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Fill factor in the negative permittivity materials are tailored within the physically permissible limits to characterize the Brillouin zone for two-dimensional crystal under the propagation of both s and p-polarized waves. Two lowermost band-gaps are computed along with corresponding mid-band frequencies, where the plane wave expansion method is invoked for computational purposes. The rectangular geometrical shape is considered for the simulation, and all the results are calculated inside the ‘Γ’ point and ‘X’ point of the first Brillouin zone. Simulated findings depict monotonous variations of both band-gap width as well as mid-band frequency for higher negative permittivity materials, when the magnitude of fill factor is comparatively low, for both TE (Transverse Electric) and TM (Transverse Magnetic) mode of propagations. Lower negative permittivity leads to random fluctuations, which makes it unsuitable for photonic component design. Multiple forbidden regions may be observed for some specific artificial materials which can be utilized in the antenna or multi-channel filter design in higher THz region. Aims: The present paper aims to compute the shape of the first Brillouin zone from the fill factor for a two-dimensional photonic crystal structure. Background: EBG (Electromagnetic Bandgap) of a photonic crystal plays a major role in determining its candidature for optical applications, which is critically controlled by the fill factor. Therefore, it is significant to investigate the effect of F.F on the wave propagation characteristics of 2D PhC(Twodimensional photonic crystal). Objective: Investigation of metamaterial-based photonic crystal structure for electromagnetic band-gap analysis in the desired spectrum of interest as a function of fill factor inside the first Brillouin zone. Methods: Maxwell’s equations are solved using the plane wave propagation method to solve the problem, and simulation is carried out in MATLAB® software. Result: Both the first and second photonic band-gaps are simultaneously computed with a variation of refractive index differences of the constituent materials as well as with the fill factors. Results are extremely significant about the formation of narrowband and wideband filters on certain material combinations and structural designs. Conclusion: Better tenability is observed for metamaterial structure compared to conventional positive index materials, and fill factor has a great role in shaping the Brillouin zone and corresponding bandgap width.

Flexible Cu2ZnSn(S,Se)4 (CZTSSe) solar cells have wide application prospects. N-type window layers and contact among the layers have an important effect on the properties of flexible CZTSSe solar c...

The post-heating treatment of the CZTSSe/CdS heterojunction can enhance the interfacial properties of kesterite Cu2ZnSn(S,Se)4 (CZTSSe) solar cells. In this regard, a two-step annealing method was developed to enhance the heterojunction quality for the first time. That is, a low-temperature (90 °C) process was introduced before the high-temperature treatment, and 12.3% efficiency of CZTSSe solar cells was achieved. Further investigation revealed that the CZTSSe/CdS heterojunction band alignment with a smaller spike barrier can be realized by the two-step annealing treatment, which assisted in carrier transportation and reduced the charge recombination loss, thus enhancing the open-circuit voltage (VOC) and fill factor (FF) of the devices. In addition, the two-step annealing could effectively avoid the disadvantages of direct high-temperature treatment (such as more pinholes on CdS films and excess element diffusion), improve the CdS crystallization, and decrease the defect densities within the device, especially interfacial defects. This work provides an effective method to improve the CZTSSe/CdS heterojunction properties for efficient kesterite solar cells.

One of the most challenging issues facing the organic photovoltaic community is to realize a high fill factor (FF) even with thick active layers. This is because the thick active layer is beneficial for photon absorption but makes charge collection difficult, which is primarily restricted by nongeminate recombination in solar cells. In this work, we have studied nongeminate recombination in four kinds of polymer solar cells based on blends of donor-conjugated polymers with different crystallinities and acceptor-conjugated polymers with a naphthalene diimide unit by using transient photovoltage and photocurrent techniques. As a result, we find that nongeminate recombination is considerably suppressed with an increasing degree of crystallinity of donor polymers, leading to a high FF of more than 0.6 even with an active layer thickness of 300 nm. The origin of such a phenomenon is further discussed in terms of variations in the states of mixed phases with a cascaded energy structure between crystalline domains and amorphous domains evaluated by conductive atomic force microscopy.

