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The perovskite crystals formed by methylammonium lead iodide (MAPbI3) have garnered growing interest owing to their exceptional photovoltaic capabilities, economical production process, and ability to be processed in solution. A multitude of techniques have been devised to produce dense and uniform perovskite thin coatings, which are critical for the proper functioning of electronic devices. In order to promote the development of CH3NH3PbI3 perovskite thin films that are uniform, dense, and exceptionally smooth, we present an additive-assisted method utilizing Copper zinc tin sulfide Cu2ZnSnS4 (CZTS) nanoparticles. The surface, optical, morphological, and structural properties were subsequently determined. The mechanisms by which the additive improves the quality of the material during the formation of CH3NH3PbI3 perovskite films are elucidated in this study. These processes are postulated to characterize the crystallization of the films. Using this beneficial technique, a high-quality CH3NH3PbI3 film with a grain size significantly larger than 1.6 μm was effectively manufactured. Additionally, the doping process resulted in enhancements in both absorption and photoluminescence intensity. The addition of CZTS NPs elevated the crystal structures and morphologies of the CH3NH3PbI3 layer to a degree that was comparatively favorable. This was evidenced by the crystallite size of 83 nm and an optical bandgap (Eg) of 1.63 eV, both of which attest to the enhanced quality of the film. With the structure of glass/FTO/TiO2/CH3NH3PbI3:CZTS NPs/spiro-oMeTAD/Au ,the power conversion efficiency (PCE) of the best cell was 15.13% with a fill factor of 66.07%. The results of this study indicate that doping CH3NH3PbI3 solar cells with CZTS NPs is a dependable method for enhancing photovoltaic performance and promoting crystal growth. [ABSTRACT FROM AUTHOR]

In this study, we investigated the optoelectronic properties of cubic (Pm3m) and orthorhombic (Pnma) CsPbX3 (X = I, Br, and Cl). We utilized the full potential linear augmented plane wave method, which is implemented in the WIEN2k code, to facilitate the investigation. Different exchange potentials were used to analyze the optoelectronic behavior using the available density functional theory methods. Our findings revealed that CsPbX3 perovskites display direct band gaps at the R and Г points for cubic (Pm3m) and orthorhombic (Pnma) structures, respectively. Among the exchange potentials, the mBJ-GGA method provided the most accurate results. These outcomes concurred with the experimental results. In both Pm3m and Pnma structures, interesting changes were observed when iodide (I) was replaced with bromine (Br) and then chlorine (Cl). The direct band gap at the R and Г points shifted to higher energy levels. Similarly, when I was replaced with Br and Cl, there was a noticeable decrease in the absorption coefficient, dielectric constants, refractive index, and reflectivity, in addition to a band gap shift to higher energy levels. [ABSTRACT FROM AUTHOR]

Controlling the crystallinity, homogeneity, and surface morphology is an efficient method of enhancing the perovskite layer. These improvements contribute toward the optimization of perovskite film morphology for its use in high-performance photovoltaic applications. Here, different solvents will be used in order to process the perovskite precursor, to improve the interfacial contacts through generating a smooth film and uniform crystal domains with large grains. The effect that the solvent has on the optical and structural properties of spin-coated methyl ammonium lead iodide (MAPbI3) perovskite thin films prepared using a single-step method was systematically investigated. The spin-coating parameters and precursor concentrations of MAI and PbI2 were optimized to produce uniform thin films using the different solvents N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and γ-butyrolactone (GBL). The effect that the solvent has on the morphology of the MAPbI3 films was examined to determine how the materials can be structurally altered to make them highly efficient for use in perovskite hybrid photovoltaic applications. Scanning electron microscopy (SEM) and X-ray diffractometry (XRD) results show that the synthesized MAPbI3 films prepared using DMSO, DMF, and GBL exhibit the best crystallinity and optical characteristics (photoluminescence (PL)), respectively, of the prepared films. The optical properties resulting from the noticeable improvement PL of the films can be clearly correlated with their crystallinity, depending on the solvents used in their preparation. The film prepared in DMSO shows the highest transmittance and the highest bandgap energy of the prepared films. [ABSTRACT FROM AUTHOR]

