Optical and Quantum Electronics最新文献

This article explores the reinforcement of the chief characteristics of the polymer blends made of polyvinyl alcohol (PVA) and polyvinylidene fluoride (PVDF) via incorporation of ZnO (zinc oxide) nanofiller. The resulting PVA/PVDF/ZnO polymer nanocomposites were fabricated by the solution casting approach and characterized by key techniques such as XRD, FESEM, UV-Vis-NIR photo-spectrometer, impedance analyzer and FTIR spectrometer to examine the enhancement in structural parameters, surface morphology, optical and electrical parameters, and mechanism of functional groups. respectively. By optimizing and enhancing the wt% of ZnO nanoparticles, the resulting nanocomposites demonstrate improved structural (increase in crystalline size from 63 nm to 70 nm, reduction in dislocation density from 9.61 × 10^− 5 to 6.49 × 10^− 5 m^− 2) and optical parameters (reduction in optical bandgap from 5.02 eV to 4.44 eV, increase in refractive index and Urbach energy from 1.98 to 2.10 and 1.5 to 4.0 eV, respectively); and dielectric performance (augmentation in dielectric constant and ac conductivity from ~ 12 to 60 and 0.003 to 0.009 S/mm, respectively) making them appropriate for a broad range of industrial applications. In FTIR spectra, the transmittance peaks at 880 cm⁻¹ and 833 cm⁻¹ indicate the -C-C-C chain characteristic of PVDF, while peaks at 1402 cm⁻¹ and 2920 cm⁻¹ correspond to -CH₂ groups in both PVA and PVDF. Additionally, peaks at 1068 cm⁻¹ and 1704 cm⁻¹ relate to -C-O and -C = O stretching, and the broad peak from 3500 cm⁻¹ to 3800 cm⁻¹ represents hydroxyl groups, with intensity increased by ZnO nanofiller. The uniform dispersion of ZnO within the PVA/PVDF polymer blends plays a key role in reinforcing the interfacial bonding between the polymers, leading to superior structural integrity and enhanced recyclability. This approach offers a sustainable pathway for the progress of high-performance polymeric nanocomposites with potential applications in electronics.

This article proposes a new Ultra-Violet (UV)-C Light emitting Diode (LED) structure based on orderly aligned Quaternary Nitride alloy based specially-designed quantized quantum barrier. In this article, we theoretically investigate the performance such as internal quantum efficiency (IQE), efficiency droop etc. of proposed structure and also compare it with the reference UV-C LED structure. In this proposed structure, there is no sudden potential barrier as in case of reference structure because of the strain compensation provided by the quantized periodic Superlattice-Al_xIn_yGa_(1-x–y)N/ Al_aGa_bN quantum barrier. Active region epilayer crystal orientation balanced by introducing ‘In' molar content in alternate sub-layers of quantum barrier (QB). This allows for stronger carrier confinement in the active region, which enhances IQE to 72% from 32% (reference structure) and reduction in efficiency droop from 11% to 0.05% at current density of 200 A-cm⁻². The variation in the density of states (DOS) for carrier allocation due to strain balance in the quantum barrier compared to the quantum wells (QW) is responsible for the significant increase in the electro-optical efficiency of the light emitting device.

High dense cadmium lead-borate glasses with nominal compositions of (75-X)B₂O₃-XPbO-5Na₂O-10CdO-10ZnO: X = 5–20 mol% in steps of 5 were fabricated via the melt quenching technique. The physical features and the capability of applying the prepared glasses as γ-ray and fast neutron shields have been investigated. The density (D_s) values increased from 4.820 g.cm⁻³ to 5.664 g cm⁻³ as PbO content increased from 5 to 20 mol% in the glass network. The polaron radius (r_p) increased, while the field strength (F) reduced as PbO content increased. The boron ion concentration (N_B) of the investigated glasses decreased from 2.231 × 10²² (ions.cm⁻³) to 1.503 × 10²² (ions/cm³). The inter-ionic distance (r_i) values increased from 3.551 to 4.051 A^o. Values of the packing density (P_d) decreased from 0.888 to 0.695. The free volume (V_f) enhanced from 2.105 to 6.698 g mol⁻¹ cm⁻². The sample BPNCZPb-20 possessed the highest exposure (EBF) and energy absorption (EABF) buildup factors values at 1– 40 MFP among all investigated glasses. The half- value layer (HVL_FCS) and the relaxation length (λ_FCS) values were the lowest for the BPNCZPb-5 glass sample. Therefore, the sample coded as BPNCZPb-20 can be considered as γ-ray shield, but BPNCZPb-5 glass can be used as a neutron shield.

In this article, a lead-free structure FTO/TiO₂/NH₃(CH₂)₂NH₃MnCl₄/spiro-OMeTAD/Au is investigated using SCPAS-1D simulator. Initially, impact of absorber thickness on performance is thoroughly examined and found 900 nm thick absorber solar cell superiuses performer (open circuit voltage = 1.18 V, short circuit current density = 24.47 mA/cm², fill factor = 70.88%, power conversion efficiency = 19.70%). Further, numerous inorganic materials are investigated through lattice mismatching ratio as substitute of organic hole transport layer and CZTSe as the most adequate materials for enhancing both efficiency and stability owing to minimal lattice mismatching, easy synthesis, efficient charge transport characteristics and superior chemical stability. Serval metallic materials like Cu, Fe, C, W, Ni and Pd are used as back contacts, are also examined with an aim of replacing the expensive Au and it is found that the proposed structure offers highest efficiency with Pd i.e., 31.60% (V_oc = 1.13 V, J_sc = 32.94 mA/cm² and FF = 84.55%). Additionally, the effect of defects density of absorber and temperature on device performance are also analysed and observed both factors adversely affects device performance. So, their values kept minimum for achieving optimal efficiency. The simulated results also illustrated in J-V and quantum efficiency (QE) curves. These optimised results obtained in present study are also compared with previously reported results. The results extracted from this simulation may play a potent role in the development of eco-friendly and efficient solar technology.

