Surface plasmon resonance (SPR) is a method that enables label-free and real-time biomolecular detection, but its sensitivity is limited to small analytes and minor refractive-index variations. Meanwhile, silver-based nano-composites (Ag-NCs), including Ag/ZnO, Ag/TiO2, and Ag/rGO, offer enhanced plasmonic performance through improved field confinement, stability, and tunable optical properties. This study aimed to investigate the localized surface plasmon resonance (LSPR) performances of the Ag-NCs. The process included the synthesis of the Ag-NCs through a green method using extracts of Moringa oleifera and Amaranthus viridis. The LSPR response was measured by using the Kretschmann configuration. The dielectric modulation was further investigated through the application of an external electric field at 0.17-0.83 V/cm. The structural, morphological, and optical analysis confirmed the successful formation of Ag-NCs with well-dispersed Ag nanoparticles. The LSPR measurements also showed that bare Au exhibited a resonance angle of 45.44 degrees with a minimum reflectance (Rmin) of 0.15. The incorporation of Ag/ZnO produced a shift of 0.14 degrees with a Rmin of 0.20 while Ag/TiO2 had 0.27 degrees with 0.24, and Ag/rGO reported 0.50 degrees with 0.34, respectively. The electro-optic (EO) evaluation also reflected progressive redshifts from 0.11 degrees to 0.47 degrees while the Rmin values increased from 0.36 to 0.46. These results showed that Ag-NCs induced a redshift in the resonance angle compared to bare Au. Ag/rGO exhibited the largest angular shift, which was a sign of the best overall SPR performance. However, Ag/ZnO and Ag/TiO2had narrower full-width at half maximum, which reflected suitability for applications requiring high detection accuracy. The integration of green-synthesized Ag-NCs with EO modulation collectively offered a promising route toward eco-friendly and high-performance biosensors.

Graphene has been proposed as an atomically thin barrier for suppressing metal oxidation. However, its effectiveness under combined thermal treatment and oxygen plasma exposure, as well as the mechanisms governing its degradation, remain insufficiently explored. Here, we reveal how defect- and grain boundary-mediated oxygen transport governs the breakdown of oxidation protection in monolayer graphene-coated copper (Cu-Gr). Raman spectroscopy confirms high-quality monolayer graphene with ≈ 3.21. Oxygen-plasma exposure (6, 8, and 10 s) progressively increases the graphene defect density from 2.50 × 1011, 2.80 × 1011, and 3.78 × 1011 cm-2, while reducing the crystallite size from 16.58 to 14.81 and 10.95 nm, thereby activating oxygen transport. SEM reveals localized oxide nucleation at graphene defects and grain boundaries, while cross-sectional TEM confirms localized interfacial oxidation beneath graphene. Arrhenius analysis shows that Cu-Gr exhibits lower oxidation rate constants than bare Cu over 100–300 °C. Graphene effectively suppresses oxidation at 100–200 °C, whereas its protective function degrades at 300 °C. Optical microscopy shows homogeneous CuO formation on bare Cu at 300 °C, whereas Cu-Gr exhibits only localized interfacial oxidation without bulk CuO formation. Cu K-edge XANES and EXAFS further reveal enhanced interfacial Cu-O coordination with increasing plasma exposure while preserving dominant Cu-Cu coordination, confirming oxidation localized at the Cu-graphene interface. Quantitative XPS analysis shows that oxygen-plasma exposure increases the CuO fraction from 63.86% to 69.88% while decreasing from 36.14% to 30.12%. Thermal annealing further accelerates the -to-CuO transformation, increasing the CuO fraction from 74.55% at 100 °C to 83.54% at 300 °C, providing direct chemical evidence for progressive defect-mediated oxidation Overall, these results demonstrate that defect-activated oxygen transport is the dominant mechanism controlling the degradation of graphene-based oxidation protection and define the operational limits of graphene as an atomically thin oxidation barrier for copper.

