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More and more attention has been paid to CsPbIBr2 material for perovskite solar cells (PSCs), owing to the trade-off between bandgap and stability. However, the reported maximum power conversion efficiency (PCE) of CsPbIBr2 PSCs is lag behind that of the congeners due to the serious interface recombination of charge carriers. In this work, the effects of interface defect density and interface band offset on the properties of CsPbIBr2 PSCs are investigated. It is found that the characteristic of the front electron transfer layer (ETL)/perovskite interface has a significant influence on the performance of PSCs than that of the back perovskite/hole transfer layer (HTL) interface. Additionally, a PCE of 15.05% with a high open-circuit voltage (VOC) of 1.54 V is obtained for the PSCs with FTO/ZnOS/CsPbIBr2/CuAlO2/Au structure. Finally, two-terminal monolithic all-perovskite double-junction tandem solar cells (TSCs) with the architecture of FTO/ZnOS/CsPbIBr2/CuAlO2/ITO/TiO2/MAPbI3/Spiro-MeOTAD/Au are constructed, and a maximum PCE of 27.4% (VOC of 2.60 V, JSC of 12.21 mA/cm2, and FF of 86.42%) is obtained for the TSCs with top and bottom absorber thicknesses of 600 nm and 500 nm respectively. Furthermore, four-terminal triple-junction TSCs are designed with silicon solar cells as bottom sub-cell, and a maximum PCE of 35.35% is achieved. These results will provide theoretical guidance for the fabrication of high performance TSCs.

It is well known that the phase stability of CsPb(I1−xBrx)3 (0 ≤ x ≤ 1) perovskite materials is enhanced under humid environments with the increase of Br− concentration in film, however, the bandgap (Eg) is also widened synchronously, resulted in limiting the light harvesting and then reducing the power conversion efficiency (PCE) of devices. Hence, how to realize the compatibility of high stability and high PCE is a challenge for device based on CsPb(I1−xBrx)3. In this work, the two- (2-T) and four-terminal (4-T) tandem solar cells (TSCs) consisting of a CsPb(I1−xBrx)3 top sub-cell and a crystalline silicon (c-Si) bottom sub-cell are constructed and compared. It is found that in the case of 2-T configuration, performance of device is very sensitive to the Eg and the thickness of top sub-cell, and a maximum PCE of 29.23% is achieved only for the CsPbI3 top sub-cell at an optimum thickness of 275 nm. However, in the 4-T formation, devices present a weak dependence on the Eg and the thickness of top sub-cell, and PCEs above 28.5% can be obtained when CsPbBr3 is used as top sub-cell. These results highly underline the application potential of 4-T CsPb(I1−xBrx)3/Si TSCs, especially for CsPbBr3/Si TSC.

In recent years, inorganic CsPbBr3-based perovskites have accomplished considerable progress owing to their superior stability under harsh humid environment. The power conversion efficiency (PCE) of CsPbBr3 perovskite solar cells (PSCs) has seen an unprecedented development from 5.74% to 10.91% with the improvement of the CsPbBr3 crystal quality. Despite extensive research efforts, the device efficiency of the CsPbBr3-based PSCs still lags behind that of other hybrid perovskite materials. Therefore, there is a significant interest in further boosting the performance of all-inorganic CsPbBr3 PSCs by the synergic optimization of films and device interfaces. In this review, we have discussed and summarized recent advances and methodologies related to CsPbBr3 films and PSCs. Furthermore, we discuss different fabrication strategies such as solution-based and vapor-based methods and their influence on the properties of CsPbBr3, particularly the morphology of films. Moreover, the timeline of improvement of the device efficiency from 2015 to 2020 is comprehensively addressed and developments are clearly sorted out by addressing critical factors influencing the photovoltaic performance. We further highlight state-of-the-art engineering strategies for CsPbBr3 PSCs that facilitate the crystallization control, charge extraction, suppression of charge recombination, and defect passivation in a systematic manner. At the end of the review, the summary and perspectives are presented along with beneficial guidelines for developing highly efficient and stable CsPbBr3 PSCs.

