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Type-II superlattice (T2SL) infrared detector has high sensitivity and fast response speed, which is suitable for longer distance imaging and higher speed tracking of moving targets. Quantum efficiency (QE) is one of the key indicators to determine whether the photodetector can achieve high quality imaging, so it is of great significance to improve the QE of T2SL infrared detector. In order to have a more intuitive understanding of how T2SL infrared detector QE can be improved, the methods to improve QE of mid-long wave T2SL infrared detector were reviewed, and the extent to which QE can be achieved under different regulatory means were summarized. The effects of band structure design, absorption layer thickness setting, absorption layer doping type selection and material improvement on QE of T2SL infrared detectors are discussed, and the research status and future development of high QE of T2SL infrared detectors are also prospected. [ABSTRACT FROM AUTHOR]

To investigate the feasibility and formation laws of fabricating micro-dimples induced by near-wall laser-induced cavitation bubble (LICB) on 7050 aluminum alloy. A high-speed camera and a fiber-optic hydrophone system were used to capture pulsation evolution images and acoustic signals of LICB. Meanwhile, a three-dimensional profilometer was employed to examine the contour morphology of the surface micro-dimple on the specimen. The results show that at an energy level of 500 mJ, the total pulsation period for the empty bubble is 795 μs, with individual pulsation periods of 412.5 μs, 217 μs, and 165 μs for the first, second, and third cycles, respectively, with most energy of the laser and bubble being consumed during the first evolution period. Under the synergy of the plasma shock wave and collapse shock wave, a spherical dimple with a diameter of 450 μm is formed on the sample surface with copper foil as the absorption layer. A model of micro-dimple formed by LICB impact is established. As the energy increases, the depth of the surface micro-dimple peaks at an energy of 400 mJ and then decreases. The depth of the surface micro-dimple increases with the increase in the number of impacts; the optimal technology parameters for the micro-dimple formation by LICB impact are as follows: the absorption layer is copper foil, the energy is 400 mJ, and the number of impacts is three. [ABSTRACT FROM AUTHOR]

With non-toxic nature, wide bandgap, and thermal stability, Sn-based perovskite materials have become a hot topic in the field of perovskite solar cell research. In this paper, the SCAPS-1D software was used to construct the FTO/TiO2/CH3NH3SnI3/Spiro-OMeTAD/ Ag perovskite solar cells and the performances of the constructed cells were calculated. The effects of the thickness of absorption and hole buffer layer, the surface defects between hole buffer layer and absorption layer, and the operating temperature on the device performance were studied, then the device performance was optimized. The photoelectric conversion efficiency of the optimized perovskite solar cell is 30. 955%. The theoretical analysis suggests a new approach for enhancing the photoelectric conversion efficiency of perovskite solar cells. [ABSTRACT FROM AUTHOR]

Cu-In-Ga-Se nanoparticles (NPs) were synthesized using a colloidal route process. The effects of growth temperature (GT) on the properties of CuInGaSe2 (CIGS) thin films made from these nanoparticles were investigated using TEM, PL, XRD, and SEM techniques. The Cu-In-Ga-Se NPs were synthesized at growth temperatures ranging from 90 °C to 105 °C and then annealed at 550 °C for 7 min under a Se ambient. The resulting CIGS thin film, formed from Cu-In-Ga-Se NPs synthesized at a GT of 90 °C (referred to as GT90-CIGS), showed a tetragonal structure, large grain size, and high sunlight absorption. It had a band gap energy (Eg) of approximately 0.94 eV. Non-vacuum GT90-CIGS-based solar cells were investigated and fabricated using varying thicknesses of a CdS buffer layer. The maximum power conversion efficiency achieved was approximately 8.3% with an optimized device structure of Al/ITO/ZnO/CdS/CIGS/Mo. [ABSTRACT FROM AUTHOR]

