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The realization of Janus monolayers presents an exciting opportunity to disrupt structural symmetry, opening up novel avenues in the realm of layered materials. While several ternary systems, comprising the group-III monochalcogenides, has been proposed for this purpose, the impact of oxygen interaction on the electronic, thermoelectric and optical characteristics of gallium and indium monochalcogenides has been observed. Interestingly, the concept of incorporating oxygen as a third element in ternary systems has not yet been explored extensively. Here we embark on the design and exploration of 2D A2OX (A = Ga, In and X = S, Se) monolayer through first-principles calculations. Our investigation includes the analysis of electronic band structure, optical and thermoelectric properties, revealing that Ga2OS, Ga2OSe and In2OS exhibit direct band nature. However, In2OSe is found to be metallic in unstrained condition. Moreover, the band gap in these materials can be fine-tuned through the application of tensile or compressive strain. Additionally, our analysis suggests strong optical absorption within the visible, and/or ultraviolet regions, depending on the specific system under consideration. Our findings reveal that Ga2OS and In2OS monolayers elevated power factors with application of tensile strain, rendering them as compelling candidates for applications in thermoelectric devices. [ABSTRACT FROM AUTHOR]

To overcome environmental problems and the energy crisis, water splitting through solar energy for the production of hydrogen fuel is a promising technique. Efficient and low-cost photocatalyst are highly desired. In the recent era, van der Waal (vdW) heterostructures have gained considerable attention due to their promising properties. Hybrid density functional theory is used to calculate the electronic and photocatalytic properties of BX-MSSe (X = P, As and M = Mo, W) vdW heterostructures. Most stable stacking is figured out among different stacking from their relaxation energy. The stability of the stable stacking is confirmed through phonon calculations. Calculated band structure shows that BAs-MoSSe and BP-WSSe have direct band gap nature while the BP-MoSSe and BAs-WSSe have indirect band gap nature. BAs-MoSSe has Type-I band alignment while BP-MoSSe, BAs-WSSe and BP-WSSe have type-II band alignment. The creation of heterostructures broadened the optical absorption from the infrared to the ultraviolet region of the solar spectrum. To tune the properties of these heterostructures compressive and tensile strain is applied. Switching in band alignment is predicted in these heterostructures with the applications of strain. Based on valence and conduction band edges potentially the photocatalytic behavior for pH = 0 is investigated, which confirms that in unstrained conditions BP-MSSe (M = Mo, W) heterostructures are efficient photocatalyst. [ABSTRACT FROM AUTHOR]

Mueller matrix polarimetry (MMP) is a fast and non-invasive optical technique for characterization of turbid media such as biological tissues, where the experimental Mueller matrix M contains the complete information of polarization properties of the sample. The individual optical properties in M are present in a complex interwoven way and need to be extracted; Mueller matrix polar decomposition (MMPD) and Mueller matrix transformation (MMT) are two widely used methods for this purpose. Here, we compared these two methods (i.e. , MMPD and MMT) and assessed the possible correlation between their corresponding parameters in a comprehensive sample cohort containing different types of tissues and associated pathologies (n = 47), tissue phantoms (n = 21) and standard optical components (e.g. , air, polarizer, quarter wave plate, etc.) (n = 09). Specifically, we calculated two sets of optical variables (Δ T , b) and (δ , t) representing depolarization and retardance for the MMPD and MMT methods, respectively. Qualitative correlation via graphical tools (i.e. , violin, parallel coordinate, scatter, Bland and Altman plots) in tandem with correlation coefficients was investigated. The parameters of both methods are indicative of the structural features of the turbid samples; however, the MMT parameters (b , t) give higher values than the MMPD parameters (Δ T , δ) with moderate statistical correlation. This study assessed the link between the two methods and would provide a useful reference for such comparative analyses. [ABSTRACT FROM AUTHOR]

