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Nickel (II) oxide, NiO, is a wide band gap Mott insulator characterized by strong Coulomb repulsion between d-electrons and displays antiferromagnetic order at room temperature. NiO has gained attention in recent years as a very promising candidate for applications in a broad set of areas, including chemistry and metallurgy to spintronics and energy harvesting. Here, we report on the fabrication of polycrystalline NiO using spray-pyrolysis technique, which is a deposition technique able to produce quite uniform films of pure and crystalline materials without the need of high vacuum or inert atmospheres. The composition and structure of the NiO thin films were then studied using x-ray diffraction, and atomic force and scanning electron microscopies (SEM). The phononic and magnonic properties of the NiO thin films were also studied via Raman spectroscopy, and the ultrafast electron dynamics by using optical pump probe spectroscopy. We found that the NiO samples display the same phonon and magnon excitations expected for single crystal NiO at room temperature, and that electron dynamics in our system is like those of previously reported NiO mono- and polycrystalline systems synthesized using different techniques. These results prove that spray-pyrolysis can be used as affordable and large-scale fabrication technique to synthesize strongly correlated materials for a large set of applications. [ABSTRACT FROM AUTHOR]

The potential of HfO 2 as a memory semiconductor material with ferroelectric properties in thin-film deposition has been recently analyzed. In this study, the preparation, composition, and physical properties of Al-doped hafnium oxides were analyzed. Hf x Al (1- x) O y (HAO) [ x = 0.33, 0.5, and 0.67] powders were prepared by controlling the ratio of Hf to Al and using ball milling. The HAO powder was calcined at 1000 °C in a furnace and then sintered in a temperature range of 1000–1600 °C by a solid-state reaction method to fabricate high-quality targets with high densities. The density and crystal size increased with the sintering temperature. The 1600-°C Hf 0.67 Al 0.33 O y target was optimal for thin-film deposition. In addition, the target properties were affected by an increase in the HfO 2 content x. The crystal structures and sizes, surface free energies, contact angles, and band gaps of the HAOs were evaluated to analyze their potential as high- k dielectric materials. HAO is a promising high- k dielectric and memory material, valuable for further studies on ferroelectric gate oxide materials. This study contributes to the increasing number of studies on the ferroelectricity of HfO 2 thin films and provides a fundamental understanding of this material and its potential for novel device applications. [ABSTRACT FROM AUTHOR]

Pristine ZnO and nanocomposite ZnO–TiO2 thin films were synthesized using the sol–gel spin-coating method on glass substrates. The thin films of ZnO and ZnO–TiO2 so obtained were calcined at 500°C in order to eliminate the volatile materials and to enhance their crystallinity. The ZnO and ZnO–TiO2 thin films were characterized by UV-Vis spectroscopy, XRD, Raman, FESEM, and FTIR for optical and structural properties. After characterization, the films were irradiated with a beam of 100 MeV Ag7+ ions at a fluence of 2 × 1013 ions/cm2. Both ZnO and nanocomposite ZnO–TiO2 thin films were again characterized after irradiation, and the data was analysed. The XRD results substantiated the preparation of ZnO–TiO2 thin films with peaks corresponding to both wurtzite ZnO and anatase TiO2, thereby verifying the synthesis of nanocomposites. Raman spectra revealed the presence of Raman-active modes at 332 and 438 cm−1, which occur due to optical phonons of ZnO in the synthesized films. The crystallite size was observed to decrease from 22.70 nm to 20.45 nm with TiO2 doping and from 22.7 nm to 16.90 nm for ZnO and 20.45 nm to 13.32 nm for ZnO–TiO2 films on ion beam irradiation. FESEM micrographs reveal a decrease in grain size with both doping and irradiation. The UV–Vis results showed a shift toward the red end of the absorption spectra and consequently the decrease in band gap from 3.32 eV to 3.24 eV and 3.20 eV to 3.14 eV for the ZnO film and the ZnO–TiO2 film, respectively, after the samples were exposed to 100 MeV Ag7+ ion beam at a fluence of 2 × 1013 ions/cm2. [ABSTRACT FROM AUTHOR]

High‐performance electro‐optic (EO) materials greatly enhance modulators and switches in various photonic applications. We investigate the evolution of the tolerance factor (t) and EO coefficient (rc) in A‐site and B‐site doped BaTiO3 (BT) thin films. Our analysis reveals that cation transmutation has a remarkable impact on their dielectric constant, spontaneous polarization, optical band gap, and EO coefficient. Notably, Pb‐doped BT samples exhibit an even higher rc value of 336.5 pm/V, representing a nearly 60% increase compared to pure BT and approximately 11 times larger than that of LiNbO3. This substantial improvement in EO performance can be attributed to enhanced local structural heterogeneity resulting from cation dopants. Furthermore, infusing dopants in BT also result in good structural uniformity and reliable EO performances, regardless of temperature and frequency. Our study offers valuable insights into doping engineering for obtaining functional perovskite oxides, enabling the development of power‐efficient, ultra‐compact integrated nanophotonic devices. [ABSTRACT FROM AUTHOR]

The perovskite solar cells (PSCs) technology translated on flexible substrates is in high demand as an alternative powering solution to the Internet of Things (IOTs). An efficiency of ∼26.1% on rigid and ∼25.09% on flexible substrates has been achieved for the PSCs. Further, it is also reported that F‐PSC modules have a surface area of ∼900 cm2, with a PCE of ∼16.43%. This performance is a world record for an F‐PSC device more significant than ∼100 cm2. The process optimization, and use of new transport materials, interface, and compositional engineering, as well as passivation, have helped in achieving such kind of performance of F‐PSCs. Hence, the review focuses mainly on the progress of F‐PSCs and the low‐temperature fabrication methods for perovskite films concerning their full coverage, morphological uniformity, and better crystallinity. The transmittance, band gap matching, carrier mobility, and ease of low‐temperature processing are the key figures of merit of interface layers. Electrode material's flexible and transparent nature has enhanced the device's mechanical stability. Stability, flexibility, and scalable F‐PSC fabrication challenges are also addressed. Finally, an outlook on F‐PSC applications for their commercialization based on cost will also be discussed in detail. [ABSTRACT FROM AUTHOR]

Three novel non‐fullerene acceptors (NFAs) (PhBu‐IDT‐BT‐IC, PhBu‐IDT‐BT‐IC4F and PhBu‐IDT‐BT‐IC4Cl) based on 3,8‐dioctyl‐indaceno[1,2‐b:5,6‐b’]dithiophene (IDT) core have been designed and synthesized with and without halogen (F and Cl) substitution. The NFAs showed high thermal stability. The ultraviolet–visible absorption studies in solution and thin film for the three acceptors revealed maximum absorption from 687 to 732 nm and 731 to 847 nm, respectively. The onset of absorption in the thin film was found to be extending up to around 960 nm for PhBu‐IDT‐BT‐IC4Cl. The optical band gap ranged from 1.30 to 1.41 eV, which are very low and useful for photovoltaic application. The introduction of halogen appreciably altered the LUMO energy levels, whereas the HOMO energy levels were nearly intact. These small molecule non‐fullerene acceptors could be used as potential acceptors in bulk heterojunction organic photovoltaic (BHJ‐OPV) applications. [ABSTRACT FROM AUTHOR]