A facile ion-exchange assisted chemical bath deposition of CuSbS 2 for thin film solar cells and exploration of chemical bath mechanism, which achieved the champion efficiency in chemical bath deposition of CuSbS 2 solar cells and enriched the environmentally friendly inorganic solar cell preparation process. [Display omitted] • A facile ion-exchange assisted chemical bath deposition is firstly explored for CuSbS 2 compound. • Pure phase CuSbS 2 thin films with uniform and crystalline were prepared. • Achieved a champion efficiency of 0.75% for CBD-based CuSbS 2 solar cells. Copper antimony sulfur (CuSbS 2) possesses a band gap of about 1.5 eV, high absorption coefficient of > 104 cm−1 and abundant compositions, which is considered as one of the potential photovoltaic absorbers. In this work, we propose a facile ion-exchange assisted chemical bath deposition (IEACBD) method, which uses Cu+ to replace Sb3+ from the matrix of Sb 2 S 3 and then combine into CuSbS 2 alloy. Through systematic study, we found that this ion-exchange is a simultaneous interdiffusion process of Cu+ and Sb3+ ions, which enables a uniform mixture of those two elements. But it also inevitably produces a Sb 2 O 3 by-product on the surface of the film because of the alkaline environment of this chemical bath. To further remove it, we introduce a mild etching process with BDCA solution for Sb 2 O 3 and then obtain a high-quality CuSbS 2. Finally, we assemble an inorganic CuSbS 2 solar cell with the architecture of FTO/TiO 2 /CdS/CuSbS 2 /Carbon/Ag, and delivering a photoelectric conversion efficiency of 0.75 %. This enriches the preparation method of CuSbS 2 thin film and also provides guidance for the synthesis of the similar multiple chalcogen compounds. [ABSTRACT FROM AUTHOR]

در این مقاله ، یک دیود تونل زنی تشدید با ساختار سد مضاعف AlAs / GaAs با استفاده از عملکرد سبز غیر تعادلی شبیه سازی شده است. یک لایه جذب InGaAs منطبق شده برای تشخیص نور در طول موج λ = 600 نانومتر به دستگاه اضافه می شود . میدان الکتریکی از طریق دستگاه و مشخصات نمودار باند انرژی ارائه شده است. جریان عکس دستگاه و منحنی های جریان جریان منبع در مقابل شدت نور مقایسه می شوند . در دمای اتاق ، بازده کوانتومی 95/0 برای دستگاه بدست آمد . پاسخ زمان گذرا دستگاه به دست آمد و وابستگی آن به پارامترهای ساختاری (ضخامت لایه جذب ، ضخامت کلکتور و انتشار دهنده ودوپینگ مخاطبین) ، شدت نور ، زاویه نور ساطع شده و سوگیری ولتاژ شبیه سازی شده و تأثیر آنها بر عملکرد دستگاه مورد تجزیه و تحلیل قرار گرفت. پهنای باند دستگاه به دست آمد. نتایج شبیه سازی نشان می دهد که وقتی بایاس ولتاژ افزایش یابد ، زمان افتادن کاهش می یابد و پاسخ دستگاه سریعتر است. با تغییر ضخامت لایه جذب و مخاطب ، پاسخ زمان RTD-PD تغییر می کند. تغییرات دوپینگ در لایه های تماس بر روی پهنای باند تأثیر می گذارد. نتیجه نشان می دهد که تغییرات شدت نور و زاویه نور ساطع شده ، پاسخ زمان گذرا را تغییر می دهند.

Large-scale deployment of the perovskite photovoltaic technology using such high-performance materials as CH3NH3PbI3 may face serious environmental issues in the future. Implementation of perovskite solar cell based on Sn could be an alternative solution for commercialisation. This paper presents the results of a theoretical study of a lead-free, environmentally-friendly photovoltaic cell using CH3NH3SnI3 as a light-absorbing layer. The characteristics of a photovoltaic cell based on perovskite were modelled using the SCAPS-1D program. Various thicknesses of the absorbing layer were analysed, and an optimised device structure is proposed, demonstrating a high power conversion efficiency of up to 28% at ambient temperature. The analysis of the thicknesses of the CH3NH3SnI3 absorbing layer revealed that at a thickness of 500 nm, performance is demonstrated with an efficiency of 27.41 %, a fill factor of 85.92 %, a short circuit current density of 32.60 mA/cm2 and an open-circuit voltage of 0.98 V. The obtained numerical results indicate that the CH3NH3SnI3 absorbing layer may be a viable replacement for the standard materials and may form the basis of a highly efficient technology of the environmentally-friendly perovskite solar cells. [ABSTRACT FROM AUTHOR]

The absorption performance of anechoic coatings depends on the material properties, layer thicknesses and cavity distribution density and cavity size. In this paper a design method based on numerical simulation was presented by combining FEM and acoustic duct method (ADM). Analyzing of anechoic coatings was performed under active sonar impinging plane wave by normal incident angle. In this approach considering a unit cell of anechoic coating and two ducts of the fluid on its both sides, the reflection characteristics, transmission and reflection coefficients of anechoic coating were calculated using acoustic duct theory. Validation was performed by comparing the results of simulation with the available experimental data. Also a design code in ANSYS software was developed. Finally using this code and the proposed model, the acoustical behavior of anechoic coatings was investigated. The results show that sound transmission coefficient for coating with cylindrical cavity is larger than that of spherical cavity. Furthermore unlike the transmission coefficient, for all frequencies upper than 1500 Hz, coating with cylindrical cavity has a greater echo reduction and therefore its anechoic performance is better than that of spherical cavity.

