Organic and inorganic solar cells parameters evaluation from single I– V plot

Extracting dc parameters of solar cells under illumination

A C++-based automatic executable program is implemented and provided in this article to integrate the current minus the short-circuit current, using the 3/8 integration rule, to compute the Co-Content function. The shunt ( Rsh ) and series resistance ( Rs ), photo ( Iph ) and saturation current ( Isat ), and ideality factor ( n ) (within the one-diode solar cell model) are then automatically calculated by the program, together with their standard deviations. When it is applied to simulated current voltage ( IV ) curves, the five solar cell parameters are extracted with less than 1% error, using only 26 points and in less than 1 s, in the case of noiseless IV curves, while in the case of 0.1% noise of the maximum current, less than 1% error is achieved with 51 points, and also in less than 1 s. The program is applied to measured IV curves in a commercial solar cell, and compared with the usual trapezoidal integration method and another method. All the solar cell parameters are reasonably extracted in under one second, whereas other techniques require at least 7 min.

Solar cell/module modeling involves the formulation of the non-linear current versus voltage (I-V) curve. Determination of parameters plays an important role in solar cell/module modeling. This paper presents an application of the improved PSO search method and Particle Swarm Optimization technique for identifying the unknown parameters of solar cell and photovoltaic module models, namely, the series resistance, shunt resistance, generated photocurrent, saturation current, and ideality factor that govern the current-voltage relationship of a solar cell/module. For the confirmation of accuracy of the proposed method, a measurement data of 57 mm diameter commercial (R.T.C. France) silicon solar cell and a module consisting of 36 polycrystalline silicon cells (Photowatt-PWP 201) has been selected and the best optimal value of each parameter has been obtained using Improved PSO. Comparative study among different parameter estimation techniques is presented to demonstrate to verify the accurateness and the effectiveness of the proposed approach.

Determination of the Intrinsic Diode Parameters of Polymer Solar Cells

With the increase in installed solar energy capacity, comparison and analysis of the physical property values of solar cells are becoming increasingly important for production. Therefore, research on determining the physical characteristic values of solar cells is being actively pursued. In this study, a diode equation, which is commonly used to describe the I-V behavior and determine the electrical characteristic values of solar cells, was applied. Using this method, it is possible to determine the diode ideality factor (n) and series resistance (Rs) based on light I-V measurements. Thus, using a commercial screen-printed solar cell and an interdigitated back-contact solar cell, we determined the ideality factor (n) and series resistance (Rs) with a modified diode equation method for the light I-V curves. We also used the sun-shade method to determine the ideality factor (n) and series resistance (Rs) of the samples. The values determined using the two methods were similar. However, given the error in the sun-shade method, the diode equation is considered more useful than the sun-shade method for analyzing the electrical characteristics because it determines the ideality factor (n) and series resistance (Rs) based on the light I-V curves.

Herein, the electrical conductivity of poly(3,4‐ethylenedioxythiophene)–poly(styrenesulfonate) (PEDOT:PSS) polymer is improved by adding dimethyl sulfoxide (DMSO) and electrical characterization of the obtained Schottky diode and organic solar cell (OSC) devices are performed from I–V measurements under the light and dark conditions. The scanning electron microscope images of the poly(3‐hexylthiophene):[6,6]‐phenylC61‐butyric acid methylester active layer and PEDOT:PSS layer are obtained. The series resistance (Rs), barrier height (Фb), and ideality factor (n) parameters are obtained from different techniques as a function of light and dark conditions. Furthermore, photovoltaic parameters are calculated for n‐Si/PEDOT:PSS/Au device without DMSO doping and with DMSO doping as a parameter of the light condition and the interface state densities of these devices are obtained for light and dark conditions. DMSO organic solvent improves the short‐circuit current density (Isc), power convert efficiency (or η), open circuit‐voltage (Voc), shunt resistance (Rsh), and series resistance (Rs) values of OSCs. In summary, DMSO solvent rearranges the conductive of PEDOT:PSS, decreases the work function of this conductive polymer (≈5 eV), decreases energy loss in the charge transportation, and increases photovoltaic parameters of Schottky barrier diode and OSC devices.

