Fill Factor Of Solar Cells Research Articles

A theoretical investigation into the impact of temperature and band gap variation of La2NiMnO6 oxide double perovskite nanostructures on the performance of La2NiMnO6/MASnI3 based hybrid solar cells

The study aimed at simulating a model of bilayer La2NiMnO6/MASnI3 hybrid perovskite solar cell having a potential benefit of better stability at higher operating temperature with higher band gap of LNMO. This numerical analysis of La2NiMnO6/MASnI3 based hybrid solar cell performance parameters has been carried out as a function of temperature and optical band gap (Eg) of La2NiMnO6 (LNMO). The analysis reveals that the fill factor of solar cells operated at room temperature has not been affected too much on varying Eg of LNMO and decreases non-linearly with increasing operating temperature. The open circuit voltage of solar cells operated at room temperature increases with increasing Eg of LNMO and drops linearly with increasing operating temperature. The short-circuit current density (JSC) increases non-linearly at different rates with increasing the operating temperature. The value of dη/dT increases up to a critical temperature (Tc) and then decreases in the solar cells comprised with higher Eg of LNMO (Eg ∼ 1.50 eV–1.60 eV). The Tc value was shifted towards higher operating temperature in the higher Eg of LNMO (Eg ≥ 1.50 eV), enabling more stable solar cell at higher operating temperature.

Heavy Boron-Doped Silicon Tunneling Inter-layer Enables Efficient Silicon Heterojunction Solar Cells.

P-type hydrogenated nanocrystalline silicon (nc-Si:H) has been used as a hole-selective layer for efficient n-type crystalline silicon heterojunction (SHJ) solar cells. However, the presence of an additional valence band offset at the interface between intrinsic amorphous hydrogenated silicon and p-type nc-Si:H films will limit the hole carrier transportation. In this work, it has been found that when a heavily boron-doped silicon oxide layer deposited with high hydrogen dilution to silane (pB) was inserted into their interface, the fill factor of SHJ solar cells increases 3% absolutely because of the reduced valence band offset and the increased opportunity to provide a hopping tunnel assisted by the doping energy level and valence band tail states. Furthermore, the additional boron incorporation in intrinsic amorphous silicon adjacent to pB helps to enhance the built-in electric field, thus increasing the hole selectivity. By these means, the power conversion efficiency was improved from 23.9% to approximately 25%.

A high effciency (11.06 %) CZTSSe solar cell achieved by combining Ag doping in absorber and BxCd1-xs/caztsse heterojunction annealing

Many literatures have demonstrated that a smaller amount of Ag doping in Cu2ZnSn(S, Se)4 (CZTSSe) can elevate the open-circuit voltage (Voc) and fill factor (FF) of CZTSSe solar cells, but decrease short-circuit current density (Jsc) due to the increase in bandgap (Eg) of the CAZTSSe by Ag doping. The decreased Jsc limits the enhancement in PCE through Ag doping. In this paper, to compensate for the deficit in Jsc and further increase Voc and FF, a strategy is proposed to substitute CdS/CAZTSSe in CAZTSSe solar cells with annealed B-doped CdS/CAZTSSe. It is found that B doping can increase the electron density of CdS (ne) and decrease the lattice mismatch between CdS and CAZTSSe. Annealing can decrease the hole density of CAZTSSe (np) and passivate the surface of CAZTSSe by diffusing B towards the surface of CAZTSSe. The increased ne and reduced np widen the depletion region, leading to an increase in photogenerated carrier density (JL), resulting in an increase in Jsc. The surface passivation and decreased lattice mismatch can reduce interfacial recombination, resulting in decrease in the reverse saturation current density (J0), so further increases in Voc and FF. By optimizing the Ag doping content, B doping content, as well as the annealing temperature and time of the BxCd1-xS/CAZTSSe, the power conversion efficiency (PCE) increases from 8.96 % to 11.06 %. This study not only advances a deeper understanding of the mechanisms behind various parameters in CZTSSe solar cells but also proposes a method to boost the PCE of CZTSSe solar cells.

Enhanced Fill Factor and Efficiency of Ternary Organic Solar Cells by a New Asymmetric Non-Fullerene Small Molecule Acceptor.