Recently, inorganic perovskite solar cells (PSCs) based on CsPbBr3 have triggered incredible interest due to the demonstrated excellent stability against thermal and high humidity environmental conditions. However, the power conversion efficiency (PCE) of the CsPbBr3-based PSCs is still lower than that of the organic-inorganic hybrid one, because of the large band gap and serious charge recombination at the interface or inside the device. Here, the working mechanism of the devices with normal n-i-p planar structure is modeled and investigated using SCAPS 1D simulation software. The simulation results state that the proper band structure of PSCs is crucial to carrier separation and transport. The high interface recombination, originated from the large band offsets of the electron transport material (ETM)/absorber and absorber/hole transport material (HTM) respectively, can be effectively diminished with the continuous gradient junction design of the absorber, and a PCE of 11.58% is obtained with a high open-circuit voltage (VOC) of 1.68 V. Moreover, by building a heterojunction bilayer absorption scenario of CsPbIBr2/CsPbBr3 and employing ZnOS and Cu2ZnSnS4 films as the ETM and HTM respectively, the PCE of PSCs is further increased to 15.89%, caused mainly by the enhancement in short-current density (JSC). Moreover, reducing the interface defect density is also very important to improve the performance of PSCs. These results will provide theoretical guidance for improving the performance of the CsPbBr3-based PSCs.

Formamidinium tin iodide (FASnI3), as one promising Pb-free halide perovskite, has received extensive attention. But perovskite solar cells (PSCs) based on FASnI3 films have yet to realize the high power conversion efficiency (PCE) achieved in its Pb-based counterparts. To investigate the limitation of FASnI3-based perovskite solar cells with inverted p-i-n planar structures, the influences of various parameters on the device performance are analyzed through device simulation. The results reveal that defect density at front hole transport material (HTM)/absorber interface is critical for high efficiency. And it is interesting to note that the doping density, rather than the doping type and its space distribution, dominates the device properties, and an upper limit of 1 × 1016 cm−3 is achieved. In addition, the response of device to band offset is investigated, and an optimum electron affinity of 3.9 eV is obtained. Finally, the effects of relative permittivity and thickness of the absorber with different carrier lifetime are studied. A maximum PCE of 9.75% is achieved at absorber thickness of 300 nm with carrier lifetime of 0.1 ns? These results show that optimizing the interface property and band offset, improving the stability of Sn2+ and reducing the defect density of absorber layer are the main challenges for high-performance FASnI3-based PSCs in the future research.

Owing to the inevitability of moisture/thermal instability in organic-inorganic hybrid perovskites, pure inorganic perovskites such as CsPbI2Br perovskite have surfaced as promising options for commercial perovskite solar cells (PSCs) due to their high photovoltaic performance and excellent inherent stability. However, designing additive engineering approaches to mitigate defect-induced crystalline phase transitions from a photosensitive perovskite phase to a non-perovskite phase has been a difficult task for researchers. In this work, using a one-step spin coating approach, we have prepared a polyvinylpyrrolidone (PVP) polymer-incorporated stable phase of CsPbI2Br at a low temperature (120 ​°C). Examinations using structural, morphological, and photo-physical measurements revealed that the optimum amount of PVP can greatly improve the optoelectronic properties of the film, which facilitates in reducing the trap states and defect in perovskite film, thus enabling charge carrier separation and suppressing charge recombination. As a result, the device based on 5 ​mg-PVP achieves a champion power conversion efficiency (PCE) of 10.47%, with a fill factor (FF) of 56.35%, a short-circuit current (JSC) of 18.47 ​mA ​cm2, and an open-circuit voltage (VOC) of 1.01 ​V, which is significantly higher than the device without PVP (6.36%). These findings suggest that PVP-CsPbI2Br has tremendous promise for future research and application in photovoltaic devices.

Since the first report in 2009, the certified power conversion efficiency (PCE) of organic-inorganic halide perovskite solar cells (PSCs) has rapidly risen to 23.3%, which successfully demonstrates the importance of film morphology and quality management, especially for the planar heterojunction architecture based on solution-processed method. In this paper, the morphology, structure, optical and electrical properties of perovskite films treated by two different multi-step thermal annealing methods have been studied and compared. For the conventional multi-step (CMS) annealing method, the surface morphologies and optical properties of films are significantly influenced by the annealing temperature due to the decomposition of CH3NH3PbI3. When the modified multi-step (MMS) method is adopted, the decomposition of CH3NH3PbI3 can be effectively suppressed. The best device treated by MMS method at 180 °C showed a short circuit current density of 20.85 mA/cm2, an open circuit voltage of 0.96 V, a fill factor of 72.7%, and a PCE of 14.7%, which is a 23.5% enhancement in PCE relative to the maximum 11.9% treated by CMS method at 160 °C. These findings suggest that the efficiency of PSCs can be further improved by optimizing the preparation process.

