Voltage Of Solar Cells Research Articles

A proposal of a procedure to estimate a standard line for contactless estimation of a solar cell voltage in a module using modulated light

AbstractIt is important to measure the operating voltage of a cell sealed in a photovoltaic module as well as well‐known faults such as abnormal hot spots observed by thermography or a dark part in electroluminescence distribution on the module for detecting a fault module. This paper proposes a method that radiating modulated light toward a cell and extracting the synchronized signal from the module output by phase detector can estimate the operating voltage quantitatively by using a standard line predicted by shading the module partially.

Improving the Open-Circuit Voltage of Sn-Based Perovskite Solar Cells by Band Alignment at the Electron Transport Layer/Perovskite Layer Interface.

Organic-inorganic lead halide perovskites are promising materials for realization of low-cost and high-efficiency solar cells. Because of the toxicity of lead, Sn-based perovskite materials have been developed as alternatives to enable fabrication of Pb-free perovskite solar cells. However, the solar cell performance of Sn-based perovskite solar cells (Sn-PSCs) remains poor because of their large open-circuit voltage (VOC) loss. Sn-based perovskite materials have lower electron affinities than Pb-based perovskite materials, which result in larger conduction band offset (CBO) values at the interface between the Sn-based perovskite and a conventional electron transport layer (ETL) material such as TiO2. Herein, the relationship between the VOC and the CBO in these devices was studied to improve the solar cell performances of Sn-PSCs. It was found that the band offset at the ETL/perovskite layer interface affects the VOC of the Sn-PSCs significantly but does not affect that of the Pb-PSCs because the Sn-based perovskite material is a p-type semiconductor, unlike the Pb-based perovskite. It was also found that Nb2O5 has the CBO that is closest to zero for Sn-based perovskite materials, and the VOC values of Sn-PSCs that use Nb2O5 as their ETL are higher than those of Sn-PSCs using TiO2 or SnO2 ETLs. This study indicates that control of the energy alignment at the ETL/perovskite layer interface is an important factor in improving the VOC values of Sn-PSCs.

English Effect of Activated Variations Carbon from Oil Palm Empty Fruit Bunch to Solar Cell Efficiency p-n Junction Layer Cu2O-TiO2.

Research about influence effect of activated activated carbon from oil palm empty fruit bunch to solar cell efficiency p-n junction layer Cu2O-TiO2 and direct of sunlight. The layer of Cu2O formed from copper (Cu) burned with temperature 550 ͦ C in 100 minutes. The solar cells are made with TiO2 layer composed of activated carbon from oil palm empty fruit bunch of 0%, 10%, 15%, dan 20%. The parameters of the solar cell can be obtained by measuring the short circuit (Isc), voltage open circuit (Voc), maximum power and Fill Factor (FF) with resitor value (R) 0-50 kΩ. The composed of TiO2 /activated carbon from oil palm empty fruit bunch analyzed using X-Ray Diffraction (XRD) and and Fourier Transform Infrared (FTIR) Spectrocopy. As a result addition of activated carbon from oil palm empty fruit bunch to solar cell efficiency is increase in the value, voltage and efficiency of solar cells. The results of the measurement of the highest efficiency of solar cells using a sun simulator and sunlight are found in variations of activated carbon 20%, with each efficiency values 0,043% and 0,0018%.

3D Structural Optimization of Zinc Phthalocyanine-Based Sensitizers for Enhancement of Open-Circuit Voltage of Dye-Sensitized Solar Cells

We designed and synthesized two zinc phthalocyanine sensitizers (PcS27 and PcS28), substituted with branched or cyclic alkoxy chains, to investigate the structural effect of peripheral alkyl chains on the performance of dye-sensitized TiO2 solar cells. The bulky cyclic alkyl chains of PcS28 decreased the adsorption density of PcS28 on the TiO2 electrode, while the terminal branches of alkoxy chains of PcS27 did not influence the adsorption density in comparison to the previously published PcS20 with linear alkoxy chains. Under one sun conditions, PcS27 cells exhibited higher open-circuit voltage but a slightly lower energy conversion efficiency, 6.0% less than PcS20. These results suggest that the small alternation of alkoxy chains resulted in decreasing electron pushing ability of peripheral phenoxy units, giving lower short-circuit current.

