Diode Equation Research Articles

Technip Energies gets FEED contract for Encina[StQuote]s commercial PFCC unit

One of the most promising renewable energy sources (RES) is photovoltaic energy system. It generates power by using a photovoltaic (PV) module. The solar illumination and temperature value are the main parameters for the PV module because a small change can affect the entire power generation. The PV module is based on the double diode equation for extracting unknown parameter values and tracking maximum power point using basic analytical methods (Newton Raphson and Lambert W-function), particle swarm optimization (PSO) and artificial neural network (ANN) algorithms are performed. Then, a deep neural network (DNN) algorithm is proposed in this work for alleviating the disadvantages of the existing methods. Particularly, the DNN algorithm is proposed for reducing the mismatching power loss. Firstly, two-parameter values retrieve from a specific location at NASA open-access source for the year 2020. Then, the parameter values optimization through two analytical methods such as Newton Raphson (NR) and Lambert-W function (W-function) methods. Based on these analytical methods, the characteristic curve is executed. It is compared one among one and also the analytical methods evaluates with soft computing algorithms. The soft computing algorithm represents particle swarm optimization and the artificial neural network. Both the analytical methods and the soft computing algorithms compare for the extraction of the unknown parameter value for the PV module. Then, the existing algorithm is compared with advanced soft computing algorithms. In that deep neural network, the algorithm is implemented for the maximum power point tracking (MPPT) process. The DNN algorithm contains two inputs, three hidden layers and one output. The input neuron is defined with the voltage and current value and the hidden layer contains the sigmoid activation function. The result evaluates in terms of percentage of error for maximum power point (PEmpp).

The Infiltration of Silver Nanoparticles into Porous Silicon for Improving the Performance of Photonic Devices.

Hybrid nanostructures have a great potential to improve the overall properties of photonic devices. In the present study, silver nanoparticles (AgNPs) were infiltrated into nanostructured porous silicon (PSi) layers, aiming at enhancing the optoelectronic performance of Si-based devices. More specifically, Schottky diodes with three different configurations were fabricated, using Al/Si/Au as the basic structure. This structure was modified by adding PSi and PSi + AgNPs layers. Their characteristic electrical parameters were accurately determined by fitting the current–voltage curves to the non-ideal diode equation. Furthermore, electrochemical impedance spectroscopy was used to determine the electrical parameters of the diodes in a wide frequency range by fitting the Nyquist plots to the appropriate equivalent circuit model. The experimental results show a remarkable enhancement in electrical conduction after the incorporation of metallic nanoparticles. Moreover, the spectral photoresponse was examined for various devices. An approximately 10-fold increment in photoresponse was observed after the addition of Ag nanoparticles to the porous structures.

Deep neural network algorithm for MPPT control of double diode equation based PV module

One of the most promising renewable energy sources (RES) is photovoltaic energy system. It generates power by using a photovoltaic (PV) module. The solar illumination and temperature value are the main parameters for the PV module because a small change can affect the entire power generation. The PV module is based on the double diode equation for extracting unknown parameter values and tracking maximum power point using basic analytical methods (Newton Raphson and Lambert W-function), particle swarm optimization (PSO) and artificial neural network (ANN) algorithms are performed. Then, a deep neural network (DNN) algorithm is proposed in this work for alleviating the disadvantages of the existing methods. Particularly, the DNN algorithm is proposed for reducing the mismatching power loss. Firstly, two-parameter values retrieve from a specific location at NASA open-access source for the year 2020. Then, the parameter values optimization through two analytical methods such as Newton Raphson (NR) and Lambert-W function (W-function) methods. Based on these analytical methods, the characteristic curve is executed. It is compared one among one and also the analytical methods evaluates with soft computing algorithms. The soft computing algorithm represents particle swarm optimization and the artificial neural network. Both the analytical methods and the soft computing algorithms compare for the extraction of the unknown parameter value for the PV module. Then, the existing algorithm is compared with advanced soft computing algorithms. In that deep neural network, the algorithm is implemented for the maximum power point tracking (MPPT) process. The DNN algorithm contains two inputs, three hidden layers and one output. The input neuron is defined with the voltage and current value and the hidden layer contains the sigmoid activation function. The result evaluates in terms of percentage of error for maximum power point (PEmpp).

