Photocurrent Iph Research Articles

New analytical expressions of photovoltaic solar module physical parameters: Effects of module temperature and incident solar irradiance

In this work, we present three methods to extract model physical parameters of a photovoltaic solar module modelled by a single-diode electronic circuit. The model physical parameters we are looking for are photocurrent Iph , saturation current Is , ideality factor η, series resistance Rs and shunt conductance Gp . The first method is based on exact solution of module characteristic equation, the second one uses exact expression of dynamic conductance and the third one makes use of exact expression of the integral of translated current-voltage characteristics (I-Isc ). In all these extraction methods, we achieve numerical fitting of experimental data of output current, differential conductance and area under translated characteristics with suitable analytical expressions to get model physical parameters at standard test conditions (STC). Then, we assume these values as initial conditions and derive exact analytical expressions reporting effects of module temperature and incident solar irradiance on photocurrent, saturation current and ideality factor using temperature coefficients provided as well as irradiance coefficients extracted from module manufacturer datasheet. We examine new analytical expressions of model physical parameters in the case of Shell SQ80 photovoltaic solar module at arbitrary operating conditions of module temperature and solar irradiance. We evidence good agreement between experimental characteristics and forecasted analytical characteristics generated by new analytical expressions.

Intersection behavior of the current–voltage (I–V) characteristics of the (Au/Ni)/HfAlO3/n-Si (MIS) structure depends on the lighting intensity

The current–voltage (I–V) and capacitance–voltage (C–V) behaviors of the (Au/Ni)/HfAlO3/n-Si (MIS) junctions at room temperature under white light with various intensities were investigated. The ln(I)–V curves show two linear behavior regions at about 1 V before and after the point of intersection that can be defined as two separate current-conduction (CMs) Mechanisms. The values of the ideality factor (n) and the zero-bias barrier height (ΦB0) were extracted using the slope and intercept of the ln(I)–V curve before and after the intersection point based on lighting power. Although the ΦB0 values decrease with increasing light power, n increases for two regions, and there is a strong linear relationship between them. The values of photo-current (Iph) increase with the increasing lighting power due to the formation of electron–hole pairs. The slope of the double-logarithmic Iph–P was changed from 0.422 to 0.852, respectively, at − 2 V and − 9 V, which indicates the ongoing distribution of Nss. In addition, the profile of surface states (Nss) ionized by light was obtained from the capacitance measured in dark and under lighting at 1 MHz. The Nss–V curve has two characteristic peaks that correspond to the region of depletion and accumulation due to a special distribution of Nss and their restructuring and reordering under the effects of lighting and an electric field.

Remarkable improved photoelectric performance of SnS2 field-effect transistor with Au plasmonic nanostructures

The development of photoelectric devices for high integration and miniaturization in the semiconductor industry can be pushed forward by the thriving research of two-dimensional layered metal dichalcogenides (2D-LMDs). SnS2 nanosheets have an evident photoresponse to both ultraviolet and partial visible light, but only with a fair photoelectric performance limited by their atomic-layer thickness. Here, we report a convenient and simple method to dramatically enhance the electrical and photoelectric performance of the SnS2 flake. By integrating SnS2 with Au plasmonic nanostructures, the photocurrent (Iph) increased by over 20 times. The corresponding responsivity (R), light gain (G), and detectivity (D*) have been improved by ∼2200%, 2200% and 600%, respectively. The responsivity and detectivity of the Au NPs-SnS2 field-effect transistor (FET) at 532 nm are 1125.9 A W−1 and 2.12 × 1011 Jones. Though atomically thin, the hybrid SnS2 photodetector, benefiting from local surface plasmonic resonance, achieves an excellent photoelectric performance that is not usually possible with a pristine SnS2-only device.

