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Solution‐processed inorganic perovskites cause chemical and structural defects unfavorable for photodetector application. Using a binary solvent, defects in CsPbIxBry (CPIB) perovskite are passivated with poly 4‐vinylpyridine (PVP) and Poly methyl methacrylate (PMMA) polymers. X‐ray photoelectron spectroscopy and FTIR spectra reveal a Lewis base‐acid interaction between Pb2+ and polymer, confirming the passivation of CPIB perovskite. Scanning electron microscopy analysis shows a dual‐surface morphology with microribbons and microcrystals in perovskites. After PMMA treatment, CPIB perovskite exhibits a blue shift in the bandgap (1.8 to 1.95 eV), while the PVP induced a redshift, reducing the bandgap to 1.7 eV. Blue shift in PL analysis indicates modification of grain boundaries. A higher lifetime obtained for CPIB/PVP confirms the restraint of non‐radiative recombinations. Photodetectors are fabricated with pristine CPIB, CPIB/PVP, and CPIB/PMMA perovskites. The passivated CPIB/PVP‐based photodetector exhibits a quick rise time of ≈23 ms and a decay time of ≈17 ms. It also demonstrates a remarkable photoresponsivity of 23 mA W−1, an internal quantum efficiency of 4.9%, and a detectivity of 15.0 × 1010 Jones at 10 mW cm−2 light intensity. This approach shows the potential for environmentally stable polymers to passivate inorganic perovskites for high photodetection performance. [ABSTRACT FROM AUTHOR]

In this work, γ-In2Se3 thin films were deposited on a p-type Si (p-Si) substrate using RF magnetron sputtering. The effects of Ar+ ion irradiation on structural, optical, morphological, and photodetector characteristics of γ-In2Se3 were investigated. Raman spectra analysis showed a decline in the crystallinity of hexagonal γ-In2Se3 as Ar+ ion fluence increased. XPS results revealed an increased oxygen peak intensity, indicating the incorporation of oxygen on the material’s surface. Additionally, shifts in the binding energies of In and Se peaks were observed. The optical band gap decreased from 2.13 to 1.85 eV after ion irradiation. SRIM 2008 Monte Carlo simulation revealed an Ar+ ion range of ~ 284 Å in γ-In2Se3 films. Morphological changes were insignificant at lower fluences, but grain agglomeration occurred at higher Ar+ ion fluence. EDS analysis indicated decreasing Se atomic % and increasing O with higher irradiation. Photodetectors exhibited improved performance with increased ion fluence, showing higher photoresponsivity, photosensitivity, photodetectivity, fast rise, and decay time. The present study provides insights into the material responses to radiation hardening and its promising applications in developing space-based photodetectors. [ABSTRACT FROM AUTHOR]

In this study, we investigated the effect of RF sputtering power on the structural, morphological, optical, and photodetector properties of γ-In2Se3 thin films. The In2Se3 films were deposited at 80 W, 100 W, 120 W, and 150 W and characterized using XRD, Raman spectroscopy, FE-SEM, and EDS. The XRD results showed that the rise in RF sputtering power enhanced the crystallinity of the prepared films. The formation of the γ phase of In2Se3 was confirmed by Raman spectroscopy. FE-SEM images showed that the In2Se3 films were compact, smooth, and had uniform grain growth. The increase in film thickness with RF power was observed in cross-sectional FE-SEM. The EDS analysis confirmed that as-prepared γ-In2Se3 films have stoichiometric chemical composition. The optical bandgap of the films decreased from 2.07 to 1.85 eV with an increase in RF power, which can be attributed to an increase in crystallite size due to an increase in RF power. The optoelectronic performance of the films was evaluated by fabricating γ-In2Se3 photodetectors. The photodetector fabricated at 100 W sputtering power had excellent performance. It had a detectivity of 2.5 × 108 Jones, photoresponsivity of 17 µA/W, fast rise time of 0.27 s, and decay times of 0.31 s. [ABSTRACT FROM AUTHOR]