Deep insights into interface engineering by buffer layer for efficient perovskite solar cells: a first-principles study

Recent years have seen swift increase in the power conversion efficiency of perovskite solar cells (PSCs). Interface engineering is a promising route for further improving the performance of PSCs. Here we perform first-principles calculations to explore the effect of four candidate buffer materials (MACl, MAI, PbCl2 and PbI2) on the electronic structures of the interface between MAPbI3 absorber and TiO2. We find that MAX (X = Cl, I) as buffer layers will introduce a high electron barrier and enhance the electron-hole recombination. Additionally, MAX does not passivate the surface states well. The conduction band minimum of PbI2 is much lower than that of MAPbI3 absorber, which significantly limits the band bending of the absorber and open-circuit voltage of solar cells. On the other side, suitable bandedge energy level positions, small lattice mismatch with TiO2 surfaces, and excellent surface passivation make PbCl2 a promising buffer material for absorber/electron-transport-layer interface engineering in PSCs. Our results in this work thus provide deep understanding on the effects of interface engineering with a buffer layer, which shall be useful for improving the performance of PSCs and related optoelectronics.

Functionalized carbon dots on TiO2 for perovskite photovoltaics and stable photoanodes for water splitting

Various types of fluorescent carbon nanoparticles, often called carbon dots (CDs), are synthesized by different polycondensation methods: microwave irradiation, hydrothermal conditions or solution chemistry at ambient temperature with subsequent chemical functionalization. The CDs are deposited on TiO2 films to be probed as electron transport layers in perovskite photovoltaics and the anode for photoelectrochemical water splitting. Nitrogen CDs, which do not contain oxygen, lead to an increase of around 50 mV in the open circuit voltage of perovskite solar cells. All the CD types produce an improved photocurrent in water splitting, particularly CDs that are functionalized with thiol groups and butyl chains. It is demonstrated that the modified electrode is stable under continuous operation. Other electrochemical characteristics of the electrode, such as the voltammogram shape, onset potentials and open circuit potentials, remain nearly unchanged upon the deposition of CDs. Only the incident photon to current conversion efficiency improves clearly, extending the absorption range by around 20 nm towards longer wavelengths. This study provides new data about mechanisms and electrode arrangements for improving the performance of n-type semiconductors in photovoltaic cells and photoelectrochemical hydrogen production.

Crystalline versus Amorphous Donor-Acceptor Blends: Influence of Layer Morphology on the Charge-Transfer Density of States

Organic small molecule solar cells are used as a test bed to investigate the influence of film morphology on the density of charge-transfer (CT) states. CT states are considered as precursors for charge generation and their energy as the upper limit for the open-circuit voltage in organic donor-acceptor solar cells. In this study the influence of morphology for two perylene donors [crystalline diindenoperylene (DIP) versus amorphous tetraphenyldibenzoperiflanthene (DBP)] with almost identical ionization energy is investigated. As acceptor material, the fullerene ${\mathrm{C}}_{60}$ is used. By combining device measurements with optical and low-energy ultraviolet photoelectron spectroscopy, a comprehensive picture is obtained that describes how morphology and the connected density of states (DOS) affect device performance and the spectroscopic signature of CT states. Especially for the crystalline donor material DIP, strong exponential tail states reaching far into the gap are observed, which can be related to the presence of grain boundaries. A voltage-dependent filling of these states is identified as the origin of a blue shift of electroluminescence spectra with increasing applied voltage. Different approaches are compared to study the influence of static and dynamic disorder in the description of CT emission and absorption spectra of organic solar cells. Despite the fact that both donors yield almost identical CT energy (and, thus, the same open-circuit voltage) the Stokes shift between photocurrent and electroluminescence spectra and, concomitantly, the width of the CT DOS varies by more than a factor of 2. We discuss this observation in terms of the donor-acceptor reorganization energy as well as an additional line broadening by static disorder. Remarkably, the more crystalline donor DIP shows a significant deviation from a Marcus-type description, while this is not the case for the amorphous DBP. This highlights the importance of film morphology in organic solar cells.