The tunability of the transition metal dichalcogenide properties has gained attention from numerous researchers due to their wide application in various fields including quantum technology. In the present work, WS2 has been deposited on fluorine doped tin oxide substrate and its properties have been studied systematically. These samples were irradiated using gamma radiation for various doses, and the effect on structural, morphological, optical and electrical properties has been reported. The crystallinity of the material is observed to be decreased, and the results are well supported by x-ray diffraction, Raman spectroscopy techniques. The increase in grain boundaries has been supported by the agglomeration observed in the scanning electron microscopy micrographs. The XPS results of WS2 after gamma irradiation show evolution of oxygen, carbon, C=O, W–O and SO4−2 peaks, confirming the addition of impurities and formation of point defect. The gamma irradiation creates point defects, and their density increases considerably with increasing gamma dosage. These defects crucially altered the structural, optical and electrical properties of the material. The reduction in the optical band gap with increased gamma irradiation is evident from the absorption spectra and respective Tauc plots. The I–V graphs show a 1000-fold increase in the saturation current after 100 kGy gamma irradiation dose. This work has explored the gamma irradiation effect on the WS2 and suggests substantial modification in the material and enhancement in electrical properties. [ABSTRACT FROM AUTHOR]

Amorphous ZrO2 thin films with increasing Mg content were deposited on quartz substrates, by dip coating method. The films are transparent in the visible domain and absorbent in UV, with an optical band gap that decreases with the increase of Mg content, from 5.42 eV to 4.12 eV. The temperature dependent conductivity measurements showed typical semiconductor comportment. The decrease of the electrical conductivity by Mg doping was related to the increase of the OH groups (37% to 63%) as seen from X-ray Photoelectron Spectroscopy. It was found out that the electrical conductivity obeys the Meyer-Neldel rule. This rule, previously reported for different disordered material systems is obtained for ZrO2 for the first time in the literature. Exploring novel aspects of Mg-doped ZrO2, the present study underscores the origin of the Meyer-Neldel rule explained by the small-polaron hopping model in the non-adiabatic hopping regime. Determination of the presence of such a conduction mechanism in the samples hold promise for comprehending the important aspects, which might be a concern in developing various devices based on Mg-doped ZrO2. [ABSTRACT FROM AUTHOR]

This study presents findings related to the characterization of cubic SnS (π-SnS) thin films and p-SnS/n-Si heterojunction structures produced simultaneously using the ultrasonic spray pyrolysis technique. In this context, the impact of different spray solution flow rates on the morphological, structural, optical, and electrical characteristics of the films was examined. Morphological analyses revealed that higher flow rates resulted in films with denser and smoother surfaces, approximately 6 nm in roughness. Additionally, it was observed that both the thickness and the growth rate of the films could be adjusted through the modulation of the flow rate. Structural analyses determined that the crystallite size increased and micro-strain values decreased with increasing flow rates. Optical evaluations indicated a decline in the optical band gap of the thin films from about 1.8 eV to 1.7 eV as the flow rates increased. This trend was consistently observed in the data obtained using the Tauc method and the derivative of transmission with respect to wavelength versus photon energy graphs. Electrical analyses revealed that the resistivity values of the thin films increased from 5.24 × 105 Ωcm to 1.64 × 106 Ωcm with increasing flow rates. Furthermore, I-V analyses of the Au/p-SnS/n-Si/Ag heterojunction structures indicated significant variability in key electrical properties. The saturation currents displayed a broad range, suggesting varying efficiencies in charge carrier collection across different samples. Similarly, the change of ideality factors pointed to differences in charge transport mechanisms, while the shifts in barrier heights indicated changes in junction properties with different fabrication conditions. The results of this study offer valuable perspectives for future research. [ABSTRACT FROM AUTHOR]

Silver (Ag), not only alters the electrical and optical properties of ZnO thin films but also has the ability to enhance its ultraviolet (UV) emission. However, the mechanism for the UV emission enhancement has not been clearly understood. The study focused on optimization of the optical properties of pristine and Ag-doped ZnO films through variation of preparation and post deposition parameters. The prepared pristine and Ag-doped ZnO films were found to be polycrystalline in nature with diffraction peaks corresponding to ZnO and Ag phases. Increase in Ag and annealing temperature led to increase in the transmittance of Ag-doped ZnO films. The refractive index was found to increase with a decrease in substrate-source distance, an increase in Ag concentration, film thickness, and annealing temperature. The extinction coefficient for the analysed films was found to decrease with increase in substrate-source distance and annealing temperature, but increased with increase in film thickness. An inherent dissipation of electromagnetic energy in pristine and Ag-doped ZnO films was observed due to strong interaction between low and wide optical band gap energies of Ag and ZnO, respectively. The optical band gap energy increased with an increase in substrate-source distance, decreased with an increase in film thickness and annealing temperature at a wavelength, λ = 650 nm . The observed trends have been explained based on polarizability, reduced structural defects, thermal expansion, and lattice vibrations in pristine and Ag-doped ZnO films. The obtained optimized properties show that Ag-doped ZnO films are good candidates for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Herein, polycrystalline magnesium selenide (MgSe) thin films are deposited onto glass and monoclinic-structured zinc phthalocyanine (ZnPc) thin film substrates under high vacuum pressure using the thermal evaporation technique. ZnPc substrates improved the crystallinity of the MgSe films and decreased the stacking faults percentages and defect concentration by 31.57 and 52.49%, respectively. MgSe films deposited onto ZnPc substrates exhibited a notable increase of up to 32% in light absorption within the visible spectrum, while maintaining the energy band gap value of MgSe without significant alteration. In addition, as both the substrate and the epilayer exhibited p-type conductivity, an isotype heterojunction device structure is formed at the ZnPc/MgSe interfaces. The valence and conduction band offsets for this interface are 0.81 and 1.16 eV, respectively. On the other hand, re-fabrication of the ZnPc/MgSe heterojunctions onto Al thin film substrates and forming three Ag/MgSe, C/MgSe, and Au/MgSe Schottky channels on the epilayer surface allowed wide control of the negative capacitance effect and the resonance-antiresonance (RA) peaks in the capacitance spectra of the Al/ZnPc/MgSe/(Ag, C, Au) hybrid devices. These two important RA and NC features of the device can also be engineered by altering the DC biasing of the device. Moreover, Lorentz model analyses on the capacitance spectra showed an increased density of oscillators and increased scattering time constant with decreasing built-in potential at the metal/MgSe interfaces. The features of the hybrid devices presented make the device promising for microwave and electro-optical applications. [ABSTRACT FROM AUTHOR]

In recent years, semiconductor devices are developing towards high heat dissipation, high breakdown field strength and low energy consumption, so the ultra-wide band semiconductor material β-Ga2 O3 has a broad application prospect. However, effective doping is the basis for realizing β-Ga2 O3 devices. In this paper, Ga2O3/Al/Ga2O3/Al/Ga2O3 composite structure is experimentally prepared by magnetron sputtering, and the Al atoms are thermally diffused into the film by high-temperature annealing at the same time, so as to form Al-doped β-Ga2O3 thin film. Then, the laser zone melting method was used to melt and recrystallize the film area to further enhance the doping quality. The Al-doped β-Ga2O3 thin films were tested and characterized in terms of crystal properties, impurity content and optical properties. The experimental results show that: Al doping basically does not change the crystal structure of β-Ga2O3 thin films; the impurity content is gradually enhanced as the sputtering time of the Al layer becomes longer; in terms of the optical properties, the ultraviolet (UV) absorptivity of the films is 40% and 50% when the Al sputtering time is 5 and 10 s, and the UV absorption of the Al-doped β-Ga2O3 thin films is gradually enhanced with the increase of Al sputtering time; the light absorption of β-Ga2O3 thin film is close to 90% when the Al sputtering time is 300 s; and the low concentration of Al doping leads to the narrowing of the band gap width of β-Ga2O3 thin film. [ABSTRACT FROM AUTHOR]