In this paper, we present a successful partial substitution of PbI2 by a much less expensive and toxic FeCl2 in perovskite films, namely MAI(PbI2)1−x(FeCl2)x (MA = CH3NH3+), and the followed effects on the performance of planar heterojunction perovskite solar cells (PSCs). The incorporation of a small content of Fe and Cl ions into the perovskite films could improve the growth morphology, enhance the crystallinity, increase the carrier lifetimes, as well as tune the material work function and Fermi level without significantly changing the band gap. Consequently, by adjusting the FeCl2 substitution fraction into the perovskite films, a power conversion efficiency above 17% is achieved with a high open-circuit voltage up to 1.10 V. Our work implies that conventional chlorides as substituting material of PbI2 have huge potential for the fabrication of more ecological PSCs.

Inorganic perovskites (CsPbX3, X = I−, Br− or Cl−) have got researchers attention in the photovoltaic community due to their exceptional photoelectric properties and high thermal stability. In this work, we have explained a two-step vapor deposition approach to fabricate the CsPbCl3 films. To improve the properties of CsPbCl3 perovskite, different reaction conditions and their influence on the structural, morphological and optical properties of resultant films were systematically examined. We found that the proposed deposition strategy has a wide reaction window and is viable for the preparation of uniform CsPbCl3 films. The optimal reaction conditions resulted in improved crystallinity, morphology and photoluminescence. The present work will provide beneficial guidance for high-quality CsPbCl3 and other CsPbX3 perovskite films for future optoelectronic applications.

Organic–inorganic hybrid perovskite solar cells have made great breakthroughs in the past few years, and spurred researchers to develop and experiment a variety of new architectures. One-dimensional nanostructures are naturally introduced in solar cells, because of their excellent charge transport properties and open-pore structure. However, the performances of these solar cells are inferior to their mesoporous counterparts, suggesting that some unique mechanisms maybe held behind devices operation. Here, a three-dimensional optical model combined with a two-dimensional axisymmetric semiconductor model is applied to investigate the influence of the architectural design of scaffolds on the properties of perovskite solar cells based on Al2O3 nanorod arrays. Simulation results show a great dependence of device performance on the density, length and porosity of Al2O3 nanorods, which decided the electron field distribution and carrier recombination loss inside the cells. Strikingly, an optimal length of 450 nm for Al2O3 nanorods is obtained for the perovskite solar cells with efficiency over 20% at porosity of 0.7. The results obtained have some guidance function on the fabrication of high efficiency PSCs based on nanorods.

CsPbI3 perovskite materials have triggered enormous research attention as promising light-harvesting or fluorescent materials, owing to their high photoluminescence quantum yields, narrow photoluminescence (PL) emission spectra and excellent photophysical properties based on the quantum confinement effect. However, the formation of desirable black-phase CsPbI3 requires complex processing at higher annealing temperatures and upon formation it suffers from instability issues at room temperature, hindering its potential for optoelectronic application. In this work, using polyvinylpyrrolidone (PVP) as an additive, highly stable CsPbI3 nanocrystalline films are prepared at a low annealing temperature of 180 °C via a one-step spin-coating method. It is found that the PVP additive not only improves the stability by inhibiting the transition of CsPbI3 from α- to δ-phase at room temperature but also influences the crystallization dynamics. In addition, the PL intensity is substantially enhanced due to the suppression of non-recombination sites with PVP. With a PVP concentration of 12 wt%, a charge carrier lifetime of 43.99 ns is obtained and a palpable orange-yellow color is formed irradiated in plane by a green laser. Finally, a simple photodetector is fabricated with a structure of FTO/PVP-CsPbI3/Ag, exhibiting excellent photodetecting response with increased PVP concentration in the film. These results suggest that PVP-CsPbI3 has strong research and application potential in the future in optoelectronic devices.

In this work, we investigate the electronic and optical properties of CsPb(I1-xBrx)3 and CsSn(I1-xBrx)3 by using density functional theory. We have proposed the method of strain modulation to efficiently tune the bandgap of CsPb(I1-xBrx)3 and CsSn(I1-xBrx)3 perovskites. Our calculations show that, the bandgap of CsPbI3 can be successfully tuned with the strain variation of −3% to 3%. Furthermore, the electronic structure changes of CsPb(I1-xBrx)3 and CsSn(I1-xBrx)3 with Br concentration, the higher the Br doping concentration, the higher will be the energy band value. We believe that the effective regulation of the energy bandgap can fulfill the requirements of a promising light-harvesting material.