An LSPR sensor incorporating silver/reduced graphene oxide-glutaraldehyde nanocomposites (Ag/rGO-GA NCs) as an active sensing interface successfully distinguishes porcine and bovine gelatin over a concentration range of 1-5 mg/mL, highlighting its potential for rapid gelatin authentication and halal verification. Ag/rGO-GA nanocomposites were synthesized via a green route using Amaranthus viridis extract and integrated into a Kretschmann configuration with a prism/Au film/(Ag/rGO-GA)/gelatin/air layer structure. The resulting sensor exhibits pronounced localized surface plasmon resonance (LSPR) responses that are highly sensitive to gelatin adsorption. Adding the Ag/rGO-GA layer to the sensor surface produces an SPR angle shift of 0.24 degrees, together with a 0.16 increase in the minimum reflectance and a 0.49 degrees change in the FWHM. Subsequent gelatin binding on the sensor surface produces significant SPR angle shifts and increases in the minimum reflectance with increasing gelatin concentration. These enhanced responses are more pronounced for porcine gelatin than for bovine gelatin, indicating a greater effective refractive-index change at the sensing interface, which may be associated with differences in amino acid composition, molecular weight distribution, and adsorption behavior between the two gelatin sources. The sensor exhibits limits of detection of 0.049-0.116 mg mL-1 , demonstrating that Ag/rGOGA functionalization significantly enhances the SPR signal through improved plasmonic response, enabling sensitive and discriminative detection of gelatin origin. This green-engineered nanoplasmonic platform further opens pathways toward sustainable, portable, and scalable sensing technologies for future halal verification and transparent food supply chains.

Abstract This study investigates the influence of layer thickness on the localized surface plasmon resonance (LSPR) properties of green-synthesized Silver/reduced Graphene Oxide (Ag/rGO) nanocomposites for biosensing applications, with a specific focus on layer thickness optimization. Novelty is introduced through the utilization of Amaranthus viridis extract as a dual reducing and stabilizing agent, establishing a sustainable and eco-friendly synthesis protocol aligned with current trends in green nanotechnology. While Ag/rGO nanocomposites have been studied, the systematic correlation between the thickness of green-synthesized layers and their plasmonic tuning efficiency remains underexplored. The nanocomposite was characterized using X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Fourier-Transform Infrared (FTIR) Spectroscopy, and UV-Vis Spectroscopy. Subsequently, layers of the Ag/rGO nanocomposite with varying thicknesses (corresponding to masses of 0.015 g, 0.025 g, 0.050 g, and 0.075 g) were deposited onto a gold-coated prism. The Surface Plasmon Resonance (SPR) response was measured for each thickness. XRD confirmed the crystalline structure of Ag and the presence of rGO. TEM showed well-dispersed Ag nanoparticles on rGO sheets, around 19 nm in size. FTIR verified functional groups and bonding between Ag and rGO. UV-Vis revealed a high absorption peak, typical of Ag nanoparticles. The SPR results revealed that as the Ag/rGO layer thickness increased, the SPR angle shifted from 46.31° to a maximum of 48.01°, and the minimum reflectance increased. This shift is attributed to the strong coupling between the propagating SPR of the gold film and the LSPR of the Ag nanoparticles, which modifies the effective refractive index of the sensing interface. These findings demonstrate that the thickness of this unique green-synthesized nanocomposite is a critical, tunable parameter. This work provides a distinct, environmentally sustainable pathway to optimize the sensitivity and performance of SPR-based biosensors.