Silver indium selenide (AgInSe2) has been proposed as an efficient absorber material for sustainable solar cells. Phase pure preparation of this exotic material in the nano regime is highly desirable. This report describes the design and synthesis of a new heterobimetallic complex [(Ph3P)2Ag(μ-SeCH2Ph)2In(SeCH2Ph)2] along with its structural characterization. This complex acts as an air enduring, normal temperature and pressure (NTP) stable versatile single source precursor for synthesizing bulk, nanocrystalline and thin film of AgInSe2. The crystal structure, phase purity, morphology, elemental composition and band gap of the synthesized materials were determined from powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and diffuse reflectance spectroscopy (DRS-UV), respectively. The band gap of the nanocrystalline AgInSe2 lies in the range suitable for solar cell applications. A prototype photoelectrochemical cell fabricated with the pristine AgInSe2 nanoparticles exhibits high photoresponsivity, which makes them a suitable candidate for clean energy applications. [ABSTRACT FROM AUTHOR]

Four new donor–acceptor conjugated polymers based on the acceptor block 8,10-bis(2-octyldodecyl)-8H-dithieno[3′,2′:5,6;2′′,3′′:7,8]naphtho[2,3-d]imidazole-9(10H)-one and various donor moieties were synthesized. Binary and ternary composites comprising new polymers, PC71BM fullerene and non-fullerene acceptors based on indacenodithiophene, were developed. The mobility of electrons and holes in thin films of the ternary composites is balanced in contrast to that in binary composite films. This is explained by less aggregation in the ternary composite films and good matching of the frontier orbital energy levels of the composite components. [ABSTRACT FROM AUTHOR]

In this study, we fabricated deep ultraviolet (DUV) photodetectors based on perovskite thin films doped with halide materials using formamidinium bromide (FABr) and methylammonium iodide (MAI). The device was fabricated using a simple surface engineering technique by post-treating the MAPbI3 perovskite film with an FABr solution. This film acts as a light absorption layer, like a depletion layer with a p-i-n (PIN) structure, with n-type of SnO2-SDBS and p-type of spiro-OMeTAD. Adding 0.10 M MACl to the MAPbI3 precursor solution during the manufacturing process could effectively reduce the trap density compared with existing films. Films with MACl added in the two-step process can control a wide band gap and improve crystallinity. In addition, the Cl atom has a smaller atomic radius than iodine and a higher electronegativity of 3.16, which can improve phase stability, and the effect of the added Cl− increases the electron mobility of the perovskite, showing a fast response. [ABSTRACT FROM AUTHOR]

The development of highly efficient deep red materials with emission wavelength beyond 650 nm remains a big challenge due to the constraints imposed by the energy gap rule. In this work, a donor‐acceptor‐donor type emitter, 4,7‐bis (10‐(4‐(tert‐butyl) phenyl)‐10H‐phenothiazin‐3‐yl) benzo[c][1,2,5] thiadiazole (TBPPTZ) is designed and synthesized. Resulting from the slight twist angle between the donor and acceptor units, TBPPTZ exhibits nearly planar conformation and an extended conjugated structure. TBPPTZ shows a deep red emission peak at 687 nm and aggregation induced emission property with a high photoluminescence quantum yield of 45 % in neat thin film. The optimized organic light‐emitting diode (OLEDs) utilizing TBPPTZ as the non‐doped emissive layer obtains a high external quantum efficiency (EQE) up to 2.51 % with an electroluminescence (EL) peak at 676 nm, aligning with the Commission Internationale de L'Eclairage (CIE) coordinates (0.68, 0.31), which shows a small EQE roll‐off of only 5.6 % at 100 cd m−2. Additionally, the doped OLED achieves an EQE up to 5.09 %, with an EL peak at 656 nm and CIE coordinates of (0.65, 0.34). The findings of this research not only contribute to achieve highly efficient deep red OLEDs but also offer a novel and effective deep red molecular strategy to realize high‐quality OLEDs. [ABSTRACT FROM AUTHOR]

The synthesis of photodetectors for ZnO nanostructure films on various substrates, including p-type (100) silicon (Si), and porous silicon (pSi), has been achieved through the utilization of a straightforward technique known as the successive ionic layer adsorption and reaction (SILAR) method. To analyze the optical properties, surface morphology, and crystal structure of the ZnO layers, UV-Vis spectrometers, field emission scanning electron microscopes (FESEM), and X-ray diffraction (XRD) were employed. The characterization of the ZnO samples revealed that the number of SILAR cycles has a significant impact on the morphology and optical band gap of the synthesized layer. The Fourier-transform infrared (FTIR) spectrum successfully detected the distinctive extended vibration mode of ZnO. By conducting 20 cycles, high-quality hexagonal ZnO was obtained. The responsivity of the planar ZnO on silicon (ZnO/Si) and ZnO on the porous silicon (ZnO/pSi) surface exhibited variations depending on the substrate surface and bias voltage. The results indicated that the (ZnO/pSi) heterojunction demonstrated a high response in the visible range (350–850 nm) at a low bias voltage. On the other hand, the (ZnO/Si) photodetector displayed a high sensitivity of 666.66% at a low voltage of 1V in comparison to the (ZnO/pSi) photodetector, which exhibited a sensitivity of 483%. [ABSTRACT FROM AUTHOR]

Methylammonium iodide (MAI) and methylammonium bromide (MABr) reactants were synthesized in powder form. Tin-based perovskites (MASnIxBr3−x (x = 3, 2, 1, 0)) were deposited as a thin film on glass substrates using the ultrasonic spray pyrolysis (USP) method. X-ray diffraction (XRD) was used to examine the crystallographic characteristics of the synthesized MAI/MABr powders and perovskite thin films. A shift occurred in the XRD peaks by changing the I/Br ratios. Morphological analysis of the MAI and MABr were carried out by scanning electron microscopy (SEM). While the average particle size was calculated a ~ 94 μm for MAI, it was obtained as ~ 188 μm for MABr. The Fourier transform infrared (FTIR) spectroscopy peaks observed for synthesized MAI and MABr were found to be compatible with commercial MAI and MABr FTIR peaks. Elemental analysis of MASnIxBr3−x (x = 3, 2, 1, 0) perovskite thin films was performed energy dispersive spectroscopy (EDS). Forbidden band gap (Eg) values of perovskite thin films were obtained from Tauc curves. The Eg value increased with an increasing I/Br ratio. The deposition of highly stoichiometric MASnIxBr3–x perovskites thin films was achieved by the USP method. This method has many parameters need to be optimized. This study gives optimum parameters that are difficult to determine. [ABSTRACT FROM AUTHOR]

The (SnS) thin films were prepared by Successive Ionic Layer Adsorption and Reaction (SILAR), a versatile and simple method. The cationic and anionic solutions SnCl2.2H2O and Na2S.9H2O respectively were used as precursor materials, which will be deposited on glass substrates to study the effect of rinsing temperature on the properties of our thin films. The structural, morphological, and optical properties were investigated by using X-ray diffraction, Energy Dispersive X-ray analysis (EDX), Scanning Electron Microscopy (SEM) and spectrophotometer. X-ray Diffraction (XRD) patterns indicated that the deposited SnS thin films have an orthorhombic crystal structure. Uniform deposition of the material over the entire glass substrate was shown by Scanning Electron Microscopy (SEM). The optical band gap energy ranged from 1.5 to 1.82eV for direct transitions and from 0.6 to 0.95eV for indirect transitions. [ABSTRACT FROM AUTHOR]