In the last two decades, the family of metal halide perovskites has received more attention in radiation detection applications. In this work, the radiation detection and dosimetric applicability of the CsPbBr 3 thin film will be investigated. The impact of gamma irradiation on the structural, morphological, optical, and electrical properties of the CsPbBr 3 thin film has been studied. The CsPbBr 3 thin film was synthesized using a thermal evaporation deposition technique. The deposited thin films were exposed to different gamma-ray doses (0, 25, 50, 75, and 100 kGy) using a 60Co gamma source with an activity of 7.328 kGy/h. X-ray diffraction analysis of the thin films confirmed the orthorhombic crystal structure and also showed an increase in the crystalline and crystallite sizes, whereas the dislocation density and microstrain decreased as the gamma dose increased. Field-emission scanning electron microscopy results revealed that the surface morphology changed considerably due to gamma exposure. The optical properties exhibited a decreasing energy band gap value (from 2.35 to 2.14 eV) as the radiation dosage increased, which may have been due to the increasing crystallite size and induced defects. The photoluminescence (PL) peaks shifted toward longer wavelengths and intensity, while the full width half maxima of PL peaks increased along with the gamma dose, which was attributed to spectral broadening and enhancement in the recombination rate of electron–hole pairs. Impedance spectroscopy of all the irradiated samples showed the single semicircle feature, which is similar to that observed in the case of unirradiated samples. The grain boundary resistance reduced gradually as the gamma dosage increased. The achieved outcomes proved that the structural defects induced by gamma exposure had a superficial influence on the structural, morphological, optical, PL, and impedance properties of CsPbBr 3 thin films. The impact of gamma dose on the properties makes CsPbBr 3 thin films significantly useful as sensing materials. [ABSTRACT FROM AUTHOR]

Luminescent mesoporous Tb(OH)3@SiO2 core-shell nanospheres were synthesized through W/O microemulsion process at ambient temperature. The negatively charged silica favors a coating of the positively charged Tb3+ composite. Thus, silicon layer was adsorbed on the surface of Tb(OH)3 groups to form Tb-O-Si through electrostatic interaction. X-ray diffraction, field emission transmission electron microscopy (FE-TEM), energy-dispersive X-ray spectrometry, and Fourier transform infrared, UV/Visible, and photoluminescence spectroscopies were applied to examine the phase purity, crystallinity, surface morphology, and optical properties of the core-shell nanospheres. The FE-TEM results have revealed typically ordered mesoporous characteristics of the material with monodisperse spherical morphology in a narrow size distribution. The luminescent mesoporous core-shell nanospheres exposed remarkable splitting with broadening in the emission transition 5D4 → 7F5 (543 nm). In addition, the luminescent mesoporous core-shell nanospheres emit strong green fluorescence (from Tb3+) in the middle of the visible region under 325 nm (3.8) excitation. The luminescent mesoporous Tb(OH)3@SiO2 core-shell nanospheres can therefore be exploited as fluorescent probes in biomarkers or biolabeling, optical sensing, and drug delivery system. Further, these nanospheres could have potential use as scattering layers in dye-sensitized solar cells. [ABSTRACT FROM AUTHOR]

The current work examines the effects of cesium lead bromide (CsPbBr3) perovskite quantum dots (PQDs) on the structural and optical properties of conjugated polymer blends of poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene] (MEH–PPV) and poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO). MEH–PPV/PFO composite thin-films containing PQDs with weight ratios between 0.5 wt.% and 10 wt.% were prepared via a solution-blending method prior to spin-coating on glass substrates. The MEH–PPV/PFO composites' crystallinity was improved, and the roughness was dramatically increased with higher PQDs content, as confirmed by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. Conversely, a higher PQDs content resulted in a gradual reduction of the Urbach tail and an increase in the steepness parameter, thereby reducing the localized density of the electronic states within the forbidden bandgap of the hybrids. Moreover, a slight reduction in the direct and indirect bandgaps was found in PQDs/(MEH–PPV/PFO) composite films containing a higher PQDs content and provided evidence of the low concentration of the localized states. The incorporation of the PQDs resulted in enhanced non-radiative energy transfer processes in the MEH–PPV/PFO hybrids, which are very important for the development of optimized optoelectronic devices. [ABSTRACT FROM AUTHOR]