Abstract Fe 3 O 4 /Ag nanocomposite has been successfully synthesized by green synthesis method using Moringa oleifera extract. Fe 3 O 4 /Ag samples were characterized and the effect of layer thickness on surface plasmon resonance (SPR) characteristics in Kretschmann prism/Au configuration was studied. The results of sample characterization using x-ray diffraction showed that the Fe3O4 crystal structure is face-center cubic inverse spinel with space group Fd-3m and has a crystallite size of 5.7 nm and for Fe 3 O 4 /Ag crystallite size of 11.3 nm. Fourier transform infra-red analysis showed the presence of C-H, C=C and Fe-O functional groups confirming the formation of Fe 3 O 4 /Ag nanocomposites. Analysis of the absorbance spectrum using a UV-Vis spectrophotometer showed a shift in the Fe 3 O 4 /Ag absorption peak to a larger wavelength region. Observation of the SPR phenomenon showed a shift in angle to a larger value as the thickness of the Fe 3 O 4 /Ag nanocomposite increased. The SPR angle values for Fe 3 O 4 /Ag nanocomposite thickness variations of 0.015 g, 0.025 g, 0.050 g, and 0.075 g are 43.70°, 43.84°, 43.95°, and 44.19°, respectively. This proves that the addition of Fe 3 O 4 /Ag nanocomposites with variations in thickness will affect the optical properties and characteristics of SPR so that it has potential in SPR-based biosensor applications.

This study presents the development of an efficient and low-cost photocatalyst for methylene blue (MB) degradation using magnetite (Fe3O4) derived from natural iron sand combined with graphene oxide (GO). The Fe3O4 was synthesized via a co-precipitation method using iron sand from Glagah Beach, Indonesia, while the Fe3O4/GO composites were prepared through a sonochemical mixing process with varying GO content (0.050, 0.075, and 0.100 g). The structural and optical properties were characterized by XRD, HR-TEM, UV–Vis, and SEM–EDX. The photocatalytic performance was evaluated under UV light for 150 min, demonstrating that the composite with 0.100 g GO achieved the highest MB degradation efficiency of 99.72

In this study, the development of a green-synthesized surface plasmon resonance (SPR) biosensor based on Fe3O4/Ag nanocomposites (NCs) for bovine serum albumin (BSA) detection through an externally applied magnetic field has been explored. The Fe3O4 nanoparticles (NPs) were synthesized using Moringa oleifera extract and incorporated with Ag NPs. Analysis of structural, optical, and magnetic characterizations confirmed crystalline Fe3O4/Ag NCs with homogeneous Ag distribution, band-gap narrowing, and near-superparamagnetic behavior. For the SPR measurements, resonance angles of 46.41°, 46.52°, and 46.64° for the integrated Fe3O4/Ag NCs in prism/Au configuration were observed depending on 1, 3, and 5 mg/mL BSA concentrations, with a detection limit of 0.40 mg/mL and a R-squared value of 0.99. For the magneto-optic SPR (MOSPR) measurements, an increase in resonance angles of 46.61°, 46.60°, and 46.70° was detected with a magnetic field strength of 40, 50, and 60 Oe, respectively, resulting in full width at half maximum broadening and an increase in detection accuracy in MOSPR compared with conventional SPR, while preserving the same detection limit. The transverse magneto-optical Kerr effect response exhibited a higher sensitivity than conventional SPR, resulting in an approximately twofold enhancement in the MOSPR configuration. The quantitative analysis reveals how the response of green-synthesized Fe3O4/Ag magneto-plasmonic NCs evolves under an applied magnetic field, enabling a magnetically modulated SPR biosensing response for BSA.

Surface plasmon resonance (SPR) has found widespread application in detecting biological and chemical analytes, food safety, and medical diagnostics. In this study, magnetite/reduced-graphene oxide nanocomposites (Fe 3 O 4 /rGO NCs) were synthesized and characterized for their SPR behavior in the prism/Au/Fe 3 O 4 /rGO system using the Kretschmann configuration. X-ray diffraction analysis confirmed that Fe 3 O 4 possesses a face-centered cubic structure, while the incorporation of rGO reduced the crystallite size with increasing concentration. Fourier transform infrared spectroscopy identified functional groups such as C=O, C=C, and Fe–O, verifying the successful formation of Fe 3 O 4 /rGO NCs. Furthermore, the SPR resonance angle shifted progressively to higher values with increasing Fe 3 O 4 :rGO ratio, indicating an enhanced refractive-index response induced by the rGO content. These results demonstrate that Fe 3 O 4 nanoparticles modified with rGO significantly affect the SPR characteristics, highlighting their potential for use in SPR-based biosensing applications.