This work aims to examine the optoelectrical, optical, and structural properties of novel polycrystalline SrZnO2 layers fabricated by a cost-effective nebulizer spray pyrolysis procedure at varying thicknesses (237, 395, 468, and 529 nm). The X-ray diffractograms have been used in this work to study the structure of the SrZnO2 films. The SrZnO2 films possessed an orthorhombic structure. The computational analysis involved determining the structural indices, including grain size, dislocation density, and lattice strain, of the SrZnO2 films. Energy dispersive X-ray analysis has been used to verify the stoichiometry of these SrZnO2 films. The surface morphology of the SrZnO2 layers has been studied using the field-emission scanning electron microscope. The optical characteristics of the SrZnO2 films have been investigated by the spectrophotometric measurements in the range 400–2500 nm. The optical results of the SrZnO2 films depicted that the enhancement of the refractive index, Urbach's energy, and absorption coefficient of these films by boosting the thickness. Meanwhile, the improvement in the crystallization process led to a small decrease in the optical band gap energy values of the SrZnO2 layers from 2.91 to 2.68 eV as the film thickness grew. Furthermore, the analysis of the optoelectrical characteristics of the SrZnO2 films showed that the boost in film thickness enhanced the values of plasma frequency, optical resistivity, optical carrier concentration, optical mobility, and optical conductivity. The nonlinear optical properties of the SrZnO2 layers have been boosted by the thickness growth. On the other hand, the hot probe equipment revealed that both the SrZnO2 layers exhibited n-type semiconducting characteristics. The acquired results validate the wide bandgap semiconductor nature of these films. Consequently, it is advisable to use them as a window layer in various solar cell applications. The electrical results illustrated that the estimated activation energy of the SrZnO2 films decreases as the thickness rises. [ABSTRACT FROM AUTHOR]

In this paper, we analyzed the structural and optical properties of quaternary semiconductor Cu2ZnSnSe4 (CZTSe) thin film. For this purpose, the structural properties of CZTSe thin film were analyzed using X-ray diffraction (XRD) and transmission electron microscopy (TEM). CZTSe nanocrystals (NCs) were formed in the kesterite phase and with good crystallinity. Optical characterization of thin film was investigated using spectroscopic measurements. Optical parameters of CZTSe film coated using the spin coating technique were determined by UV-Vis-NIR spectroscopy. The refractive index, extinction coefficient, and dielectric constant of the thin film were calculated using transmittance and reflectance data. Moreover, dispersion parameters such as oscillator energy, and dispersion energy were obtained by the Wemple DiDomenico model. For CZTSe film in the visible wavelength region, the transmission has values of 70–75%. The thin film of CZTSe has a direct band gap of 1.4 eV which is suitable for absorbed layer for solar cell. [ABSTRACT FROM AUTHOR]

Thin films of zinc sulfide (ZnS) with varying thicknesses have been successfully fabricated using radio frequency magnetron sputtering on glass substrates at a temperature of 300 K. Structural analysis via X-ray diffraction and selected area electron diffraction confirmed the presence of nanocrystalline cubic ZnS phases in the films. The crystallite size, determined from X-ray diffraction lines, ranged between 42 and 55 nm. We also explored the morphological attributes of these surfaces and observed significant changes in both grain shape and size. Our atomic force microscopy analyses revealed that the thinner film displayed a topography marked by thinner, elongated rough peaks. As the film thickness increased, these rough peaks gradually transformed into wider, flatter features. Additionally, the films exhibited distinct percolation properties, which were undeniably tied to the alterations in the shape and size of the ZnS grains on their surfaces. Thinner samples demonstrated more pronounced surface percolation (FS > 0.5) compared to thicker samples, which displayed reduced surface percolation. Furthermore, we noted that the 250 nm film predominantly showcased strongly multifractal 3D spatial patterns in contrast to the other films. Spectroscopic measurements in the UV–visible-near infrared region revealed high transparency across the 350–850 nm spectra, with a noticeable blue shift in the absorption edge. Calculations yielded direct allowed band gaps within the range of 3.69–3.85 eV. These results indicate that the optical properties of films can be tailored by their structural and morphological characteristics, thereby offering valuable guidance for their appropriate applications. [ABSTRACT FROM AUTHOR]

In this study, novel Li2ZnSnS4 (LZSS4) thin films have been manufactured using the inexpensive spray pyrolysis system. The study of the X-ray diffraction (XRD) of the LZSS4 films demonstrated that these LZSS4 samples have crystalline structures with monoclinic phases. The elemental analysis of the LZSS4 samples refers to the presence of Li, Zn, Sn, and S in the LZSS4 samples. Their ratio is near 2:1:1:4. Meanwhile, the linear optical study of the LZSS4 samples indicates that the LZSS4 samples have a direct energy gap (Eg), and the growth of thickness led to a decrease in the Eg values from 1.73 eV to 1.48 eV. Conversely, the refractive index of the LZSS4 samples increases from 2.56 to 4.18 by raising the thickness of the investigated samples. Moreover, the Wemple-Didomenico single oscillator model was applied to compute the dispersion parameters of the LZSS4 samples. It was found that the dispersion energy, Ed, improved from 15.87 to 17.26 eV, and the oscillator energy, Eo, dropped from 6.44 to 4.91 eV by raising the thickness from 261 to 486 nm. Also, the study of the optoelectrical and nonlinear optical parameters refers to enhancing the non-linear refractive index (n2), optical resistivity (), optical carrier concentration (), relaxation time (τ), and optical mobility (). [ABSTRACT FROM AUTHOR]

Adopting an integrated and consolidated strategy to energy generation, conversion, and storage is linked to energy sustainability in the modern day. Current investigation explores the lanthanide triple doping mechanism coupled with temperature optimization using (cerium, praseodymium, and neodymium)-oxide to modify CsPbI 2.2 Br 0.8 forming the stable [Ce3+-Pr3+-Nd3+]:CsPbI 2.2 Br 0.8 (CPN:CPVSK) hetero-system. CPN:CPVSK thin films have remarkable optical output for the prolonged duration of 28 days with the band gap energy spanning around 1.64–1.67 eV. These thin films have cubic phase with the 65.44 nm average crystallite size and these thin films have excellent surficial binding without any holes or cracks. CPN:CPVSK was employed as an active light trapping material inside perovskite solar cells processed and analyzed at ambient conditions. The temperature increment from 100 to 200 °C subsequently lead to improvement in efficiency from 6.91% to 15.5% with considerable improvement in fill factor. CPN:CPVSK effectively generated pure H 2 with the minor overpotential and Tafel slope values of 132 mV and 122.3 mV dec−1 while the O 2 production activity was unappreciable. CPN:CPVSK is a potential material for battery application with the excellent unit capacity of 354 mA H g−1 and lower R s of 0.44 Ω. Rare earth doped perovskite material is a sustainable, cost effective, and facile to prepare with the greater candidature for practical applications. [ABSTRACT FROM AUTHOR]

NiV2O6 thin films were grown on glass slides with varying thicknesses using nebulizer spray pyrolysis. The impact of thickness on the thin films' optical, structural, morphological, and electrical characteristics was systematically investigated. X-ray diffraction and micro-Raman analysis confirmed the formation of the triclinic NiV2O6 system. Surface morphology and roughness variations in the as-deposited NiV2O6 films were studied using scanning electron microscopy (SEM) and a profilometer. Optical properties, including optical band gap (Eg), extinction coefficient (k), absorption coefficient (α), and refractive index (n), were determined through optical reflectance and transmittance measurements. The optical energy gap of the as-deposited NiV2O6 films decreased from 2.02 eV to 1.58 eV with increased layer thickness. Furthermore, the photo-detectivity of the films demonstrated an enhancement corresponding to the prolonged spray time. The sensitivity values obtained for visible irradiation were 328, 511, and 433 for samples S1, S2, and S3, respectively. The obtained results can be imputed to the specific porous microstructure. [ABSTRACT FROM AUTHOR]