The effect of halide composition on the structural, electronic, and optical properties of CsPb(Br1−xClx)3 perovskite was investigated in this study. When the chloride (Cl) content of x was increased, the unit cell volume decreased with a linear function. Theoretical X-ray diffraction analyses showed that the peak (at 2θ = 30.4°) shifts to a larger angle (at 2θ = 31.9°) when the average fraction of the incorporated Cl increased. The energy bandgap (Eg) was observed to increase with the increase in Cl concentration. For x = 0.00, 0.25, 0.33, 0.50, 0.66, 0.75, and 1.00, the Eg values calculated using the Perdew–Burke–Ernzerhof potential were between 1.53 and 1.93 eV, while those calculated using the modified Becke−Johnson generalized gradient approximation (mBJ–GGA) potential were between 2.23 and 2.90 eV. The Eg calculated using the mBJ–GGA method best matched the experimental values reported. The effective masses decreased with a concentration increase of Cl to 0.33 and then increased with a further increase in the concentration of Cl. Calculated photoabsorption coefficients show a blue shift of absorption at higher Cl content. The calculations indicate that CsPb(Br1−xClx)3 perovskite could be used in optical and optoelectronic devices by partly replacing bromide with chloride. [ABSTRACT FROM AUTHOR]

The structural, electronic, and optical properties of inorganic CsPb(I1−xBrx)3 compounds were investigated using the full-potential linear augmented-plane wave (FP-LAPW) scheme with a generalized gradient approximation (GGA). Perdew–Burke–Ernzerhof generalized gradient approximation (PBE-GGA) and modified Becke–Johnson GGA (mBJ-GGA) potentials were used to study the electronic and optical properties. The band gaps calculated using the mBJ-GGA method gave the best agreement with experimentally reported values. CsPb(I1−xBrx)3 compounds were wide and direct band gap semiconductors, with a band gap located at the M point. The spectral weight (SW) approach was used to unfold the band structure. By substituting iodide with bromide, an increase in the band gap energy (Eg) values of 0.30 and 0.55 eV, using PBE-GGA and mBJ-GGA potentials, respectively, was observed, whereas the optical property parameters, which were also investigated, demonstrated the reverse effect. The high absorption spectra in the ultraviolet−visible energy range demonstrated that CsPb(I1−xBrx)3 perovskite could be used in optical and optoelectronic devices by partly replacing iodide with bromide. [ABSTRACT FROM AUTHOR]

Composite materials with different concentration ratios of a hybrid of zero-dimensional (0-D) Cs4PbBr6 perovskite, which acts as a donor (D), and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), which acts as an acceptor (A), were successfully prepared via a solution blending method prior to being deposited onto glass substrates by a spin-coating technique. The influence of acceptor content on the structural, optical, and energy transfer properties of the donor was investigated. The perovskite nanocrystals formed thin films without any chemical interactions within a matrix of MEH-PPV in the blend. The possibility of dipole–dipole (non-radiative) energy transfer from the 0-D Cs4PbBr6 to the MEH-PPV was proven. The energy transfer parameters such as Ro (critical distance of the energy transfer), kapp (apparent quenching constant), ∅ D A (quantum yield of D in the presence of A), τ D A (lifetime of D in the presence of A), PDA (probability of energy transfer), η (efficiency of energy transfer), RDA (energy transfer radius), kET (energy transfer rate constant), TDR (total decay rate), Ao (critical concentration of A), and Aπ (conjugation length) were calculated based on the absorption and emission measurements. [ABSTRACT FROM AUTHOR]