This study investigated and calculated the fill factor and efficiency of N719 and D149 organic dyes in titanium dioxide (TiO2) solar cell systems using a current equation that we derived using a quantum transition-state theory (TST). The theory of charge transfer reactions was used to investigate the electronic current to enhance both the fill factor and efficiency of both N719/ and D149/TiO2 solar cell systems. The current calculated for Di-terabtylammoniumcis-bis (isthiocyanato) bis (2,2-bipyridyl-4,4dicarboxylato) ruthenicyanatoum (II)(N719) and 5-[[4-[4-(2,2-Diphenylethenyl) phenyl]-1,2,3-3a,4,8b-hexahydrocyclopent [b] indol-7-yl] methylene]-2-(3-ethyl-4-oxo-2-thioxo-5-thiazolidinylidene)-4-oxo-3-thiazolidineacetic acid indicated that the molecules of D149, an indoline-based dye, have to be in contact with the semiconductor due to the quantum donor-acceptor scenario model. The efficiency of N719/and D149/TiO2 solar cells were significantly affected due to transition energy, which is caused by the mechanisms of the charge transfer process. Solvents; such as trifluoroethanol (C2H3F3O), propanol (C3H8O), ethanol (C2H5OH), and acetonitrile (C2H3N); were used to determine the current, fill factor, and efficiency. Coefficients of charge transfer; such as transition energy, barrier, driving force energy, current, power-conversion efficiency, fill factor (FF), and efficiency; were evaluated theoretically. The current of the N719/ system with acetonitrile and ethanol solvents was higher than current of the N719/ system with trifluoroethanol and propanol solvents. While the current of the D149/ system with trifluoroethanol and propanol solvents was higher than current of the D149/ system with acetonitrile and ethanol solvents. The current and transition energy efficiencies of both systems varied. devices were found to have the best power conversion efficiency and low transition energies while the power conversion efficiency was large for devices with sizeable current density and activity with lower transition energies. Keywords: Fill Factor, Efficiency, Molecule/Semiconductor, Solar Cells.

In this study, the modeling and experimental analysis of photovoltaic parameters of the GaInP/GaAs dual–junction (DJ) p–i–n solar cell structure were examined. The design of the GaInP/GaAs DJ p–i–n solar cell structure was done with the drift–diffusion model (DDM), and this structure was grown with the molecular beam epitaxy (MBE) system. The fundamental parameters (open–circuit voltage ( $${V}_{\mathrm{OC}}$$ ), short–circuit current density ( $${J}_{\mathrm{SC}}$$ ), fill factor ( $$\mathrm{FF}$$ ), and energy conversion efficiency ( $$\eta$$ )) of these structures were determined by both modeling and the current–voltage experimental measurements. All electrical output parameters of the GaInP/GaAs DJ p–i–n solar cells obtained from modeling and experimental were compared. An increase in solar cell efficiency was observed with the integration of the i–layer.

In this study, we present an effective method of improving the performance of pure sulfide Cu(InGa)S2 (CIGS) solar cells via injection annealing system. The injection annealing system can perform annealing at desired temperatures, and therefore, the CIGS thin film passed over the temperature range in which secondary phases occurs. Via the injection annealing system, secondary phase InSx was effectively removed from the surface of the CIGS thin films at the temperatures over 550°C. This resulted in the formation of good-quality P–N junction CIGS devices, thereby improving significantly the performance of the CIGS solar cell. In addition, the open-circuit-voltage (VOC) and fill factor (FF) of the CIGS devices increased gradually with increasing annealing temperature in the range of 550–640°C. It is speculated that the bulk defects were decreased as the annealing temperature increased. Finally, via injection annealing system, a pure sulfide CIGS solar cell with an efficiency of 12.16% was achieved.

Over 200 nm thickness of active layers are essential for achieving efficient organic photovolatics (OPVs) using the roll-to-roll (R2R) large-scale production technology. In this study, a series of OPVs with 300 nm thick active layers were prepared with PM6:BTP-4F-12:BP-4F as active layers. The PM6:BTP-4F-12- and PM6:BP-4F-based binary OPVs achieve power conversion efficiencies (PCE) of 14.62% and 14.14%, respectively, with 300 nm thick active layers, also exhibiting complementary photovoltaic parameters. A PCE of 15.63% is achieved by the optimized ternary thick-film OPVs by combining the superiorities of two binary thick-film OPVs, deriving from a short circuit current density (JSC) of 26.57 mA cm−2, an open circuit voltage (VOC) of 0.840 V and a fill factor (FF) of 70.03%. The performance improvement of ternary thick-film OPVs should be mainly ascribed to the optimized molecular arrangement and phase separation for efficient charge transport in ternary thick active layers, which can be confirmed from the significantly improved FFs of ternary thick-film OPVs. This study indicates that the ternary strategy has great potential in preparing efficient thick-film OPVs.

Summary In-field characterization of photovoltaics is crucial to understand performance and degradation mechanisms, subsequently improving overall reliability and lifespans. Current outdoor characterization is limited by logistical difficulties, variable weather, and requirements to measure during peak production hours. We capitalize on Suns-VOC, which is widely used for laboratory measurements of single solar cells and discuss the barriers in extending the technique to outdoor systems. We demonstrate the normalization of measurements using both backsheet temperature sensors and on-site weather stations. Despite weather variation, VOC, ideality factor, and pseudo fill factor all fall within 1% of the laboratory measurements. It is also demonstrated that monitoring the system VOC at 0.05 to 0.1 suns, during minimal power production, provides a figure of merit that can indicate early degradation of the system. Extensive simulations show that shading portions of a system has minimal effect on measurements, allowing the technique to be used in all weather conditions.