We conducted a simple solution-based method to fabricate Bi2S3 nanowire thin film solar cells by spin coating with varying sulfur-to-bismuth ratios. Spherical nanoparticles were observed in the thin film with low-concentration sulfur solution, with these nanoparticles gradually changing to nanorods. Finally, nanowires of Bi2S3 were observed in the thin film with a high sulfur concentration in solution. The band gap gradually decreased with the increase in sulfur concentration. The solar cell performance was significantly improved with the nanowire structure. During film fabrication, sulfur vacancy defects appeared primarily because of high annealing temperatures. These defects were somewhat reduced by the high concentration of sulfur in the solution, supported by the energy-dispersive x-ray spectroscopy (EDS) results. The elemental chemical composition of Bi2S3 material showed an increase in the sulfur-to-bismuth ratio, reaching saturation at almost 0.9. In this work, we systematically observed the effect on the optical properties, surface morphology, and photovoltaic properties by changing the concentration of sulfur in the precursor. The nanowire structure with a high concentration of sulfur in the solution is a promising way to improve the Bi2S3 thin film solar cell. [ABSTRACT FROM AUTHOR]

In this work, numerical simulations were employed to examine the influence of thickness and band gap energy of the Cu2ZnSnS4 (CZTS) absorber and Zn(O,S) buffer layer on the performance of the earth-abundant and nontoxic Mo/Cu2ZnSnS4/Zn(O,S)/i-ZnO/ZnO:Al structure. Firstly, simulation was performed on the CZTS-based solar cell with experimental values of thickness (610 nm) and band gap energy (1.51 eV) obtained for the absorber layer CZTS. We found an open-circuit voltage Voc = 1.17 V, a short-circuit current density Jsc = 23.26 mA/cm2, a fill factor FF = 57.31%, and a conversion efficiency η = 15.61%. Then we varied the thickness (from 500 nm to 3000 nm) and gap (from 1.40 eV to 1.60 eV) of CZTS thin film and concluded that the optimized thickness and band gap energy were 2400 nm and 1.48 eV, respectively. Finally, we used these values to found the optimal performance of the device. The optimized results were FF = 21.24%, Jsc = 28.05 mA /cm2, Voc = 3.63 V, and η = 21.64%. It is noted that the solar cell performance remained stable by varying the thickness and gap energy of the Zn(O,S) buffer layer. [ABSTRACT FROM AUTHOR]

Lead sulfide (PbS) colloidal quantum dots (CQDs) is emerging as a promising material for infrared photodetectors because of its strong absorbance in the near infrared region, the tunable energy gap, facile fabrication, and excellent electrical properties. This Tutorial gives a comprehensive introduction of materials and devices of PbS CQD based infrared photodetectors. First, we introduce the concept of CQDs and the typical characters of CQDs. The synthesis of PbS CQDs and a solid film fabrication method are then summarized. Subsequently, the study for defect passivation and carrier transport in a PbS CQD thin film is presented. In the end, the device structure, the electrical diagram, and strategies for enhancing device performance of three kinds of infrared photodetector are concluded. [ABSTRACT FROM AUTHOR]

Pulsed laser deposition (PLD) technique was used to grow undoped, Eu-doped, and Sm, Dy, and Er-co-doped YVO4 thin-film phosphor samples on silica substrates at in situ substrate temperature of 650 °C. The thin films were characterized by grazing incidence X-ray diffraction (GIXRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray, Raman, UV–visible, and photoluminescence (PL) spectroscopic analysis. GIXRD studies confirmed the formation of crystalline tetragonal phase of YVO4 with unit cell parameters: a = b = 7.10 Å and c = 6.27 Å. FESEM studies showed uniform and dense surface morphology of the samples. The thickness of undoped, Eu-doped, and co-doped films was 164, 434, and 217 nm, respectively, and the average particle size was 112, 122, and 127 nm, respectively. The crystallite size was in range of 31–48 nm. Energy-dispersive X-ray elemental mapping scans confirmed the uniform distribution of rare earth ions on the surface without any agglomeration effects in highly stoichiometric YVO4 films. The optical band gap energy of the thin-film samples was found to lie in the range of 4.6–4.9 eV and PL studies found strong blue, red, and white light emission from undoped, Eu-doped, and co-doped YVO4 thin-film samples, respectively, due to an effective energy transfer from the vanadate group to the dopant rare earth ions. [ABSTRACT FROM AUTHOR]

Multi-oxide photocatalytic materials derived from metal organic frameworks (MOFs) are attracting widespread attention in recent years. The heterostructure originating from oxide–oxide junctions and nonmetal doping due to the combustion of organics from MOFs provide desirable properties to the photocatalytic material. In this study, the effects of annealing temperature on the material properties and photocatalytic activity of ZIF-8-derived ZnO/TiO2 thin films were investigated. XRD, XPS, and FTIR analyses confirmed the oxidation of ZIF-8 to ZnO and SEM analysis revealed the formation of a porous structure at the annealing temperature of 500 °C. UV–Vis analysis indicated that the band gap energy decreased from 3.23 to 2.04 eV with increasing annealing temperature. Photocatalytic methylene blue degradation experiments showed that the thin film annealed at 500 °C had higher activity than the films annealed at lower temperatures. The thin film annealed at 500 °C had more than two times the dye degradation efficiency of the film annealed at 400 °C (72% and 33%, respectively). This film was also active in the photocatalytic degradation of caffeic acid which is a colorless pollutant. The high photocatalytic activity of the thin film annealed at higher temperature was attributed to its narrower band gap energy, higher porosity, and more efficient electron–hole separation, which are due to the presence of heterostructure, nonmetal doping, and deficient zones formed by the oxidation of imidazole rings. [ABSTRACT FROM AUTHOR]

Chalcogenide perovskites are a family of compounds related to perovskite structures or compositions, which have witnessed rapid advances in recent years. They possess favorable properties such as high stability, low toxicity, direct band gaps, good carrier transport abilities, strong light absorption, and potential luminescent properties, making them stand out in emerging applications, such as photovoltaics, photodetectors, light-emitting devices, and photocatalysts, among others. In this review, we aim to provide a comprehensive overview of the properties, synthesis, and applications of chalcogenide perovskites. First, we first survey the reported material structures/compositions and current understanding of their structural/optical/electrical properties, mechanics, magnetics, and stabilities. Furthermore, we discuss the synthesis strategies of these materials covering various material types such as powders, pellets, thin films, nanocrystals, and single crystals, with a focus on their potential applications, including photovoltaics, photodetectors, and other devices. Finally, we outline a brief conclusion and some prospects for the further research of chalcogenide perovskites, thus promoting more studies and developments in this field. This review can provide new insights into the fundamental properties and potential applications of chalcogenide perovskites, and thereby facilitating their further studies and developments. [ABSTRACT FROM AUTHOR]

This study reports the successful synthesis of a new copolymer based on N-vinylcarbazole (NVC) and Eriochrome black T (EBT) monomers as well as (nano)composites based on carbon nanotubes (CNTs) as nano-filler. For this, the copolymer poly (N-vinylcarbazole-co-black eriochrome T), noted poly (NVC-co- EBT) was synthetized by electro-copolymerization of the selected monomers deposited on Indium Tin Oxide (ITO) electrode in lithium perchlorate electrolyte, using cyclic voltammetry method. The (nano)composites poly (NVC-co- EBT)/CNTs were synthesized in the same conditions as the copolymer, in presence of different CNTs content (3 wt. %, 5wt. %, 10 wt. %). The electrodeposition of the copolymer (nano)composites was successfully occurred after the first cycle and thin films were formed. Remarkably, their thickness was increased by increasing the cycle's numbers. The electro-chemical properties of the new copolymer, as well as (nano)composites, were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The synthesized (nano)composites display a diffusion process related to Warburg impedance, for a low and intermediate frequencies but they exhibit a capacitive behavior at high frequencies which implies the increase of the conductivity character. Furthermore, the obtained copolymer poly (NVC-co- EBT) exhibits low transmittance in the UV–visible region, with a gap energy value of 1.95 eV. Interestingly, by doping with CNTs nano-filler at 3 wt. % and 5 wt. %, the energy gap was relatively increased to achieve a value of 2.41 eV and 2.71 eV, respectively. Therefore, at 10 wt. % of CNTs, the energy gap of the copolymer (nano)composite becomes equal to zero. Consequently, these results highlight the importance of the synthesized copolymer to have a semi-conductor and conductor behavior according to the CNTs content in the material, which promote its application in many devices, as photocatalysis and photovoltaic fields. [ABSTRACT FROM AUTHOR]

