Current-voltage Characteristics Of Solar Cells Research Articles

Fluorinated polymer additives in Spiro-OMeTAD to improve the efficiency and stability of perovskite solar cells

This study demonstrates the transformative impact of incorporating poly(vinylidene fluoride-co-trifluoroethylene) P(VDF-TRFE) as an additive in the hole transport layer (HTL) of 2,2′,7,7′-Tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (Spiro-OMeTAD). The P(VDF-TRFE) additive forms resilient coordination bonds with 4-tert-butylpyridine (TBP) and lithium bis(trifluoromethanesulfonyl)imide additives, which mitigates TBP evaporation and improves Spiro-OMeTAD film quality. In addition, we observed improvements in solar cell current–voltage characteristics consistent with increased Spiro-OMeTAD conductivity and suppressed non-radiative recombination at the HTL/perovskite interface. P(VDF-TRFE)-integrated devices exhibit an increment in power conversion efficiency (PCE) up to 24.1 % (reverse scan) from a reference PCE of 21.4 %. Furthermore, the unencapsulated P(VDF-TRFE)-integrated devices demonstrate improved stability, retaining over 90 % PCE after 45 days in an ambient atmosphere in the dark and 94 % PCE after 1080 h of continuous light-soaking in a nitrogen environment. This work demonstrates how additive engineering, as exemplified by P(VDF-TRFE), can effectively address stability and performance challenges within Spiro-OMeTAD in perovskite solar cells.

Experimental approval of the working modes of the Sunbrick sun simulator

Commissioning and experimental testing of technical capabilities and modes of operation were carried out, and test measurements of light current-voltage characteristics of solar cells were carried out using a modern measuring complex based on the Sunbrick sun simulator. Automated measurement of the light-voltage-current characteristics of solar cells by the compensation method using the Keithley 2400 measuring device was implemented. During the approbation of the measuring complex based on the Sunbrick sun simulator, the possibility of reproducing different modes of simulator operation was tested and the ability to control radiation in terms of energy in the range from 100 to 1100 W/m2 and by spectral composition. It was established that the spatial unevenness of illumination for the investigated device is less than 2 % with an illumination area of more than 400 cm2. It is shown that the tested measuring complex allows for automated research of solar cells in irradiation regimes corresponding to both terrestrial irradiation conditions and extraatmospheric solar radiation conditions. The possibility of individual adjustment of each of the 36 channels of the emitting element in the range from 400 to 1100 nm has been tested, which adds flexibility in the use of the Sunbrick sun simulator during the study of both solar cells as a whole and the properties of functional semiconductor materials by irradiation with monochromatic or mixed illumination. It is shown that due to the rapidity of conducting research and the ability to immediately visualize the measured current-voltage characteristic on the computer screen, it is possible to significantly speed up the process of researching solar cells. Thus, it is possible to immediately divide the investigated solar cells into groups in relation to their efficiency and determine the presence of possible defects or damage in their structure.

Direct correlation between the built-in potential and the power conversion efficiency of NFA organic solar cells

While it is known that too low built-in potential is detrimental to cells' performance, there is no consensus regarding the importance of maximizing the internal electric field or the built-in potential for achieving the highest power conversion efficiency of non-fullerene acceptor (NFA) organic solar cells. We use one of the prototypical NFA bulk heterojunction solar cells to show a direct correlation between the built-in potential, the open circuit voltage, the fill factor, and the device's efficiency. This is achieved using statistical analysis of devices made of two different cathodes (Ag, Mg) and a simple, intuitive model for the solar cell's current–voltage characteristics. Designing device structures with enhanced built-in potential (internal electric field) is crucial for surpassing the 20% efficiency limit.