Plasmonics is a new promising approach to enhance the light absorption in the thin film solar cells. The plasmonic effects of the metal nanoparticle introduced in thin film solar cells could also be detrimental for the higher optical absorption and hence the higher efficiency of solar cells. The effects of the Ag nanospheres arrays on the absorption of amorphous silicon solar cells were investigated by a numerical simulation based on the finite element method. The light absorption under different radius and width of the grating has been calculated. The optimization results show that the absorption of the solar cell with Ag nanospheres is enhanced up to 64 % under AM1.5 illumination in the 500–730 nm wavelength range compared with the reference cell. The physical mechanisms of absorption enhancement in different wavelength range have been discussed. These results are promising for the design of amorphous silicon thin film solar cells with enhanced performance.

The scattering from metal nanoparticles near their localized surface plasmon resonance is a promising way to increase the light absorption in solar cells. In this article, we investigate the light scattering of silver (Ag) nanoparticles on the microcrystalline silicon (μc-Si) substrate with various sizes and shape by finite element method. The results show that large spherical particles lead to enhanced scattering efficiency, whereas reduced coupling efficiency. The scattering cross section and coupling efficiency are very sensitive to the shape of the particles. Compared with spherical particles, hemispherical and cylindrical particles show much lower and broader scattering cross section, containing two surface plasmon resonance modes, and much higher coupling efficiency at longer wavelengths. However, with the increase in the longitudinal size (or height) of the particles, the coupling efficiency decreases, especially at shorter wavelengths, due to backscattering by the longitudinal resonance mode. Finally, we simulate the absorption enhancement in μc-Si thin film solar cells by Ag nanoparticle arrays with various shape. These results will be useful for enhancing performance of the μc-Si thin film solar cells by optimizing the light-trapping design.

Recently, organo–metal halide perovskites have attracted much attention of the scientific community relating to their successful application in the absorber layer of low-cost solar cells. However, enough is known about the material and device properties, to realize that much remains to be learned. In this study, a two-dimensional modeling of planar heterojunction perovskite solar cells was performed combining the optical and electrical responses to reveal the impact of the carrier diffusion length, the relative permittivity of absorber layer and the valence band offset of absorber/hole transport material (HTM). Simulation results presented a great dependence of power conversion efficiency (PCE) on the carrier diffusion length of perovskite layer. Meanwhile, to achieve high PCE, the frequency depended dielectric constant should not exceeded 40 and the double HTMs design was very effective to match the valence bands between the absorber and HTM.

In recent years, the organic-inorganic perovskite materials have revolutionized the Photovoltaic industry with highly efficient power conversion devices accompanied by a high growth rate. However, these devices experience major environmental and stability issues that hinder their true potential. More recently, a rarely studied perovskite material Cs2SnI6 is gaining enormous attention due to its superior stability and suitable bandgap. In this work, we developed a modified two-step process to prepare uniform Cs2SnI6 films, and the influence of the reaction conditions on the properties is explored. The structural, morphological, optical, and electrical properties of the prepared films were investigated using x-ray diffraction, Raman spectroscopy, scanning electron microscopy, UV–vis spectrometer, photoluminescence, and Hall Effect measurements, respectively. Phase stability and morphology of the films are improved with optimizing the reaction conditions. The results confirm the n-type semiconductor nature of Cs2SnI6 with bandgap ranging from 1.29 eV to 1.42 eV with maximum carrier mobility of 425 cm2 V−1 s−1. The present study will further provide potential research directions in improving the device efficiency of air-stable Cs2SnI6 perovskite solar cells.

The morphology control of CH3NH3PbI3 (MAPbI3) thin-film is crucial for the high-efficiency perovskite solar cells, especially for their planar structure devices. Here, a feasible and effective post-treatment method is presented to improve the quality of MAPbI3 films by using methylamine (CH3NH2) vapor. This post-treatment process is studied thoroughly, and the perovskite films with smooth surface, high preferential growth orientation and large crystals are obtained after 10 s treatment in MA atmosphere. It enhances the light absorption, and increases the recombination lifetime. Ultimately, the power conversion efficiency (PCE) of 15.3% for the FTO/TiO2/MAPbI3/spiro-OMeTAD/Ag planar architecture solar cells is achieved in combination with this post-treatment method. It represents a 40% improvement in PCE compared to the best control cell. Moreover, the whole post-treatment process is simple and cheap, which only requires some CH3NH2 solution in absolute ethanol. It is beneficial to control the reaction rate by changing the volume of the solution. Therefore, we are convinced that the post-treatment method is a valid and essential approach for the fabrication of high-efficiency perovskite solar cells.