An improved mathematical model of photovoltaic cells based on datasheet information

In order to tackle the nonlinear transcendental equation and intractability of traditional photovoltaic (PV) cells model, this paper proposes a two-step modeling method based on datasheet information. Firstly, grounded on the assumption that the open circuit voltage and short circuit current are independent of series resistance Rs and shunt resistance Rsh, the PV cells model is separated as the ideal model part and the resistance network part. Then, according to the data provided by the manufacturer under Standard Test Conditions (STC) and Nominal Operating Cell Temperature (NOCT) conditions, the parameters photocurrent Iph, reverse saturation current Io and ideality factor n are obtained to achieve the purpose of modeling the ideal model part. Meanwhile, the parameters Rs and Rsh are obtained according to the data provided by the manufacturer under STC to achieve the purpose of modeling the resistance network part. Finally, the open circuit voltage and short circuit current of three different material types of PV cells are obtained by the modeling method and compared with the actual experimental data to verify the mentioned assumption. Moreover, the current-voltage characteristic curves of these three PV cells are also obtained and the corresponding errors are analyzed and discussed.

3D-printed Cu2O photoelectrodes for photoelectrochemical water splitting.

Photoelectrochemical (PEC) water splitting is an alternative to fossil fuel combustion involving the generation of renewable hydrogen without environmental pollution or greenhouse gas emissions. Cuprous oxide (Cu2O) is a promising semiconducting material for the simple reduction of hydrogen from water, in which the conduction band edge is slightly negative compared to the water reduction potential. However, the solar-to-hydrogen conversion efficiency of Cu2O is lower than the theoretical value due to a short carrier-diffusion length under the effective light absorption depth. Thus, increasing light absorption in the electrode–electrolyte interfacial layer of a Cu2O photoelectrode can enhance PEC performance. In this study, a Cu2O 3D photoelectrode comprised of pyramid arrays was fabricated using a two-step method involving direct-ink-writing of graphene structures. This was followed by the electrodeposition of a Cu current-collecting layer and a p–n homojunction Cu2O photocatalyst layer onto the printed structures. The performance for PEC water splitting was enhanced by increasing the total light absorption area (Aa) of the photoelectrode via controlling the electrode topography. The 3D photoelectrode (Aa = 3.2 cm2) printed on the substrate area of 1.0 cm2 exhibited a photocurrent (Iph) of −3.01 mA at 0.02 V (vs. RHE), which is approximately three times higher than that of a planar photoelectrode with an Aa = 1.0 cm2 (Iph = −0.91 mA). Our 3D printing strategy provides a flexible approach for the design and the fabrication of highly efficient PEC photoelectrodes.

Photodetection Performance Of The Electrochemical Cells Formed With Sb3+ Doped Cd0.92 Hg0.08S Electrodes

Abstract The present investigation deals with the preparation of Sb3+ doped (0.01 mol % to 1 mol %)Cd0.92Hg0.08S thin films onto the well-polished and cleaned stainless steel substrates. The previously optimized conditions were used for the deposition. The electrochemical photosensing cells were fabricated out of these series of Sb3+ doped Cd0.92Hg0.08Sphotoactive electrodes and sulphide / polysulphide (0.2 M) as an electrolyte. The cells were then characterized through the various properties and their performance has been studied with a special reference to the Sb3+ doping concentration. The cells were illuminated with a white light of 13 mW/cm2 intensity and the cell performance such as photocurrent (Iph), photo voltage (Vph), the electrochemical conversion efficiency (η), fill factor (ff), etc. have been determined. It is found that Iph, Vph, η% and ff% have been boosted significantly with Sb3+ doping concentration up to 0.1 mol % and then decreased. Typically, Iph enhanced from 0.152 mA/cm2 to 0.214mA/cm2 and that Vph from 297 mV to 391 mV whereas η increased from 1.27 % to 2.41 % and ff from 36.44 % to 38.65 %. The junction ideality factors were then determined andindicated that the recombination mechanism is the dominant mechanism at the electrode / electrolyte interface. The capacitance – voltage measurements showed Vfbto be enhanced from - 1.068 V to - 1.297 V (Vs SCE). Barrier potential measurements showed Pool - Frenkel type conduction mechanism. Overall the photovoltaic (PV) detector performance has been found to be boosted significantly at 0.1 mol % Sb3+ doping concentration in Cd0.92Hg0.08Selectrode. The electrochemical photovoltaic detector performance has been explained on the basis of the improved properties of the electrode material as a result of Sb (III) dopent