In CZTS based solar cells, there have been intensive research to replace the toxic CdS buffer layer with alternative materials. In this paper, we proposed and simulated structure of CZTS/CZTSe based Solar Cell Al-ZnO/i-ZnO/ZnSe/Absorber/Mo with ZnSe as a buffer layer using SCAPS-1D simulator. Further, we have investigated the same structure employing different absorber layers such as CZTS, CZTSe and stacking of CZTS and CZTSe sequentially. The optimization of solar cell device is carried out and efficiency found to be 16.24%, 19.59% and 21.17% where the thickness of the absorber layer is 1.5 µm, 1 µm, 2.5 µm and 1 µm, respectively, for CZTS, CZTSe and stacking of CZTS and CZTSe. The calculated values of efficiency (η), fill factor (FF), open circuit voltage (Voc) and current density (Jsc) are compared with the data available in literature with CdS as the buffer layer.

Fused Deposition Modelling (FDM) is presently the most common utilized 3D printing technology. Since this printing technology makes the bodies anisotropic, therefore, investigate the process with different settings is worthwhile. Tensile test specimens of two plastics have been carried out to examine the mechanical properties. Polylactic acid (PLA) and High Temperature PLA (HT-PLA) are the used materials for this purpose. A total of seventy-two test pieces of the two used polymers were printed and evaluated. Three parameters were examined in twelve different settings when printing the tensile test specimens. The considered settings are; six raster directions, three build orientations and two filling factors. The differences in stress-strain curves, tensile strength values and elongation at break were compared among the tested samples. The broken specimens after the tensile test are illustrated, which gave insight into how the test pieces printed with different parameters were fractured. The optimum printing setting is represented at crossed 45/−45° raster direction, X orientation and 100 % fill factor, where the highest tensile strength of 59.7 MPa at HT-PLA and the largest elongation of about 3.5 % at PLA were measured.

The effect of partial shading results in increased mismatch losses and decreased power output of the solar Photovoltaic (PV) array, requiring reconfiguration of the shading pattern of the panels. H...

Despite recent breakthroughs in the fabrication of spin-coated small-area devices (≤0.1 cm2) with power conversion efficiencies (PCEs) of more than 17%, printed large-area organic solar cells (OSCs) are significantly less efficient because of the intrinsic differences between the coating dynamics of the two types of OSCs. The PCEs of printed large-area (∼100 cm2) OSCs have typically been decreased compared with those of small-area spin-coated devices. In this work, an efficient low-temperature printing method to fabricate high-efficiency large-area nonfullerene-based OSC modules is successfully demonstrated. A systematic study of the relationship between the concentration of the photoactive solution and the resulting film properties reveals that the large-area modules (85 cm2) produced in this work deliver excellent performance, yielding PCEs of up to 8.18% with a geometric fill factor of 85%. These novel OSC modules are ∼87% as efficient as small-area printed single cells (cell PCE ∼9.43% with 1 cm2).

Hybrid perovskite solar cells attract a great deal of attention due to the feasibility of their low-cost production and their demonstration of impressive power conversion efficiencies (PCEs) exceeding 25%. However, the insufficient intrinsic stability of lead halides under light soaking and thermal stress impedes practical implementation of this technology. Herein, we show that the photothermal aging of a widely used perovskite light absorber such as MAPbI3 can be suppressed significantly by using polyvinylcarbazole (PVC) as a stabilizing agent. By applying a few complementary methods, we reveal that the PVC additive leads to passivation of defects in the absorber material. Introducing an optimal content of PVC into MAPbI3 delivers a PCE of 18.7% in combination with a significantly improved solar cell operational lifetime: devices retained ∼70% of the initial efficiency after light soaking for 1500 h, whereas the control samples without PVC degraded almost completely under the same conditions.

Dye-sensitized solar cells (DSSC) have been assembled using natural dyes extracted from the red (Gracilaria) and green (Ulva) algae as photosensitizers and the effect of adding Graphene quantum dot (GQD) has been investigated. The open-circuit voltage (VOC) values of natural dyes of Gracilaria, Gracilaria + GQD, Ulva, and Ulva + GQD are 0.64, 0.73, 0.70, and 0.75, respectively. The short circuit current density (JSC) values are varied from 0.96 to 2.26 mA cm−2, and the fill factor (FF) from 52 to 56% for the mentioned samples. The best-energy conversion efficiency of approximately 0.94% has been achieved for DSSC with Gracilaria + GQD with JSC equal 2.26 mA cm−2, VOC is 0.73 V, and FF is 56%.

Summary Perovskite solar cells (PSCs) have seen rapid advance in power conversion efficiencies (PCEs). However, the state-of-the-art PSCs still suffer from inhomogeneously distributed nonradiative recombination and carrier transport losses. Here, we report a promising evaluation strategy of combining the generalized optoelectronic reciprocity theorems and camera-based luminescence imaging techniques for PSCs. Excess lead chloride compositional engineering increases homogeneity and suppresses nonradiative recombination, leading to an external luminescence efficiency of 1.14% of devices (corresponding to a nonradiative voltage loss of 0.116 V). A favorable local and global carrier extraction property at maximum power point is also observed under moderate illumination level. As a result, we achieve a 25.49 cm2 perovskite solar module with a 17.88%-certified efficiency and a record fill factor over 78%. This quantitative and spatially resolved characterization is applicable at specific operating points, offering enormous potential for future real-time tracking of the lab-scaled devices and fast assessment of screening the large-area modules.