Light trapping is one of the key issues to improve the light absorption and increase the efficiency of thin film solar cells. The effects of the triangular Ag nanograting on the absorption of amorphous silicon solar cells were investigated by a numerical simulation based on the finite element method. The light absorption under different angle and area of the grating has been calculated. Furthermore, the light absorption with different incident angle has been calculated. The optimization results show that the absorption of the solar cell with triangular Ag nanograting structure and anti-reflection film is enhanced up to 96% under AM1.5 illumination in the 300–800 nm wavelength range compared with the reference cell. The physical mechanisms of absorption enhancement in different wavelength range have been discussed. Furthermore, the solar cell with the Ag nanograting is much less sensitive to the angle of incident light. These results are promising for the design of amorphous silicon thin film solar cells with enhanced performance.

In this study, we successfully prepared Er 3+ –Yb 3+ co-doped TeO 2 –PbF 2 oxyfluoride tellurite glasses with different Yb 3+ concentrations and characterized their upconversion properties. Intense emission bands at 527, 544, and 657 nm corresponded to the Er 3+ transitions, and the maximum was obtained at an Yb 3+ -to-Er 3+ molar ratio of 3. When this glass was applied at the back of amorphous silicon solar cells in combination with a rear reflector, a 0.45% improvement in efficiency was obtained under co-excitation of AM1.5 and 400 mW 980 nm laser radiation. Maximum external quantum efficiency and luminescence quantum efficiency of 0.27% and 1.35%, respectively, were achieved at 300 mW excitation.

The upconversion (UC) properties of β-NaYF4:Yb3+(10%),Er3+(1%) microprisms synthesized using a hydrothermal method were studied under different excitation conditions. It was found that the UC emission of β-NaYF4:Yb3+(10%),Er3+(1%) was more sensitive to the 980 nm photons than the 1560 nm photons, because of the high mole ratio of Yb3+/Er3+ in crystals. Applying this material at the back of a hydrogenated amorphous silicon (a-Si:H) solar cell, a short-circuit current density of 64 μA/cm2 was measured under 0.53 W/cm2 980 nm laser excitation. This corresponds to an external quantum efficiency of 0.015% of the solar cell. When co-excited with the 980 nm and 1560 nm lasers, a very weak enhancement in the current was shown, which resulted from the slightly increased red emission. This indicates that co-excitation with multiple wavelengths accessible to the β-NaYF4:Yb3+(10%),Er3+(1%) microprisms is not an effective method to enhance the efficiency of a-Si:H solar cells.

β-NaYF 4 :Er 3+ (10%) microprisms, synthesized using a hydrothermal method, were applied to the back of a thin film hydrogenated amorphous silicon (a-Si:H) solar cells to investigate response to sub-band gap near-infrared irradiation. Currents of 0.3 μA and 0.01 μA were measured during single-illumination with 60 mW (80 mW/cm 2 ) 980 nm and 1560 nm diode lasers, respectively, due to frequency upconversion (UC). Under co-excitation by 60 mW 980 nm and 100 mW 1560 nm lasers, a current improvement to 0.54 μA was obtained, resulting from enhancements in red emission. The finding indicates that co-excitation with multiple wavelengths accessible to UC materials is very effective in enhancing the efficiency of solar cells.

Detection of weak underwater signals is an area of general interest in marine engineering. A weak signal detection scheme was developed; it combined nonlinear dynamical reconstruction techniques, radial basis function (RBF) neural networks and an extended Kalman filter (EKF). In this method chaos theory was used to model background noise. Noise was predicted by phase space reconstruction techniques and RBF neural networks in a synergistic manner. In the absence of a signal, prediction error stayed low and became relatively large when the input contained a signal. EKF was used to improve the convergence rate of the RBF neural network. Application of the scheme to different experimental data sets showed that the algorithm can detect signals hidden in strong noise even when the signal-to-noise ratio (SNR) is less than −40d B.

Ag2O film was prepared on glass substrate by direct current reactive magnetron sputtering under a careful control of the preparation parameters. The analysis of the dielectric constants of the Ag2O film related to the optical properties was conducted by spectroscopic ellipsometry (SE) and single-oscillator model. The dielectric constants were fitted in terms of general oscillator model (a model combined with three Tauc–Lorentz oscillator models) by using the measured SE data. Refractive-index dispersion data below the interband absorption edge of the Ag2O film were analyzed using a single oscillator fit of the form n 2 − 1 = E d E 0 / ( E 0 2 − ℏ 2 ω 2 ) proposed by Wemple and DiDomenico, where ℏω is the photon energy, E0 is the single oscillator energy, and Ed is the dispersion energy. The optical energy gap of approximately 2.32 eV was fitted by single oscillator model, which was in good agreement with that in terms of Tauc relation. The fitted dispersion energy Ed of approximately 20.28 eV determined the parameter β of approximately 0.32 by a simple empirical relationship Ed=βNcZaNe, which indicated that Ag2O film falls into covalent class. Additionally, the band gap parameter Ea and plasma frequency ℏωp fitted were 1.16 and 4.85 eV, respectively.