2-Methylimidazole as an interlayer for the enhancement of the open-circuit voltage in perovskite solar cells

The loss of open-circuit voltage is a major obstacle for approaching the theoretical value of the power conversion efficiency in hybrid perovskite solar cells. In this study, a feasible and effective strategy for modifying the interface between the perovskite and the mesoporous TiO2 layer is proposed and implemented for the first time using 2-methylimidazole as a coating layer. As a result, the open-circuit voltage in the perovskite solar cells is significantly improved by 80 mV. The electronic impedance spectroscopy and photoluminescence spectroscopy results demonstrate that the modification of 2-methylimidazole as an interfacial insulating layer suppresses the electron transfer back from the anode electrode to the perovskite active layer, thereby inhibiting the recombination of the carriers at the interfaces, which results in an enhancement of the open-circuit voltage in the device. The cell modified with 2-methylimidazole shows increases in the open-circuit voltage from 1.05 to 1.13 V and in the power conversion efficiency from 17.48% to 19.45%. The optimal device with an area of 1 cm2 also exhibits an impressive efficiency of 16.38%.

Phthalocyanine-silver nanoparticle structures for plasmon-enhanced dye-sensitized solar cells

The localized surface plasmon resonance of silver nanoparticles (Ag NPs) was examined to improve the performance of phthalocyanine (MTXPc) in the plasmon-enhanced phthalocyanine-sensitized solar cells. When MTXPc dyes directly conjugated to Ag NPs (MTXPc-AgNPs) were used to sensitize solar cells, both of short-circuit current density (JSC) and open-circuit voltage (VOC) of phthalocyanine-sensitized solar cells were significantly increased. In the case of MTXPc conjugated to Ag@ZIF-8 (MTXPc-Ag@ZIF-8), slightly increasing in the JSC compared to alone MTXPc are observable but their VOC are significantly greater than alone MTXPc. Increasing in the JSC and VOC of the MTXPc-AgNPs and MTXPc-Ag@ZIF-8 lead to improve the performance of phthalocyanine in plasmon-enhanced phthalocyanine-sensitized solar cells compared to alone MTXPc. Also, the examination of the effect of the carboxyl- and sulfonyl-anchored dye (ZnTCPc-AgNPs and ZnTSPc-AgNPs, respectively) in conjunction with plasmonic NPs on the performance of DSSCs showed that ZnTCPc-AgNPs and ZnTSPc-AgNPs perform significantly better than their unsubstituted analogues. The studying the effect of the metal in the central cavity of phthalocyanine using zinc, manganese, iron, cobalt, and nickel showed that the metal in the central cavity of phthalocyanine has the critical role toward the photovoltaic performance of the plasmon-enhanced phthalocyanine-sensitized solar cells.

Relation between the Electronic Properties of Regioregular Donor-Acceptor Terpolymers and Their Binary Copolymers.

By analyzing the optical band gap and energy levels of seven different regioregular terpolymers in which two different electron-rich donor moieties are alternating with a common electron-deficient acceptor unit along the backbone, we establish a direct correlation with the properties of the corresponding binary copolymers in which one donor and one acceptor are combined. For this study, we use diketopyrrolopyrrole as the common acceptor and different π-conjugated aromatic oligomers as donors. We find that the optical band gap and frontier orbital energies of the terpolymers are the arithmetic average of those of the parent copolymers with remarkable accuracy. The same relationship is also found for the open-circuit voltage of the bulk heterojunction solar cells made with the ter- and copolymers in combination with [6,6]-phenyl-C71-butyric acid methyl ester. Comparison of these findings with data in the literature suggests that this is a universal rule that can be used as a tool when designing new π-conjugated polymers. The experimental results are supported by a semiempirical quantum chemical model that accurately describes the energy levels of the terpolymers after parametrization on the energy levels of the copolymers and also provides a theoretical explanation for the observed arithmetic relations.