Optimizing light collection is essential to enhance power conversion efficiency in perovskite solar cells (PSCs). Understanding the optical characteristics of perovskite materials is key to designing improved structures and enhancing device performance. Precise characterization of these optical properties, especially in complex, multi-layered systems, is crucial. Spectroscopic ellipsometry (SE) is a vital technique for analyzing thin films. It provides insights into optical constants such as the dielectric function, refractive index, and absorption coefficient. SE is commonly used to study perovskite thin films, focusing on aspects such as optical model generation and data analysis, temperature-dependent behavior, thermal degradation, and the chemical composition of perovskites, all of which critically affect the performance and stability of solar cell devices. This review discusses recent progress in SE-based techniques as an effective tool for thoroughly and systematically evaluating the optoelectronic properties of perovskite thin films. Specifically, this review examines the analytical approaches for analyzing the perovskite properties, selecting theoretical optical models and data fitting methods, extracting key optical constants, and interpreting SE measurements. Further, the current advancement and prospects in using SE for optimizing the performance and stability of PSCs are discussed, which serve as critical points in accelerating the commercialization of PSCs in the future.

Surface plasmon resonance (SPR)-based sensors are being developed to detect pathogenic bacteria such as Escherichia coli (E. coli). Fast, accurate, and sensitive detection of foodborne pathogens is very important in early disease detection. This study reports using Ag/rGO/L-His as an interface layer in SPR-based sensors to detect E. coli bacteria. Ag/rGO/L-His with various rGO concentrations were green-synthesized utilizing spinach (Amaranthus viridis) extract. Localized surface plasmon resonance (LSPR) behaviour of Ag/rGO/L-His (AGL) was investigated utilizing the Kretschmann configuration with pris/Au/AGL/E. coli/air array. The concentration of E. coli was varied, and the sensor performance was analysed to evaluate the effect of varying bacterial concentration on the LSPR curve parameters. The analysis results show that there is an LSPR angle shift between pris/Au /air and pris/Au/AGL/air of 0.21 degrees for Ag/rGO1 and 0.34 degrees for Ag/rGO5. The angle shift value increases as the concentration of rGO added increases. The angle of Ag/rGO1/L-His shifted by 0.32, 0.46, and 0.58 after detecting E. coli at concentrations of 6 x 106 CFU/mL, 6 x 107CFU/mL, and 6 x 108 CFU/mL, respectively. The same results also occur in Ag/rGO5/L-His, where resulted an increase in the LSPR angle shift values of 0.51, 0.65, and 0.74. In addition, the minimum reflectance value increased in both samples along with the increase in E. coli concentration. Furthermore, the effectiveness of the SPR sensor was calculated by the low detection limit (LOD). The results showed that the application of Ag/rGO/L-His nanocomposite resulted in a lower LOD ranging from 0.22-0.27 CFU/mL. The low LOD value indicates that the incorporation of rGO into Ag/rGO/L-His plays an important role in enhancing the signal of the SPR-based sensor to detect E. coli bacteria. In addition, the sensor showed good repeatability. Therefore, the use of green-synthesized Ag/rGO/L-His nanocomposite as an interface layer can be a promising alternative to improve the performance of SPR biosensors in detecting various biomolecules such as viruses, bacteria, and other microorganisms.

We have performed first-principles calculations to investigate the effect of change in the number of electrons on optical properties of Cu, Ag, and Au metals in visible and near-infrared energy ranges for surface plasmon resonance (SPR) applications in Kretschmann configuration. We find that an increase in the deviation of the number of electrons leads to a decrease in the real part of the optical conductivity, sigma 1 , and an increase in the real part of the dielectric constant, epsilon 1 , for Ag and Au, but the decrease occurs in Cu. The changes in optical properties correspond to changes in the characteristics of the SPR curves; for Ag and Au, the SPR angle decreases, and the minimum reflectance increases, and in contrast, for Cu, the SPR angle increases, and the minimum reflectance decreases. Band-by-band decomposition analysis identifies that the prominent peak of optical conductivity arises from the interband transitions between the unoccupied uppermost d state and the conduction sp-like state, where an increase in the number of electrons causes a decrease in the prominent peak of optical conductivity in the metal, and vice versa. SPR simulation based on the calculated optical properties delineates the observed trend in SPR measurements. The results provide a scenario to improve the SPR biosensor's performance by applying an electric field through the change in the number of electrons.

