Optical and Quantum Electronics最新文献

Molybdenum oxide ((MoO_x)), a wide band-gap material with low optical absorption, has emerged as a promising candidate for the hole-selective front contacts for silicon solar cells. However, the carrier selectivity is limited by the absence of a sufficiently high electron barrier. In this study, numerical simulations demonstrate that incorporating an ultra-thin aluminum oxide tunnel layer ((le) 2 nm) enhances the hole selectivity in (MoO_x)-based front contacts. Introducing the tunnel layer at the (MoO_x)/c-Si (n) interface resulted in a relative increase of 5.36 % over the control cell efficiency of 17.77 %. A systematic variation of the energy-band alignment of the tunnel layer revealed that the observed performance enhancement is primarily due to the additional conduction band energy barrier formed by the tunnel layer. A strong influence of the tunnel layer thickness, interface defect density, and pinholes through the tunnel layer on the open-circuit voltage was observed. Subsequently, the tunnel layer was also found to reduce the temperature sensitivity of the solar cell performance. The tunnel layer reduced the magnitudeof the simulated (P_{max}) temperature coefficient of the structure from −0.39 %/°C to −0.15 %/°C, signifying its role in developing high-efficiency silicon solar cells.

In this paper, a theory for rapid light generation based on a cascaded structure of coherent population oscillations (CPO) at room temperature is proposed. Through theoretical calculations, we first compare the effects of the hybrid pump (1480 nm and 980 nm) cascade structure with the dual-pump (1480 nm and 980 nm) single fiber structure on the fast light. Then the phenomenon of fast light saturation in the cascade structure is studied in detail. Finally, the effect of pump ratio M on time advancement is demonstrated. This may facilitate the optimization of optical communication systems.

p-Si/n-ZnO heterojunction diodes have garnered significant attention for energy conversion applications due to their superior optoelectronic properties. In this study, we synthesized n-Zn(1-_x)In_xO two-dimensional (2D) nanoflakes using a phytochemical-assisted synthesis technique, enabling precise control over nanoflake size via In³⁺ dopant concentration. This eco-friendly approach offers a sustainable and scalable method for fabricating high-performance nanostructures. Structural analysis confirmed the hexagonal wurtzite crystal structure of Zn_(1−x)In_xO, while transmission electron microscopy revealed 2D flake-like morphologies ranging from 100 nm to 250 nm. Optical characterization demonstrated bandgap tunability, with pristine ZnO exhibiting a bandgap of 3.38 eV and In³⁺-doped ZnO (1%, 3%, and 5%) showing bandgaps of 3.42 eV, 3.46 eV, and 3.48 eV, respectively, due to the Burstein-Moss effect. The p-Si/n-Zn_(1−x)In_xO heterojunction diodes exhibited enhanced rectification, electrical conductivity, and optoelectronic performance. Under forward bias, the dark current and photocurrent values of the p-Si/ZnO and p-Si/Zn_0.95In_0.05O diodes were 6.4 × 10⁻⁴ A & 8.8 × 10⁻⁴ A and 4.3 × 10⁻³ A & 6.3 × 10⁻³ A, respectively, indicating a significant enhancement due to In³⁺ doping. These findings demonstrate a novel pathway for engineering high-performance heterojunction diodes through sustainable synthesis and precise dopant engineering, paving the way for next-generation optoelectronic and energy conversion devices.