Single-mode waveguide devices are necessary in photonic integrated circuits. Previous studies on the single-mode conditions (SMCs) of the thin film lithium niobate (TFLN) either only focus on wire waveguide, or lack comprehensive discussions on the influence of the rib waveguide with different cross-section area at a certain height. In this paper, a systematical study on the SMCs of rib waveguide based on TFLN is carried out by using finite difference method (FDM). By comparing the effective refractive index between the first-order mode in the central rib region and the fundamental mode in the slab waveguide, and the fraction of the mode power flux between the TFLN rib region and the whole waveguide region, the SMCs in the central rib region are analyzed in terms of geometric parameters of the TFLN rib waveguide. The simulation results suggest that no single equation could meet the SMCs of different waveguide structures simultaneously in a small TFLN with the height no more than 900 nm. Ultimately, new approximate expressions as functions of rib-waveguide width and etching depth are proposed to precisely describe the single-mode condition at these dimensions.

Effect of shading conditions on photovoltaic (PV) systems reduces the power output and produces the mismatch losses. In this paper, an experimental approach is used to study the effect of shading conditions on various configurations of PV array (4 × 4 size) such as Series–Parallel (SP) configuration, Honeycomb (HC) configuration, Bridge-Link (BL) configuration, and Total cross-tied (TCT). For extensive comparative analysis of experiment, the present study shows the effective behavior of considered solar PV configurations under three shading cases. During the study, the performance parameters such as global maximum power point (called GMPP), local maximum power point (LMPP), power loss (PL), and fill factor (FF) are analyzed to show the best PV array configuration. From the obtained results, it is observed that TCT configuration has best values in terms of maximum power (49.59 W, 54.33 W, 48.28 W), respectively, in comparison to SP (46.25 W, 53.01 W, 40.63 W), BL (47.7 W, 51.9 W, 39.76 W), and HC (48.9 W, 50.68 W, 44.83 W) configurations, respectively, under three partial shading conditions (PSCs).

In this article, a comparative experimental and simulations analysis has been carried out to understand the role of tapered gap region on current density and energy of pseudospark (PS)-based electron beam emission. These studies have been performed for 5-gap and 8-gap regions in a tapered multigap multiaperture-based PS electron beam source, keeping the same electron beam fill factor, and other geometrical parameters identical. The source has been operated in a self-breakdown mode. Around four-times increase in the beam current has been observed in the 8-gap case at the fixed applied gap potential ranging between 20 and 25 kV, whereas the tapered interelectrode gap angle has been reduced from 7.5° to 4.5°. The field penetration inside the hollow cathode cavity and tapered region have also been analyzed using simulations, and the obtained results are explained based on built-up space charge in these regions.

By using numerical simulation, the operating temperatures of a thin-film solar cell based on CuInSe2 have been determined and the solar radiation density values, at which stabilization of the temperature operating conditions of the thin-film solar cell is not required, have been optimized. The maximum possible efficiency value of ~14.8 % is achieved under actual operating conditions, and is maintained by the incoming thermal energy as both emitted in this cell and infrared radiation of the sun and the environment. A model of the proposed thin-film solar cell was implemented in the COMSOL Multiphysics program environment with the use of the Heat Transfer Module. The operating temperatures of the solar cell without thermal stabilization under conditions of the diurnal and seasonal variations of both the ambient temperature and the power density of the AM1.5 solar spectrum have been determined. The maximum value of this power density was varied from 1.0 to 500 kW/m2 when using concentrators. The obtained values of operating temperatures of the thin-film solar cell were used to determine its main parameters in the SCAPS-1D program. The graphs of the operating temperature, efficiency and fill factor of the thin-film solar cell versus the solar radiation density are provided. It is shown that in order to obtain the highest possible efficiency of a solar cell, it is necessary to use concentrated solar radiation with a power density, the maximum value of which should be 8 kW/m2 in July and 10 kW/m2 in January. In the case of lower and higher values of power density, an appropriate thermal stabilization of the cell under consideration is necessary. The dependencies of efficiency, fill factor and open-circuit voltage versus the stabilization temperature of the solar cell, temperature gradients at the interfaces of the thermoelectric layer were also calculated. It is shown that by choosing optimal values of the thermal stabilization, the efficiency of the proposed solar cell may be about 15 % or more.

Thin-film cadmium telluride (CdTe) solar cells with an absorber thickness range of 0.4–1.2 μm were fabricated by close-space sublimation on a transparent MgZnO window layer. Microscopy cross sections showed that a significant fraction of the CdTe crystallites extended throughout the absorber layer, and capacitance measurements demonstrated that the absorbers were depleted into forward bias. Current and fill factor loss analyses were used to identify dominant loss mechanisms in the devices as a function of absorber thickness, and photoluminescence measurements were increasingly influenced by back-surface recombination as the absorber was made thinner. The thinner CdTe devices showed modest current and fill-factor reduction but overall good diode quality, and the highest efficiency of 15% was achieved with 1.2-μm CdTe.