Deep-ultraviolet sensing characteristics of transparent and flexible IGZO thin film transistors

Recently, deep-ultraviolet (DUV) photodetectors with useful functions including transparency and flexibility have been developed for a real-time environmental monitoring, a wearable monitoring system, transparent wireless communication, and a smart window system. In this study, we investigate the DUV sensing characteristics of transparent and flexible IGZO thin-film transistors (TFTs) fabricated by a dry transfer printing, which is a very promising technique affording the device fabrication on unconventional surfaces. The fabricated TFT devices show high mechanical stability even at a bending radius of 1.4 mm, and the repeatable and gate bias-dependent DUV photoresponse characteristics. The gate bias-dependent photocurrent (Iph) decay characteristics are likely attributed to the different surface re-adsorption rates of oxygen molecules depending on the gate bias polarity, which are qualitatively described based on energy band diagrams. In addition, the wavelength-dependent photoresponse characteristics of the IGZO TFT device upon UV illumination with λ = 245 nm show a 10 times faster Iph decay behavior than that upon UV illumination with λ = 365 nm. The result implies that the dissociative oxygen arising from the DUV illumination could accelerate the Iph decay due to the increased surface adsorption.

Wavelength-Dependent Charge Carrier Dynamics for Single Pixel Color Sensing Using Graded Perovskite Structures.

We report smart color-sensing devices of two-dimensional lead halide perovskites that exhibit a graded band gap across the film. We observe that the device short-circuit photocurrent is strongly dependent on excitation wavelength λ, and this arises through photoabsorption at different depths in the sample due to the graded bandgaps present. This λ signature in the response of the device is observed in case of steady-state excitation when incident from the high bandgap side of the film, where a complete reversal in the polarity of the photocurrent Iph(t) is obtained as the excitation wavelength is spanned across the visible spectrum. The transient photocurrent reveals λ-specific response arrived from a combination of positive and negative Iph(t) components. The uniqueness of Iph(t) as a function of incident λ can be utilized to examine spectral purity without dispersive optical elements. An equivalent circuit model description provides a possible glimpse into the physical sources involved in contributing to these features.

Charge collection efficiency in photoconductive detectors under small to large signals

Hecht collection efficiency η0 and its formulations for exponential absorption have been widely used in modeling charge collection efficiency in photoconductive detectors. The basic assumption of the Hecht formulation is that the electric field in the device is uniform, i.e., the photoinjected carriers do not perturb the field. Here, we have used Monte Carlo simulations to model the initial injection of electron and hole pairs and their subsequent transport and trapping in the presence of an electric field, which is calculated from the Poisson equation. Each injected carrier is tracked as it moves in the semiconductor until it is either trapped or reaches the collection electrode. Trapped carriers do not contribute to the photocurrent but continue to contribute to the field through the Poisson equation. The instantaneous photocurrent iph(t) is calculated from the drift of the free carriers through the Shockley–Ramo theorem. iph(t) is integrated over the duration of the photocurrent to calculate the total collected charge and hence the collection efficiency ηr. ηr has been calculated as a function of the charge injection ratio r, the electron and hole ranges (drift mobility and lifetime products, μτ), mean photoinjection depth δ, and drift mobility ratio b. The deviation of the collection efficiency ηr from the uniform field case η0 can be as much as 30% smaller than the small signal model prediction. However, for a wide range of electron and hole schubwegs and photoinjection ratios, typical errors remained less than 10% at full injection, the worst case. The present study provides partial justification to the wide-spread use of the uniform-field collection efficiency η0 formula in various applications, even under high injection conditions.