In the present paper, we have conducted both theoretical and experimental investigations on thin films of lead sulfide (PbS). The structural and morphological properties of these films, which were prepared using the spray pyrolysis method, were analyzed utilizing X-ray diffraction (XRD) and scanning electron microscopy (SEM). Theoretical calculations were performed employing the first principles full potential linearized augmented plane wave (FP-LAPW) approach. The findings of this study reveal that the PbS film that was deposited is polycrystalline and possesses a rock-salt structure. The SEM image depicts a planar structure with dimensions ranging from 480 to 930 nm. The results obtained through energy dispersive spectroscopy (EDS) indicate high crystalline quality, and the film surface exhibits a rough texture and a dense morphology. In terms of its behavior, PbS acts as a semiconductor with a direct optical band gap situated at the L point of the Brillouin zone (BZ). The density of states on both sides of the band gap is primarily of s-p character. The ionic nature of PbS can be attributed to charge transfer. A substantial level of agreement has been observed between the experimental and theoretical results. Our ongoing research endeavors aim to explore biosensors and their various applications. The novelty of this work lies in the combined study of the structural and morphological properties of PbS films grown using the spray pyrolysis technique, employing both experimental and theoretical approaches. This paper describes a comprehensive approach to understanding bulk and thin-film PbS materials through theory and experimentation. [ABSTRACT FROM AUTHOR]

As part of this study, we elaborated and characterized samples of thin layers of cobalt oxide, doping them with different concentrations of nickel (2%, 4% and 6%). These films were deposited on ordinary glass substrates at a temperature of 400 °C, with a deposition time of 5 min, using the spray pyrolysis technique. The main objective of this research was to explore the influence of nickel doping on the physical properties of cobalt oxide. The results obtained by Raman spectroscopy confirmed the presence of Co+2 cations located in tetrahedral sites and Co+3 in octahedral sites, thus validating the spinel-type cubic structure. Morphological analysis revealed that the incorporation of nickel into the Co3O4 thin films, synthesized by spray pyrolysis, resulted in a significant transformation of the porous surface morphology. This transformation resulted in the transition from a porous structure to a dense and uniform configuration, characterized by nanoflower grains. Analyzes by EDS spectrometry revealed peaks associated with the elements Co and O, thus confirming the composition of the films. An improvement in the durability and overall performance of the solar device in humid environments by obtaining the hydrophobic character (CA = 99°) for the Co3O4/6%Ni film. The transmittance decreased with increased as a function of Ni concentration. Optical studies show direct band gaps Eg1 and Eg2 varying between 1.41 and 1.3 eV and between 2.09 and 1.99 eV respectively. Notably, the electrical resistivity experienced a significant decrease from 28.39 to 0.178 Ω.cm for the undoped and 2% Ni-doped films, respectively. However, for Ni concentrations ≥ 4%, the electrical resistivity increased from 3.47 to 10.2 Ω cm. [ABSTRACT FROM AUTHOR]

Bi2S3 has gained considerable attention as a semiconductor for its versatile functional properties, finding application across various fields, and liquid phase exfoliation (LPE) serves as a straightforward method to produce it in nano-form. Till now, the commonly used solvent for LPE has been N-Methyl-2-pyrrolidone, which is expensive, toxic and has a high boiling point. These limitations drive the search for more sustainable alternatives, with water being a promising option. Nonetheless, surfactants are necessary for LPE in water due to the hydrophobic nature of Bi2S3, and organic molecules with amphoteric characteristics are identified as suitable surfactants. However, systematic studies on the use of ionic surfactants in the LPE of Bi2S3 have remained scarce until now. In this work, we used sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS) and sodium hexadecyl sulfonate (SHS) as representative species and we present a comprehensive investigation into their effects on the LPE of Bi2S3. Through characterizations of the resulting products, we find that all surfactants effectively exfoliate Bi2S3 into few-layer species. Notably, SDBS demonstrates superior stabilization of the 2D layers compared to the other surfactants, while SHS becomes the most promising surfactant for obtaining products with high yield. Moreover, the resulting nano-inks are used for fabricating films using spray-coating, reaching a fine tuning of band gap by controlling the number of cycles, and paving the way for the utilization of 2D Bi2S3 in optoelectronic devices. [ABSTRACT FROM AUTHOR]

The tandem solar cell presents a potential solution to surpass the Shockley–Queisser limit observed in single-junction solar cells. However, creating a tandem device that is both cost-effective and highly efficient poses a significant challenge. In this study, we present proof of concept for a four-terminal (4T) tandem solar cell utilizing a wide bandgap (1.6–1.8 eV) perovskite top cell and a narrow bandgap (1.2 eV) antimony selenide (Sb2Se3) bottom cell. Using a one-dimensional (1D) solar cell capacitance simulator (SCAPS), our calculations indicate the feasibility of this architecture, projecting a simulated device performance of 23% for the perovskite/Sb2Se3 4T tandem device. To validate this, we fabricated two wide bandgap semitransparent perovskite cells with bandgaps of 1.6 eV and 1.77 eV, respectively. These were then mechanically stacked with a narrow bandgap antimony selenide (1.2 eV) to create a tandem structure, resulting in experimental efficiencies exceeding 15%. The obtained results demonstrate promising device performance, showcasing the potential of combining perovskite top cells with the emerging, earth-abundant antimony selenide thin film solar technology to enhance overall device efficiency. [ABSTRACT FROM AUTHOR]

The objective of this study is to thoroughly investigate the synthesis and application of a thin film MnS2:CoS:Al2S3. To produce the thin film, diethyldithiocarbamate as a source of sulphur through a technique called physical vapour deposition was utilized. A wide range of analytical techniques were used to examine the structural, morphological, and optical properties of the fabricated material. X‐ray diffraction (XRD) analysis revealed the crystallite size 26.4 nm with a crystallinity of 77%. The optical properties determined the band gap energy to be 4.02 eV. Cabbage‐like assemblies were confirmed through scanning electron microscopy (SEM). X‐ray photoelectron spectroscopy unveiled distinct core level peaks associated with Mn 2p, Al 2p, Co 2p, and S 2p. To evaluate the electrochemical properties of the material, voltammetry measurements were conducted. The results from these experiments revealed an exceptional specific capacitive performance with a value of 792.6 Fg−1. This outstanding performance, coupled with the notable stability of the thin film during multiple cycles, positions it as a highly promising candidate for various energy storage applications. Furthermore, an extensive investigation was carried out to assess the photocatalytic capabilities of the fabricated material. Its efficiency in degrading different environmental pollutants was carefully evaluated. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of alpha particle irradiation on the optical characteristics of zinc oxide (ZnO) thin films, which were produced using various concentrations. A zinc oxide thin film was fabricated using the chemical bath deposition (CBD) technique, and glass was selected as the substrate material. A 5 MeV alpha particle beam was emitted during the irradiation process, created by a 241-Americium source. The optical properties of ZnO films within the wavelength range of 200 to 800 nm was measured using a UV-Vis spectrophotometer. The Fourier transform infrared (FTIR) spectrum exhibits a distinct peak at 490 cm-1, characteristic of zinc oxide (ZnO). Increasing the duration of alpha particle irradiation leads to a significant increase in intensity while causing only a slight alteration in the peak at 2500 cm-1. Optical measurement revealed a decrease in the direct energy band gaps as the radiation doses increased. This trend was observed for different durations 20, 40, 60, 80, and 100 minutes and across various concentrations 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5 M. The energy band gaps ranged from (3.48 - 3.12) eV, (3.02 - 2.61) eV, (3.25 - 2.84) eV, (3.01 - 2.69) eV, (2.65 - 2.32) eV. Similarly, the band gaps diminish as the irradiation doses increase at various durations and concentrations. Additionally, the energy is likewise characterized as indirect. The energy ranges are as follows: (3.74 - 3.52) eV, (3.63 - 3.37) eV, (3.58 - 3.26) eV, (3.49 - 3.25) eV, (3.47 - 3.20) eV, and (3.42 - 3.20) eV. Our research revealed that the most favorable and smallest direct energy gap value ranges from 2.65 to 2.32 eV, while the indirect energy gap value ranges from 3.42 to 3.20 eV. These optimal values were seen at a concentration of 0.5 M, and the ideal irradiation time was determined to be 100 minutes. The energy gap for direct and indirect transitions can be reduced by increasing the concentration of alpha particle irradiation during the growth of ZnO nanotubes using the CBD method. These nanotubes have potential use in nano-photodetectors. [ABSTRACT FROM AUTHOR]

