The emission and absorption of Cs₂AgBiBr₆ are dominated by the strong carriers–phonon coupling.

The candidate photovoltaic absorber antimony selenide Sb2Se3 has been prepared by the commercially attractive close-space sublimation method. Structure, composition, and morphology are studied x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy. Large rhubarb-like grains favorable for photovoltaics naturally develop. temperature-dependence of direct band gap is determined photoreflectance between 20 320 K well described Varshni Bose–Einstein relations,...

The room temperature synthesis and photoluminescence properties of hexagonal phase NaBiF4 nanocrystals doped with lanthanide ions have been presented. An efficient infrared Stokes emission upconverted from the rare-earth (Yb3+, Er3+) codoped into bismuth–fluoride nanomatrix allows for dual modality pressure sensing in VIS NIR spectral regions. Upconversion shows nearly quadratic dependence intensity on excitation light power, confirming a two-photon induced process allowing by low-power CW...

The application of high pressure allows tuning physicochemical properties materials by changing interatomic distances. Pressure may also induce structural phase transitions into new phases with enhanced or novel functional properties. Here, we report complementary high-pressure single-crystal X-ray diffraction, Raman spectroscopy, and optical studies a two-dimensional (2D) perovskite, MHy2PbBr4, comprising very small spacer cation (methylhydrazinium, MHy+). This crystal exhibits highly...

Bi-induced changes in the band structure of Ga–V–Bi and In–V–Bi alloys are calculated within density functional theory (DFT) for with Bi ≤3.7% observed chemical trends discussed context virtual crystal approximation (VCA) valence anticrossing (VBAC) model. It is clearly shown that incorporation atoms into III–V host modifies both conduction (CB) (VB). The obtained shifts bands GaP1−xBix, GaAs1−xBix, GaSb1−xBix, InP1−xBix, InAs1−xBix, InSb1−xBix respectively, 15, −29, −16, −27, −15, −10...

Abstract We are presenting some physical and chemical basis of ammonothermal method bulk gallium nitride (GaN) synthesis in ammonobasic route. The substrates polar, non‐polar, semi‐polar orientation can be obtained by this method. Excellent structural wide spectrum electrical parameters truly GaN crystals way revealed. Large progress manufacturing large size (1‐in.) non‐polar is reported. A preliminary results on performance the devices grown will shown.

Semiconductors known as highly mismatched alloys (HMAs) have unique properties that make them useful in the fabrication of intermediate band solar cells (IBSCs). Now a theoretical and experimental study GaNPAs with ~40% phosphorus up to 2% nitrogen finds this HMA has an electronic structure well suited for IBSC applications.

The epitaxial growth, structural, and optical properties of GaSb1–xBix alloys have been investigated. Bi incorporation into GaSb is varied in the range 0 < x ≤ 9.6% by varying growth rate (0.31–1.33 μm h−1) at two temperatures (250 275 °C). content inversely proportional to rate, but with higher contents achieved 250 than °C. A maximum = greater 99% substitutional. Extrapolating linear variation lattice parameter GaSbBi films enabled a zinc blende GaBi be estimated 6.272 Å. band gap...

Abstract The electronic band structure of MoS 2 , MoSe WS and WSe crystals has been studied at various hydrostatic pressures experimentally by photoreflectance (PR) spectroscopy theoretically within the density functional theory (DFT). In PR spectra direct optical transitions (A B) have clearly observed pressure coefficients determined for these to be: α A = 2.0 ± 0.1 B 3.6 meV/kbar 2.3 4.0 2.6 4.1 3.4 5.0 0.5 . It found that are in an excellent agreement with theoretical predictions....

Abstract Transition metal dichalcogenides (TMDs), especially in two-dimensional (2D) form, exhibit many properties desirable for device applications. However, performance can be hindered by the presence of defects. Here, we combine state art experimental and computational approaches to determine formation energies charge transition levels defects bulk 2D MX 2 (M = Mo or W; X S, Se, Te). We perform deep level transient spectroscopy (DLTS) measurements TMDs. Simultaneously, calculate defect...

For the first time, large-area, flexible organic–inorganic tin perovskite solar modules are fabricated by means of an industry-compatible and scalable blade-coating technique. An 8-cell interconnected mini module with dimensions 25 cm2 (active area = 8 × 1.5 cm2) reached 5.7% power conversion efficiency under 1000 W/m2 (AM 1.5G) 9.4% 2000 lx (white-LED).

Here, we investigate the role of interlayer magnetic ordering CrSBr in framework ab initio calculations and by using optical spectroscopy techniques.