EFFECT OF MAGNETIC FIELD ON GERMANIUM P-N HOMOJUNCTION

In this study, the effect of magnetic field, which is perpendicular to junction current, on diffusion current has been investigated in Germanium based p-n homojunction diodes, theoretically. The magnetic field dependent diffusion current has been derived analytically. Resulting magnetic field dependent diode equation has been used to produce current – voltage theoretical data. Using this data, current – voltage curves of devices, I(B) - V have been plotted under different magnetic fields and effect of magnetic field on current – voltage characteristics has been investigated. According to these results, it has been observed that increasing magnetic field increases potential barrier Vth, decreases junction current and reverse saturation current I0. Also effect of magnetic field on static and dynamic magnetoresistances, using Rd(B) – V and Rs(B) – V graphs which is plotted using theoretical data, have been analyzed and it has been observed that increasing magnetic field increases static and dynamic magnetoresistance in Germanium based devices.

Electrical evolution of W and WC Schottky contacts on 4H-SiC at different annealing temperatures

In this paper, we investigate the electrical evolution of tungsten (W) and tungsten carbide (WC) Schottky contacts on 4H-SiC subjected to thermal treatments at different annealing temperatures from 475 °C to 700 °C. For each annealing temperature, the uniformity of the Schottky barrier height (ΦB) and ideality factor (n) was monitored by current–voltage (I–V) measurements in forward bias, performed over sets of equivalent diodes. Good values of n (below 1.05) were found for both contacts up to thermal annealing at 700 °C. On the other hand, the barrier of the two contacts behaves differently. For the W/4H-SiC diode, the ΦB increases with the annealing temperature (from 1.14 eV at 475 °C to 1.25 eV at 700 °C), whereas the Schottky barrier in WC/4H-SiC features a slight reduction already with thermal annealing at 475 °C, remaining almost constant at around 1.06 eV up to annealing at 700 °C. A deeper characterization was performed on the 700 °C-annealed contacts by studying the temperature-dependence of the Schottky parameters by current–voltage–temperature (I–V–T) characterization. The ΦB and n behaviour with temperature indicates the presence of a nanoscale lateral inhomogeneity for both Schottky contacts, which can be described by Tung’s model. Finally, the temperature-dependence of the reverse characteristics could be described by the thermionic field emission model, accounting for the temperature dependent barrier height determined from forward characterization.

Carrier-Density-Wave Multiple Lifetime Imaging in a Multicrystalline Silicon Solar Cell Using Quantitative Heterodyne Lock-In Carrierography and Localized Current–Voltage Characteristics

Trap-state kinetic parameters of a multicrystalline silicon solar cell were investigated using dynamic heterodyne lock-in carrierography (HeLIC) imaging under various conditions of illumination intensity and load resistance. Physical relaxation times associated with free-carrier-density-wave (CDW) band-to-band recombination, capture in and emission from two intraband-gap traps were obtained and imaged using camera-based HeLIC pixel frequency responses and a nonlinear rate equation model which provided physical insight on dynamic interactions between the CDW and the traps in the solar cell. An optoelectronic analog to the conventional diode equation was used to determine the solar cell parameters and, thus, enable the measurement of local I–V characteristics imaged over the device surface. The dc photoluminescence image at an open circuit was used as a reference and its pixel statistics and electrical parameters (maximum power, series resistance, saturation current, and generation current) were imaged using the optoelectronic equivalent of the electrical Shockley equation. The optoelectronic lifetime images were then compared with lifetime images derived from these electrical solar cell parameters and the effects of the trap states were explored. Regions with maximum power were found to be associated with low trap concentrations exhibiting low thermal emission and capture rates, with the surface/shallow trap density affecting the maximum power. The trap type (surface versus bulk) limiting the solar cell maximum power was found to vary under different values of photovoltage from open circuit to short circuit.

