Azure A chloride nanostructured thin films were deposited by thermal evaporation under vacuum and subjected to controlled ultraviolet (UV) irradiation for varying exposure durations. Optical transmittance and reflectance spectra were used to determine the linear optical constants, including the absorption coefficient, refractive index, and extinction coefficient. The indirect optical bandgap (Eg1) decreased from approximately 1.69 eV to 1.59 eV with increasing UV irradiation. The second indirect transition (Eg2) shifted from 3.38 eV to 3.12 eV, which may be associated with higher-energy electronic transitions and UV-induced modifications of electronic states. Concurrently, the refractive index increased from 2.01 to 2.23, accompanied by an enhancement of the high-frequency dielectric constant from 4.0 to 5.0, reflecting increased electronic polarizability. The complex dielectric function exhibited systematic changes with UV irradiation. The estimated χ(3) and n2 increased with UV exposure, whereas the maximum calculated nonlinear absorption coefficient (β), occurring near 1.35–1.45 eV, decreased with increasing irradiation time. The β response remained strongly photon-energy-dependent, indicating that UV treatment modifies the spectral nonlinear absorption behavior rather than producing a uniform change over the entire energy range. These results demonstrate that controlled UV irradiation provides an effective post-deposition approach for tuning the linear, dielectric, and estimated nonlinear optical properties of Azure A chloride thin films, highlighting their potential for future photonic and optoelectronic applications.
Flexible capacitive sensors are widely used in smart wearables and human–machine interaction due to their conformal and flexible characteristics. However, their performance is constrained by the trade-off between sensitivity and range, insufficient dynamic response, and local stress concentration. This paper proposes a flexible capacitive pressure sensor featuring a dual microstructure that combines internal micropores with surface willow-leaf-shaped protrusions. Using multi-walled carbon nanotube-doped polydimethylsiloxane as the dielectric layer, micropores are formed via the NaCl leaching method and an array of willow-leaf protrusions is designed. Leveraging the synergistic protrusion–micropore mechanism, the willow-leaf protrusions enhance low-pressure sensitivity while the micropores extend the detection range and disperse stress, achieving synergistic enhancement of contact area and plate separation. Experimental results show that the sensor achieves a low-pressure sensitivity of 0.62 kPa−1, a range up to 200 kPa, a detection limit as low as 19.6 Pa, a hysteresis rate of only 4.4
Efficient and low-cost platinum-free counter electrodes are essential for the practical application of dye-sensitized solar cells (DSSCs). In this work, a metal–organic framework-derived porous carbon/polyaniline (MOF-C/PANI) hybrid counter electrode was developed to improve the electrocatalytic activity towards the iodide/triiodide (I−/I3−) redox couple. The MOF-derived carbon provides a high surface area and abundant electrocatalytic active sites. The conductive PANI network improves electron transport throughout the electrode. X-ray diffraction (XRD) confirmed the successful incorporation of PANI into the carbon framework without forming secondary crystalline phases. Scanning electron microscopy (SEM) showed a uniform PANI coating on the porous carbon framework and confirmed the formation of an interconnected hybrid structure. Brunauer–Emmett–Teller (BET) analysis revealed that the MOF-derived carbon possessed a specific surface area of 512 m2 g−1. The MOF-C/PANI hybrid retained a surface area of 356 m2 g−1. It also exhibited a pore volume of 0.52 cm3 g−1 and an average pore diameter of 6.1 nm. These characteristics facilitate electrolyte diffusion and provide easy access to catalytic active sites. Electrochemical characterization showed that the MOF-C/PANI counter electrode exhibited high electrocatalytic activity, delivering high cathodic peak current density, low charge-transfer resistance of 6.2 Ω and high exchange current density. The DSSC assembled with the MOF-C/PANI counter electrode achieved power conversion efficiency of 8.02
In this work, the primary focus is on investigating the structural, optical, and electrical properties of lanthanum- and cobalt-co-substituted BiFeO3 (BFO). Polycrystalline (Bi1−xLax)(Fe1−xCox)O3 (BLFCO) samples (where x = 0.0, 0.1, and 0.2) were synthesized using the conventional high-temperature solid-state reaction method. Room-temperature x-ray diffraction (XRD) analysis confirmed that all compositions crystallize in a rhombohedrally distorted perovskite structure with the R3c space group, suggesting that La3+ ions preferentially occupy the Bi3+ sites, while Co ions substitute for Fe ions at the B-site of the perovskite lattice. Scanning electron microscopy (SEM) revealed a systematic decrease in the average grain size with increasing La and Co co-substitution. Energy-dispersive x-ray spectroscopy (EDS) confirmed the presence of the constituent elements in the synthesized samples. The optical bandgap, determined from ultraviolet–visible (UV–Vis) spectroscopy, increased from 2.34 eV to 3.67 eV with increasing La and Co co-substitution. Frequency-dependent dielectric measurements revealed an increasing trend in the dielectric constant with increasing dopant concentration. Detailed analysis of the impedance spectra as a function of frequency and temperature enabled the separation and evaluation of the grain and grain-boundary contributions to the electrical response, including their respective resistive and capacitive characteristics.
Research on double-absorber solar cells, particularly the combination of lead-free metal halide perovskite with complementary secondary absorbers, has attracted significant research interest owing to its potential for improved spectral utilization. In this work, an all-lead-free double-absorber solar cell employing MASnI3 and antimony selenosulfide (Sb2(S1−x,Sex)3), as the primary and secondary absorbers, is proposed. Zinc sulfide (ZnS) and copper zinc germanium sulfide (CZGS) are employed as the electron transport layer (ETL) and hole transport layer (HTL), respectively. Four Se compositions (x = 0.1, 0.3, 0.5 and 0.7) are investigated using SCAPS-1D simulation software, with simulation parameters adopted from established theoretical and experimental studies. The ZnS ETL thickness is fixed at 100 nm, while 100 nm is selected for the CZGS HTL and as a practical reference thickness for Sb2(S1−x,Sex)3. The MASnI3 absorber is optimized at 700 nm. Based on band alignment and spectral complementarity analysis, the MASnI3/Sb2(S0.9, Se0.1)3 configuration demonstrates the best photovoltaic performance, with an 11.45