Real-time measurement of the current–voltage characteristics of a solar cell for laboratory experiment

The sensors and data acquisition universal interface provide more powerful choices for experimental teaching. In this paper, we introduce a teaching experimental setup that uses current and voltage sensors combined with universal interface to realize real-time automatic measurement of solar cell current–voltage characteristics. The current–voltage (I–V) and power–voltage (P–V) curves at various distances from the light source can be easy and fast obtained. At the same time, the effect of temperature on the electrical performance of photovoltaic modules can also be directly demonstrated using the cooling fan. Compared with the data read by ammeter and voltmeter, the experimental setup we built can enable students to obtain data faster under the same experimental conditions. We suggest that the real time I–V and P–V curves can help students experiment with the output characteristics of solar cells directly and allow them to relate electrical concepts such as short-circuit current, open-circuit voltage and maximum output power to the operation of the solar cells.

Explicit three-piece quadratic model for accurate analytic representation of S-shaped solar cell current–voltage characteristics

Some interest has been recently directed towards analytic mathematical models for reproducing the current–voltage (I–V) characteristics of solar cells, mainly due to their convenient property of expressing current as an explicit function of voltage (which is not true for the traditional one-diode model). However, as is the case with the one-diode model itself, existing analytic models do not yield a good fit in the case of S-shaped I–V characteristics. In this brief paper, an analytic explicit model based on a three-piece quadratic curve is proposed that surpasses such difficulty and enables accurate representation of S-shaped curves. To evaluate the proposed model, validation was carried out against three empirical solar cell I–V characteristics. In all cases, simulation results show that the proposed approach is more accurate than other closed-form models in the literature.

External Gettering of Metallic Impurities by Black Silicon Layer

Black silicon (b‐Si) has many attractive properties and is currently being adopted in various fields of semiconductor technology. It is shown here that b‐Si during thermal activation may serve as an external gettering layer to remove metallic impurities and associated defects from bulk Si. The gettering efficiency by b‐Si is estimated according to the results of studying the resistivity, defect density, interstitial iron concentration, and effective minority carrier lifetime on gettered test and ungettered reference Si samples. It is shown that in the thermal oxidation process, the b‐Si layer serves as an effective drain for excess iron atoms and other fast‐diffusing impurities, thereby significantly reducing the density of oxidation‐induced stacking faults in Si. In addition, the resistivity of the substrates decreases, and the bulk carrier lifetime increases significantly. Finally, gettering by b‐Si is introduced into the solar cells fabrication process and its effect on solar cell current–voltage characteristics is investigated. It has been shown that all electronic parameters of the solar cells are improved. The conversion efficiency of ungettered solar cells is 16.8%, and for gettered solar cells, depending on the oxidation temperature, it increases by 1.36–1.96%.

The impact of SnO2 photoelectrode’s thickness on photovoltaic properties of the solar cell FTO:SnO2:PTB7-TH:ITIC/Mo/Ag

The paper reports the results of a study of the morphological, optical and electrophysical parameters of SnO2 films. SnO2 films are applied by spin-coating at different revolutions of the centrifuge. The topography of the surface and the thickness of the SnO2 films are studied using an atomic force microscope. The current-voltage characteristics of solar cells are measured. The optical properties with different thicknesses of SnO2 films are also investigated. It is shown that an increase in the rotation speed of the substrate leads to a decrease in the surface roughness of the SnO2 films. It is found that changes in the morphology of SnO2 films contribute to the rapid transport of injected holes to the external electrode and reduce the probability of reverse recombination. Cells with an electron transport layer of SnO2 at 2000 revolutions showed a low efficiency of 0.17%. With a decrease in the thickness of the SnO2 films to a value of 62 nm, there is an increase in the value of the short-circuit current by 2.3 times and a change in the no-load voltage by 1.12 times.

Photovoltaic characteristics of structures with porous silicon obtained by various technological plans

In this work, the influence of technological parameters on the current-voltage characteristics of solar cells with porous silicon is investigated. It is shown that for photosensitive structures with a porous layer, the optimal mode is pore formation by electrochemical etching followed by diffusion. The effect of etching modes affects the character of the photosensitivity curve.