Numerical Study of the Impact of Junction Depth and the Surface Recombination Velocity on Electrical Parameters of GaAs-Solar Cell

Solar energy based on the solar cell is the most promising source among renewable energy sources. The photocurrent (Iph), open circuit voltage (Voc), maximum voltage (Vm), form factor (FF) and efficiency (η) of the solar cell are the most important parameters that can define the quality of this cell. In this work, we study the impact of the junction depth Xj and the surface recombination velocity Sn on these parameters in both external and internal cases of the solar cell in Arsenic gallium (GaAs) technology using the MATLAB software as a tool. Results show that in order to obtain highperformance of GaAs-solar cells must be the surface recombination velocity value is low, and the junction depth in submicron scale. Numerical results gave higher values of efficiencies 19.21 % and 30.1 % in external and internal cases respectively, and best electrical parameters of the GaAs-solar cell when the junction depth and the surface recombination velocity are equal to 0.2 μm and 102 cm/s respectively.

Exploring the photoelectrocatalytic behavior of free-standing TiO2 nanotube arrays on transparent conductive oxide electrodes: Irradiation direction vs. alignment direction

Although one-dimensional TiO2 nanotube arrays (TNA) grown on Ti substrates via electrochemical anodization are extensively studied in photoelectrochemistry, the photo(electro)catalytic activity of TNA detached from the Ti substrates remains unexplored. Herein, we synthesize TNA samples with various pore sizes (40–100 nm) and tube lengths (4–15 μm) via two-step electrochemical anodization, and transfer them to transparent conducting oxide (i.e. fluorine-doped tin oxide; FTO) substrates in normal (n) alignment (front plane outward) and reverse (r) alignment (backplane outward). The front and back planes of the as-fabricated TNA film are the same based on X-ray diffraction (anatase structure), X-ray photoelectron spectroscopy (Ti and O), and UV–vis transmittance data, though the tubes are open in the front and closed in the back. Regardless of the direction of irradiation (SE: FTO → TNA vs. EE: TNA → FTO), longer tubes generate a higher photocurrent (Iph) due to the large light absorption. However, for the same alignment of TNA (either n- or r-TNA), SE irradiation leads to a very large Iph (e.g., nSE >nEE), whereas n-TNA consistently generates a larger Iph than r-TNA for a given irradiation direction (i.e., n >r). The photocatalytic decomposition of phenol follows the same tendency (n >r); however, the Faraday efficiency (based on the photocharge) is higher with EE (nEE 28%, rEE 20%) than SE (rSE 11%, nSE 7%) irradiation. These photoelectrochemical and photocatalytic behaviors are explained in terms of charge carrier generation (FTO/TNA vs. TNA/solution), dissimilar charge carrier transfer pathways (e− transfer through tube framework vs. h+ transfer via radial direction), and charge injection at the tube (open vs. clogged tube mouth)/solution interface. The time-resolved photoluminescence (TRPL) emission and incident photon-to-current efficiency (IPCE) are also studied to gain insight into the charge transfer kinetics.

Modeling and Simulation of Solar Module performance using Five Parameters Model by using Matlab in Baghdad City