Enhancing the open-circuit voltage and efficiency of CZTS thin-film solar cells via band-offset engineering

Limits on the conversion efficiency and open-circuit voltage lead to low kesterite thin-film solar cell performance. The conduction band offset (CBO) between the absorber and buffer layers (p-CZTS and n-CdS) is considered to be one of the effective factors for the performance of these devices. The simulation results demonstrated that the optimal thickness and doping concentration for obtaining a high performance in the solar cell which is based on CZTS/CdS absorber/buffer layers would respectively be 50 nm and 1.5 × 1017 cm−3. The CBO at absorber/buffer interface plays a significant role in solar cell performance and the highest CZTS-based solar cell efficiency is obtained within the range of − 0.4 eV and + 0.4 eV of the CBO. Solar cell performance decreases from 5.12 to about 3% when the positive CBO increases from 0.4 to 0.7 eV. Moreover, the impact of CBO on device quantum efficiency was investigated. The optical response range changed with an increase in + ΔEC and the highest value (about 80%) was observed in visible and near ultraviolet light within the range of 400–520 nm. In − ΔEC, electrons can be transferred from the buffer layer to the window layer and the optical photons proportional to the buffer layer’s band gap help generate free electrons and holes, which cause a slower reduction of the quantum efficiency within the negative offsets and the above-mentioned range, through electric field bending. In addition, a large number of n-type materials such as CdS, SnS2, ZnO, ZnTe, ZnS, Zn(O, S), (Mg, Zn)O, In2S3, TiO2, and CdTe were analyzed as buffer layers in CZTS-based thin-film solar cell. The CZTS-based thin-film solar cells with SnS2, ZnO0.55S0.45, ZnO0.80S0.20, and Mg0.2Zn0.8O led to a conversion efficiency of about 13%. Furthermore, an open-circuit voltage of above 700 mV was obtained by using ZnO0.40S0.60 and Mg0.1Zn0.9O buffer layers. By introducing the CZTSe/CZTS absorber layer and SnS2 buffer layer in the structure of the proposed solar cell, the best efficiency and open-circuit voltage is deduced as 16.28% and 780 mV, respectively.

Impact of charge carrier recombination and energy disorder on the open-circuit voltage of polymer solar cells

Charge carrier recombination and energy disorder in organic solar cells both have a profound impact on the open-circuit voltage of the device. In this paper, both traditional fullerene-(PC<sub>71</sub>BM) and nonfullerene-(O-IDTBR) based solar cells were fabricated using the same electron donor material (PTB7-Th). The room-temperature current density–voltage characteristics showed that despite the values of their power conversion efficiencies were very close, there was a huge open circuit voltage (<i>V</i><sub>oc</sub>) difference between the PC<sub>71</sub>BM and O-IDTBR devices. To understand the sources of the <i>V</i><sub>oc</sub> variation, characterization techniques such as impedance spectra, low temperature electrical characterization method, transient photovoltage, and electroluminescent spectra were carried out. Temperature-dependent <i>V</i><sub>oc</sub> of the devices were measured in a large temperature range between 120 K and 300 K. The charge transfer state energy (<i>E</i><sub>CT</sub><italic/>) of the fullerene and the nonfullerene cells were determined to be 1.13 V and 1.34 V, respectively. Furthermore, the Mott-Schottky equation was applied to analyze the capacitance- voltage curves of the fabricated devices. Results showed that the built-in voltage (<i>V</i><sub>bi</sub>) of the O-IDTBR based cell (1.38 V) was much higher than that of the PC<sub>71</sub>BM cell (1.15 V). By analyzing the above data, it was easy to speculate that charge carrier recombination loss in the PC<sub>71</sub>BM device was more serious since the net electric field was relatively weak. Impedance spectra were used to measure the charge carrier recombination process in both devices. Fitting results through the equivalent circuit stated clearly that values of the recombination resistance in the O-IDTBR device were much higher in the test range, indicating that the charge carrier was less easy to recombine in the nonfullerene device. This speculation could be verified by the transient photovoltage (TPV) measurements since the carrier lifetime in the O-IDTBR device was much longer. The excited states in the devices were investigated by the electroluminescence spectra. Since the full width at half maximum (FWHM) of the O-IDTBR emission spectrum was narrower, the excited state energy distribution in the O-IDTBR device was more uniform. Based on the above analyses, the higher <i>V</i><sub>oc</sub> in the O-IDTBR device was attributed to the mild charge carrier recombination and low energy disorder.