We report the synthesis of tungsten sulfide (WS2) films using RF‐magnetron sputtering at different RF powers. X‐ray diffraction (XRD) data confirm the hexagonal crystal structure of WS2 with an average crystallite size of ∼44.54 Å. With increased RF power, the preferred orientation of WS2 crystallites shifts from (002) to (100). Linear sweep voltammetry (LSV) was used to assess the Photoelectrochemical (PEC) activity of WS2 films. The film deposited at 150 W demonstrated the highest photocurrent density of 5.44 mA/cm2. The 150 W film also showed a lower Tafel slope of ∼0.374 V/decade, indicating superior PEC activity. Mott Schottky's (MS) analysis revealed a notable shift in the flat band potential towards the negative side, suggesting a shifting of the Fermi level towards the conduction band. WS2 film grown at 150 W demonstrated a majority charge carrier density of 6.2×1021 cm−3 and a depletion layer width of 1.54 nm. The observed low charge transfer resistance of 155 Ω contributed to the enhanced PEC activity with a relaxation time constant of 37 ms. These properties suggest that WS2 can be suitable for PEC water splitting. [ABSTRACT FROM AUTHOR]

Topologically active, crystalline layered PbBi2Se4 has been probed for significantly low thermal conductivity and excellent thermal properties. The present work focuses on the investigation of thermal properties of the PbBi2Se4 composite, such as diffusivity, effusivity, specific heat, Debye temperature, thermal conductivity, lattice thermal conductivity using temperature, and incident laser power-dependent Raman scattering. The thermal properties are very important for thermal energy harvesting applications. The obtained results have been substantiated with first-principles calculations. It is observed that the septuple interface Se atoms govern high-frequency Raman Active modes, and their role is crucial for thermal properties. High phonon density of states at low-frequency, strong phonon coupling drove scattering, and low phonon lifetime of optically active E g 2 and A 1 g 2 modes govern the low thermal conductivity (55 Wm−1 K−1). The thermal conductivity of PbBi2Se4 is an order of magnitude lower than the other ternary compounds from the PbxBi2ySe3x+y family but is comparable to that of transition metal chalcogenide materials (e. g. MoS2). The present work provides an efficient method to investigate the thermal conductivity of layered material. Further, it can be used to tune the thermal properties of the topological insulators by exploring the phonon dynamics. [ABSTRACT FROM AUTHOR]

Developing efficient semiconductor photoanodes demonstrating strong light absorption, efficient separation of photogenerated charge carriers, and reduced charge carrier recombination rate can benefit PEC water splitting. Integrating a wide band gap semiconductor with narrow bandgap material with suitable band alignment can enhance PEC performance. Herein, we have fabricated novel MoO3/γ-In2Se3 heterostructure photoanodes using RF magnetron sputtering. The films structural, optical, morphological, and elemental composition were investigated in detail using low-angle XRD, Raman spectroscopy, XPS analysis, EDAX, and FESEM. The XRD, Raman, XPS, and EDAX results strongly confirmed the presence of desired phases of MoO3 and γ-In2Se3 layers in heterostructure without forming any impurity or alloy. FESEM micrographs revealed a uniform, dense grain structure. Optical analysis of MoO3/γ-In2Se3 done by UV–Visible spectroscopy shows increased absorption compared to pristine-MoO3. Conduction and valence band-edge potential values indicate that MoO3/γ-In2Se3 films are suitable for PEC hydrogen production. The PEC performance of these heterostructure photoanodes was evaluated by performing LSV, Chronoamperometry, EIS, and Mott–Schottky analysis. LSV results of MoO3/γ-In2Se3 showed a 10-fold increase in photocurrent density and attained higher photoconversion efficiency (0.5%) compared to pristine-MoO3 photoanode. EIS analysis revealed that MoO3/γ-In2Se3 photoanodes had small charge transfer resistance. Investigation of Mott Schottky results shows carrier density increases from 2.8 × 1019 cm−3 to 2.1 × 1020 cm−3 after incorporating γ-In2Se3 over MoO3. An increase in time-dependent photocurrent density reveals that MoO3/γ-In2Se3 films have effective electron-hole separation. Our finding suggests that MoO3/γ-In2Se3-based heterostructure photoanode can enhance light harvesting capacity and suppresses carrier recombination rate, eventually boosting PEC performance. Moreover, these results encourage the development of highly efficient photoelectrodes based on heterostructures for solar water-splitting applications. [ABSTRACT FROM AUTHOR]