We propose a dual-directional plasmonic metamaterial absorber (MMA) with a simple multilayered architecture that simultaneously achieves ultra-narrowband and ultra-broadband absorption. The structure comprises a SiO₂/Ag/SiO₂/Ti/SiO₂ stack with integrated monolayer graphene sheets, featuring a dual bowtie aperture pattern for strong field confinement. Under top illumination, it exhibits nine near-perfect narrowband peaks (avg. ~98% absorptance, 400–1200 nm), while bottom illumination induces broadband absorption (> 90%). The resonant wavelengths are dynamically tunable via electrostatic gating, enabling active control. Full-wave simulations reveal Fabry-Pérot-like cavity resonances enhanced by plasmonic hotspots, yielding exceptional sensing performance (sensitivity: 1306 nm/RIU, FOM: 261.21/RIU, Q-factor: 215.4). Fabrication-compatible with CVD graphene and FIB patterning, our design outperforms existing MMAs in efficiency, bidirectional functionality, and ease of fabrication. This platform uniquely enables switching between hyperspectral sensing and solar thermal harvesting in a single device, with applications in refractive index sensing, optical switching, and energy harvesting.

Early detection and screening of colorectal cancer are challenging due to the low sensitivity of conventional diagnostic methods in detecting trace levels of carcinoembryonic antigen (CEA), as the main clinically validated biomarker for colorectal cancer. In this study, we developed an advanced plasmonic biosensor that utilizes a regularly patterned arrangement of asymmetric crescent-shaped gold nanoparticles constructed on a quartz foundation. Its sensing mechanism is based on the localized surface plasmon resonance (LSPR), allowing for direct, marker-free detection of CEA in real-time measurements. Using detailed Finite-Difference Time-Domain (FDTD) computational analysis, we established strong localized electromagnetic field enhancement around the crescent nanostructures, producing a clear extinction peak near 900 nm. Parameter optimization studies revealed that maximum sensitivity and figure of merit (FoM) are obtained with a crescent configuration angle of roughly 100° and particle separation of 40 nm. The biosensor shows predictable linear wavelength shifts when exposed to refractive index variations in the detection medium, confirming its ability to identify minute CEA concentrations. These results demonstrate the considerable potential of this plasmonic technology as a high-performance, marker-free sensing solution for early cancer detection. This optimized nanostructure design, combined with advanced plasmonic properties, provides a powerful tool that overcomes existing limitations in current cancer screening approaches, potentially enabling more precise and earlier identification of colorectal cancers through enhanced biomarker detection capabilities.

In this work, the SCAPS-1D modeling program was used to study the impact of an inorganic buffer layer (BL) of ZnOS on the performance of perovskite solar cells (PSCs). The proposed solar cell structure consisted of a glass/TCO/TiO₂/ZnOS/CsPbI₃/CuSbS₂/Au configuration. Incorporating ZnOS-BL between the electron transport layer (ETL) and absorber layer (AL) improved the charge transportation, enhancing the overall performance. The effects of material characteristics, such as the thickness of AL as well as the electron affinity of ETL, BL, and hole transport layer (HTL), were studied. Moreover, the doping densities of ETL, BL and HTL were also examined and optimized to achieve the highest device performance. Consequently, the device performance parameters improved significantly, such as the device incorporating BL achieved J_SC of 22.98 mA/cm², V_OC of 1.13 V, FF of 86.25% and power conversion efficiency (PCE) of 22.04% compared to the reference device without BL with J_SC of 18.46 mA/cm², V_OC of 0.79 V, FF of 78.81%, and PCE of 11.14%. The proposed modeling process opens a new path for researchers to develop this BL-based PSC experimentally.

This study presents a semi-analytical and numerical approach to enhancing the performance of organic solar cells (OSCs) based on the PM6:Y6 system. To model the optical properties of the plasmonic active layer, we utilized the Maxwell-Garnett Effective Medium Theory to determine the complex refractive index of a composite containing 10 vol% silver nanoparticles (Ag-NPs). These derived optical constants were then integrated into a Transfer Matrix Method (TMM) to simulate light absorption and optoelectronic performance. Our results demonstrate that Ag-NPs significantly boost light absorption via localized surface plasmon resonance (LSPR) and enhanced scattering, leading to a substantial increase in simulated device efficiency. The plasmonic device achieved a power conversion efficiency (PCE) of 13.92%, a notable improvement over the pristine device’s 10.19%. Furthermore, a detailed analysis of active layer thickness across a range of 100 to 280 nm revealed that optimal performance is architecture-dependent. Inverted OSCs (IOSCs) reached their peak PCE of 14.29% at a thickness of 220 nm, while conventional OSCs (COSCs) performed best at 240 nm with a PCE of 11.49%. This finding highlights the superior charge extraction and collection efficiency of the inverted configuration. Overall, this research establishes that combining a semi-analytical plasmonic model with precise thickness optimization is a powerful and efficient strategy for designing high-efficiency OSCs.