This work presents the modeling of the electrical response of monocrystalline photovoltaic module by using five parameters model based on manufacture data-sheet of a solar module that measured in stander test conditions (STC) at radiation 1000W/m² and cell temperature 25 . The model takes into account the series and parallel (shunt) resistance of the module. This paper considers the details of Matlab modeling of the solar module by a developed Simulink model using the basic equations, the first approach was to estimate the parameters: photocurrent Iph, saturation current Is, shunt resistance Rsh, series resistance Rs, ideality factor A at stander test condition (STC) by an iteration process. To implement the iteration process, a numerical approach based on the Newton Raphson method has been implemented and programmed in Matlab. The second mathematical model used in Matlab/Simulink using equations for each parameter to determine the parameters at all operating conditions. The Matlab program gives the information about the behavior of the practical PV module, under different atmospheric conditions. The model accuracy was also analyzed through finding out the compatibility between the practical and the theoretical aspects at different solar radiation intensity 500, 750 and 1000 W/m2 by extracting the error ratios. The results show that there is difference between theoretical (modeled) and experimental, the best validation (less error) between five parameters model and experimental maximum power results at radiation 500, 750, 1000 W/m2 and STC was 5.5%, 19%, 18% and 12.3% in January respectively, due to the decreases in ambient temperature and thus decreases in the temperature of solar module in January led to increase in maximum output power and producing best validation between model and experimental in this month. 

New analytical approach for modelling effects of temperature and irradiance on physical parameters of photovoltaic solar module

In this paper, a new exact method has been presented to extract physical parameters of single diode equivalent circuit modelling a photovoltaic solar module operating at standard test conditions. The method uses four equations, three are linking output current to output voltage in short-circuit, maximum power and open-circuit points, the fourth equation is the first derivative of output power with regard to output voltage in maximal power point. According to this method, we used ideality factor η as variation parameter and solved the system of four nonlinear equations to get values of photocurrent Iph, saturation current Is, series resistance Rs and shunt conductance Gp. We then varied ideality factor to minimize root mean square error and maximize the coefficient of determination. We assumed series resistance and shunt conductance constant, and derived analytical expressions describing effects of module temperature and incident solar irradiance on photocurrent, on ideality factor and also on saturation current using both temperature coefficients available as well as irradiance coefficients extracted from module datasheet. We considered standard test conditions numerical values of physical parameters as initial conditions and determined numerical models for Iph(T,G), η(T,G) and Is(T,G). We also derived new mathematical expressions of maximum power point voltage and module efficiency. We tested these numerical models as well as mathematical expressions derived on Kyocera KC200GT and Shell SQ80 photovoltaic solar modules under different conditions of module temperature and incident solar irradiance and found good agreement between experimental and forecasted characteristics.

Broad-Band High-Sensitivity ZnO Colloidal Quantum Dots/Self-Assembled Au Nanoantennas Heterostructures Photodetectors.

Tunable plasmonic resonance induced by the collective oscillation of the electrons on metallic nanostructures can excellently enhance the light response of ZnO films, which provides an effective way to break through the limitation of the performance of ZnO photodetectors. Here, broad-band high-performance ZnO/Au heterostructures photodetectors with various morphologies of self-assembled Au nanoantennas are fabricated via a facile approach under the spin-coated ZnO colloidal quantum dots films. With a systematic control on growth condition, the self-assembled Au nanoantennas undergo a drastic evolution from the corrugated nanomounds to the island-like nanostructures, and the light absorption of the resulting ZnO/Au heterostructures correspondingly exhibits a strongly morphological dependence on the Au nanoantennas. Meanwhile, the photoresponse of the ZnO-based photodetectors is significantly improved throughout a wide spectrum between UV and visible regions owing to the enhanced light absorption induced by the localized surface plasmon resonance. As a result, the optimal switch ratio of the ZnO/Au heterostructures photodetector increases by 1 order to ∼1.13 × 105 than that of the pristine ZnO one because of the obviously increased photocurrent ( Iph) and comparable dark current, thus leading to ∼9.1 and ∼4.9 times increases in the photoresponsivity and the normalized detectivity. Meanwhile, the significant increases in the Iph of ∼5.2 and ∼9.7 times are likewise observed with the ZnO/Au heterostructures under 530 nm and white-light illumination. This work can offer a handy and effective approach for the fabrication of ultrasensitive ZnO-based photodetectors within a broad-band wavelength by utilizing the Au plasmonic nanostructures.