Rutile-TiO2 microspheres were synthesized by the single-step hydrothermal method and were subsequently annealed in an argon environment at 200 °C, 400 °C, and 600 °C. The influence of annealing temperature on structural, optical, morphological, and humidity sensing performance of rutile-TiO2 microspheres was examined. As-synthesized and annealed rutile-TiO2 microspheres were characterized using different characterization techniques. SEM confirmed the spherical shape morphology of TiO2 microspheres. XRD confirmed the tetragonal structure and rutile phase of TiO2 microspheres. The rutile phase of TiO2 was also confirmed by Raman spectroscopy. No significant change in the bandgap has been observed in rutile-TiO2 with increased annealing temperature. The presence of various chemical groups in rutile-TiO2 microspheres was studied using FTIR spectroscopy. The Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) analysis showed a decrease in surface area and pore volume and an increase in average pore radius with an increase in annealing temperature. The humidity sensing performance of TiO2 microspheres thin films deposited on interdigital electrodes (IDEs) was studied between 11 to 97% relative humidity (RH). The humidity sensor fabricated using rutile-TiO2 microspheres annealed at 600 °C showed excellent humidity sensing properties. The sensor has the highest sensitivity (~ 71.5%), fast response, and recovery time of ~ 11.1 s and ~ 0.8 s, respectively. [ABSTRACT FROM AUTHOR]

Indium selenide (γ-In2Se3) films were prepared using RF magnetron sputtering. Influence of deposition time on structural, optical, morphological, and photoelectrochemical (PEC) performance was studied. Formation of γ-In2Se3 is confirmed by low angle XRD, Raman spectroscopy, and XPS analysis. Surface morphology investigated using FE-SEM shows that γ-In2Se3 films are uniform and have a dense grain structure, without cracks and holes. Optical properties show that γ-In2Se3films absorb mainly in the UV region, and the bandgap energy decreases from 2.81 to 2.27 eV as deposition duration increases. Conduction and valance band-edge potential values show that γ-In2Se3 films are suitable for photoelectrochemical hydrogen evolution. PEC activity of γ-In2Se3 photoanodes was evaluated using linear sweep voltammetry (LSV), and there was an increase in photocurrent density with deposition time. Electron impedance spectroscopy (EIS) analysis revealed that γ-In2Se3 photoanodes had high charge transfer resistance, and it decreases with deposition time, which leads to improved PEC performance. Investigation of Mott Schottky's (MS) results shows a shifting of flat band potential towards negative potential, suggesting movement of fermi level towards conduction band edge. Carrier density increases from 3.7 × 1019 cm−3 to 8.9 × 1020 cm−3 and depletion layer width of γ-In2Se3 photoanodes are found in the range of ~ 2.67–9.10 nm. The gradual increase in electron lifetime indicates a decrease in the recombination rate of photo-generated charge carriers. An increase in time-dependent photocurrent density reveals that γ-In2Se3 films have effective electron–hole separation. Our work demonstrates that γ-In2Se3 can be a probable candidate for PEC water splitting and opto-electronic applications. [ABSTRACT FROM AUTHOR]