In this theoretical study we investigate the electronic, optical, and photocatalytic properties of monolayer titanium dioxide (TiO2), nickel dioxide (NiO2), and germanium dioxide (GeO2), as well as the effects of strain and stacking on these monolayers. The first principle calculations were performed using density functional theory (DFT) to determine the band structure, density of states, and optical properties of the monolayers. The photocatalytic activity of the monolayers was evaluated based on the water-splitting reaction. The results showed that the electronic and optical properties of the monolayers were significantly affected by strain and stacking. Specifically, the bandgap of TiO2, NiO2, and GeO2 decreased under tensile strain, while it increased under compressive strain. Furthermore, the stacking order of the monolayers affected their electronic and optical properties. The photocatalytic activity of the monolayers was found to be highest for TiO2. This study provides a valuable insight into the properties of monolayer oxides TiO2 and GeO2 and their van der Waal heterostructure GeO2–TiO2 as a potential candidate for photocatalytic water splitting. [ABSTRACT FROM AUTHOR]

In this study, all-inorganic two-dimensional Dion–Jacobson halide perovskites (DJ-HPs) CsMX 2 Y 2 (M = Sb, Bi; and X/Y= I/I, I/Br, Br/Br, I/Cl, Br/Cl, Cl/Cl) have been studied for photovoltaic, photoemission and other potential applications in optoelectronic devices using first principle calculations within the framework of density functional theory (DFT). The ground state crystal symmetry is tetragonal with a P 4/ mmm (No. 123) space group. In these compounds, Cs+ is a spacer cation, which separates the octahedral layers and balances the charge. The corner sharing M-centered (Sb, Bi) [MX 2 Y 4 ]3– unit constructs the 2D [MX 2 Y 2 ] n n– plane, where the X and Y (halogens) atoms occupy the out of plane apical and in-plane bridging sites, respectively. The DJ-HPs with P 4/ mmm crystal symmetry exhibit pseudo-direct band gap semiconducting nature and the spin orbit (SO) effect reduces the band gaps as well as splits the Sb/Bi-p orbital in the bottom of conduction band (CB) and X/Y-p orbital at the top of valence band (VB). Among these DJ-HPs, the band gap energies of CsSbI 2 Cl 2 (0.87 eV), CsSbBr 2 Cl 2 (1.00 eV), CsSbCl 4 (1.40 eV), CsBiI 4 (1.10 eV), CsBiI 2 Br 2 (1.40 eV) and CsBiBr 4 (1.60 eV) lie in a band gap energy range (0.9–1.6 eV) suitable for photovoltaic applications. The M-s (Sb-5s and Bi-6s) and X/Y-p (Cl-3p, Br-4p and I-5p) orbitals are responsible for the electron transition from the valence to conduction band, while the spacer cation (Cs+) has a limited effect on the charge carrier mobility. The effective masses of the charge carriers and exciton binding energies of these materials are suitable for solar cell and optoelectronic applications. From the optical coefficients it is clear that these DJ-HPs have excellent response to the incident photons in the visible and ultraviolet light region. • New Dion–Jacobson two dimensional halide are investigated for optoelectronic applications. • These compounds belongs to tetragonal symmetry having space group P 4/ mmm. • Band gap of these semiconductors are pseudo direct and spin orbit (SO) effect increases from Sb to Bi and Cl to I. • The effective masses of the carriers are increasing linearly with the increasing band gaps. [ABSTRACT FROM AUTHOR]