Perovskite and Organic Solar Cells on a Rocket Flight

Summary Perovskite and organic solar cells possess a revolutionary potential for space applications. The thin-film solar cells can be processed onto thin polymer foils that enable an exceptional specific power, i.e., obtainable electric power per mass, being superior to their inorganic counterparts. However, research toward space applications was mainly restricted to terrestrial conditions so far. Here, we report the launch of perovskite and organic solar cells of different architectures on a suborbital rocket flight. This is an in situ demonstration of their functionality and power generation under space conditions. We measured solar cell current-voltage characteristics in variable illumination states due to different rocket orientations during flight. Under strong solar irradiance, the solar cells perform efficiently, and they even produce power with weak diffuse light reflected from Earth’s surface. These results highlight both the suitability for near-Earth applications as well as the potential for deep-space missions for these innovative technologies.

Interfacing Low‐Temperature Atomic Layer Deposited TiO2 Electron Transport Layers with Metal Electrodes

AbstractLow‐temperature atomic layer deposited (ALD) TiO2 is an electron transport layer that is relatively unreactive with mixed halide perovskite semiconductors. This amorphous, ALD‐grown metal oxide is typically interposed between the perovskite layer and a low work function metal electrode, prompting interest in the electronic and chemical structure of the resulting TiO2/metal interface. Here, the interfaces between TiO2 and two common metal low work function electrodes, polycrystalline thin films of silver and aluminum are studied. It is found that a Schottky barrier forms between Ag and low‐temperature ALD‐grown TiO2, consistent with the observed solar cell current–voltage characteristics, and confirmed by in situ measurement of Ag deposition‐induced core level shifts in X‐ray photoelectron spectra and barrier height extraction from temperature‐dependent current–voltage data. On the other hand, Al reacts chemically with the surface of TiO2 during its deposition. The resulting interface acts as an Ohmic contact, due to the apparent oxygen vacancy doping of the underlying ALD‐TiO2. These findings provide lessons for metal electrode selection in future halide perovskite device structures.

CURRENT-VOLTAGE CHARACTERISTICS OF SOLAR CELLS p-n JUNCTION ZnO AND TiO2 PARAREL ON Cu2O LAYER

Current-Voltage Characteristics of solar cells p-n junction ZnO and TiO<sub>2</sub> parallel in the Cu<sub>2</sub>O layer has been determined using solar irradiation. Metal oxide has been used as a semiconductor material, such as ZnO and TiO<sub>2</sub> is an n-type semiconductor. The material has a gap energy of 3.37 eV and 3.2 eV. Thermal oxidation is applied to commercial Cu plates for 60 minutes to produce Cu<sub>2</sub>O layers as p-type semiconductors. The process varies in temperature, namely 300, 400, and 500 °C. The process of thermal oxidation on Cu plates at a temperature of 300 °C increases the impurity in the Cu<sub>2</sub>O layer. The impurity layer is CuO. Then the CuO layer formed decreases with increasing temperature thermal oxidation. CuO layer increases the efficiency of solar cells p-n junction TiO<sub>2</sub>-ZnO parallel in the layer Cu<sub>2</sub>O. The results of measurements with sunlight showed that the TiO<sub>2</sub>-ZnO/Cu<sub>2</sub>O (300) samples had the highest solar cell efficiency, which was 0.28 %.

Laser Application in Photovoltaics for Surface Texturization of Silicon and Front Electrode Deposition

Abstract The laser technology in the manufacturing of solar cells has become an indispensable element of modern photovoltaic technology. The main reason for taking up such research is because conventional methods used for monocrystalline silicon texturization are ineffective when applied to polycrystalline silicon texturing. This is related to random distribution of grains of different crystalographic orientations on the surface of polycrystalline silicon. Texturing a polycrystalline silicon surface using an Nd:YAG laser makes it possible to increase absorption of the incident solar radiation. The additional technological operation of etching in potassium hydroxide solution introduced into the technology of the photovoltaic cells manufactured from laser-textured wafers allows for improvement in electrical performance compared with cells produced from nontextured wafers. Moreover, this article presents the influence of selective laser sintering of front metallization that was manufactured using paste based on silver nanopowder on contact resistant. The electrodes were formed on monocrystalline silicon solar cells. The microstructures of laser-textured silicon and sintered front metallization were investigated by scanning electron microscope and confocal laser scanning microscope. The reflectance of produced textures was measured by spectrophotometer with an integrating sphere. Current-voltage characteristics of solar cells manufactured from laser-textured polycrystalline silicon wafer were measured under standard AM 1.5 radiation. The contact resistance between the metal and semiconductor was investigated using the transmission line model.