Hydrogen production via photoelectrochemical water splitting is a promising route to convert solar energy into chemical fuel, reducing energy crises and boosting environmental health. Here, we report the fabrication of ternary ZnO/CuO/Au heterostructures by electrodeposition and chemical bath deposition methods. The heterojunction formed can enhance the optical absorption, and photogenerated electrons and holes can efficiently separate due to the built-in electric field, which reduces recombination losses. Au plasmons incorporated in ZnO/CuO heterojunction enhance the optical absorption and promote fast free charge carrier transport at the interface through the surface plasmon resonance (SPR) effect. The ZnO/CuO/Au photoanode exhibits a photocurrent density of 1.08 mA/cm2 at 1.6 V Vs RHE, two times higher than pristine ZnO. The ZnO/CuO/Au photoanode exhibits the lowest charge transfer resistance of 600 Ω from electrochemical impedance spectra(EIS). The Bode plot revealed that the most extended lifetime of 8.69 μs is observed for ZnO/CuO/Au photoanode, which is larger than pristine ZnO. The synthesized thin films showed good stability and reusability for the photooxidation of water. • Fabrication of ternary ZnO/CuO/Au heterostructures by electrodeposition and chemical bath deposition methods. • Enhancement of optical absorption and reduction in recombination losses due to heterojunction. • Au plasmons incorporated in ZnO/CuO heterojunction enhances the optical absorption. • Au plasmons promote fast charge carrier transport at interface via surface plasmon resonance (SPR) effect. • ZnO/CuO/Au photoanode exhibits photocurrent density ∼ 1.08 mA/cm2, higher than pristine ZnO. [ABSTRACT FROM AUTHOR]

A promising method for producing hydrogen from solar energy and transforming it into chemical fuel is photoelectrochemical (PEC) water splitting. This ecologically friendly process can also avoid energy crises. Herein, we present the electrodeposition and chemical bath deposition methods used to create ZnO-nanorod/CdS nanoparticle (ZnO/CdS) heterostructures. The structural, optical, morphological, and PEC properties are investigated. UV–Visible spectroscopy analysis reveals the ZnO/CdS films have absorption edges in the visible and ultraviolet regions. The CdS loading directly impacts the PEC result of ZnO/CdS photoanodes. The M-S plots show a positive slope, indicating the n-type nature of ZnO and CdS. Under illumination intensity of 100 mW cm−2, the ideal photocurrent density reaches 4.90 mA/cm2 at a bias of 1.35 V versus reversible hydrogen electrode (vs. RHE) and is five times greater than the pristine ZnO nanorods. The maximum applied bias photon to the current conversion efficiency of 0.23 % at 0.26 V vs. RHE is observed in the pristine ZnO photoanodes. In contrast, the ZnO/CdS photoanode has achieved 3.02 % at 0.26 V vs. RHE, almost 13 times greater than the pristine ZnO photoanode. Finally, the hydrogen evolution process and the mechanism of charge transfer in ZnO/CdS heterostructure are discussed. • ZnO/CdS fabrication by electrodeposition and chemical bath deposition. • Efficient photoelectrochemical water splitting by ZnO/CdS. • The Mott-Schottky analysis revealed p-n junction formation. • Photocurrent density up to 4.90 mA/cm2 at 1.35 V vs. RHE under 100 mW/cm2 illumination. • Applied bias photon to current conversion efficiency of 3.02 % at 0.26 V vs. RHE. [ABSTRACT FROM AUTHOR]