Hydrogen energy is expected to contribute to a decarbonized society because it does not emit CO2 during combustion. In particular, CO2 emissions from hydrogen production can also be prevented by utilizing renewable energy such as solar light and wind power. As water electrolysis is one of major hydrogen production methods, combination of water electrolysis and solar cell can make hydrogen production without CO2 emission. However, single solar cells usually have not enough voltage to electrolyze water. Therefore, modularization of several solar cell units is needed to electrolyze water to hydrogen. We have fabricated organic thin-film solar cells using organic materials in the photoelectric conversion layer and have aimed to achieve highly efficient conversion of light energy to hydrogen energy through water electrolysis using these cells. In this study, we fabricated solar cell modules for water electrolysis using two donor polymers, P3HT and PBDB-T and fullerene derivative, PC61BM and two non-fullerene acceptors, ITIC and IT-4F. The solar cell architecture consisted of indium tin oxide (ITO) cathode/ZnO/photoactive layer/MoO3/Ag anode. ZnO was deposited by sol-gel method, polymer donor:fullerene or non-fullerene acceptor by spin coating method, and MoO3 and Ag by vacuum deposition method. First, three types of solar cells composed of A fullerene-based P3HT:PC61BM, non-fullerene-based PBDB-T:IT-4F and PBDB-T:ITIC were fabricated, and their performance was evaluated using a solar simulator. The short-circuit current density (Jsc) and open-circuit voltage (Voc) were increased by changing to the non-fullerene system, indicating that the non-fullerene system has longer wavelength absorption and larger energy gap between HOMO of donor polymer and LUMO of acceptor, respectively. In addition, the PBDB-T:ITIC system was expected to reduce the number of series solar cell units in the module for water electrolysis because Voc was higher than that of the PBDB-T:IT-4F system. The photovoltaic performance of the PBDB-T:ITIC system was then evaluated by changing film thickness in the PBDB-T:ITIC solar cell. Jsc reached its maximum at the film thickness indicating absorbance of 0.73 at 637 nm, while Voc did not depend on film thickness, and the fill factor (FF) decreased with increasing film thickness. As a result, the power conversion efficiency (PCE) was achieved to be 6.75%. Currently, the maximum output voltage (Vmax) is 0.63 V. Therefore, it was found that a module with three single solar cell units connected in series on the same substrate was required in order to achieve above the voltage of 1.23 V, which is thermodynamically necessary for water electrolysis.3-cell series module with an area of 1.16 cm2 per cell were fabricated and their performance was evaluated. As a result, ideally, a 3-cell series module would have similar Jsc to that of a single solar cell, and Voc becomes about 3 times that of a single solar cell. However, the 3-cell series module has a particularly low FF of 0.40 compared to 0.48 for the single solar cell, resulting in decrease in PCE to 4.38%. To investigate the effect of cell area, single-cell solar cells with 1.16 and 0.126 cm2 were then fabricated and evaluated for performance. Jsc and Voc are comparable whereas FF is 0.57 for the small area, while it is lower at 0.48 for the large one. This indicates that an increase in area leads to an increase in series resistance and a decrease in FF. In addition, to investigate the effect of module structure, we evaluated the performance of 3 single solar cells with a cell area of 1.16 cm2 connected in series and parallel by crocodile clip. As a result, a large decrease in FF was observed for both connections, suggesting that crosstalk happened, caused by that ZnO, the electron transport layer was uniformly coated on the substrate. We will examine whether the performance of single solar cells can be maintained by changing the module structure.

Since their inception, organic solar cells have been a cynosure of photovoltaic (PV) community, owing to their simplicity, affordability and mass-production capabilities. Research on organic solar cells has been propelled by advances in nanotechnology, polymer synthesis, and semiconductor processing; efforts to achieve high power conversion efficiencies (PCE) through refined device geometry, tailored synthesis and/or combination of new low-bandgap materials, and heuristic process optimization have fructified as ~10 % efficiency in single-junction organic solar cells. Recent PCE enhancement in organic solar cells has mostly attributed to the development of small bandgap materials that extend absorption of the sun into the red and infrared wavelengths.Utilizing tandem cells comprised of both large and small bandgap sub-cells enables light harvesting of different parts of the solar spectrum to be separately optimized, yielding higher PCE than single junction solar cells. But the challenges in achieving highly efficient organic tandem solar cells include optimal combination of materials for each sub-cell and interconnecting layers between sub-cells that are process compatible. Optimal combination of materials can be achieved by selection of two materials having complementary absorption windows. The interconnecting layer provides electrical and optical coupling between the two sub-cells and plays a key role in the performance of tandem cells. For the design of the interconnecting layer, electrical, optical, chemical and structural characteristics should be considered. Ideally, it should effectively facilitate charge transport between two sub-cells. Moreover, high transmittance and negligible absorption in the spectral region where two sub-cells absorb is desirable. Last but not least, the interconnecting layer should be designed to survive the subsequent solution coating and provide conformal surface coating for tandem cells with solution processed top cells. Here we evaluate some of candidate metal oxides for tunnel junction layers for organic tandem solar cells. Metal oxides are grown by Atomic Layer Deposition (ALD) for thin defect-free conformal layer to circumvent miscibility issues and negligible absorption. Normal and inverted interfaces are examined. The influence of annealing under different conditions and methods will be presented. Tunneling properties are qualified by J-V characteristics and optical properties evaluated by UV-Vis are contrasted to suggest optimal design tradeoffs of tunnel junctions for solution processed organic tandem solar cells.