We review the recent developments in GaAs-based 1.55-mum lasers grown by molecular beam epitaxy (MBE). While materials growth is challenging, window appears to be relatively broad and described detail. The key considerations for producing high-quality GalnNAsSb material emitting at regime are examined, including nitrogen plasma conditions, ion removal from flux, surfactant- mediated growth, roles of various V-II ratios, temperature, active region thermal budget, proper annealing,...

It is shown that compressively strained Ge1-xSnx/Ge quantum wells (QWs) grown on a Ge substrate with 0.1 ≤ x 0.2 and width of 8 nm d 14 are very promising gain medium for lasers integrated an Si platform. Such QWs type-I direct bandgap positive transverse electric mode material gain, i.e. the modal gain. The electronic band structure near center Brillouin zone has been calculated various use 8-band kp Hamiltonian. To calculate these QWs, occupation L valley in barriers taken into account....

Band gap alignment in GaAs1−xBix/GaAs quantum wells (QWs) was studied experimentally by photoreflectance (PR) and theoretically, ab initio, within the density functional theory which supercell based calculations are combined with alchemical mixing approximation applied to a single atom supercell. In PR spectra, optical transitions related excited states QW (i.e., transition between second heavy-hole electron subband) were clearly observed addition ground state GaAs barrier transition. This...

Modulated reflectance (contactless electroreflectance (CER), photoreflectance (PR), and piezoreflectance (PzR)) has been applied to study direct optical transitions in bulk MoS2, MoSe2, WS2, WSe2. In order interpret observed CER, PR, PzR spectra, the electronic band structure for four crystals calculated from first principles within density functional theory various points of Brillouin zone including K H points. It is clearly shown that at point very symmetric similar point, therefore,...

Photoreflectance (PR) spectroscopy was applied to study the band gap in GaSb1−xBix alloys with Bi < 5%. Obtained results have been interpreted context of ab initio electronic structure calculations which supercell (SC) based are joined alchemical mixing (AM) approximation a single atom cell. This approach, we call SC-AM, allows on one hand very small content, and other avoid limitations characteristic pure AM approximation. It has shown that does not reproduce determined from PR while...

Photoacoustic (PA) and modulated reflectance (MR) spectroscopy have been applied to study the indirect direct band gap for van der Waals (vdW) crystals: dichalcogenides (MoS2, MoSe2, MoTe2, HfS2, HfSe2, WS2, WSe2, ReS2, ReSe2, SnS2 SnSe2) monochalcogenides (GaS, GaSe, InSe, GeS, GeSe). It is shown that can be determined by PA technique while probed MR which not sensitive optical transitions. By measuring spectra a given compound comparing them with each other it easy conclude about character...

Abstract The ReX 2 system (X = S, Se) exhibits unique properties that differ from other transition metal dichalcogenides. Remarkably, its reduced crystal symmetry results in a complex electronic band structure confers this material in-plane anisotropic properties. In addition, multilayered presents strong 2D character even bulk form. To fully understand the interlayer interaction system, it is necessary to obtain an accurate picture of structure. Here, we present experimental and theoretical...

There are a variety of possible ways to tune the optical properties 2D perovskites, though mutual dependence among different tuning parameters hinders our fundamental understanding their properties. In this work, we attempt address issue for (CnH2n+1NH3)2PbI4 (with n = 4, 6, 8, 10, 12) using spectroscopy in high magnetic fields up 67 T. Our experimental results, supported by DFT calculations, clearly demonstrate that exciton reduced mass increases around 30% low-temperature phase. This is...

A key material system for opto- and high-power electronics are III-nitrides. Their functionality can be expanded when bandgap engineering is extended beyond common materials such as AlN, GaN, InN. Combining these three compounds with boron nitride other III–V (GaP, GaAs, GaSb, InP, etc.) an intuitive method of expanding in semiconductor devices. This may allow improvement current devices which performances limited by the intrinsic properties III-nitride alloys, well creation novel...

Within a decade, perovskite solar cells (PSCs) leaped to the forefront of photovoltaic research, rapidly moving toward industrial phase. Despite impressive progress in technology development and new efficiency records, there still remains large scope for further advancement. Utilization scalable deposition methods good control crystallization process, especially with industrially compatible fabrication protocols, require more understanding ascertain reproducible, large-format manufacturing....

Abstract Lamellar structures of transition metal phosphorus trisulfides possess strong intralayer bonding, albeit adjacent layers are held by weak van der Waals interactions. Those compounds received enormous interest due to their unique combination optical and long‐range magnetic properties. Among them, iron trisulfide (FePS 3 ) gathered special attention for being a semiconductor with an absorption edge in the near‐infrared, as well showing Ising‐like anti‐ferromagnetism. A successful...