Structural, electronic, elastic and magnetic properties of CaCu 3 Mn 4-x Ir x O 12 (x = 0, 2 and 4) along with the optical properties of CaCu 3 Mn 4 O 12 perovskites have been carried out in the framework of density functional theory (DFT). The investigation of structural optimization reveals that CaCu 3 Mn 2 Ir 2 O 12 is stable in Pn-3 space group and CaCu 3 Mn 4 O 12 and CaCu 3 Ir 4 O 12 perovskites are stable in Im-3 space group. The cohesive energy and enthalpy of formation reveal the stability of these compound and shows that CaCu 3 Mn 2 Ir 2 O 12 is more stable than the rest compounds. Substitution of Ir by Mn not only transforms these compounds from semiconductor to metallic nature but also transform the host compound from ferrimagnetic to anti-ferromagnetic via spin glass state. The DFT electronic behavior is also supported by the electrical resistivity. Elastic properties demonstrate the mechanical stability, anisotropic and ductile nature of these compounds. The optical properties indicate that CaCu 3 Mn 4 O 12 is optically active for infrared electromagnetic radiations and could be used in optical devises. The ferrimagnetic ductile nature of CaCu 3 Mn 4 O 12 , spin glass and anti-ferromagnetic nature of CaCu 3 Mn 2 Ir 2 O 12 and CaCu 3 Ir 4 O 12 makes these perovskites suitable candidates for spintronic and magnetic cloaking applications. [Display omitted] • Structure symmetry is evaluated from Im-3 to Pn-3 via Ir substitution. • Substitution of Ir transform these compounds from semiconductor to metallic nature. • The ferrimagnetic is transform to anti-ferromagnetic via Spin glass state. • CaCu 3 Mn 4 O 12 is optically active in infrared region of electromagnetic spectrum. [ABSTRACT FROM AUTHOR]

The development of three-dimensional (3D) hybrid organic–inorganic perovskites has sparked much interest because of their rich light-harvesting capabilities in solar cells. However, the understanding of the electronic and optical properties, particularly the excitonic shifts upon structural phase transition with temperature in these materials, is not fully clear. Here, we report the accurate description of electronic and optical properties of mostly studied FAPbI3 across the cubic–tetragonal–hexagonal phases, using the relativistic GW method and Bethe–Salpeter Equation (BSE), including the spin–orbit coupling effects. Our GW calculations reveal that the bandgap values vary from 1.47 to 3.54 eV from the room temperature cubic phase to the low temperature hexagonal phase. Our optical analysis shows that excitonic peaks are blue-shifted, and exciton binding energies estimated by the model BSE approach increase from 74 to 567 meV going from the cubic to hexagonal phases. Our results may have important impacts on the practical uptake of hybrid perovskite based solar cells under different climatic conditions. [ABSTRACT FROM AUTHOR]

• Electronic structure and optical properties of Mo 2 CO 2 /W 2 CO 2 and Mo 2 CF 2 /W 2 CO 2 heterostructures and their corresponding monolayers are investigated. • The bandstructure topology of Mo 2 CO 2 /W 2 CO 2 indicates a possible topological nature. • Mo 2 CO 2 /W 2 CO 2 heterostructure forms a type-II band alignment. • In case of Mo 2 CF 2 /W 2 CO 2 , an n-type Schottky contact is formed. M 2 CX 2 (M = Mo,W; X = O,F) MXenes and their van der Waals heterostructures are investigated by first-principle calculations. Phonon spectrum has shown that Mo 2 CO 2 /W 2 CO 2 and Mo 2 CF 2 /W 2 CO 2 heterostructures and corresponding monolayers are dynamically stable. W 2 CO 2 exhibits the properties of topological insulator and Mo 2 CO 2 is narrow band gap semiconductor, while Mo(W) 2 CF 2 are metals. Mo 2 CO 2 /W 2 CO 2 heterostructure indicates a possible topological feature similar to corresponding monolayers and reveals type-II band alignment. Mo 2 CF 2 /W 2 CO 2 heterostructure generating n-type Schottky contact with 0.139 eV barrier height. Large absorption in the visible region is observed for Mo 2 CO 2 and blue shift is noticed for W 2 CO 2 and W 2 CO 2 /Mo 2 CO 2 heterostructure, especially the part contributed by Mo 2 CO 2. [ABSTRACT FROM AUTHOR]