In this study, high-quality γ-In 2 Se 3 thin films were successfully deposited on p-Si substrates via the RF sputtering technique. Structural characterization using XRD and Raman spectroscopy confirmed the formation of the hexagonal γ-phase of In 2 Se 3 film. FESEM analysis revealed the presence of small, homogeneous, and well-defined grains in the prepared γ-In 2 Se 3 film. EDS analysis confirmed the stoichiometric composition (∼ 2:3) of the In 2 Se 3 films. XPS further validated the presence of In, Se, and Si elements in the deposited films. Band gap analysis using UV-visible spectroscopy yielded a value of 1.96 eV for the γ-In 2 Se 3 film. Integration of γ-In 2 Se 3 with p-type Si enhanced photoresponsivity of 47.9 mA/W, photosensitivity of 282, and photo detectivity of 8.45 × 10 10 Jones. The self-powered γ-In 2 Se 3 /p-Si heterojunction-based photodetector exhibited rapid rise time attributed to the type II band alignment structure, facilitating efficient electron-hole pair separation and minimizing recombination. Furthermore, humidity and light intensity-dependent photodetector properties of γ-In 2 Se 3 /p-Si heterojunction photodetector were also investigated. An increase in photocurrent from 271 to 291 µA was observed with rising humidity levels, indicating the device's sensitivity to humidity variations. Furthermore, light intensity dependence studies revealed a linear relationship between photocurrent and incident light intensity, demonstrating the device's reliable response across various illumination levels.

Lead-free double perovskites (DPs) will emerge as viable and environmentally safe substitutes for Pb-halide perovskites, demonstrating stability and nontoxicity if their optoelectronic property is greatly improved. Doping has been experimentally validated as a powerful tool for enhancing optoelectronic properties and concurrently reducing the defect state density in DP materials. Fundamental understanding of the optical properties of DPs, particularly the self-trapped exciton (STEs) dynamics, plays a critical role in a range of optoelectronic applications. Our study investigates how Fe doping influences the structural and optical properties of Cs 2 AgBiCl 6 DPs by understanding their STEs dynamics, which is currently lacking in the literature. A combined experimental-computational approach is employed to investigate the optoelectronic properties of pure and doped Cs 2 AgBiCl 6 (Fe-Cs 2 AgBiCl 6 ) perovskites. Successful incorporation of Fe 3+ ions is confirmed by X-ray diffraction and Raman spectroscopy. Moreover, the Fe-Cs 2 AgBiCl 6 DPs exhibit strong absorption from below 400 nm up to 700 nm, indicating sub-band gap state transitions originating from surface defects. Photoluminescence (PL) analysis demonstrates a significant enhancement in the PL intensity, attributed to an increased radiative recombination rate and higher STE density. The radiative kinetics and average lifetime are investigated by the time-resolved PL (TRPL) method; in addition, temperature-dependent PL measurements provide valuable insights into activation energy and exciton-phonon coupling strength. Our findings will not only deepen our understanding of charge carrier dynamics associated with STEs but also pave the way for the design of some promising perovskite materials for use in optoelectronics and photocatalysis., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Cu 2 ZnSnS 4 (CZTS) thin films have attracted considerable attention as potential candidates for photovoltaic absorber materials. In a vacuum deposition technique, a sputtering stacked metallic layer followed by a thermal process for sulfur incorporation is used to obtain high-quality CZTS thin films. In this work, for fabricating CZTS thin films, we have done a 3LYS (3 layers), 6LYS, and 9LYS sequential deposition of Sn/ZnS/Cu metal stack ( via . metallic stacked nanolayer precursors) onto Mo-coated corning glass substrate via . RF-sputtering. The prepared thin films were sulfurized in a tubular furnace at 550 °C in a gas mixture of 5% H 2 S + 95% Ar for 10 min. We further investigated the impact of the Sn/ZnS/Cu metal stacking layers on the quality of the thin film based on its response to light because metal inter-diffusion during sulfurization is unavoidable. The inter-diffusion of precursors is low in a 3-layer stack sample, limiting the fabricated film's performance. CZTS films with 6-layer and 9-layer stacks result in an improved photocurrent density of ∼38 μA cm -2 and ∼82 μA cm -2 , respectively, compared to a 3-layer sample which has a photocurrent density of ∼19 μA cm -2 . This enhancement can be attributed to the 9-layer approach's superior inter-diffusion of metallic precursors and compact, smooth CZTS microstructure evolution., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)