A planner heterojunction quantum dot solar cells (QDSCs) structure of FTO/TiO2/PbS-EMII/PbS-EDT/Au is fabricated via layer-by-layer spin coating method, and then the temperature dependent photovoltaic performance of QDSCs is studied. The results indicate that the environment temperature has great influence on the current density-voltage (J-V) characteristics of quantum dot solar cell. The short-circuit photocurrent density (JSC), open-circuit voltage (VOC) and fill factor (FF) are all increased when the temperature decreases from 353 K to 253 K. A top value of power conversation efficiency (PCE, 9.78%) is obtained for the QDSCs when the environment temperature is lowered to 253 K, with a VOC of 0.63 V, JSC of 33.1 mA/cm2 and FF of 0.47, which is 33% above the PCE at room temperature (7.34%). In conclusion, it is necessary to cool the device for keeping the high efficiency operation of solar cell.

In this work, a unique 2,2′-diphenyl-5,5′-bipyrimidine building block is used to synthesize two new hole transport materials (HTMs), named MD–T and MD–C, which are applied in conventional perovskite solar cells (PSCs). Carbazole derivatives and dimethoxydiphenylamine moieties are included in MD–C and MD–T as periphery groups, respectively. The introduction of the electron-withdrawing bipyrimidine group increases the molecular dipole moment, thus leading to an enhanced dipole–dipole interaction, which promotes charge transfer and affords a high hole mobility. Notably, MD–C with carbazole periphery groups exhibits well-matched energy levels with perovskite materials and shows a higher hole mobility along with a better film morphology. Eventually, the devices containing the MD–C HTM achieve a superior power conversion efficiency (PCE) of 19.93% with a high fill factor (FF) of 80.02%, surpassing that of MD–T based devices (PCE = 15.55%). Thereby, the newly designed MD–C with the 2,2′-diphenyl-5,5′-bipyrimidine core structure could be a promising candidate for constructing HTMs in PSCs.

Charge recombination is a major loss process in state-of-the-art organic photovoltaics (OPVs). Nongeminate recombination (NGR) is typically in competition with collection of photogenerated charge carriers to each electrode not only at the short-circuit but also at the open-circuit conditions, and therefore impacts on both external quantum efficiency (EQE) and fill factor (FF). In most cases, therefore, the optimised active layers are kept as thin as possible (typically ∼100 nm) to avoid NGR loss although it is not thick enough to absorb the solar light effectively. As such, a key to efficient EQE and FF is suppressing NGR beyond limitations arising from the Langevin recombination. In addition, NGR is closely related to open-circuit voltage (VOC) as well. In particular, nonradiative NGR is a critical loss process in OPVs. In this review, we aim to summarise our current understanding of underlying photophysics that governs NGR in OPVs. Recent experimental results and proposed mechanisms relevant to NGR are summarised where we highlight the significant importance of morphology and energetics for suppressing NGR. These insights will provide a comprehensive understanding of the recombination and future materials/devices design principles.

The ternary strategy exhibits great potential in optimizing the photon harvesting and phase separation of active layers. In this work, non-fullerene MF1 was selected as the third component to prepare efficient ternary organic solar cells (OSCs) by finely optimizing the MF1 content in the acceptors. The optimized power conversion efficiency (PCE) of 15.31% is achieved in the ternary OSCs with 20 wt% MF1 content in the acceptors and 100 nm active layer thickness, also exhibiting a relatively high fill factor (FF) of 78.05%. The relatively high FF indicates efficient charge transport and collection in the optimized ternary OSCs, which should be beneficial to achieve efficient thick-film OSCs. It is highlighted that a PCE of 14.57% is achieved in the optimized ternary OSCs with 300 nm thick active layers compatible with the roll-to-roll (R2R) large-scale printing process. To date, high performance thick-film ternary non-fullerene OSCs have seldom been reported. This work indicates that the thick-film ternary strategy has great potential in achieving efficient large-scale OSCs.

Photovoltaic (PV) power generation technology is the main renewable energy utilization technology. However, dust deposition severely affects the PV power generation efficiency and decreases the production capacity of PV power plants. In this study, the factors affecting PV technology were divided into the following three types: occlusion, corrosion, and temperature rise. A dust-collecting PV model considering dust deposition and rainfall scouring was established; a PV performance index was proposed. By conducting experiments with different dust mass densities, it was found that the short-circuit current (SCC), open-circuit voltage (OCV), and PV output power of PV decreased with the increase in dust mass density. In the initial stage of dust deposition, dust exhibited the greatest effect on the performance of PV. In the later stage of dust deposition, the effect of dust deposition became stable. The initial 10 g/m2 dust decreased the PV output power by 34%. In addition, the conversion efficiency and fill factor (FF) decreased with the increase in dust mass density; both of them were exponential functions. When the dust mass density was low (less than 30 g/m2), the dust mass density increased by 10 g/m2, and the conversion efficiency decreased by an average of 3.4%. Finally, by conducting economic calculations, it was found that a PV power plant where dust has not removed for one year will cause 12% loss of power generation.