Two-dimensional materials have demonstrated outstanding electronic, optical, and photocatalytic characteristics. In this article, the physical properties of pentagonal-like structure penta-PtPX (X = S, Se, Te) monolayers are systematically investigated by employing density functional theory. Phonon spectra and ab initio molecular dynamics simulations confirmed that these systems are thermodynamically stable. The hybrid HSE06 functional demonstrated that the PtPX monolayers are indirect band gap semiconductors, having band gap of 2.85 eV, 2.69 eV, and 2.14 eV for PtPS, PtPSe, and PtPTe respectively. The optical properties calculated using GW 0 +BSE approach reveal strong anisotropic absorption along x- and y-directions and the optical transitions are dominated by excitons. High absorbance in the visible and ultraviolet light region is observed, and the excitonic peaks are red shifted for heavy chalcogens. Furthermore, the photocatalytic study show that the PtPX monolayers can oxidize H 2 O/O 2 to O 2 and reduce H+ to H 2 , similar to the PdPX (X = S, Se, Te) monolayers. Our results suggest that the PdPX and PtPX (X = S, Se, Te) monolayers have potential for optoelectronic and photovoltaic devices, and are promising photocatalysts for water splitting reaction. [Display omitted] • Square-planar pentagonal structure of penta-PdPS, -PdPSe, -PdPTe, -PtPS, -PtPSe, -PtPTe monolayers. • Electronic and optical properties penta-PtPX and -PdPX (X = S, Se, Te) monolayers. • High visible light absorbance by penta-PtPX and -PdPX (X = S, Se, Te monolayers. • Water splitting ability of penta-PtPX and -PdPX (X = S, Se, Te monolayers. [ABSTRACT FROM AUTHOR]

Ternary palladates CaPdO and SrPdO have been studied theoretically using density functional theory approach. The calculated structural properties are consistent with the experimental findings. Mechanical properties show that these compounds are elastically stable, anisotropic and ductile in nature. The electronic properties reveal that they are narrow band gap semiconductors with band gaps 0.12 and 0.10 eV, correspondingly. Both materials are optically active in the infrared ranges of the electromagnetic spectrum. Narrow band gap semiconductors are efficient thermoelectric (TE) materials; therefore, TE properties are also studied and discussed. Furthermore, DFT and post-DFT calculations confirm the paramagnetic nature of these compounds. [ABSTRACT FROM AUTHOR]

DFT is used to study various transition metal based ceramics LiAA′O 6 (A = Nb, Ta, and A′ = W, Mo) in tetragonal phase with space group 421 m (No. 113). The calculated structural and geometrical parameters are found in closed agreement with the experiments. Electronic clouds explain the chemical bonding and reveal that Li atom occupy central position and form ionic bond. Other bonds in these compounds are significantly covalent due to the sharing of electrons between O and A/A′. The electronic properties demonstrate that these compounds are wide bandgap semiconductors in the energy range of 2.18–2.60 eV. These bandgap energies confirm the suitability of these oxides in optoelectronic devices operating in the visible range of the electromagnetic spectrum. [ABSTRACT FROM AUTHOR]

This paper communicates the structural, electronic and optical properties of L-alanine, monofluoro and difluoro substituted alanines using density functional calculations. These compounds exist in orthorhombic crystal structure and the calculated structural parameters such as lattice constants, bond angles and bond lengths are in agreement with the experimental results. L-alanine is an indirect band gap insulator, while its fluorine substituted compounds (monofluoroalanine and difluoroalanine) are direct band gap insulators. The substitution causes reduction in the band gap and hence these optically tailored direct wide band gap materials have enhanced optical properties in the ultraviolet (UV) region of electromagnetic spectrum. Therefore, optical properties like dielectric function, refractive index, reflectivity and energy loss function are also investigated. These compounds have almost isotropic nature in the lower frequency range while at higher energies, they have a significant anisotropic nature. [ABSTRACT FROM AUTHOR]