• The structural, elastic, electronic, magnetic, and optical properties of vacancy-ordered Rb 2 TcCl 6 have been thoroughly examined through the use of first-principles calculations. • The stability of Rb 2 TcCl 6 is demonstrated by the formation energy, optimization curves and phonon curves. • The spin-plarized electronic band structure and density of states (DOS) predict the semiconductor nature in both spin states. • The obtained magnetic moments for Rb 2 TcCl 6 reveal the potential of for spintronics. • An optical band gap with maximum absorption reveals that this compound is also useful for the application in optoelectronics. Due to their versatile properties, vacancy-ordered double perovskites offer a wide range of potential uses due to their versatile properties. We have thoroughly examined the physical characteristics of vacancy-ordered Rb 2 TcCl 6 in its cubic phase by employing the spin-polarized computations. The ground state energy and optimum structural parameters are obtained in order to assess the structural stability, which is further validated using the tolerance factor and formation energy values. The ductile character of Rb 2 TcCl 6 is revealed by a comprehensive evaluation of mechanical properties. Vickers hardness factor suggests that Rb 2 TcCl 6 can withstand against pressure-induced disturbance more strongly. A direct bandgap for spin-up is measured up to 2.33 eV, while for spin-dn it is 2.02 eV. According to the magnetic moments of 2.69 μ B , Rb 2 TcCl 6 is an attractive material for spintronic devices. A number of optical parameters are determined. For optoelectronic applications, Rb 2 TcCl 6 is an excellent choice due to its strong polarization in the visible and ultraviolet regions, as shown by its optical characteristics. [ABSTRACT FROM AUTHOR]

Magnetic double perovskites have garnered significant interest due to their unique magnetic properties and are promising candidates for various spintronic applications. Spin-polarized method is used to investigate the physical attributes of magnetic cubic double perovskites Cs 2 XCeI 6 (X = Li, Na) using density functional theory. Elastic constants and mechanical properties are evaluated to assess the mechanical stability of studied perovskites. The confirmation of the structure stability is accomplished via formation and cohesive energies, optimization plots, octahedral tilting and tolerance factor. Electronic properties revealed that Cs 2 LiCeI 6 possess an indirect bandgap of 2.06 eV and 2.43 eV in spin up and down channels, and Cs 2 NaCeI 6 have an indirect bandgap of 2.30eV and 2.64 eV in spin up and down channels, respectively. The computed magnetic moment for both perovskites is reported as 1 μ B. Kramers-Kronig complex equations are used to analyze the optical behavior. The peak absorption in the UV range is revealed with minimal energy loss for both perovskites. The maximum peaks for optical conductivity and extinction coefficient also observed in UV spectrum. According to an analysis of the derived properties, optoelectronics and spintronic are two areas for which these double perovskites are well suited. [ABSTRACT FROM AUTHOR]

• The effects of compressional strain on double perovskite Rb 3 TlCl 6 using DFT is studied. • The optimization cures, negative formation energy and tolerance factor show the stability. • The compressional strain ranging from 10 % to 70 % resulted into substantial reduction in the bandgap. • A prominent shift in the optical properties towards the visible region after applying the strain is seen. Bandgap engineering provides diverse modifications in semiconducting materials which leads to a wide range of technological applications. In this work, we have employed the effects of compressional strain on double perovskite Rb 3 TlCl 6 using DFT. First and foremost the crystal structure is relaxed via volume optimization. The attained tolerance factor and octahedral tilting values ensure structural stability and cubic formation at room temperature. Rb 3 TlCl 6 when subjected to the compressional strain ranging from 10 % to 70 % resulted into substantial decline in the bandgap from 2.37 eV to 1.88 eV. The computed elastic constants for all applied compressional strains ensure complete mechanical stability. Ductile, anisotropic and endurance to high melting temperatures are reveled via mechanical properties for applied strain effects. The optical properties signify a prominent shift in the properties of Rb 3 TlCl 6 towards the visible region which shows the ability of strain engineering to alter the optical properties of materials, providing opportunities for tailoring their features for a variety of technological applications such as optoelectronics. [ABSTRACT FROM AUTHOR]

Abstract In this paper, titanium dioxide (TiO 2) thin films, deposited on single crystal Si (111) substrates under different temperature conditions by Atomic Layer Deposition (ALD), have been systematically studied by X-ray diffraction, photoluminescence spectroscopy and spectroscopic ellipsometry methods. X-ray diffraction analysis showed that the prepared films have a polycrystalline brookite phase over a growth temperature range of (150–300 °C). Increasing the growth temperature resulted in systematic increase of texturing the polycrystalline grains along the (200) direction, with the film at 300 °C having the highest textur along the (200) direction. This was accompanied by improved photoluminescence of the TiO 2 films with the increasing the growth temperature. The improved crystallinity at higher temperatures was also reflected by higher refractive indices, which were deduced from spectroscopic ellipsometry measurements carried out on the grown films. Highlights • TiO 2 thin films with brookite phase successfully deposited on Si(111) using ALD. • Correlated Structural and optical properties perceived and studied. • Reduction of refractive index observed for films with ultra-small thicknesses. [ABSTRACT FROM AUTHOR]