[Display omitted] Convenient, small-sized, and self-powered sensor units are easier to integrate, making them the future development direction of photodetectors. GaN materials with wide band gap are powerful candidates for UV detection, but most GaN based self-powered UV photodetectors have poor detection ability for the weak UV light, which limits their applications. This study reports a self-powered UV photodetector based on BaTiO 3 /GaN heterojunction, which can detect ultra-weak UV light at a minimum of 0.68 nW/cm2 by coupling the ferroelectric polarization, anti-reflection effect, and pyro-phototronic effect. The polarized BaTiO 3 thin film on the surface of GaN has an enhanced residual polarization field and generated anti-reflection effect, which can regulate the heterojunction band structure, suppress the dark current and minimize surface reflection of GaN. Simultaneously enhanced pyro-phototronic effect can significantly improve the response speed and responsivity of the device. The response time and recovery time of the device are as low as 8.794 ms and 5.018 ms. The maximum responsivity and detectivity are 88.206 mA/W and 7.392 × 1013 Jones, respectively, increased by 359% and 6065% compared to the device before polarization. Thanks to excellent material stability, the device has a sensitive and uniform response to continuously incident UV light. In addition, by simulating flame generation, it has been proven that the device has brilliant performance in flame detection and can achieve remote monitoring and fire warning functions. These results can promote the potential application of self-powered UV photodetectors based on BaTiO 3 /GaN heterojunction in environmental monitoring and space communication fields. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) metal halide perovskites feature several specific advantages over others 2D materials, such as facile wet chemical synthesis and layers exfoliation, high composition combination especially the choice of organic cations as well as 2D phase, excellent confinement for exciton. In this paper, we present a fundamental study of diaminonaphthalene lead iodide (DANPI) perovskite, a Dion–Jacobson 2D perovskite based on divalent cation organic spacer 1,5-diaminonaphthalene. We report its material synthesis, optical and structural characterization as well as DFT calculations. Hydro-iodic acid-based wet chemistry was used to prepare DANPI crystals and, by cast-capping, thin films as well. Both DANPI materials show a dominant emission peak at about 519 nm with a full width at half-maximum as small as 14 nm. This peak coincides with the absorption edge of the material at 510 nm (2.43 eV) which suggests an exciton-related recombination process. According to single-crystal X-ray diffraction measurements the crystal structure could be either monoclinic P21/c or tetragonal P4212. DFT calculations including spin–orbit coupling show that the DANPI band gap is direct, with a valence band of s-symmetry and a conduction band of p-symmetry. A dominant emission peak at about 519 nm with a full width at half-maximum as small as 14 nm. The crystal structure could be either monoclinic P21/c or tetragonal P4212. The DANPI band gap is direct, at 2.43 eV, with a valence band of s-symmetry and a conduction band of p-symmetry. Suggested Dexter electron exchange process for Wannier excitons to organic Frenkel excitons. [ABSTRACT FROM AUTHOR]

This study focuses on investigating a potential method for depositing zinc sulfide (ZnS), in thin film form at room temperature. A facile and effective approach was employed in this study, wherein a suspension of ZnS powder in methanol was applied onto flexible plastic substrates using a spray deposition method. Structural analysis of the resulting films revealed a broad X-ray diffraction peak along the (100) plane, indicating the presence of nanoscale crystallites. The band gap of the ZnS films was determined to be 3.78 eV. Furthermore, the films exhibited photo luminescence emission centered at a wavelength of 410 nm, which corresponds to the blue edge of the chromaticity diagram. [ABSTRACT FROM AUTHOR]

Copper Zinc Sulphide (Cu0.5Zn0.5S) alloy and thin films were fabricated in a vacuum. Nano crystallized (CZS) film with thick 450±20 nm was deposit at substrates glasses using thermal evaporation technique below ~ 2 x 10-5 mbar vacuum to investigated the films structural, morphological and optical properties depended on annealing temperatures ( as-deposited, 423, 523 and 623) K for one hour. The influences annealed temperature on structurally besides morphologically characteristics on these films were investigated using XRD and AFM respectively. XRD confirms the formation a mixed hexagonal phase of CuS-ZnS in (102) direction with polycrystalline in nature having very fine crystallites size varying from (5.5-13.09) nm. AFM analysis shows the uniform distribution of closely packed grains, grain size for that film diverge on ranges as of (52.37 to 89.25) nm after annealed. The optical properties of all films prepared had been examined for the wavelength range 400 - 1000 nm using UV-Vis-NIR spectrometer. The band gaps of (Cu0.5Zn0.5S) films are obtained in the range of 2.4 to 1.9 eV, which makes it a suitable absorber as well as buffer/window layer for solar cell applications. [ABSTRACT FROM AUTHOR]

The sewage water is tested as a source of hydrogen production with a high efficiency value of 25.44% using Cu/CuFeO2 (delafossite)/CZTS (Cu2ZnSnS4, kesterite) as an investigated photocatalyst. The X-ray diffraction (XRD) analysis of the investigated photocatalyst (Cu/CuFeO2/CZTS) revealed a compact crystalline material, as witnessed by the diffraction peaks with high intensities. From the optical characterization, the recorded band gap values of Cu/CuFeO2/CZTS, Cu/CuFeO2, and CZTS are 1.15, 1.97, and 1.43 eV, respectively, inferring an obvious enhancement in the optical properties of the investigated photocatalyst, Cu/CuFeO2/CZTS. The photoelectrochemical (PEC) performance of the investigated photocatalyst for hydrogen (H2) generation was examined in wastewater. The current–time characteristic and the PEC behavior of Cu/CuFeO2/CZTS in dark and under light illumination using various power densities, monochromatic wavelengths, and different temperatures were studied. The current densities (JPh) under light illumination and (Jo) in the dark were − 8.0 and − 0.7 mA cm−2, respectively. The H2 generation rate for the Cu/CuFeO2/CZTS electrode was 0.049 mA/h. The thermodynamic parameters, respectively, ΔS*, ΔE, and ΔH* were 28.76 kJ mol−1 K−1, 21.0, and 18.28 kJ mol−1 at 390 nm. The findings of the work hold great promise for addressing energy production and the hindrances of sewage treatment at the same time. [ABSTRACT FROM AUTHOR]