Photovoltaic (PV) Model Evaluation with Maximum Power Point Tracking (MPPT)

The use of solar energy is widespread due to increase in its demand across the world. This is because this form of energy can supply steady, stable, regular and clean energy. Evaluation of PV (photovoltaic) model with maximum power point tracking (MPPT) using matlab/simulink cell model for estimating the I-V characteristic curves of photovoltaic panel with respect to changes on environmental parameters (temperature and irradiance) and cell parameters (parasitic resistance and ideality factor) were evaluated. The PV model equations were modelled and simulated using MATLAB/SIMULINK Approach. This paper confirmed the usefulness of MATLAB/SIMULINK in the development of MPPT (maximum power point tracking) algorithm. Using a Shockley diode equation, an accurate simulink PV panel model was developed. It was concluded that the MPPT is able to achieve maximum power output when there is variation in solar irradiance.

A generalized theoretical approach for solar cells fill factors by using Shockley diode model and Lambert W-function: A review comparing theory and experimental data

Solar Cells (SCs) energy-conversion technologies have been widely studied from their physical fundamentals to potential commercial applications. In particular, SCs Fill Factors (FFs) are a key factor for evaluating the transport efficiency of the photo-generated current and consequently the potential photovoltaic of the device. However, FF dependence on other solar cell relevant electronic properties is not entirely clear, blearing the physical meaning of this factor. In this context, this work reports the derivation of a self-consistent and generalized analytical equation by using simple Shockley diode equation and Lambert W-function that explicitly relates solar cells FFs with simple key electronic parameters. The photo-generated (JL)-to-reverse saturation (J0) current density ratio (JL/J0) was the key parameter considered for this approach because of its considerable limiting impact on FF magnitude. The accuracy of this equation was tested by an exhaustive contrast with a wide variety of experimental data for different solar cells technologies.

A review of modeling of luminescent coupling effect in multi-junction solar cell based on diode equation

Abstract The luminescent coupling effect in multi-junction solar cell is a phenomenon where extra photocurrent in one sub-cell is driven by radiative recombination of electron–hole pairs in another sub-cell. This paper focuses on the analysis of the modeling of luminescent coupling effect in multi-junction solar cell. These modelings are based on the two-diode equivalent circuit. Finally, it concludes that the study of the luminescent coupling effect requires not only a suitable modeling but also a good experimental method for detecting the characteristics of sub-cells in multi-junction solar cell.

Space-charge effect on photogenerated-current and -voltage in III-nitride optoelectronic semiconductors

In this study, we attempted to elucidate the carrier dynamics behind the abnormal characteristics of photogenerated current and voltage ( I Ph and V Ph ) at cryogenic temperature in III-nitride optoelectronic semiconductors by employing space-charge theory. To this end, we carefully investigated and analyzed excitation-power-dependent I – V (PDIV) curves operated by quasiresonant excitation of an AlGaInN-based p − i − n junction semiconductor at 300 K and 15 K. At 300 K, the curves exhibited typical characteristics and were well described by the conventional theory. However, the PDIV curves at 15 K could no longer be described by the conventional theory. To elucidate the mechanism behind this phenomenon, we proposed a model in which the space-charge effect (SCE) plays a key role. Based on this model, we proposed the modified Shockley diode equation, which can explain the PDIV characteristic at 15 K, including the SCE. We also discussed the SCE on the efficiency of devices.

Voltage boost effects in two-step photon upconversion solar cells with a modulation-doped structure

A two-step photon upconversion (TPU) solar cell is a single-junction solar cell with a suitably designed heterointerface in the intrinsic layer. At this interface, upconversion can take place by absorbing infrared light, which excites carriers to energies above the heterojunction barrier, and then an electric field extracts these upconverted carriers to the barrier material. In this work, we study this photoabsorption process in a TPU solar cell with a modulation-doped structure. The modulation doping technique enables us to control the electric field at the heterointerface, and we demonstrate that the efficiency of the TPU process strongly depends on the electric field at the heterointerface. While we show that the TPU process induced by infrared light leads to a significant increase in the external quantum efficiency, we also note that this TPU process is an adiabatic process. It is shown that the adiabatic intraband photoexcitation at the heterointerface is able to increase the open-circuit voltage even above the open-circuit voltage that we predict from the diode equation and the actual current increase. We demonstrate obvious voltage boost effects and elucidate the relationship between the current and voltage.