Inorganic-organic metal halide perovskite solar cells (PSCs) have drawn tremendous attention as a promising next-generation solar-cell technology because of their high efficiencies and low production cost. Since the first report in 2009, the recorded power conversion efficiency (PCE) of PSCs has rapidly risen to 22.1% by using 2, 2', 7, 7'-tetrakis (N,Ndi-p-methoxyphenyl-amine) 9,9-spirobifluorene (spiro-MeoTAD) as hole transport material (HTM), with the efforts devoted to the device architecture optimization, material compositional engineer and interface engineering. Nevertheless, the synthesis and cost of the organic HTM (OHTM) become a major challenging issue and therefore alternative materials are required. In the past few years, the applications of inorganic HTMs (IHTMs) in PSCs have shown large improvement in PCE and stability. For example, PSCs with CuOx as IHTM reached a PCE of 19.0% with better stability. Even more exciting, the theoretical PCE of PSC based on Cu2O HTM reaches 24.4%. So, Cu2O is a promising IHTM for future optimized PSC and the large area uniform preparation is very important. In this paper, Cu2O films have been successfully prepared using electron beam evaporation followed by air annealing. The influences of annealing temperature and time on the composition, structure, and photoelectric characteristics of film are investigated in detail. It is found that the as-deposited film is a mixture of Cu2O and Cu. With the increase of annealing temperature, material composition is transformed from mixture to pure Cu2O phase, and then to CuO, due to the oxidation in air. In an annealing temperature between 100℃ to 150℃, pure Cu2O film can be obtained with an average transmission rate over 70%, optical band-gap of 2.5 eV, HOMO level of -5.32 eV, and a carrier mobility of 30 cm2·V-1·s-1. When the film is treated with a UV lamp, the structure and composition of the film can be changed more easily because of the enhancement of oxidation. Finally, reverted planar PSCs with the structure of Ag/PCBM/CH3NH3PbI3/HTMs/ITO are constructed and compared carefully based on HTMs of Cu2O, with poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)(PEDOT:PSS), and Cu2O/PEDOT:PSS layers, respectively. An optimum thickness of 40 nm of Cu2O HTM is achieved with high carrier extraction rate. However, the performances of all of the PSCs are inferior to those of PEDOT:PSS-based devices, due to the formation of pinholesin absorber layer resulting from the strong hydrophobicity of Cu2O film. However, the efficiency of PSC based on Cu2O/PEDOT:PSS double-HTM is deteriorated because of the chemical interaction between PEDOT:PSS and Cu2O. These findings provide some important guidelines for the design of HTMs.

Towed fishery detector in horizontality works passively to detect the location of the shoals of fish through detecting their noises. It can facilitate the detection and reduce the cost as well. It can offset the noise in the signals received by the two vector hydrophones in the tow and reduce the interference from the ship for the efficient range of target detection. It can indicate the azimuth of each target by computing relatively on sound pressure and vector velocity and with the help of non-linear optimizing technology and multi-sources distinguishing by single vector hydrophone.

All as-deposited AZO films by direct current magnetron reactive sputtering (DC-MS) exhibit ZnO characteristic (002) and (103) diffraction peaks. Especially, AZO films prepared at 200° C show a strongest (002) c-axis preferential orientation due to the minimum stress along the (002) orientation. The results show that larger stress easily induces a rougher surface. The film real and imaginary parts of dielectric constants show a sharp changes near the optical absorption edge due to the interband direct transition. The film blue and red shifts of the optical absorption edge can be explained in terms of the change of free-electron concentration in as-deposited AZO films.

Intrinsic microcrystalline silicon has been deposited by very high frequency plasma enhanced chemical vapor deposition technique at frequency of 75 MHz. Different gas mixtures of silane and hydrogen were utilized, and the evolution of microstructure and phase in film were studied, while keeping the substrate temperature at 200 °C and the chamber pressure at 0.5 Torr. Optimised material was inserted in p–i–n solar cells: preliminary efficiency of 5.5% was reached for 1 μm-thick solar cells with the V oc around 0.6 V.