It is known that compound parabolic concentrators (CPCs) can improve electrical performance of a photovoltaic (PV) flat-plate system. However, a lumped electrical model of a PV cell/module with CPC for assessing performance under different operating conditions is unavailable. In this paper, a six-parameter based model is developed and applied to a PV cell, two PV models with CPC, and a PV module with 2D asymmetric CPC (trough). For validation, CPC with a single PV cell and two CPC modules with 2×2 and 9×9 PV cells are fabricated and measured in an indoor laboratory under standard test conditions. Results show that the optimised algorithm precisely predicts the six model parameters. A sensitivity analysis is performed to identify the importance of each parameter in the model. Ideality factor, circuit current and reverse saturation current are found to be the most dominant factor, while shunt resistance is the least important with CPC gain coefficient and series resistance are in between. Transient performance of a PV cell with CPC under variable outdoor climate conditions is also examined by coupling optical, thermal and electrical effects.

The value and temperature dependence of the ideality factor provides essential information about the dominant recombination route in solar cells. This study presents experimental results of accurate ideality factor determination for representative organic photovoltaic cells (OPV) evaluated at different temperatures over a large current density regime. It is noted that standard dark I–V curves strongly deviate from those obtained by evaluations based on short circuit current density (J SC)–open circuit voltage (V OC) pairs. This is attributed to the applied external voltage in a dark I–V measurement not being representative of internal chemical potential, particularly at lower temperatures. Complementary electroluminescence measurements attest that the current density dependence of the ability of the solar cell to emit light is better correlated to the series resistance free ideality factor. For the studied set of OPV devices it is observed that the ideality factors are quite low, and with very weak temperature dependence. The J SC–V OC method to determine ideality factors further allows good estimates of activation energies as well as recombination current prefactors J 00. The findings imply that the principal OPV non‐radiative recombination mechanism is not recombination of free carriers with trapped carriers in an exponential density of tail states as previously reported.

Recent advances in polymer and perovskite based third-generation solar cell devices

\(\hbox {In/ZnIn}_{2}\hbox {Te}_{4}/\hbox {n-Si/Ag}\) diode structure was fabricated by the thermal deposition of a \(\hbox {ZnIn}_{2}\hbox {Te}_{4}\) thin film on n-Si wafer substrate with Ag metal back contact. The structural characteristics of the film were investigated in terms of composition, X-ray diffraction and topographic measurements. The diode structure was completed by evaporating In metal on the film surface as a top contact. The diode parameters as saturation current, barrier height, ideality factor and series resistance values were determined from the semi-logarithmic forward bias current–voltage characteristics of the diode. According to the assumption of the thermionic emission model, the ideality factor was found higher than unity and it was also observed that the barrier height and ideality factor showed a temperature-dependent profile resulting from the non-ideality in the current–voltage behaviour of the diode. As a result, the model was modified by considering inhomogeneous barrier formation and Gaussian distribution was expected to be dominant on 1.37 eV mean barrier height with a deviation of 0.18. In addition, the voltage dependence of these Gaussian diode parameters was investigated. The forward and reverse bias capacitance and conductance measurements showed that there was a slight change in capacitance values with frequency whereas the conductance values decreased with increase in frequency. In addition to the current–voltage analysis, the distribution of density of interface states and the values of series resistance were evaluated as a function of bias voltage and frequency.

Parameter estimation of solar cells and modules using an improved adaptive differential evolution algorithm

A life cycle assessment case study involving organic photovoltaic technology using phenyl‐C61‐butyric acid methyl ester and poly(3‐hexylthiophene) is presented. Although solar technology converts freely available solar radiation into more useful forms of energy, potential environmental impacts can occur during the life cycle of the product. A cradle‐to‐gate life cycle assessment is completed, comparing organic solar cells with traditional silicon‐based cells across 18 multiple criteria. The functional unit is defined as the production of 1 watt‐peak of electricity produced. The inventory is based on prospective organic solar cell technology and two traditional silicon technologies. The results demonstrate that from a life cycle perspective, organic solar cells can outperform conventional silicon solar cells with impacts reduced by 93%. The energy payback time for the default organic photovoltaic cell was 0.21 years (75 days) compared with multicrystalline silicon and amorphous silicon's 2.7 and 2.2 years, respectively. The minimum required lifetime of the organic cells, so that their impacts were no worse than amorphous silicon's over 25 years, was measured between 1.2 and 8.9 years. Results of the sensitivity analysis demonstrate that consideration of manufacturing routes (e.g., fullerene or solar cell production) can be targeted using life cycle assessment for further improvements in the environmental, human health, and ecotoxicity profile of organic solar cells. Copyright © 2015 John Wiley & Sons, Ltd.

This paper presents Simulated Annealing based approach to estimate solar cell model parameters. Single diode solar cell model is used in this study to validate the proposed approach outcomes. The developed technique is used to estimate different model parameters such as generated photocurrent, saturation current, series resistance, shunt resistance, and ideality factor that govern the current-voltage relationship of a solar cell. A practical case study is used to test and verify the consistency of accurately estimating various parameters of single diode solar cell model. Comparative study among different parameter estimation techniques is presented to show the effectiveness of the developed approach.