The crystallization techniques of organic-inorganic hybrid perovskites (OIHP) are considered an effective method for light collector or light emitting applications. In this article, the optical band gap, electron-hole behavior, and energy band alignment are all key optoelectronic properties of crystalline perovskite structures studied in this study. For this reason, a perovskite solution was prepared in a single step and tetrahydrofuran (THF) was used as a solvent to dissolve both perovskite precursors. Rapid crystallization of perovskite in solution was observed, preventing the formation of homogenous perovskite thin films. Subsequently, the effect of THF solvent on the direct crystallization of MAPbI 3 perovskite without thermal annealing was investigated. Thermal annealing is considered necessary for perovskite crystal formation as it gives the molecules enough thermal energy to self-organize and form a well-ordered crystalline layer. The procedures that create perovskite crystals without thermal annealing give a novel method for room temperature film preparation (RT) and pave the way for the manufacture of low-cost, stable perovskite solar cells (PSCs). UV–vis absorption/reflectance, photoluminescence, XRD, and SEM were used to explore the effects of this approach on the optical and structural properties of MAPbI 3 perovskite thin films. • Crystallizing Growth of MAPbI 3 Perovskite Nanorod was demonstrated. • Perovskite precursor solution in THF is dried to form perovskite powder. • Fabrication of perovskite films without annealing. • Perovskite films were tested under ns laser. • The strong light emission allows the observation of ASE. [ABSTRACT FROM AUTHOR]

The structural, electronic, and optical features of CsPb(I 1-x Br x) 3 (x = 0, 0.25, 0.50, 0.75, and 1.0) compounds were evaluated using first-principles calculations based on the full-potential linear augmented plane wave (FP-LAPW). The ground-state properties were examined, with a focus on the structural, electronic, and optical properties of the compounds. The structural features were computed using the PBE-GGA potential, revealing that both the lattice constant and bulk modulus varied nonlinearly with respect to the bromide concentration. Theoretical X-ray diffraction analyses revealed peak shifts to larger angles when the average fraction of bromide incorporated increased, indicating shrinkage in the lattice. While the E g values were calculated using the PBE-GGA potential and resulted the 1.45, 1.43, 1.53, 1.50, and 1.77 eV values, the mBJ-GGA potential values resulted the 1.90, 1.81, 2.11, 2.12, and 2.50 eV for CsPbI 3 , CsPbI 2.75 Br 0.25 , CsPbI 1.5 Br 1.5 , CsPbI 0.25 Br 2.75 , and CsPbBr 3 respectively. In addition to that, the E g values of CsPbI 1.5 Br 1.5 which were calculated using other potentials: LDA and PBEsol potentials have resulted the 1.43 and 1.49 eV values, respectively. The E g of CsPb(I 1-x Br x) 3 obtained using mBJ-GGA potential has relatively matched with previously reported experimental values. The calculated effective masses are highly correlated with the energies of E g, the valence-band maximum (VBM), and conduction-band minimum (CBM). We observed that there was an increase, with small bowing parameters (b), in E g value as the Br concentration increases in the CsPb(I 1-x Br x) 3 compounds. The semiconductor characteristic was prominent in the observed band profiles when PBE-GGA and mBJ-GGA potentials were applied. Additionally, the optical properties were examined in details. The calculations indicate that the CsPb(I 1-x Br x) 3 compounds are promising candidates for optoelectronics. Image 1 • The structural, electrical and optical properties of CsPb(I 1-x Br x) 3 were investigated using the PBE-GGA and mBJ-GGA. • An increase in the band gap energy (Eg) values of 0.32 eV (PBE-GGA) and 0.60 eV (mBJ-GGA) when substituting I with Br. • The calculated band gap (Eg) values using the mBJ-GGA were better matched with the experimental values. • The effective masses of electron and hole were calculated using PBE-GGA and mBJ-GGA potentials. • All the optical properties of CsPb(I1-xBrx)3 were investigated using PBE-GGA and mBJ-GGA potentials in details. [ABSTRACT FROM AUTHOR]