The study of optical properties and localized surface plasmon resonance (LSPR) of magnetite/silver nanocomposites (NCs) has been successfully investigated. The NCs were synthesized using the co-precipitation method and coated on the Au film surface with a four-layer Kretschmann configuration system. Light source wavelengths of 405 and 450 nm were used to investigate the influence of the varied wavelength on t the optical properties and LSPR curve characteristics. Electric fields of 1.6, 2.4, and 3.2 V/cm were applied to the substrate/Au film/magnetite/silver NCs/air sample structure for ellipsometer and SPR testing. The findings indicate that the use of an electric field improves the optical properties, a real part of optical conductivity σ _1 , complex dielectric constant (real part, ϵ _1 and imaginary part, ϵ _2 ), complex refractive index (real part, n and imaginary part, k ), and optical absorption ( α ), resulting in a rise in the LSPR angle and a decrease in minimum reflectance. Furthermore, the variation in the incident light wavelength at 405, 450, and 632.8 nm causes an increase in the LSPR angle by 1.21o, 0.97o, and 0.66o, respectively. At a wavelength of 405 nm, the application of electric fields of 1.6, 2.4, and 3.2 V/cm induced shifts in the LSPR angle from 65.87º to 65.99º, 66.23º, and 66.49º, respectively. At 450 nm, the LSPR angle shifted from 63.41º to 63.62º, 63.77º, and 63.94º, respectively. The significant change in the LSPR angle and minimum reflectance due to the applied electric field and wavelength indicates that applying an electric field to the LSPR sensor surface with varied wavelengths provides the scenario to improve the performance of the SPR biosensor for future applications.

The application of a magnetic field to surface plasmon resonance (SPR) is very attractive for biosensing applications because it can increase the performance and detection accuracy of the SPR biosensors. Ferrite nanoparticles (NPs) have been used for surface modification to accommodate the magneto-optical effect. This study successfully investigated and compared the characteristics of the effect of the magnetic field with a transverse configuration on SPR on Fe3O4, CoFe2O4, and MnFe2O4 NPs prepared using the green synthesis method with Moringa oleifera extract, which is environmentally friendly, cost-effective, and sustainable. The effect of the magnetic field on the SPR sensor was investigated using a Kretschmann configuration with a prism/Au thin film/ ferrite NP/air layer structure with a wavelength of 632.8 nm. Magnetic fields of 40, 50, and 60 Oe were applied to the surface of the layered structure, and the SPR angle shift was directly proportional to the magnitude of the magnetic field. The angle shift of SPR with magnetic fields of 40, 50, and 60 Oe was greater than that on the SPR sensor without the magnetic field applied. The angle shift for Fe3O4 NPs was +0.55 degrees, +0.62 degrees, and +0.67 degrees; that for CoFe2O4 NPs was +0.42 degrees, +0.46 degrees, and +0.49 degrees, and for MnFe2O4 NPs it was +0.25 degrees, +0.29 degrees, and +0.31 degrees, respectively. The SPR angles of the Fe3O4 NPs were +0.50 degrees, CoFe2O4 NPs is +0.36 degrees, and MnFe2O4 NPs is +0.19 degrees, respectively. Meanwhile, the value of full width half maximum (FWHM) increases after application of the magnetic field; the FWHM of Fe3O4, CoFe2O4, and MnFe2O4 NPs with 60 Oe is 2.29, 2.28, and 2.29, respectively. In addition, the detection accuracies (DA) of the sensors with Fe3O4, CoFe2O4, and MnFe2O4 NPs with 60 Oe were 0.29, 0.21, and 0.13, respectively. Increases in the SPR angle, FWHM, and DA indicated an increase in the performance of the SPR biosensor. A non-reciprocal investigation showed that the SPR characteristics changed when a magnetic field was applied in different directions. These results indicate that the effect of the magnetic field on SPR systems using ferrite NPs can improve the performance of SPR-based biosensors.