In this article, the design approach for a miniaturized high-current-density sheet electron beam (SEB) source has been reported. A study through simulation using COMSOL Multiphysics has been carried out to analyze the role of geometrical parameters of the hollow cathode in miniaturized SEB generation. These geometrical parameters play a very important role in defining the discharge inside the hollow cathode geometry and subsequent beam generation through a rectangular aperture. The hollow cathode diameter “D”, the length of the hollow cathode “L”, and the aspect ratio of the sheet beam defined by the aperture size in front of the hollow cathode region have been optimized for the generation of a SEB. The ratio of the length to the width of the rectangular aperture defines the aspect ratio of the SEB. It has been found that the beam aspect ratio plays an important role in the penetration of the accelerating field inside the hollow cathode geometry, which affects the transient behavior of the discharge. The hollow cathode dimensions have been optimized for the applied gap voltage varying between 15 and 25 kV, while the beam aspect ratio has been analyzed for the range between 5:1 and 12:1 keeping the fill factor constant.

A thin TTF-py film combined with PEDOT:PSS film was introduced to enhance the device performance of conventional polymer solar cells. The origin of the enhanced Jsc and fill factor was systematical...

Organic photovoltaics (OPVs) were fabricated with J71, PBT1-C or their blends as donor and IT-2F as acceptor. The power conversion efficiency (PCE) of J71 and PBT1-C based binary OPVs arrive to 10.45% and 10.23%, respectively. Although the very similar photovoltaic performance of two binary OPVs, three photovoltaic parameters are distinctly different. Meanwhile, three materials also exhibit complementary absorption range to cover solar light as wide as possible. Integrating the advantages of materials and binary OPVs, the optimized ternary OPVs are obtained with 12.26% PCE and 75.53% fill factor by incorporating 20 wt% PBT1-C in donors. The enhanced photovoltaic performance should result from enhanced photon harvesting and optimized phase separation. The two polymer donors should prefer to form alloyed state, which can reasonably interpret the enhanced photovoltaic performance of ternary OPVs with PBT1-C content from 10 wt% to 50 wt% in donor.

The power conversion efficiency (PCE) of low-bandgap mixed Pb–Sn perovskite solar cells (PSCs) has been significantly hindered by large open-circuit voltage (Voc) loss and poor fill factor (FF). He...

Compared with inorganic photovoltaics, organic photovoltaics (OPVs) still have a low fill factor (FF) that restricts their power conversion efficiency (PCE). The FF is determined by the resistances...

In outer space, the electrical power needed to perform missions in most often provided by so-lar cells interconnected in series (cell-by-cell). Silicon solar cells had been used since 1957 as the primary source of electrical power in space. However, these early cells typically had very low con-version efficiency (about 10% or 12%). Therefore, many silicon solar cells were required for proper power generation in orbit. Recently, in order to produce more electrical power with fewer cells, GaInP/GaAs/Ge solar cells were selected for use after considering their conversion efficiency and space durability in space against such as radiation effects, cosmic rays and so on. The electrical circuits and interconnections are crucial for increasing the power conversion efficiency; however, the mechanical substrate is also an important consideration for space solar cell array design. If these devices are to be used for space applications, their functions must be verified on the ground. A standard coupon for solar cell array verification was designed and manufactured for space applications, and its performance was measured through a flash test. Finally, the results for a standard coupon using the GaInP/GaAs/Ge III-V compounds were compared with those from simulation. We found a difference within 3% in the fill factor. So as to fulfill the requirements for the solar cell arrays to be used in space, we propose a general purpose the standard solar cell array coupon for ground verification of readiness for space applications.

Until now the Dark Lock-in Thermography (DLIT) based "Local I-V" method for analyzing the inhomogeneity of the two-diode parameters of solar cells was applied mostly to multicrystalline silicon cells. In this contribution it is applied to three high-efficiency monocrystalline cells of the hetero junction type (HJT), one showing very good and two showing slightly degraded cell parameters. It is shown that the degradation of the lower performing cells is mainly due to additional local J02-type current contributions, which are partly stemming from surface injuries and mainly degrade the fill factor. It can be estimated that the local inhomogeneous dark current contributions, which can be imaged and quantified by DLIT, degrade the efficiency of the best cell only by 0.1%, but that of the stronger degraded cells by 0.3% and 0.6% (absolute) respectively. Under reduced illumination intensity the differences between the cells are even higher. The possibilities and limitations of the "Local I-V" evaluation of solar cells for investigating high-efficiency cells are discussed.