A two-dimensional perovskite photonic crystal structure of Methylamine lead iodide (CH3NH3PbI3, MAPbI3) is rationally designed as the absorption layer for solar cells. The photonic crystal (PC) structure possesses the distinct “slow light” and band gap effect, leading to the increased absorption efficiency of the absorption layer, and thus the increased photoelectric conversion efficiency of the battery. Simulation results indicate that the best absorption efficiency can be achieved when the scattering element of indium arsenide (InAs) cylinder is arranged in the absorption layer in the form of tetragonal lattice with the height of 0.6 μm, the diameter of 0.24 μm, and the lattice constant of 0.4 μm. In the wide wavelength range of 400–1200 nm, the absorption efficiency can be reached up to 82.5%, which is 70.1% higher than that of the absorption layer without the photonic crystal structure. In addition, the absorption layer with photonic crystal structure has good adaptability to the incident light angle, presenting the stable absorption efficiency of 80% in the wide incident range of 0–80°. The results demonstrate that the absorption layer with photonic crystal structure can realize the wide spectrum, wide angle, and high absorption of incident light, resulting in the increased utilization efficiency of solar energy.

Abstract Ternary compound semiconductor CdSe x S 1-x (x = 1, 0.8, 0.6, 0.4, 0.2 and 0) thin films were prepared on glass substrates by using simple solution processed spin coating technique. Cadmium acetate, sodium selenosulfate and thiourea were used as source materials for Cd2+, Se2− and S2− ions, while triethanolamine was used as a capping agent. The 25% concentred NH 4 OH solution was used as a complex reagent and also used to adjust the pH of the final solution ~ 11. The deposition conditions (rotation speed 2000 rpm for 30 s and substrate dried in the air at 120 °C for 2 min) were remain same for all the samples. The as-deposited thin films on glass substrate were annealed at 350 °C for 30 min. The X-ray diffraction pattern shows that all the samples were polycrystalline in the nature with hexagonal structure. The most of prepared thin films were highly textured along (002) plane and peak position for plane (002) is shifted with change in composition 'x'. The average crystallite size in CdSe x S 1-x thin films were found between 62.6 nm to 93.4 nm. Scanning electron microscopy images showed uniform deposition morphology with spherical shaped grains distributed over entire glass substrate. Samples CdSe 0.8 S 0.2 and CdSe 0.6 S 0.4 thin films indicated interesting morphological features with the combination of spherical shaped nanoparticles and interconnected nanofibers which form hierarchical flowerlike microstructure. Energy dispersive X-Ray studies confirmed that thin films were having approximately same stoichiometry of atomic ratio of elements Cd, Se and S as present in volumetric ratio of the reactants in chemical solution. Fourier transform infrared studies confirmed the formation of the Cd(Se,S) bonding in materials. The optical band gap of CdSe x S 1-x thin films were found as direct band gap in the range of 1.82 eV to 2.32 eV. As the incorporation of sulphur element increases, the band gap of CdSe x S 1-x thin film also increases. The CdSe x S 1-x thin films can be used as absorption layer in solar photovoltaic cell which is due to wide and fine tenability of the energy band gap. Highlights • Simple, fast and convenient technique to produce uniform CdSe x S 1-x thin films. • Minimum material wastage, low cost and easily obtain desirable thickness method. • Spherical shape nanoparticles with interconnected nanofibers features. • Optical band gap tuned from 1.82 eV to 2.32 eV as incorporation of sulphur increased. [ABSTRACT FROM AUTHOR]

To obtain an optimum absorption layer based on hydrogenated polymorphous and nanocrystalline silicon thin films in a plasma-enhanced chemical vapor deposition, radio frequency (RF) power was varied from 25W to 100W using a mixture of dichlorosilane and hydrogen. By Raman spectroscopy, the crystalline fraction was found to be varied from 7% to 69%, and RF power value of 75W was found to be suitable with an appropriate mixture of amorphous and crystalline phases, respectively. Thickness measurements performed by profilometry were cross-checked with the value obtained from the cross-sectional scanning electron microscopy micrographs. Micrographs obtained using high-resolution transmission electron microscopy confirmed the presence of silicon nanocrystals in the range of 2-5nm with a strong probability of confinement effect. B and gap value of 1.55eV at 75W upheld the suitability of this particular RF power for active absorption layer, which has also shown maximum photosensitivity. By varying the RF power in a plasma-enhanced chemical vapor deposition (PECVD) system, control over the morphology and phase transition (a-Si to nc-Si) of silicon thin films has shown. Furthermore, control over the size of nanoparticles and hence, effective band gap (absorption coefficient) of the material is also reported. Overall, the use of the present material as a proficient absorption layer in silicon solar cells shown excellent optoelectronic properties. [ABSTRACT FROM AUTHOR]