Structural, electronic, optical and magnetic properties of titanium based perovskites La 2 MTiO 6 (M = Co, Ni, Cu and Zn) are investigated in monoclinic phase with space group (P2 1 /n) in the domain of density functional theory (DFT). The generalized gradient approximation plus Hubbard potential (GGA + U) is utilized to study these high correlated electrons systems. Structural parameters are found in closed agreement with experiments. Cohesive energy reveals that La 2 CoTiO 6 is more stable among these compounds. The electronic properties show the semiconductor behavior of these compounds with band gap varies from 1.02 to 2.3 eV. Optical properties demonstrate that all these compounds are potential candidates for optoelectronic devices. The electrical resistivity which increases in a sequence from Co to Zn also confirms the semiconductor nature of these compounds. The magnetic susceptibility curves show that La 2 CoTiO 6 , La 2 NiTiO 6 and La 2 CuTiO 6 are antiferromagnetic whereas La 2 ZnTiO 6 is a paramagnetic material. Based on the semiconductor antiferromagnetic nature of La 2 CoTiO 6 , La 2 NiTiO 6 and La 2 CuTiO 6 it is expected that these compounds could be used as pinning layers in spin valves and storage devices. • La 2 MTiO 6 (M = Co, Ni, Cu and Zn) perovskites are semiconductors with band gaps ranges from 1.2 to 2.3 eV. • These compounds are optically active in the broad range electromagnetic spectrum. • Electrical resistivity increases in a sequence from Co to Zn and confirms the semiconductor nature of these compounds. • Perovskites La 2 CoTiO 6 , La 2 NiTiO 6 and La 2 CuTiO 6 are antiferromagnetic whereas La 2 ZnTiO 6 is a paramagnetic material. [ABSTRACT FROM AUTHOR]

Two-dimensional magnetic materials are high desirable for realizing advanced optoelectronic and spintronic devices. In this paper, we report systematic studies the effects of strain on the electronic structure, magnetic states and optical properties of Mn-doped SnS 2 monolayer (ML) by means of first-principles calculations. Ab-initio molecular dynamics simulations and formation energy reveal that the Mn-doped SnS 2 ML is stable at 500 K and can be fabricated under the S-rich condition. The substitution of a Mn for a Sn atom induces 3 μ B magnetic moment in nonmagnetic SnS 2 ML, which is consistent with the Hund's rule and Aufbau principle. Based on classical Heisenberg model and mean-field approximation the Curie temperature is calculated to be 476.13 K. Due to symmetry reserved crystal structure, the net magnetic moment of Mn-doped SnS 2 ML is robust even if considerable strains (−10 to 10%) are applied. The blue-shift and red-shift of the absorption peaks are observed in the optical spectrum by biaxial compressive and tensile strains. The biaxial strain effectively improves the optical properties of Mn-doped SnS 2 ML, particularly in the visible light region. This study provide useful guidance for practical application in magnetic and optoelectronic devices. The VBM and CBM shifts of the Mn-doped SnS 2 ML under biaxial strain. [Display omitted] • The electronic, magnetic and optical properties of Mn-doped SnS 2 monolayer are studied. • Mn-doped SnS 2 monolayer is stable at 500 K and can be fabricated under S-rich condition. • Under biaxial strain the Mn-doped SnS 2 monolayer is always a magnetic semiconductor with 3 μ B moment. • The optical properties of Mn-doped SnS 2 monolayer can be tuned by biaxial strain. • Mn-doped SnS 2 monolayer is a vigorous nominee for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Effect of spin orbit coupling (SOC) on the physical properties of perovskites A 3 SnO (A = Ca, Sr and Ba) have been studied in the domain of density functional theory (DFT). It is found that SOC effect has great influence on the electronic band structures, optical and thermoelectric properties of these perovskites. Dirac cones are observed in the band structures and SOC opens the gap between valence and conduction bands. These compounds have narrow direct band gaps with values 0.27, 0.13 and 0.1 eV respectively. Mechanical properties show that these compounds are elastically stable, anisotropic and ductile. Optical properties show that these compounds are optically active in the infrared region of the electromagnetic spectrum. Thermal conductivity, heat capacity, Seebeck coefficient, Power factor and Figure of merit show that these perovskites could be used in thermoelectric generators. • Spin orbit coupling effect has great influence on the electronic band structure, optical and thermoelectric properties of these perovskites. • Dirac cone are observed by GGA and GGA + mBJ whereas GGA + SOC reveal narrow direct bandgaps semiconducting nature of these compounds. • These compounds are elastically stable, anisotropic and ductile. • These compounds are optically active in infrared region of electromagnetic spectrum. • Thermoelectric properties explore that these perovskites could be used as efficient thermoelectric materials. [ABSTRACT FROM AUTHOR]