General scaling laws of space charge effects in field emission

The characteristics of field electron and ion emission change when the space charge formed by the emitted charge is sufficient to suppress the extracting electric field. This phenomenon is well described for planar emitting diodes by the one dimensional (1D) theory. Here we generalize for any 3D geometry by deriving the scaling laws describing the field suppression in the weak space charge regime. We propose a novel corrected equivalent planar diode model, which describes the space charge effects for any geometry in terms of the 1D theory, utilizing a correction factor that adjusts the diode’s scaling characteristics. We then develop a computational method, based on the particle-in-cell (PIC) technique, which solves numerically the space charge problem. We validate our theory by comparing it to both our numerical calculations and existing experimental data, either of which can be used to obtain the geometrical correction factor of the corrected equivalent planar diode model.

Characteristics and Electronic Band Alignment of a Transparent p-CuI/n-SiZnSnO Heterojunction Diode with a High Rectification Ratio.

Transparent p-CuI/n-SiZnSnO (SZTO) heterojunction diodes are successfully fabricated by thermal evaporation of a (111) oriented p-CuI polycrystalline film on top of an amorphous n-SZTO film grown by the RF magnetron sputtering method. A nitrogen annealing process reduces ionized impurity scattering dominantly incurred by Cu vacancy and structural defects at the grain boundaries in the CuI film to result in improved diode performance; the current rectification ratio estimated at ±2 V is enhanced from ≈106 to ≈107. Various diode parameters, including ideality factor, reverse saturation current, offset current, series resistance, and parallel resistance, are estimated based on the Shockley diode equation. An energy band diagram exhibiting the type-II band alignment is proposed to explain the diode characteristics. The present p-CuI/n-SZTO diode can be a promising building block for constructing useful optoelectronic components such as a light-emitting diode and a UV photodetector.

Dielectric relaxation and electrical conduction mechanism of Neodymium doped Yttrium Chromite

This research article represents the fabrication and characterization of Neodymium doped YCrO3. Different optical parameters like optical bandgap energy and Urbach energy are evaluated. The gradual decrement of activation energy is observed when Neodymium doping content gradually increases. From the capacitance-voltage characteristics, free carrier concentration and trap carrier concentration are calculated, which increase with Nd doping content. Current-Voltage Characteristics of the different samples are measured at different temperatures. It follows the diode equation for the Schottky Barrier Diode (SBD) following thermionic emission. The graphical representation of current and voltage shows non-linearity, which cites the concept of Schottky diode. Another observation is that the barrier height is reduced, and the ideality factor is increased with the increase of doping concentration of Neodymium. The obtained value of the ideality factor is large, and it may be due to generation-recombination of charges inside the depletion layer and also tunneling through the barrier.

Numerical Solving for Nonlinear Problems Using Iterative Techniques

Three numerically algorithms are described and compared; newton's; Predictor-Corrector Hally and Accelerated Predictor-Corrector Hally methods have been applied in the present work. Algorithm development for solving the voltage of a solar cell based on it's a single diode equation; programmed using Matlab language. This example is given for induced the idea of this algorithm with the various values of load resistance. The results indicated the suggested algorithm is more efficient with the comparison with other two algorithms.

Voltage dependence of equivalent circuit parameters of bilayer organic photovoltaics

Despite the very different underlying physics of organic photovoltaics (OPVs), inorganic p-n junction’s Shockley’s diode equation is often applied to describe current density–voltage (JV) curves of OPVs. The model parameters, including the diode saturation current, diode ideality factor, series, and parallel resistances, are usually extracted and treated as constants in JV curve analyses. In this work, we develop a drift-diffusion bilayer interface (DD-BI) model for bilayer OPVs, which treats the donor–acceptor (D–A) heterojunction using the detailed balance between densities of polaron pairs, free electrons, and free holes. From the DD-BI model, we derive a diode equation, which is of Shockley’s equation form, but each parameter is explicitly written in terms of the D–A interface properties. We call this model the self-consistent diode (SCD) model as it is consistent with the DD-BI results provided that the key parameters are from the simulation data. By studying the effects of light intensity and carrier mobility, we find that the Shockley SCD parameters are voltage dependent because of space charge accumulation around the D–A heterojunction. Our models are successful in explaining the common discrepancies in OPV JV curve analyses, such as the validity of fitting for series resistance, deviation of ideality factor from the theoretical values, and different resistance values under light and dark conditions. The results provide a better understanding of OPVs with a D–A heterojunction and how we can capture its physics using the SCD equation.