African-Americans (AA) with congestive heart failure (CHF) are typically sicker, poorer, less educated, and have more co-morbid conditions than White older adults with CHF. Despite evidence of benefits of home tele-monitoring on mortality and hospitalizations, few care models have been designed specifically for African-Americans with CHF. This session reports on an intervention program conducted in South Carolina, where rates of hospitalization for CHF are among the highest in the country. The intervention was informed by qualitative research documenting specific needs for improving self-care and treatment compliance as identified by AA patients in a hospital-based Home Care Program. The low-cost intervention utilizes a mobile phone with a software application that: monitors CHF symptoms; improves self care by providing educational and motivational messages to reduce risks for CHF progression; and improves health care navigation by making it easy for patient to connect to health care providers.

The thin-film solar cell structure with a broadband absorption enhancement is reported. We designed spherical silver (Ag) nanoparticle arrays on or embedded partially into indium tin oxide (ITO) layer of the hydrogenated microcrystalline silicon ([Formula: see text]c-Si:H) thin-film solar cells. The geometrical parameters, such as nanoparticle radius ([Formula: see text], array period ([Formula: see text] and ITO layer thickness ([Formula: see text] are optimized by using the finite element method (FEM). The numerical results show that the key parameter that influences the integrated absorption is period/radius ratio ([Formula: see text]/[Formula: see text] for Ag nanoparticle arrays. Embedding nanoparticle arrays partially into ITO layer with the appropriate thickness can improve broadband light-trapping. The optimized structure shows 50.1% enhancement in the integrated absorption compared to the reference cell when [Formula: see text][Formula: see text]nm, [Formula: see text][Formula: see text]nm and [Formula: see text][Formula: see text]nm. Furthermore, physical mechanisms of absorption enhancement in different wavelength range are discussed according to the electrical field amplitude distributions in the solar cells.

We have observed light emission with a luminance of 3.5 cd m−2 from a diamond:Ce thin-film electroluminescence device at an applied voltage of 150 V. The electroluminescence spectrum at room temperature shows main peaks centred at 454 and 490 nm, which are attributed to isolated emission centres of Ce3+ ions.

The key problems to be solved in stereo HMD (Head-Mounted Display) used in augmented reality are analyzed, such as brightness of image, fusion of virtual and real scene, binocular rivalry, occlusion, distortion, stereo vision and tracking of head and line of sight. An experimental platform of HMD is developed by discrete elements to research the key problems. The problem of fusion of virtual and real scene can be solved effectively by replacing the common beam splitter with polarization beam splitter in combiner. The variations of HMD vision effects including binocular rivalry with binocular overlapped range are investigated, and the results indicate that the optimal effect is achieved when the binocular overlapped range is 33~50% of the monocular field of view (FOV). At last, stereo vision is realized in HMD by the stereo image pairs made up according to the parallax theory.

Image enhancement technology plays a very important role In image processing. By enhancing some information and restraining other information selectively, it can improve image visual effect. Colour medical image is becoming more and more significant in medical diagnosis. In this paper, an enhancement arithmetic used for colour medical image is discussed. After the enhancement based on wavelet analysis, the color space transform method is applied to the color medical image. The method can improve the image sharpness and make the image characteristics more evident. The enhancement result is useful for further analysis.

After a series of pretreatments, the 3D stereogram of seafloor is built by using sounding data. In this paper, the image enhancements to 3D stereogram are discussed. First the noise reduction based on wavelet transform is applied, and then the color space transform technology is introduced. The experiments prove that the image enhancements about stereogram are effective. The 3D stereogram of seafloor is becoming clearer after image enhancements.

Recently, organo-metal halide perovskites have attracted much attention from the scientific community because of their successful application in the absorber layer of low-cost solar cells. For the further improvement of the performance of such cells, a thorough understanding of the influence of the material properties on the working mechanism of a device is very necessary and important. In this study, two-dimensional modeling of hole transport material free planar heterojunction solar cells was performed, in which electromagnetic simulation was directly linked to carrier transport calculations. An optimum absorber thickness of 200 nm was reproduced in the simulation at carrier diffusion length of 100 nm, in good agreement with previous experiments. This optimum thickness increased with the increase of diffusion length, and an efficiency of about 11% was obtained at 300 nm with a diffusion length of 300 nm. Finally, it was demonstrated that the relatively low efficiency of such solar cells was directly related to the low short-circuit photocurrent density (J SC) and the low open-circuit voltage (V OC) due to the insufficient absorption of the long-wavelength region and the nearly intrinsic doping concentration, respectively.