Легкий гибкий солнечный элемент на основе гетероэпитаксиальной структуры InGaP/GaAs

The article considers the problems of formation the light flexible III–V compounds-based solar cell. Approaches of the problems solves were proposed. Was fabricated the light flexible solar cell based on the InGaP/GaAs heteroepitaxial structure. The solar cell weight and size characteristics have been determinate. The solar cell specific weight was 0.51 kg / m2.The bending tests showed that the minimum bending radius of the solar cell is 36 mm. The solar cell current-voltage characteristics were measured for AM0 and AM1.5D spectrum at 28.6°C и 25°C respectively. The efficiency was 23.1% for AM0 and 28.32% for AM1.5D.

Temperature Coefficient Imaging for Silicon Solar Cells

As a usual procedure, silicon solar cells are characterized in test laboratories at standard testing conditions (STC) and are also optimized for these. However, as the cells’ performance parameters are dependent on temperature, which differs in real operation conditions to STC, extended characterization of solar cell current–voltage characteristics is necessary to calculate annual yields. In this paper, we study the temperature sensitivity of three multicrystalline silicon solar cells with different cell concepts and bulk material qualities but similar performance at STC. It is shown that at least for multicrystalline silicon solar cells the temperature sensitivity can only be understood by using spatially resolved characterization techniques. We apply temperature-dependent and spectrally resolved measurement techniques such as light-beam induced current, photoluminescence imaging, as well as quasi steady-state photoluminescence. Cell areas with high concentration of impurities show increased temperature sensitivity, especially of the open-circuit voltage $V_{{\text{OC}}}$ and the lifetime of excess charge carriers τ . Results gathered by averaging the spatially resolved measurements are in good agreement with global values which confirms the applicability of our approach. Our proposed method improves understanding of the influence of temperature on parameters of cell operation and enables a detailed analysis especially of multicrystalline silicon solar cells.

Experimental investigation of tensile mechanical strain influence on the dark current of organic solar cells

Abstract In this paper we have experimentally studied the electrical behavior of organic solar cells (OSCs) under mechanical strain in dark condition. Dark current-voltage characteristics of solar cells provide valuable information on the defect states inside the device. The samples under tests here are two commercial polymeric solar cells with different electrode types. So, instead of studying merely the dark current changes of the solar cells versus strain, the electrodes effects due to the applied strain are compared at different environment temperatures. The most important electrical parameters of the strained cells are extracted as a function of the strain at different temperatures for two conditions: when the cells are under strain and when they are relaxed for 3 min after applying the strain. The only parameter that shows a considerable meaningful change by strain is the series resistance. The final results confirm that the cell with silver electrodes, shows a current increase by tensile strain due to the polymeric chains alignment along the strain direction. But the cell with carbon electrodes experiences a current decrement by increasing the strain. We believe that the carbon electrode, due to the larger carbon Young's modulus, in comparison with the silver electrode cells creates more defect states in the flexible polymeric cells under the same amount of the applied strain. Furthermore, the cell with softer and more stretchable silver grid electrodes can withstand a higher level of strain before suffering any permanent damage.

Metal Halide Perovskites as Mixed Electronic-Ionic Conductors: Challenges and Opportunities-From Hysteresis to Memristivity.

Metal halide perovskites are promising candidates for many classes of different optoelectronic devices. Apart from being a semiconductor, they additionally show ionic conductivity. It expresses itself in slow response times, reversible degradation, and hysteresis in the current-voltage characteristics of solar cells. This Perspective gives a condensed overview about experiments and theory on ion migration in metal halide perovskites focusing on its effects in solar cells. Apart from being a potential stability concern for photovoltaics, ion migration paired with the excellent optoelectronic properties of this material offers opportunities for novel devices such as optically controlled memristors and switchable diodes.