In the aim to develop the field of low cost materials for highly efficient hydrogen evolution electro-catalysis, photo-catalysis, and low cost solar cells applications, thin films of transition metal dichalcogenide materials (RuSe 2 , FeSe 2 , RuS 2 , FeS 2 , ....etc) are promising candidates especially. Indeed, thin films of transition metal dichalcogenide (TMD) materials, such as RuSe 2 , are promising alternatives to platinum (Pt) for the hydrogen evolution reaction (HER). Herein, growth of RuSe 2 thin films, having desired properties for several applications, using the simple and non-cost technique, spray pyrolysis, makes the main object of this work. In a first step, an aqueous solution of RuCl 3.3H 2 O (0.03 M) was sprayed for 5 min onto ordinary glass substrates pre-heated at 350 °C. Dark amorphous thin films were obtained. In a second step, the as obtained amorphous thin films were heat treated under selenium atmosphere (∼10−4Pa) at various temperatures (450, 500, and 550 °C) for 3 h in RTP oven. A single hexagonal RuSe 2 -phase (h-RuSe 2) was picked up by the XRD analysis. The obtained layers presented a high absorption coefficient (α > 6x104cm−1 for the layers selenized at 450 °C, and α > 106cm−1, λ < 1000 nm for the layers selenized at 500 and 550 °C). The plots of (α.h.ν)2 vs (h.ν) showed direct band gaps corresponding to the photon energies of about 1.56 eV, 1.75 eV, and 1.86 eV of the layers selenized at 450, 500, and 550 °C, simultaneously. The surfuce morphology was treated by SEM: clustred structure was observed for the layers obtained after selenization at 450 °C, and grannular structures were observed for the layers obtained at 500 and 550 °C. The grain size becomes so large for the layers obtained at 550 °C; that confirms their high absorbance. The interesting obtained results provide for improving more the domain of low cost materials having encouraging properties for several applications domains (photovoltaic, hydrogen evolution, electrocatalysis and photocatalysis) using the spay pyrolysis technique. [ABSTRACT FROM AUTHOR]

V-, Ce-, and Mn-doped NiO/rGO bilayer nanocomposite thin films were prepared by the sol–gel spin-coating method. The structural, optical, and magnetic properties of the thin films have been investigated by XRD, XPS, Raman, SEM, UV-visible spectra, photoluminescence (PL) spectra, and SQUID-VSM analysis. The XRD patterns revealed the polycrystalline nature of the NiO thin films and the rGO layering decreased the crystallite size. The binding energy of all the thin films have been calculated using XPS spectra, confirming the cubic structure of NiO. Raman spectra analysis revealed the presence of increased defects corresponding to rGO in the layered films. rGO layering changed the surface morphology of all the doped films. Higher transmittance values have been observed for all the NiO and rGO layered NiO thin films in the visible and IR regions. The layering and doping changed the band gap values significantly. A PL quenching was observed in the rGO layered undoped and doped NiO thin films. Analysis of the magnetic properties revealed the increased values of saturation magnetization and magnetic moment in the rGO layered thin films. [ABSTRACT FROM AUTHOR]

The present paper presents a straightforward method for producing thin film layers of sulfide quantum dots (PbS-QDs) on a glass substrate using chemical solution deposition (CSD) assisted by dipcoating technique. The deposited PbS-QDs films were subjected to a comprehensive analysis using atomic force microscopy (AFM), energy dispersive X-ray (EDX) scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–vis–IR absorption, and photoluminescence spectroscopic (PL) techniques to investigate the effects of varying concentrations of diethanol amine (DEA) on their morphology, crystal structure, elemental composition, light absorption, and emission characteristics. The spherical shape of the PbS-QDs was confirmed by AFM and SEM images with average sizes around 100 and 50 nm, respectively. The energy dispersive X-ray (EDX) analysis provides evidence the existence of Pb and S elements within the PbS matrix. X-ray diffraction (XRD) results validate that the deposited films exhibit high crystallinity, with a preferential orientation along the (111) plane and a face-centered cubic lattice structure of PbS. The crystallite size of PbS is measured to be 46.6 nm. Based on the optical absorption measurements, we have determined the size range of PbS nanocrystals to be between 4.3 and 11.5 nm. The optical studies reveal the presence of two optical absorption edges within the visible and infrared spectrum, two direct band gap energy, two cut-off wavelengths, two confinement energy, two Urbach energy tail, and dual emission peaks of PbS-QDs at room temperature. The analysis reveals the presence of two distinct band gap energies, one in the visible range (1.3–2.28 eV) and the other in the infrared range (0.65–0.88 eV), which can be attributed to the formation of two distinct sizes of quantum dots situated in two different layers. The first layer, deposited directly on the glass substrate, comprises quantum dots with an average size of approximately 5.2 nm, while the second layer contains quantum dots with an average size of about 9.5 nm. This ability to tune the band gap of PbS in the visible range up to the IR band (0.65–2.28 eV) is a critical feature that holds the potential for the development of innovative optoelectronic devices. [ABSTRACT FROM AUTHOR]

Finding low-cost, solution-processed, stable, and environmentally friendly materials that absorb visible light is the main challenge in designing optoelectronic devices such as photovoltaic (PV) cells. Spinel-structured p-type CuFe2O4 (CFO) is an environmentally stable, non-toxic complex oxide known for its superparamagnetic properties. Having a narrow bandgap with a high-absorption coefficient, it has been used for photocatalytic activities and photo-electrochemical water splitting. Here, we explore the feasibility of solution-processed CFO thin film as an absorber layer in n-p heterojunction PV cells. Spin-coated CFO thin film on a fluorine-doped tin oxide (FTO) coated glass substrate shows a single-phase spinel tetragonal crystal structure with an optical band gap of around 2 eV and a high absorption coefficient of 105 cm−1. A steady rise under illumination in the transient photocurrent response of the CFO films confirms its visible light sensitivity. The solution-processed all oxide TiO2/CFO-based n-p heterojunction shows typical diode-like characteristics, and under 1 sun illumination, it shows a photovoltage over 430 mV and photocurrent density of 0.432 mA cm−2. Hence, the studied optoelectronic properties of CFO thin films indicate the possibility of CFO as an active material in PV cells that further strengthens its multifunctionality. [ABSTRACT FROM AUTHOR]

In the paper, optical, electrochromic, surface, and microstructural properties have been investigated to determine the properties of WO 3 material doped with graphene and MXene. It was observed that the crystallite size and dimensions were small according to the analyses. When graphene and MXene were added to WO 3 , the band gap values shifted to a higher energy level. 2D material peak positions were assigned to Raman shift spectra analyses. Microstructural variations were observed into X-Ray diffraction patterns. MXene peaks for XRD were determined at approximately 30°. Current density-voltage measurements were obtained at 20, 40, 80, and 160 mV/s, and clear oxidation and reduction peaks were observed. Cathodic peaks of 2D material-doped WO 3 were observed at approximately −1.2 V and the positions of anodic peaks can be altered depending on the type of 2D material. For graphene, the anodic peak occurs at −0.7 V and −0.1 V after MXene doping. 2D materials increased the diffusion coefficient of undoped WO 3 by about 100–1000 times. The intercalation charge amount of WO 3 material doped with 2D is more than 10–20 times greater than the undoped sample. It was found that graphene and MXene improved various properties of the sample. [ABSTRACT FROM AUTHOR]

Cu2Sn1-xGexS3 (CTGS) is a compound composed of relatively abundant elements in the crust of the earth. The band gap of CTGS can be tuned by substituting elements at the Sn and Ge sites, making it an attractive material for low-environmental-impact solar cells. In this study, CTGS thin films were fabricated with a controlled [Ge]/([Ge] + [Sn]) composition ratio (x) by combining the co-evaporation method and sulfurization in an infrared furnace. Furthermore, the effect of Na on the CTGS and changes in the solar cell properties were investigated by stacking and sulfurizing NaF on the precursor fabricated using the co-evaporation method. As a result, CTGS with varying x was successfully fabricated by varying the deposition time of the Cu2GeS3 layer using co-evaporation. Additionally, CTGS prepared by doping with Na showed enlarged CTGS crystals compared to Na-free CTGS. The fabricated CTGS solar cells achieved a power conversion efficiency of more than 4.5% after doping with Na. [ABSTRACT FROM AUTHOR]