Metal nanoparticles with low cost and high performance have good potential applications in light-trapping of solar cells. In this paper, a three-dimensional model is proposed to simulate the light absorption of microcrystalline silicon (μc-Si:H) thin film solar cells. The effects of spherical and hemispherical Al nanoparticle arrays located on the front surfaces of solar cells are investigated, and the particle radius and array period are optimized by the finite element method. The results show that the optimal Al nanoparticle arrays can enhance broadband absorption in thin film solar cells. For spherical particle arrays, the key parameter that influences light absorption in solar cells is period/radius ratio (P/R) or particle surface coverage. When P/R=4-5, the optimum integrated absorption enhancement (Eabs) is over 20% under AM1.5 illumination compared with the solar cell without nanoparticles. The value of Eabs is small and decreases with the increase of P/R when P/R>5, and Eabs is less than zero when P/RP=500 nm and R=120 nm, the spectral absorption rate as a function of wavelength shows broadband absorption including four distinct peaks, which are attributed to quadrupole plasmon resonance mode, dipole resonance mode and waveguide mode respectively according to the electric field distribution in the solar cell. For hemispherical particle arrays, the maximum value of Eabs is 24.5%, which is higher than that of the solar cell with optimized spherical particle arrays. This is due to the high coupling efficiencies of the particles, so that most of the scattered light is directly coupled into the substrate. However, the value of Eabs is very sensitive to the hemispherical particle radius. As the radius decreases, the scattering cross-section and scattering efficiency of the particle decrease dramatically. As the radius increases, the dipole plasmon resonance wavelength rapidly shifts towards longer wavelength (red shift). Both of these are detrimental to absorption enhancement of solar cells. Thus we conclude that spherical Al particle arrays are more preferable in actually fabricating the light-trapping of solar cells.

The intrinsic silicon thin film for passivation of the crystalline silicon wafer surfaces in silicon heterojunction cells was prepared by very high fregucency plasma enhanced CVD (VHF-PECVD). Plasma emission versus time was recorded by optical emission spectroscopy (OES) during the silicon thin film deposition. Results show that the Hα* and SiH* signals stabilize soon (about 25 s after deposition) under the optimized deposition conditions, and the variation of SiH*/Hα* ratio is little, thus avoiding the structure non-uniformity of silicon film during the growth. The reason is that the SiH4 back diffusion is avoided owing to SiH4 being not fully depleted. The study of the influence of the deposition parameters on steady-state plasma emission spectra and properties of silicon films shows that as the SiH4 concentration increases, the Hα* decreases and the SiH* increases, the silicon film will transit from microcrystalline to amorphous, and the good passivation effect can be achieved in the amorphous silicon film. Hα* and SiH* increase firstly and then decrease with the deposition pressure, the decrease of Hα* and SiH* under high pressure can be attributed to a high polymer formation which is not beneficial to the formation of high quality silicon film, and therefore the passivation effect of silicon films decreases under high pressures. Hα* and SiH* increase with power density, and are saturated when the power density is 150 mW/cm2; for this the quality and passivation effect of the silicon film begin to decrease, the passivation effect of the silicon film at a power density of 50 mW/cm2 is poor, which may be due to the low concentration of atomic H being unable to fully passivate the dangling bonds at the silicon surface.

The directional pattern of array is a kind of spatial filter for signal processing. For the signal coming from different azimuth can be expressed as a periodic function of, it can be expanded in Fourier series. With the help of a cross vector sensor array, more directional patterns such as quadrupoles and octopoles can be obtained. By solving equations, the first few coefficients of Fourier series can be determined. A combine directional pattern of the vector sensor array, which has a maximum value at the required direction and very small value at other directions, is properly chosen to improve the performance of the final directional pattern. The method of determining virtual directional pattern proposed in this paper greatly reduces calculation quantity rather than full-space scanning.

Bi-static long-range bottom reverberation in shallow water is investigated, and the impulse response function is derived using the linear theory of sound channel. For the case of almost layered medium, the adiabatic mode solution is introduced for the derivation of transfer function. The reverberation intensity is calculated for the range-dependent waveguide, and then both the intensities and the decaying rules are compared with their corresponding counterparts in different wedged sea areas. It is shown that the propagation effect on intensity of distant bottom reverberation can not be neglected for the bi-static active sonar in shallow water waveguide.

The impulse reflection of a semiburied object is strongly complicated due to a multipath channel effect in a shallow‐water environment, and usually also mixed with unavoidable bottom reverberation. An efficient method of signal processing in order to obtain necessary characteristics of the object, which can be used for object identification, is discussed, and several experimental examples are given.