Due to the ironless structure of the toroidal winding in the tubular linear voice coil motor (TLVCM), the winding thickness is one of the critical parameters that have an impact on air-gap flux density, and hence affects the copper loss at rated thrust. This paper investigates and determines the thickness of the ironless toroidal winding of the TLVCM for the purpose of a minimum copper loss. Magnetic equivalent circuit (MEC) method is used to analyze the air-gap flux density with respect to winding thickness, and the corresponding copper loss at the rated thrust is assessed by considering the slot fill factor. The optimal solution is obtained according to the U-shaped curve of the copper loss. Moreover, the finite-element analysis is combined to validate the results of MEC method, and a good agreement is reached. Two prototypes of TLVCMs having similar slot fill factor are made, one of which is with the optimal winding thickness. The expected current at the rated thrust is obtained by a test platform of static thrust, so as to obtain the corresponding copper loss for each prototype. The experimental results show that the TLVCM with optimal winding thickness features a lower copper loss. Hence, the attempt to minimize the copper loss by designing the thickness of the ironless winding is highly effective.

Much has been reported on the effects of air action on the physical entities related to the transport processes in organic solar cells, for example, the electronic mobility, the lifetime of the charge carriers and the recombination kinetics. These effects have a direct impact on the series and parallel resistances (Rs and Rsh) of the solar cell, but studies of the action of the air environment on these resistances have been little explored. Here we present an experimental study of the environment action on an ITO/PEDOT:PSS/PTB7-Th:PC71BM/Ca/Al device, exploring mainly the variation of the series and the shunt resistances with the air exposure time. We used the classical equation of the current–voltage of an equivalent circuit of a solar cell to fit the experimental results, and used Rs and Rsh as adjustment parameters. We also correlated these resistances with the fill factor by the help of an approach developed by M. A. Green in 1982.

A finite volume technique in a commercial computational fluid dynamics (CFD) code is employed in this study to simulate transient, incompressible, non-Newtonian and non-isothermal rubber mixing. The simulation processes are conducted in a two-dimensional(2D) domain, where a mixing chamber partially-filled with rubber is equipped with a pair of two-wing non-intermeshing counter-rotating rotors. The main objective is to assess the effect of different fill factors of rubber on dispersive and distributive mixing characteristics by simulating 15 revolutions of the rotors rotating at 20 min−1. 50%, 60%, 70%, 75%, 80% and 90% are the six different fill factors chosen for the study. An Eulerian multiphase method has been applied to solve for the two different phases, rubber and air. The non-Newtonian property of rubber is handled using the shear rate dependent Carreau-Yasuda model, along with an Arrhenius function to include the temperature dependency. In addition to the governing equations related to the conservation of mass, momentum and energy, the volume of fluid (VOF) method is chosen to track the interface between air and rubber. With regard to the results, flow patterns, thermal distributions, viscosity behavior and volume fraction are analyzed for the different fill factors. In addition, dispersive and distributive mixing behavior is also assessed in detail using Lagrangian statistics, such as mixing index, cumulative distribution of maximum shear stress, cluster distribution index (CDI), scale of segregation (SOS) and length of stretch (LOS), calculated from massless particles. Both the Eulerian and Lagrangian results showed that fill factors between 70% and 80% presented the most reasonable and efficient mixing scenario, and also exhibited the best dispersive and distributive mixing characteristics combined.

Flexible perovskite solar cells (PSCs) were ideal candidates for wearable devices due to the merits of flexibility, high efficiency, and being lightweight, and they could be fabricated in a continuous roll-to-roll production process to achieve large-area and low cost devices. Herein, the high efficiency (up to 18.53%) and fill factor (0.81) of flexible PSCs (ITO/SnO2/KCl/MAPbI3/spiro-OMeTAD/Ag) were achieved by low-pressure assisted solution processing under low temperature (⩽100 °C). The surface morphology and crystallinity of perovskite films were effectively promoted by the KCl modification and the defect density of perovskite films as well as the hysteresis of the corresponding devices was reduced accordingly. In addition, the stability and bendability of the KCl-modified flexible PSCs were improved simultaneously. To the best of our knowledge, both the efficiency and fill factor are the best among all flexible PSCs reported to date. Therefore, the insertion of KCl between SnO2 and MAPbI3 layers provi...

The influence of the subaperture fill factor fs and the conformal aperture fill factor fc on the thermal blooming of array laser beams in the air is studied numerically and analytically, where coherent beam combination (CBC) and incoherent beam combination (IBC) are considered. It is shown that the array laser beam with larger values of fs and fc (when fc

Lockheed Martin Space Systems Company Optical Payloads Center of Excellence is in process of standing up the Robotic Optical Assembly System (ROAS) capability at Lockheed Martin Coherent Technologies in Colorado. This currently implemented Robotic Optical Assembly has enabled Lockheed Martin to create world-leading, ultra-lowSWAP photonic devices using a closed-loop control robot to precisely position and align micro-optics with a potential fill factor of