This study investigates the application of graphene oxide (GO) as a hole transport layer (HTL) to improve the performance of perovskite solar cells (PSCs). GO was dispersed in 2-propanol and applied via spin-coating to passivate perovskite grain boundaries, promoting a smooth, uniform layer. The effects of low-concentration GO dispersions (0.25, 0.50, and 0.75 mg.mL-1) on device performance were investigated. The optimal device, incorporating 0.75 mg/mL GO, reached a power conversion efficiency (PCE) of 3.75 %, with a short-circuit current density (JSC) of 8.36 mA.cm-2, an open-circuit voltage (VOC) of 0.769 V, and a fill factor (FF) of 29.2 %. These results highlight the promising potential of GO as an effective, scalable HTL material for improving PSC efficiency.

In light of growing environmental concerns, the issues of toxicity and stability have impeded the progress of lead-based perovskite solar cells (PSCs), prompting the development of lead-free alternatives such as cesium tin bromide (CsSnBr3) perovskites. This study provides a comprehensive evaluation of lead-free CsSnBr3 integrated with a two-dimensional (2D) material charge-transporting layer, utilizing density functional theory (DFT) and one-dimensional solar cell capacitance simulator (SCAPS-1D). We systematically optimized various parameters to enhance the PSC performance, including the thickness of CsSnBr3, defect density, interface defects, resistances, and operating temperature. These optimizations resulted in a notable simulated power conversion efficiency (PCE) of 25.11 %, accompanied by a short-circuit current density (JSC) of 33.90 mA cm-2, an open-circuit voltage (VOC) of 0.894 V, and a fill factor (FF) of 82.82 %. The proposed device with refined parameters not only supports ongoing experimental efforts but also presents an innovative approach to structural optimization for all-inorganic flexible lead-free PSC devices, paving the way for future research in this field.

This study explores the potential of Fe3O4/Graphene Oxide (GO) nanocomposites for enhancing the photocatalytic degradation of rhodamine-B (RhB) textile dye waste. Fe3O4 was extracted from natural iron sand from Glagah Beach, Kulon Progo, Indonesia, and synthesized via a co-precipitation method. Characterization using scanning electron microscopy and energy-dispersive X-ray analysis revealed the nanocomposite comprises three key elements: Fe (28.07

In this study, a fast response, real time, accurate, and non destructive alcohol detection method using surface plasmon resonance (SPR) technique was purposed. The SPR measurement was performed using 5-layers Krestchmann configuration with a layer structure of prism/Au thin film/Fe3O4/rGO nanocomposite/alcohol compounds/air. The Fe3O4/rGO nanocomposite was successfully synthesized using the green route utilizing Moringa oleifera and Amaranthus viridis leaf extract. X-ray diffraction analysis showed the nanocomposite has a face-centered cubic with an inverse spinel structure with a crystallite size of 5.6-5.8 nm. The size of Fe3O4 NPs in the Fe3O4/rGO nanocomposite was variated from 10.6-13.0 nm and showed that there is no impurities in the sample. Fourier transform infra-red analysis also validates the existence of Fe3O4 and rGO indicated by the FeO and CC bond, respectively. The interaction between Fe3O4 and rGO can also be observed through the coordinational bonding FeOC, which is validated by the presence of FeO and CO bonds. The optical properties were studied using ultraviolet-visible spectroscopy, which shows an energy gap of 2.36 eV. Magnetic properties of Fe3O4/rGO nanocomposite show a superparamagnetic characteristic with the saturation magnetization of 40.53 emu/g, magnetic susceptibility of 3.62 × 10-2, and the domain size is 6.22 nm. The SPR angle shifts when applied with Fe3O4/rGO nanocomposite. The addition of alcohol compound further shifted the SPR angle by 0.22°, 0.61°, and 1.19° for methanol, ethanol, and IPA, respectively. This noticeable shift shows a possibility for early detection to differentiate these 3 compounds. The presence of a magnetic field further shifts the SPR angle by 0.08°, 0.08°, and 0.10° for 40, 60, and 80 Oe, which indicates an increase in sensitivity. Therefore, the combination of applied magnetic field and green synthesized Fe3O4/rGO nanocomposite as an eco-friendly interface layer are potential to enhance the sensitivity of SPR to detect the alcohol compounds.