A lateral-type spin-photodiode based on Fe/x-AlOx/p-InGaAs junctions with a refracting-facet side window

A lateral-type spin-photodiode having a refracting facet on a side edge of the device is proposed and demonstrated at room temperature. The light shed horizontally on the side of the device is refracted and introduced directly into a thin InGaAs active layer under the spin-detecting Fe contact in which spin-polarized carriers are generated and injected into the Fe contact through a crystalline AlOx tunnel barrier. Experiments have been carried out with a circular polarization spectrometry set up, through which helicity-dependent photocurrent component, dI, is obtained with the conversion efficiency F ~ 0.4 %, where F is the ratio between dI and total photocurrent Iph. This value is the highest reported so far for pure lateral-type spin-photodiodes. It is discussed through analysis with a model consisting of drift-diffusion and quantum tunneling equations that a factor that limits the F value is unoccupied spin-polarized density-of-states of Fe in energy region into which spin-polarized electrons in a semiconductor are injected.

Oxalate-TiO2 complex-mediated oxidation of pharmaceutical pollutants through ligand-to-metal charge transfer under visible light

Oxalate-adsorbed TiO2 shows visible activity for the oxidation of ranitidine, although neither oxalate nor pure TiO2 alone absorbs visible light. The formation of an oxalate-TiO2 complex facilitates electron transfer from oxalate to the TiO2 conduction band (CB) (i.e., a ligand-to-metal charge transfer (LMCT)) and generates superoxide/hydroperoxyl radicals (O2−/HO2), which are primarily responsible for ranitidine oxidation, under visible light. The attenuated total reflection Fourier transform infrared (ATR-FTIR) spectra of oxalate-adsorbed TiO2 indicates that the formation of a LMCT complex between oxalate and TiO2 occurs through bidentate carboxylate linkages. The visible light-induced generation of photocurrent (Iph) on the TiO2/FTO electrode in the presence of oxalate confirms the LMCT mechanism in the oxalate-TiO2 complex under visible light. Kinetic studies with varying oxalate concentrations, initial pH values, and TiO2 types demonstrate that the oxidation efficiency increases as the adsorption of oxalate and the molar fraction of O2− increase. Not only ranitidine but also other pharmaceutical pollutants, such as cimetidine, propranolol, imidazole, and nizatidine, were oxidized in the pure TiO2/oxalate/visible light system. The oxidation efficiency of the oxalate-TiO2 complex was higher than that of other organic ligand-TiO2 complexes (i.e., citrate-, EDTA-, malonate-, acetate-, and glucose-TiO2 complexes). In this regard, the pure TiO2/oxalate/visible light system can be proposed as a practical method for the treatment of pharmaceutical-contaminated water and wastewater.

Biocompatible, large-format, inkjet printed heterostructure MoS2-graphene photodetectors on conformable substrates

An inkjet printed, biocompatible, heterostructure photodetector is described that was constructed using inks of photo-active molybdenum disulfide (MoS2) and electrically conducting graphene which facilitated charge collection of the photocarriers. The importance of such devices stems from their potential utility in age-related-macular degeneration, which is a condition where the photosensitive retinal tissue degrades with aging, eventually compromising vision. The absence of effective therapeutic remedies for patients with this disorder has motivated the development of such devices to restore some degree of visual function. Inkjet printed, flexible prosthetic devices offer design simplicity where additive manufacturing can enable large format, low-cost arrays. The biocompatible inkjet printed two-dimensional heterojunction devices were photoresponsive to broadband incoming radiation in the visible regime, and the photocurrent Iph scaled proportionally with the incident light intensity, exhibiting a photoresponsivity R ~ 0.30 A/W. This is 103 times higher compared to prior reports, and detectivity D was calculated to be ~3.6 × 1010 Jones. Strain-dependent measurements were also conducted with bending, indicating the feasibility of such devices printed on flexible substrates. Drop cast and printed CT-MoS2 inks were characterized using techniques, such as Raman spectroscopy, photoluminescence measurements and scanning electron microscopy. Both mouse embryonic fibroblast and human esophageal fibroblast were used for the biocompatibility analysis for inks drop cast on two types of flexible substrates, polyethylene terephthalate and polyimide. The biocompatibility of inks formed using two-dimensional graphene and MoS2 on polyimide substrates was extremely high, in excess of 98% for mouse embryonic fibroblast.