Micro-concentrator photovoltaics (micro-CPV) consists of the reduction in size of the components of the conventional concentrator photovoltaic (CPV) technology, attaining equally high efficiencies and reducing material costs and manufacturing costs. In this publication we focus on the implementation of high throughput manufacturing methods for the interconnection of the solar cells. The goal is to enable large area interconnection of thousands of micro-solar cells with a low cost of 3€/m2 . A proof-of-concept was achieved for interconnection via directly printing onto the front contact pads. Prototypes using two different cell technologies where manufactured achieving good results. The highest achieved fill factor (FF) is of 84.3% at 200X with a short circuit current (Isc) of 2.4mA and open circuit voltage (Voc) of 3.41V

The present paper is about an investigation on the temperature dependence of efficiencies of individual energetic process (Absorption efficiency, Thermalization efficiency, Thermodynamic efficiency and Fill factor) and overall conversion efficiencies of a polycrystalline silicon solar cell which has been investigated in temperature range 10–50 °C. All these individual efficiencies present a decrease versus the increase of the temperature. However, the thermodynamic efficiency and the fill factor are more sensitive to the temperature increase more than the absorption and thermalization efficiencies. The thermodynamic efficiency and the fill factor degradation is explained by decrease of open circuit voltage in temperature. The performance parameters as open circuit voltage, maximum power and the overall efficiencies are found to decrease with temperature while the short circuit current is observed an increase. The resistance of the semiconductor decreases with the increase of the temperature. The minoritary carriers charge acquire excessive kinetic energy which can exceed the gap energy causing an over-excitement when the temperature increase. However, this over-excitement of the minoritary carriers charge does not participate to the external current improvement.

Cylindrical microlens arrays (CMLAs) play a key role in many optoelectronic devices, and 100% fill-factor CMLAs also have the advantage of improving the signal-to-noise ratio and avoiding stray-light effects. However, the existing preparation technologies are complicated and costly, which are not suitable for mass production. Herein, we propose a simple, efficient, and low-cost manufacturing method for CMLAs with a high fill-factor via the electric-field-driven (EFD) microscale 3D printing of polydimethylsiloxane (PDMS). By adjusting the printing parameters, the profile and the fill-factor of the CMLAs can be controlled to improve their optical performance. The optical performance test results show that the printed PDMS CMLAs have good image-projecting and light-diffraction properties. Using the two printing modes of this EFD microscale 3D-printing technology, a cylindrical dual-microlens array with a double-focusing function is simply prepared. At the same time, we print a series of specially shaped microlenses, proving the flexible manufacturing capabilities of this technology. The results show that the prepared CMLAs have good morphology and optical properties. The proposed method may provide a viable route for manufacturing large-area CMLAs with 100% fill-factor in a very simple, efficient, and low-cost manner.

The metallization of solar cells remains a dominating factor for the total cost of solar cell manufacturing and must be reduced. A prime candidate to replace the traditional Ag is Cu since it is close in conductivity but about 100 times lower cost. However, the oxidation of Cu in atmosphere and its diffusion into Si have been troublesome factors preventing its implementation. These two challenges were considered to formulate the thick film Cu paste and the 19.4% efficiency, fill factor of 76.02%, short-circuit current density of 39.0 mA/cm2 and open-circuit voltage of 654.4 mV, show these challenges have been overcome.

In recent years, PERC solar cells have been the dominant industrial cells compared with Al-BSF solar cells. Fill factor (FF) is a vital indication of the performance of solar cells. In this paper, a comparative study on the temperature coefficients of FF for PERC solar cells and Al-BSF solar cells are investigated under non-standard test conditions. It is found that the absolute value of the temperature coefficient of FF for PERC solar cell is always lower than that for Al-BSF solar cell under non-standard conditions, which agrees with the calculated result. The obtained results are beneficial to understand the performance of solar cell under non-standard conditions.

In this work, we discuss the use of epsilon-near-zero (ENZ) metamaterials to efficiently couple light radiated by a dipolar source to an in-plane waveguide. We exploit both enhanced and directional emission provided by ENZ metamaterials to optimize the injection of light into the waveguide by tuning the metal fill factor. We show that a net increase in intensity injected into the waveguide with respect to the total power radiated by the isolated dipole can be achieved in experimentally feasible conditions. We think the proposed system may open up new opportunities for several optical applications and integrated technologies, especially for those limited by outcoupling efficiency and emission rate.

This paper presents an experimental investigation on photovoltaic array (PV array) power output affected by partial shading conditions (PSCs). An experiment setup of a PV array with a series configuration using 2 × 4 photovoltaic modules (PV modules) was built. The power output loss due to the shading effect on the first photovoltaic cells (PV cell) connected with bypass diodes of each photovoltaic module, installed in the PV array in the horizontal direction, was evaluated. Depending on the direction of the sun relative to the PV array configuration, the shading percentage was measured during the test and recorded the current and voltage of the PV array. The performance evaluation of the PV array configurations is referred to with respect to the values of maximum power voltage, the maximum power current, maximum power output, power output losses and fill factor (FF). The experimental results show that 44% shading of the first PV cells affects PV array power output loss by more than 80%.