The microstructures and mechanical properties of aluminum matrix composites (AMCs) reinforced by varying weight percents of silicon carbide (SiC = 2.5

The effect of electric field application on the optical properties of gold (Au) thin film for spectroscopic ellipsometry-based surface plasmon resonance (SPR) biosensor applications has been successfully studied. The optical properties, such as the complex refractive index, complex dielectric constant, real optical conductivity, and absorption coefficient, were determined by fitting data from the psi and Delta functions obtained through measurements using a homemade rotating analyzer ellipsometer. The applied electric fields of 0.8 V/cm, 1.6 V/ cm, 2.4 V/cm, and 3.2 V/cm were induced by applying voltages of 1 V, 2 V, 3 V, and 4 V for ellipsometer tests, and 1.6 V/cm to 3.2 V/cm for the SPR test. The Au thin film was deposited onto a glass slide using an evaporator for ellipsometer testing and a BK7 half-cylinder prism was employed for SPR testing. The experimental results show that the real part of the refractive index (n) increases in the spectral range from 1.5 eV to 2.2 eV and from 3 eV to 5 eV and tends to be constant in the range from 2.3 eV to 2.8 eV. Conversely, the imaginary part of the refractive index (k) decreases from 2.8 eV to 3.6 eV and tends to remain consistent from 3.9 eV to 5.0 eV. The dielectric constant (e1) consistently shows a significant increase within the spectral range of 3 eV-5.0 eV, with a tendency to decrease between 2.1 eV and 2.4 eV. Meanwhile, the imaginary part (e2) demonstrates an increase in the spectral range of 1.5 eV-2.4 eV and 3.3 eV-5.0 eV while maintaining relatively stable values in the energy spectral range of 2.6 eV-3.0 eV. Moving to the real part of optical conductivity (01), it increases within the spectral range from 1.5 eV to 2.4 eV and from 3.5 eV to 5 eV, with relatively constant values between 2.6 eV and 3.1 eV. The absorption coefficient (alpha) exhibits a decrease in the spectrum between 2.8 eV and 3.6 eV, but the values remain stable within the range of 3.9 eV-5.0 eV. The alpha slightly decreases in the energy range of 1.8 eV-2.6 eV. The outcomes obtained from these experiments are directly linked to the SPR results, revealing a noticeable shift in the SPR angle (theta SPR) of 45.51 degrees, 45.61 degrees, and 45.73 degrees and an increase in the minimum reflectance (Rmin) of 0.05, 0.09, and 0.13 for electric field strengths of 0 V/cm, 1.6 V/cm, and 3.2 V/cm, respectively. These results imply that the application of an external electric field to the surface of the Au thin film disrupts the matching condition between the evanescent wave vector and the surface plasmon wave vector, thereby altering the reflected light under resonance conditions indicated by an increase in the minimum reflectance and SPR angle. This development holds significant promise to further enhance the sensitivity of electro-optic modulationbased biosensors.

The urgent necessity to remove dangerous lead from the commonly used metal halide perovskite solar cells (PSCs) requires the exploration of effective and reliable lead-free perovskite substitutes. In this study, we conduct a performance analysis of Sn-based PSCs incorporating a low-temperature indium sulfide electron transporting layer (ETL) and use SCAPS-1D simulation to evaluate the PSC performance. We investigate multiple parameters that determine the PSC performance, such as the thickness and defect density of the Sn-based perovskite layer, as well as the defect density at the ETL/perovskite interface. The optimization procedure produced outstanding outcomes with maximum power conversion efficiency (PCE) of 21.57