Differential imaging of the metabolism of bacteria and eukaryotic cells based on light-addressable potentiometric sensors

A light-addressable potentiometric sensor (LAPS) is a field-effect-based potentiometric sensor with an electrolyte/insulator/semiconductor (EIS) structure, which is able to monitor analyte concentrations of (bio-)chemical species in aqueous solutions in a spatially resolved way. Therefore, it is also an appropriate tool to record 2D-chemical images of concentration variations on the sensor surface. In the present work, two differential, LAPS-based measurement principles are introduced to determine the metabolic activity of Escherichia coli (E. coli) K12 and Chinese hamster ovary (CHO) cells as test microorganisms. Hereby, we focus on i) the determination of the extracellular acidification rate (ΔpH/min) after adding glucose solutions to the cell suspensions; and ii) recording the amplitude increase of the photocurrent (Iph) related to the produced acids from E. coli K12 bacteria and CHO cells on the sensor surface by 2D-chemical imaging. For this purpose, 3D-printed multi-chamber structures were developed and mounted on the planar sensor-chip surface to define four independent compartments, enabling differential measurements with varying cell concentrations. The differential concept allows eliminating unwanted drift effects and, with the four-chamber structures, measurements on the different cell concentrations were performed simultaneously, thus reducing also the overall measuring time.

Investigation of helicity-dependent photocurrent at room temperature from a Fe/x-AlOx/p-GaAs Schottky junction with oblique surface illumination

In view of a study on spin-polarized photodiodes, the helicity-dependent photocurrent (ΔI) in a Fe/γ-AlOx/p-GaAs Schottky diode is measured at room temperature by illuminating a circularly polarized light beam (λ = 785 nm) either horizontally on the cleaved sidewall or at an oblique angle on the top metal surface. The plane of incidence is fixed to be parallel to the magnetization vector of the in-plane magnetized Fe electrode. The conversion efficiency F, which is a relative value of ΔI with respect to the total photocurrent Iph, is determined to be 1.0 × 10−3 and 1.2 × 10−2 for sidewall illumination and oblique-angle illumination, respectively. Experimental data are compared with the results of a model calculation consisting of drift-diffusion and Julliere spin-dependent tunneling transports, from which two conclusions are obtained: the model accounts fairly well for the experimental data without introducing the annihilation of spin-polarized carriers at the γ-AlOx/p-GaAs interface for the oblique-angle illumination, but the model does not fully explain the relatively low F in terms of the surface recombination at the cleaved sidewall in the case of sidewall illumination. Microscopic damage to the tunneling barrier at the cleaved edge would be one possible cause of the reduced F.

Effect of Measurement Factors on Photovoltaic Cell Parameters Extracting

In this paper, we study the influence of external factors on the measurement for the current–voltage (I-V) characteristic of the photovoltaic cell. These factors are the size of the number of measurements, the range of the cell generated voltage and the influence of measures step and mode combination of photovoltaic cells (parallel, serial, or hybrid). The main extracted parameters solar cell are the photocurrent Iph, the reverse diode saturation current I0, the ideality factor of diode n, the series resistance Rs and the shunt resistance Rsh. A method for finding these parameters, according to the single-diode model, was developed by Newton-Raphson’s method using Matlab. To assess the accuracy of this method, measured and calculated I–V characteristics were compared with provided data by the manufacturer at standard test condition (STC). The measurement results showed that these parameters are highly dependent on these four factors.