Impact of Contacting Geometries When Measuring Fill Factors of Solar Cell Current–Voltage Characteristics

We analyze the influence of a variety of different contacting geometries on the fill factor (FF) of solar cell I–V measurements. For this analysis, we compare a wide variety of modeled and measured FFs of Si solar cells. We consistently find large FF differences between individual contacting geometries. These differences amount to up to 3 ${\%_{{\rm abs}}}$ for high busbar resistivities of up to 40 $\Omega/\hbox{m}$ . We analyze the contacting geometries for their sensitivity on uncontrolled variations of the contacting resistances. In this analysis, we find that using triplet rather than tandem configurations and using a larger number of test probes reduces the impact of varying contacting resistances to below 0.02 ${\%_{{\rm abs}}}$ . We propose a contacting geometry that we consider to be suitable for calibrated I–V measurements. This contacting scheme is a configuration with a total of five triplets consisting of two current probes and one sense probe. The sense probe is positioned to measure the average busbar potential between the current probes. This is the optimal contacting geometry in terms of a low sensitivity to the busbar resistivity and variations of contacting resistances. In addition, this geometry does not impose unnecessarily large mechanical stress to the cell under measurement.

Research of the bench means for measuring current-voltage characteristics of solar cells and batteries

The methods and means to control of the current-voltage characteristics of solar batteries are considered. The construction of industrial solar radiation simulators and automated control system for current-voltage characteristics of solar batteries is described. It is revealed that they are used exclusively in the production of solar batteries, and there are no appropriate means for their control directly at operation location

Magnetron Sputtered Molybdenum Oxide for Application in Polymers Solar Cells

Thin films of molybdenum oxide were deposited by radio frequency (RF) magnetron sputtering in Ar from a MoO3 target at different deposition power on glass and silicon substrates. The thickness of the films was determined by profilometer measurements and by ellipsometry. The films were annealed in air at temperatures between 200 and 400°C in air. The optical transmission and reflection spectra were measured. The conductivity of the as deposited and annealed films was determined. The crystal structure was probed by Raman spectroscopy. The oxidation state of the surface was studied by X-ray photoelectron spectroscopy (XPS) spectroscopy. The deposition technique described above was used to experiment with MoOx as a hole transport layer (HTL) in polymer solar cells with bulk hetrojunction active layer, deposited by spin coating. The performance of these layers was compared with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), which is the standard material used in this role. The measured current-voltage characteristics of solar cells with the structure glass/ITO/HTL/Poly(3-hexyl)thiophene (P3HT):[6,6]-phenyl-C61- butyric acid methyl ester (PCBM)/Al demonstrate that the studied MoOx layer is a good HTL and leads to comparable characteristics to those with PEDOT:PSS. On the other hand the deposition by magnetron sputtering guarantees reliable and repeatable HTLs.

Performance Loss in Solar Photovoltaic Array due to Non-ideal Natural Conditions

Performance of a SPV system is dependent on temperature, array configuration, solar insolation, and shading across it. Shading can occur when the PV arrays/modules get covered by shadows of passing clouds, buildings, etc., or even by shadows cast by other modules/arrays. As a result the ideal operation of the PV systems is severely affected the P-V and I-V characteristics. The modeling of nonlinear current-voltage characteristics of solar cells for performance prediction becomes difficult under the influence of shading. Non-uniform solar radiation due to shadows casted by the other panels/ modules, buildings, clouds, etc. can cause maximum power to change drastically. Partial shading of PV installations has an impact on its power production. For the simulated results it has been observed that 74.66% loss in I-V characteristics and 85.41% loss in P-V characteristics respectively. The power losses in the individual shaded cells would result in local heating and create thermal stress on the entire module/array resulting in hot-spot formation.