thought. This is explained by the formation energy and lattice distortion. Based on the impurity atomic radius, interstitial site radius and formation energy, C and B are also potential suitable impurities. In addition, introducing interstitial impurities into phase-change materials with van der Waals gaps in stable phase such as GeSb4Te7, GeSb2Te4, Ge3Sb2Te6, Sb2Te3 will produce high optical contrast amorphous-metastable-stable phase transition. This research not only reveals the important role of interstitial impurities in increasing the optical contrast between metastable-stable phases, but also proposes varieties of candidate matrices and impurities. This provides new phase-change materials and design methods for non-volatile optical devices with multi-switching states.

Nanocrystal heterostructures are one of the frontline energy materials widely known for enhancing the rate of photocatalysis and tuning optical properties and are also used in photovoltaics. These nanostructures where two crystalline nanomaterials are placed together in a single building block and share lattices are extensively studied for chalcogenide semiconductors and metal oxides but limited for recently emerged perovskite nanocrystals. Due to differences in the crystal bonding nature, interface chemistry, and also the formation mechanism, some constraints are present in designing common reaction pathways for the simultaneous formation of perovskites and chalcogenides or similar nanocrystals sharing common lattice planes. Hence, more fundamental understanding of both nucleation and growth of both materials is required for inducing heteronucleations of one on the surface of another. Literature reports also revealed that epitaxial growth of lead halide perovskites with nonhalide or chalcogenide colloidal 0D nanocrystals could not be established yet. Hence, the field remains challenging, and more investigations on both experimental as well as theoretical studies are timely required. Keeping these in mind, in this perspective the state-of-the-art issues related to the formation of all inorganic halides and nonhalide heterostructures formed with epitaxial relations are discussed. At the beginning, the chemistry of these nanocrystals with similarities and dissimilarities in their nature and examples of different heterostructures are summarized, and then, different synthetic possibilities for overtaking the hurdles and designing such heterostructures are proposed.

Chalcogenide-based quantum dots are useful for the application of memory-switching devices because of the control in the trap states in the materials. The control in the trap states can be achieved using a hot-injection colloidal synthesis method that produces temperature-dependent size-variable quantum dots. In addition to this, formation of a nanoscale heterostructure with an insulating material adds to the charge-trapped switching mechanism. Here, we have shown that the colloidal monodispersed CdSe quantum dots and poly(4-vinylpyridine) (PVP) formed a nanoscale heterostructure between themselves when taken in a suitable ratio to fabricate a device. This heterostructure helps realize memory-switching in the device with a maximum on-off current ratio of 105. The switching in the device is mainly due to the trap states in the CdSe quantum dots. The conduction in the off state is due to thermal charge injection and space charge injection conduction and in the on state, due to the Ohmic conduction mechanism.

The heterostructure consisting of lead chalcogenide and halide perovskite materials are recently identified as excellent candidates for optoelectronic devices such as solar cells. Several theoretical works are carried out to understand the nanoscopic structures and properties of halide perovskite/lead chalcogenide heterostructures. However, the detailed features of the heterosystems, including the effects of the solute concentration, types of lead chalcogenide, and polaronic states are not investigated. In this manuscript, we employ first-principles calculations to provide an alternative view of the halide perovskite/lead chalcogenide heterostructure, focusing on CsPbI3 and the molecular size of PbS/PbSe lead chalcogenide. The calculations confirm the constituent concentration and the elemental substitution can be employed to fine tune the optoelectronic properties of halide perovskite/lead chalcogenide heterostructures. This work facilitates the fundamental understanding of the halide perovskite/lead chalcogenide systems toward optoelectronic applications.

The realization of electrically tunable plasmonic resonances in the ultraviolet (UV) to visible spectral band is particularly important for active nanophotonic device applications. However, the plasmonic resonances in the UV to visible wavelength range cannot be tuned due to the lack of tunable plasmonic materials. Here, we experimentally demonstrate tunable plasmonic resonances at visible wavelengths using a chalcogenide semiconductor alloy such as antimony telluride (Sb2Te3), by switching the structural phase of Sb2Te3 from amorphous to crystalline. We demonstrate the excitation of a propagating surface plasmon with a high plasmonic figure of merit in both amorphous and crystalline phases of Sb2Te3 thin films. We show polarization-dependent and -independent plasmonic resonances by fabricating one and two-dimensional periodic nanostructures in Sb2Te3 thin films, respectively. Moreover, we demonstrate electrically tunable plasmonic resonances using a microheater integrated with the Sb2Te3/Si device. The developed electrically tunable Sb2Te3-based plasmonic devices could find applications in the development of active color filters. Agency for Science, Technology and Research (A*STAR) Accepted version The authors (K.V.S. and R.S.) acknowledge the funding support from Advanced Manufacturing and Engineering (AME) Programmatic (Grant No. A18A5b0056) by Agency for Science, Technology and Research.

In atomic solids, substitutional doping of atoms into the lattice of a material to form solid solutions is one of the most powerful approaches to modulating its properties and has led to the discovery of various metal alloys and semiconductors. Herein we have prepared solid solutions in hierarchical solids that are built from atomically precise clusters. Two geometrically similar metal chalcogenide clusters, Co6Se8(PEt3)6 and Cr6Te8(PEt3)6, were combined as random substitutional mixture, in three different ratios, in a crystal lattice together with fullerenes. This does not alter the underlying crystalline structure of the [cluster][C60]2 material, but it influences its electronic and magnetic properties. All three solid solutions showed increased electrical conductivities compared with either the Co- or Cr-based parent material, substantially so for two of the Co:Cr ratios (up to 100-fold), and lowered activation barriers for electron transport. We attribute this to the existence of additional energy states arising from the materials' structural heterogeneity, which effectively narrow transport gaps.

Amorphous chalcogenide glasses are intrinsically metastable, highly photosensitive, and therefore exhibit numerous light-induced effects upon bandgap and sub-bandgap illumination. Depending on the pulse duration of the excitation laser, ChGs exhibit a series of light-induced effects spanning over femtosecond to seconds time domain. For continuous wave (CW) illumination, the effects are dominantly metastable in terms of photodarkening (PD) and photobleaching (PB) that take place via homopolar to heteropolar bond conversion. On the other hand, under nanosecond and ultrafast pulsed illumination, ChGs exhibit transient absorption (TA) that is instigated from the transient bonding rearrangements through self-trapped exciton recombination. In the first part of the review, we pay special attention to continuous wave light-induced PD and PB, while in the second part we will focus on the TA and controlling such effects via internal and external parameters, e.g., chemical composition, temperature, sample history, etc.

While manganese (Mn2+)-doped chalcogenide and perovskite CsPbX3 nanocrystals (NCs) have been extensively investigated, the research of color-tunable dual-emissive Mn2+-incorporated two-dimensional ...