The Effect of Environmental Factors (Temperatures & Humidity) on the Solar Cell Performance / Matlab Model

This paper provides an accurate modeling method for the photovoltaic panel using Matlab software. The mathematical model discusses the effect of the environmental factors on PV panels. The model based on specifications given on the manufacturer’s plate, a previous Simulink model was developed using Matlab code, to include the effect of humidity on the solar cell performance and efficiency. In the previous work on P-V characteristics, the temperature effect is discussed adequately, without mention the humidity side effects. In this paper, the effect of humidity on the fill factor and efficiency of solar cells is discussed. The conclusions come with many side effects of the humidity on the solar cell, which is the sediments trapped by water molecules, and energy loss due to the reflections of light from the condensed water surface. In addition to the heat carried by moister. The effect of this kind of heat has been studied through calculating the enthalpy of the moist air, and feel like temperature). According to this model and in Silicon solar cell, the lost energy due to reflection was equal to (Gave=842.0175 w/m2) on average. Due to this loss, solar cell current and voltage will be different. All these effects lead to a decrease in the fill factor and the efficiency of the solar cell, because of a reduction in the absorbing energy.

A Proposal of a Procedure to Estimate a Standard Line for Contactless Estimation of a Solar Cell Voltage in a Module using Modulated Light

A Proposal of a Procedure to Estimate a Standard Line for Contactless Estimation of a Solar Cell Voltage in a Module using Modulated Light

High voltage vacuum-processed perovskite solar cells with organic semiconducting interlayers.

In perovskite solar cells, the choice of appropriate transport layers and electrodes is of great importance to guarantee efficient charge transport and collection, minimizing recombination losses. The possibility to sequentially process multiple layers by vacuum methods offers a tool to explore the effects of different materials and their combinations on the performance of optoelectronic devices. In this work, the effect of introducing interlayers and altering the electrode work function has been evaluated in fully vacuum-deposited perovskite solar cells. We compared the performance of solar cells employing common electron buffer layers such as bathocuproine (BCP), with other injection materials used in organic light-emitting diodes, such as lithium quinolate (Liq), as well as their combination. Additionally, high voltage solar cells were obtained using low work function metal electrodes, although with compromised stability. Solar cells with enhanced photovoltage and stability under continuous operation were obtained using BCP and BCP/Liq interlayers, resulting in an efficiency of approximately 19%, which is remarkable for simple methylammonium lead iodide absorbers.

Impact of the III-V/Ge nucleation routine on the performance of high efficiency multijunction solar cells

This paper addresses the influence of III-V nucleation routines on Ge substrates for the growth of high efficiency multijunction solar cells. Three exemplary nucleation routines with differences in thickness and temperature were evaluated. The resulting open circuit voltage of triple-junction solar cells with these designs is significantly affected (up to 50 mV for the best optimization routine), whereas minimal differences in short circuit current are observed. Electroluminescence measurements show that both the Ge bottom cell and the Ga(In)As middle cell present a VOC gain of 25 mV each. This result indicates that the first stages of the growth not only affect the Ge subcell itself but also to subsequent subcells. This study highlights the impact of the nucleation routine design in the performance of high efficiency multijunction solar cell based on Ge substrates.