Melt quenching was utilized to produce Er⁺³-doped lead–bismuth tellurite glasses with the following composition: (75-x) TeO₂–15 PbO–10 Bi₂O₃–xEr₂O₃, where x = 0, 0.5, 1, 1.5, 2, and 2.5 mol%. The impact of Er³⁺ doping was assessed by analyzing its optical and physical properties. Using XRD, the non-crystalline character of the materials was determined. The density of the samples was increased from 6.387 to 6.528 g.cm⁻³. The absorption spectra show eight transition bands corresponding to the transitions from ⁴I_15/2 to ⁴I_13/2, ⁴I_11/2, ⁴I_9/2, ⁴F_9/2, ⁴S_3/2, ²H_11/2, ⁴F_7/2 and ⁴F_5/2, respectively. Judd–Ofelt theory was utilized to compute both the experimental and calculated oscillator strengths. The trends of the intensity parameters are as follows: Ω₂ > Ω₆ > Ω₄. A total of three emission bands were detected in the spectrum of fluorescence. The green transition ⁴S_3/2 → ⁴I_15/2 is the strongest among other transitions. To ascertain the color coordinates, the CIE 1931 chromaticity diagram was applied. 95.11% was the maximum quantum efficiency for the transition ⁴S_3/2 → ⁴I_15/2. The findings indicate that TPBE2 glass exhibits considerable potential as a material for photonic applications and the production of laser optical systems.

Numerical simulation of a lead–tin perovskite (MAPb0.75Sn_0.25I₃) solar cell was conducted. The simulation was validated against measurements (Li et al., J. Mater. Chem. C Mater. 5:2360–2367, 2017) and the photovoltaic conversion efficiency (PCE) closely matched the measured value, 12.19≈12.08%. Subsequently, optimization strategies to enhance the SC performance were pursued. Doping hole and electron transport layers (HTL, ETL) with various elements as well as adjusting HTL, ETL, and perovskite thicknesses have improved PCE and carriers’ extraction. These optimizations led to an enhancement in PCE to 12.93%. Further improvements using Copper oxide (Cu₂O) as HTL yielded a PCE of 13.38%. Doping Cu₂O with Tellurium pushed PCE to 14.73%. Copper doping of Zinc Oxide outperformed other ETLs and increased PCE to 15.33%. Overall, these findings represent significant strides in advancing the design of perovskite solar cells, providing valuable insights for further enhancements in photovoltaic conversion efficiency.

The development of efficient energy absorbers is essential for optimizing solar energy utilization, particularly for applications such as thermophotovoltaics and other solar energy harvesting technologies. Current research typically focuses on improving the efficiency of the solar absorbers with low-cost materials. This study addresses this limitation by introducing a broadband solar absorber with a staircase-shaped resonator structure. The absorber employs tungsten as the substrate due to its high thermal conductivity and stability, with a GaInAsP layer forming the staircase resonator. Simulations using finite element methods demonstrate that the proposed two-layered structure achieves over 90% absorption within the 200–3000 nm wavelength range, including ultraviolet and visible spectra. This broad absorption range maximizes solar energy capture and conversion efficiency. A parametric examination demonstrates how geometric factors like substrate depth and resonator dimensions affect the absorption effectiveness. The unique staircase shape of the resonator enhances light trapping and absorption across the full spectrum. Under real-world conditions, the absorber effectively captures solar energy across various angles and polarizations. These findings contribute to the advancement of energy absorber design and offer insights for future innovations in solar energy harvesting.

In this article, a comprehensive research was carried out to investigate the elastic, structural, and optoelectronic properties of double perovskite compounds K₂InAgCl₆, K₂InAgBr₆, and K₂InAgI₆ by using density functional theory. Goldsmith’s tolerance factor (t_G), whose values are near to unity, was used to assess the structural stability of the cubic perovskite structure. According to the analysis of electronic characteristic, K₂InAgCl₆, K₂InAgBr₆, and K₂InAgI₆ are semiconductors with a tiny band gap, calculated using the mBJ-PBE sol potential with band gap values of 2.48 eV, 1.47 eV, and 0.23 eV, respectively. A comprehensive analysis of the optical characteristics of these compounds was conducted across an energy range from 0 to 10 eV. The results revealed that K₂InAgCl₆, K₂InAgBr₆, and K₂InAgI₆ exhibit significant conductivity and absorbance properties in wide energy ranges, which is confirmed by density of states analysis. Moreover, the optical characteristics shows that lower photon energy relates to high optical transmission, while higher energies result in more optical absorption of material. These results demonstrate that K₂InAgCl₆, K₂InAgBr₆, and K₂InAgI₆ are viable material candidates for use in high-frequency UV optical devices.