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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, we report on the synthesis of rutile-TiO2 nanostructures for field electron emission studies using a simple one-step hydrothermal method at various TiCl4 molar concentrations. The formation of the pure and tetragonal rutile phase of TiO2 films has been confirmed by X-ray diffraction and Raman spectroscopy. The scanning electron microscopy analysis shows TiO2 has nanorods and nanoflower-like morphology with sharp petals. UV–Visible spectroscopy study exhibited broad absorption in the visible range with a band gap energy ranging from 2.32 to 3.01 eV over the entire range of TiCl4 molar concentration varied. A possible crystal growth mechanism and electron emission properties of TiO2 films are also discussed. At 0.6 M molar concentration of TiCl4, rutile-TiO2 film exhibited excellent field emission properties, including a low turn-on field of 1.11 V/µm for 10 µA/cm2, a maximum current density of 331.91 µA/cm2 at the applied bias of 3.44 V/μm, and superior current stability for three hours at a preset current of 1.08 µA. The results revealed that the rutile-TiO2 nanostructures can be used for various practical applications such as optoelectronics, biomedical devices, and supercapacitors. [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]