The microstructure of absorption layer at the liquid–solid interface in nanofluids is investigated by molecular dynamics simulation, with consideration of various influential factors including: nanoparticle shape, nanoparticle size, and nanoparticle material. By analyzing number density distribution, radial distribution function, and potentials of mean force the microscopic mechanism in absorption layer is depicted. It is found that the microstructure of absorption layer due to the adding of nanoparticles is entirely different from that of single-phase base fluid. The absorption layer has two denser locations of liquid atoms. The microscopic structure of absorption layer is more ordered and is close to that of solid material. A large energy barrier with a different cis–trans direction of energy barrier is found in potentials of mean force which reveals the mechanism of absorption layer formation. Furthermore, through calculating the mean square displacement and self-diffusion coefficient, the microscopic behavior of liquid atoms is connected to the macroscopic thermal conduction of nanofluids. [ABSTRACT FROM AUTHOR]

Sol-gel processed CuZnSnS (CZTS) thin films were fabricated without sulfurization for application as a photovoltaic absorber layer. The precursor solution was made from CuCl, Zn(ac), SnCl, thiourea, and 2-methoxyethanol and the spin-coated film was annealed at temperature above 500 °C under a N atmosphere. A homogeneous and compositionally uniform film with single CZTS phase was obtained. Film composition featuring larger grains, which is desirable in photovoltaic cells, was obtained with heat treatment at 540 °C. The grain size was up to 1 μm and the Cu/(Zn + Sn) and Zn/Sn ratios were 0.93 and 1.07, respectively and the band gap energy was 1.56 eV. [ABSTRACT FROM AUTHOR]

Molecular dynamic model of nanofluid between flat plates under shear flow conditions was built. The nanofluid model consisted of 12 spherical copper nanoparticles with each particle diameter of 4 nm and argon atoms as base liquid. The Lennard-Jones (LJ) potential function was adopted to deal with the interactions between atoms. Thus, the motion states of nanoparticles during the process of flowing were obtained and the flow behaviors of nanofluid between flat plates at different moments could be analyzed. The simulation results showed that an absorption layer of argon atoms existed surrounding each nanoparticle and would accompany with the particle to move. The absorption layer contributed little to the flow of nanoparticles but much to the heat transferring in nanofluids. Another phenomenon observed during shear flowing process was that the nanoparticles would vibrate and rotate besides main flowing with liquid argon and these micro-motions could strengthen partial flowing in nanofluids. [ABSTRACT FROM AUTHOR]

Using the finite element method (FEM) and boundary element method (BEM) and considering the sound absorption layer which is covered on the backing of the sonar dome, the interior field in the dome which is excited by the incident plane wave has been studied. This method is validated by comparing numerical results with that of classic elastic theory. Then the effect of parameters of the sound absorption layer on interior sound field has been analyzed. The numerical calculation results show that uniformity of interior sound pressure is improved when the backing is covered with a sound absorption layer. The thicker the layer is, or the higher the loss factor of layer is, the more uniform the sound field is. [ABSTRACT FROM AUTHOR]

The function of the interfacial transition zone (absorption layer) in resin-modified glass-ionomer cements bonded to deep dentin remains obscure. This study tested the hypotheses that the absorption layer is formed only in the presence of water derived from hydrated dentin and allows for better bonding of resin-modified glass-ionomer cements to dentin. Ten percent polyacrylic acid-conditioned, hydrated, and dehydrated deep dentin specimens were bonded with 2 resin-modified glass-ionomer cements and sealed with resins to prevent environmental water gain or loss. A non-articulate absorption layer was identified over hydrated dentin only, and was clearly discernible from the hybrid layer when bonded interfaces were examined with transmission electron microscopy. This layer was relatively more resistant to dehydration stresses, and remained intact over the dentin surface after tensile testing. The absorption layer mediates better bonding of resin-modified glass-ionomer cements to deep dentin, and functions as a stress-relieving layer to reduce stresses induced by desiccation and shrinkage. [ABSTRACT FROM AUTHOR]

We have studied matching of a p-i-n photodiode (PD) with a single serial inductive element for broadband operation. The bit rate and rise time may be significantly improved, compared to a device without inductor for nonreturn-to-zero (NRZ) modulation. The matched device offers improved pulse equalization leading to increased receiver sensitivity, and reduces the need for an additional pulse-equalizing filter. The material is presented so that it can serve as a guideline of how the inductor can be included when choosing the thickness of the absorption layer and/or area for a p-i-n PD design, and ends with typical design examples [ABSTRACT FROM PUBLISHER]