Physical origin of the temperature-dependent open-circuit voltage in solar cells

After the contribution of hot carriers to the current in solar cells has been considered, a physical and analytical model of open-circuit voltage is proposed. A variety of experiments on the temperature-dependent open-circuit voltage in solar cells that is one critical factor to determine their overall efficiency are successfully modeled based on the consideration of hot carriers. While previous modeling studies focused on numerical techniques, a physical and analytical model of the open-circuit voltage has been developed. Such a study is an important step toward a quantitative model of solar cells, leading to a deeper understanding of the physical effects in these materials. The analysis of the open-circuit voltage reveals how it depends on temperature, the acceptor density, the light-generated current density, the donor density, the bandgap, the effective mass, and the dielectric constant. A material parameter variation is performed to understand its effects on the open-circuit voltage. It will benefit to optimize the device performance by tuning material parameters through the simplicity and analytic nature of the proposed model. It is also helpful to characterize the material properties using the open-circuit voltage.

A Machine Learning–Based Design Rule for Improved Open‐Circuit Voltage in Ternary Organic Solar Cells

Organic solar cells (OSCs) based on ternary blends are among the most promising photovoltaic technologies. To further improve the power conversion efficiency (PCE), the materials selection criteria must be focused on achieving high open‐circuit voltage (Voc) through the alignment of the energy levels of the ternary blends. Hence, machine‐learning approaches are in high demand for extracting the complex correlation between Voc and the energy levels of the ternary blends, which are crucial to facilitate device design. Herein, the data‐driven strategies are used to generate a model based on the available experimental data, and the Voc is then predicted using available machine‐learning methods (the Random Forest regression and the Support Vector regression). In addition, the Random Forest regression is developed to find the appropriate energy‐level alignment of ternary OSCs and to reveal the relationship between Voc and electronic features. Finally, an analysis based on the ranking of variables in terms of importance by the Random Forest model is performed to identify the key feature governing the Voc and the performance of ternary OSCs. From the perspective of device design, the machine‐learning approach provides sufficient insights to improve the Voc and advances the comprehensive understanding of ternary OSCs.

Improved open-circuit voltage and ambient stability of CsPbI2Br perovskite solar cells by incorporating CH3NH3Cl

Inorganic cesium metal halide perovskites have gained research interest as absorbers in perovskite solar cells due to their superior thermal stability. Among these, CsPbI2Br, with a narrower band gap than CsPbBr3 and a better phase stability than CsPbI3, has received tremendous interest of the researchers. However, CsPbI2Br takes adverse phase transfer easily with an exposure to the water vapor in ambient air which not only brings inconvenience for researches but also puts forward very high requirement for encapsulation. Herein, a dense and uniform film is obtained by incorporating hydrophobic CH3NH3Cl (MACl) into the precursor solution. Being attributed to a good passivation effect, the defect density is decreased from 3.12 × 1016 to 1.49 × 1016 cm−3 and the average photoluminescence lifetime is increased from 8.84 to 20.6 ns. The photovoltaic device achieves a high open-circuit voltage of 1.22 V based on optimized MACl-doped film and accordingly a higher power conversion efficiency (PCE) of 12.9% which is 21.7% higher than the pristine CsPbI2Br device with PCE of 10.6%. In addition, the ambient stability of MACl-doped device has been enhanced, which is greatly attributed to the hydrophobic properties of MACl. This work provides a clue to improve ambient stability of inorganic perovskite solar cells and inspires toward further development of this material.

Influence of shading to the output power of photovoltaic in Indonesia

Indonesia, being a tropical country, has a high photovoltaic (PV) energy generation potential that can help meet demand due to the impending shortage of power supplies in the coming years. The shading effect is a negative effect that causes the Photovoltaic power output to drop from its normal state. The performance of Photovoltaic Panels (PV) is a shared module surface exposed to sunlight. Shading effects usually occur from the influence of clouds, but the influence of these clouds often causes a lack of uniform illumination of sunlight received by the photovoltaic. This is also often called Partial Shaded. Partially shaded PV systems cannot operate at maximum efficiency because of shadows cast by surrounding structures, foliage and cloud cover. This is done to see the effect of partial shading pattern effect on solar cell PV. Characteristics of I-V can be influenced by pattern shading effect. The voltage and current of PV solar cells will drop from partial shading effect experiment which consists of 20%, 40%, 60%, 80% and 100% shading area.