Automated method for measuring the energy gap of p–n junction semiconductor diodes with the temperature–voltage method

An automated system for measuring the energy gap E g of a p–n junction semiconductor diodes was presented in this study. The system, based on temperature–voltage (T–V) measurement, was designed and developed as a teaching tool to support teaching for undergraduate students. The energy gap of diodes was measured by varying the diode temperature from 273 to 343 K and by measuring the voltage drop across the diode while the bias current of diodes was kept constant at a specific value. In the proposed system, an Arduino UNO R3 microcontroller was employed to automatically acquire the temperature and voltage drop across the diode. T–V data were plotted, and then the slope and intercept were used to calculate the energy gap by a simplified diode equation. In this system, the temperature and voltage of the two diodes were measured simultaneously at different constant bias currents in the range of 10 μA–10 mA. The average E g value of 1.22 eV obtained in this work is in good agreement with that reported in the literature.

Optoelectronic reciprocity in hot carrier solar cells with ideal energy selective contacts

AbstractHot carrier solar cells promise theoretical power conversion efficiencies far beyond the single junction limit. However, practical implementations of hot carrier solar cells have lagged far behind those theoretical predictions. Reciprocity relations for electroluminescence from conventional single junction solar cells have been extremely helpful in driving their efficiency ever closer to the theoretical limits. In this work, we discuss how the signatures of a functioning hot carrier device should manifest experimentally when driven in reverse, that is, in electroluminescent mode. Hot carrier properties lead to deviations of the dark I–V from the Shockley diode equation that is typical for conventional single junction solar cells. These deviations are directly linked to an increase in temperature of the carriers and therefore the temperature measured from electroluminescence spectra. We also elucidate how the behaviour of hot carrier solar cells in the dark depends on whether Auger processes play a significant role, revealing a stark contrast between the regime of negligible Auger recombination (carrier conservation model) and dominant Auger recombination (impact ionisation model) for hot carrier solar cells.

Modelling effect of temperature and irradiance changes of Assa, Morocco on photovoltaic modules’ performance

A mathematical representation of a photovoltaic (PV) solar cell and module performances is demonstrated in this paper. One diode based on the Shockley diode equation model is adopted for simulation and extract the performance indications. The simulated solar module is a particular 235W solar module operating in an existing 806.52 kWp grid connected photovoltaic power plant located at Assa, southern Morocco. The model demonstrates power-voltage (P-V) and current-voltage (I-V) characteristic curves with weather conditions changes. These external conditions include temperature and solar irradiance level (represented by sun unit 1sun=1000w/m2) which greatly affect the performance of the PV system. This paper also presents PV simulation with a maximum power point tracking (MPPT) converter and the general model was implemented in Matlab/Simulink software and used as an example verifying the performance of the tested module under Assa city weather variable.

R/G/B Micro-LEDs for In-Pixel Integrated Arrays and Temperature Sensing

In this paper, we demonstrate that nitride-based R/G/B micro-LEDs allow temperature sensing through a forward voltage response on both temperature and display devices. In temperature sensing, micro-LEDs operate in current constant mode, exhibiting an excellent performance with a sensitivity of 2.6/2.7/2.2 mV/K for blue/green InGaN micro-LEDs and red AlGaInP micro-LED under an injection current density of 1 mA/cm2, which is about two times lower sensitivity than the sensitivity limit obtained from the Shockley ideal diode equation. It is speculated that the lower sensitivity originated from parasitic resistances. It is also found that the band gaps of ternary InGaN and quaternary AlGaInP obtained from temperature-dependent electroluminescence spectra of red micro-LED agrees with the calculated values by using the semiempirical Varshni relationship. The EL of micro-LEDs is characterized by narrow emission widths of 18–41 nm, leading to wide color gamut covering up to 170/97% of the DCI P3/BT 2020, which are the standard color space of ultrahigh definition television system.