Mueller matrix polarimetry (MMP) has evolved as a tool of paramount importance to study the polarization properties of biological tissues. The conventional 4 x 4 Mueller matrix M is constructed by sixteen measurements involving both linear and circularly polarized light. Alternatively, the concept of 3 × 3 M has been introduced where M is constructed from linear polarization measurements alone, thus simplifying the experimental geometry and procedure significantly. The individual polarization properties of the sample are encrypted in M. Several methods have been proposed to extract the encrypted polarization parameters of the sample from its M ; Mueller matrix polar decomposition (MMPD) and Mueller matrix transformation (MMT) are two broadly utilized methods for this purpose. Here, we compared these two methods (i.e., MMPD and MMT) in the regime of 3 x 3 M. In particular, we have compared two important polarization parameters, namely linear depolarization and linear retardance for both MMPD and MMT methods. The results showed no significant difference between the mean linear depolarization values (n=10) (74.64 ± 14.39% vs 73.01 ± 13.74%, p = 0.799), while the mean linear retardance values (1.79 ± 0.10 vs 0.18 ± 0.17 radian, p < 0.001) were significantly different for MMPD and MMT methods. However, a good correlation between the two methods was observed for both linear depolarization (R 2 = 0.87) and linear retardance (R 2 = 0.89). This preliminary study indicates that the optical variables of both MMPD and MMT methods are sensitively correlated to the microstructure of the tissue samples, and there is a good correlation between the two decomposition methods. • Mueller matrix (MM) polarimetry is a robust optical tool for tissue characterization. • MMPD & MMT are two methods for decoding individual optical metrics from MM. • MMPD and MMT are compared in the regime of 3 x 3 M. • Mean linear depolarization calculated with MMPD & MMT methods showed good agreement. • Mean linear retardance showed significant differences between MMPD & MMT methods. [ABSTRACT FROM AUTHOR]

Thulium (Tm) doped aluminum nitride (AlN) thin films are deposited by radio frequency (RF) magnetron sputtering in a pure nitrogen atmosphere. As-deposited thin films are irradiated at room temperature with 335 keV protons and a fluence of 1 × 1014 ions/cm2. The effects of irradiation on the structural and optical properties of the deposited thin films are investigated. Rutherford backscattering (RBS) is performed to determine the thickness and stoichiometric properties of the films while the structural properties of the material before and after irradiation are investigated with x-ray diffraction (XRD). Non-ionizing energy loss (NIEL) study demonstrates that scattering events increase as the ions penetrate deep into the matrix and result in higher damage in the material. Fourier transform infrared spectroscopy (FTIR) is used to see the absorption spectra of thin films which reveals that the implanted films have great capabilities of solar energy storage. Bandgap of the film is determined using diffused reflection spectroscopy (DRS) technique, where a slight upwards shift in bandgap is observed due to irradiation induced material damages. • AlN:Tm thin films are fabricated using RF magnetron sputtering on Si substrate. • AlN:Tm are irradiated with 335 keV protons with a fixed fluence and energy. • Irradiated films resist the proton fluence and their crystal structure is not disturbed. • Slight increase in bandgap due to irradiation is observed due to Burstien-Moss effects. [ABSTRACT FROM AUTHOR]

• Electronic and optical properties. • Effects of chemical bond strength and electronegativity difference on electronic properties. • Accuracy of improved TB-mBJ exchange potential. • Improved TB-mBJ approach results compared with experimental. The recently developed improved Tran and Blaha modified Becke-Johnson exchange potential (TB-mBJ) approach within the framework of DFT is used to calculate band gaps and optical properties of cubic perovskites ABO 3 (A = Ca, Sr, Ba and B = Ti, Zr, Hf). The bonding nature and electronegativity difference between B-cation and O atoms are considerably influencing the electronic band gaps of these compounds. Improved TB-mBJ treats the electronic density appropriately between them, producing accurate band gaps. The optical response shows wide range of light absorption, from visible to ultraviolet, in these compounds expecting their possible applications in various optoelectronic devices. [ABSTRACT FROM AUTHOR]