Single-junction perovskite solar cells, part of the emerging third-generation photovoltaic technologies, face intrinsic limitations such as poor charge separation, instability, and elevated recombination losses. To overcome these challenges and address the environmental concerns associated with lead-based perovskites, a novel, lead-free next-generation, tin-based dual absorber perovskite solar cell (TDAPSC) featuring the device architecture Au/FTO/(textrm{SnS}_{2})/(textrm{BaSnS}_{3})/(textrm{Rb}_{2}textrm{SnI}_{6})/PEDOT/Ni is proposed here. Through the integration of two complementary tin-based absorbers, (textrm{Rb}_{2}textrm{SnI}_{6}) (a halide perovskite variant) and (textrm{BaSnS}_{3}) (a sulfide perovskite) this architecture eliminates lead-related toxicity while leveraging broad spectral absorption, superior carrier mobility, and high quantum efficiency. Detailed SCAPS-1D simulations to optimize key performance parameters including recombination pathways, absorber thicknesses, defect densities, charge carrier distributions, and energy level alignment across interfaces are conducted. As a result, the optimized TDAPSC achieved an open-circuit voltage ((V_{textrm{oc}})) of 1.20 V, a short-circuit current density ((J_{textrm{sc}})) of 35.83 mA/cm², and a fill factor (FF) of 89.33%, leading to a remarkable power conversion efficiency (PCE) of 38.44%. This enhanced performance stems from suppressed recombination and efficient charge extraction facilitated by energy-level alignment between (textrm{BaSnS}_{3}) and (textrm{Rb}_{2}textrm{SnI}_{6}). Moreover, the fully inorganic composition ensures excellent chemical and thermal stability, while also offering scalable fabrication potential. Altogether, this TDAPSC design presents a highly promising pathway toward next-generation photovoltaic technologies that prioritize environmental safety, performance, and long-term durability.

Human activities are increasingly contaminating surface and groundwater reserves. Among various pollutants, ethylene glycol (EG) contamination in water is particularly dangerous. At low concentrations it can enter the body undetected and causes serious health problems such as kidney failure and gastrointestinal disorders. This study demonstrates the use of symmetrically etched single-mode plastic optical fiber (POF) sensor model operating at 1550 nm for detecting EG presence in water using COMSOL Multiphysics. The working of the sensor is based on evanescent field interactions with surrounding medium to detect refractive index (RI) changes, while transmission variations through etched POF serving as the sensing metric. Simulations were conducted for aqueous EG solutions ranging from 0 to 0.15 weight fraction, corresponding to RI values ranging between 1.316 and 1.330. The sensor design was optimized by examining the impact of etched cladding diameter and etched length on sensitivity. These parameters were varied from 60 to 7.05 and 1 to 30 μm, respectively. This in turn lead to sensitivity values in the range of 0.39 × 10⁻³ to 99.50 × 10⁻³ Trans. (A.U)/RIU. Highlighting the importance of evanescent field-surrounding interaction for etched POF sensors, these findings revealed that sensitivity has direct relation with the length of etched region and inverse relation with cladding diameter. The maximum sensitivity of 99.50 × 10⁻³ Trans. (A.U)/RIU was achieved with a 30 μm etched length and 7.05 μm cladding diameter. The proposed POF-based sensor demonstrates strong potential for applications in biomedical engineering, biochemical monitoring, and beverage industry offering a compact and sensitive solution for EG contamination detection in water.