Asymmetric non-fullerene small molecules acceptor (as-NF-SMAs) exhibit greater vitality in photovoltaic materials compared to their symmetric counterparts due to their larger dipole moments and stronger intermolecular interactions, which facilitate exciton dissociation and charge transmission in organic solar cells (OSCs). Here, we introduced a new as-NF-SMAs, named IDT-TNIC, as the third component in ternary organic solar cells (TOSCs). The asymmetric IDT-TNIC used indacenodithiophene (IDT) as the central core, alkylthio-thiophene as a unilateral π-bridge and extended end groups as electron-withdrawing. Due to the non-covalent conformational lock (NCL) established between O⋅⋅⋅S and S⋅⋅⋅S, the IDT-TNIC molecule preserves its coplanar structure effectively. Furthermore, IDT-TNIC exhibits complementary absorption and excellent compatibility with donor and acceptor materials, as well as optimized ladder energy level arrangement, resulting in a higher and more balanced μh/μe value, more homogeneous and suitable phase separation morphology in TOSCs. Thus, the PCE of the TOSCs reached 17 % when the weight ratio of PM6 : Y6 : IDT-TNIC was 1 : 1.1 : 0.1, and it is noteworthy that when the device area was increased to 1 cm2, the PCE could still be maintained at over 14 %. Detailed studies and analysis indicate that IDT-TNIC has great potential as a third component in OSCs and for large-scale printing in the future.

High-efficiency ultra-thin GaAs solar cells based on ITO/Ag/ITO transparent electrodes and photonic crystals

Ultrathin photovoltaic technology has great potential to improve efficiency and reduce costs. However, achieving optical thickness requires an effective light capture strategy. In this study, for GaAs thin film solar cells with an active layer thickness of 500 nm, we adopt a combination strategy of front-end ITO/Ag/ITO transparent electrodes and back-end photonic crystals (PC). By employing the finite difference time domain (FDTD) simulation, we verify that ITO/Ag/ITO transparent electrodes and AlGaAs PC can effectively enhance the light-harvesting capacity of cells. The proposed cell structure has a spectral absorption rate (SAR) of 0.9781 in the visible wavelength range. To further optimize the photovoltaic performance parameters, we optimize the doping concentration of the pn junction in the cell. Finally, the short circuit current density Jsc, open circuit voltage Voc, fill factor (FF) and photoelectric conversion efficiency (PCE) of GaAs thin film solar cells are successfully increased to 31.10mAcm−2, 1.28V, 88.18% and 35.12%, respectively. This provides crucial experimental validation and theoretical guidance for advancing ultra-thin photovoltaic technology.

Enhancing the fill factor and power conversion efficiency of n-type TOPCon solar cells by using electron migration technique

Improving the efficiency and performance of the solar cells by enhancing the quality and conductivity of the contacts was studied using electron migration (EM). By using intense light that covers the entire cell area at high current densities, the process of EM creates a huge number of charge carriers and helps for enhancing overall cell performances. This study examined the effects of various parameters, including temperature, voltage, time, incident light, and current, on the enhanced performances of n-type tunnel oxide passivated contact (n-TOPCon) solar cells. According to experimental data, 60 V and 10 s at room temperature are the ideal circumstances for optimising both voltage and time. As compared to before the EM experiment in the n-TOPCon solar cells, the illuminated current–voltage (I-V) characteristics of the optimised condition are Jsc of 39.24 mA/cm2, Voc of 707.45 mV, FF of 69.954 %, and PCE of 19.42 %. After the EM condition, this study shows improvements in PCE (19.04 %) and FF (48.02 %). This work provides insight into optimizing the maximum performance in developing solar technologies.

Optimizing the metallization process for high fill factor of n-type crystalline silicon TOPCon solar cells

The primary challenge in solar cell manufacture concerning the metallization process is the need to achieve a balance between the electrical and optical performance of the metal contacts as the contribute to shading and the series resistance (Rs) of solar cells. Addressing these challenges with the optimization of the metallization process is crucial for achieving a high fill factor (FF) in solar cells, as FF is a key parameter indicating the quality and efficiency of a solar cell. An impact of different snap-off, distances between mask and cells, of n-type TOPCon (Tunnel Oxide Passivated Contact) solar cells during the screen-printing process was conducted. This experiment employs testing and analysis to determine the most effective snap-off distance that minimizes the Rs variability, resulting in an overall enhancement in cell efficiency. The smaller snap-off distance can lead to better performance in n-TOPCon solar cells due to finer lines, uniform contacts, and lower Rs. The I-V characteristics of 1.4 mm are Jsc of 39.58 mA/cm2, Voc of 684.63 mV, FF of 80.54 %, and power conversion efficiency (PCE) of 21.83 %, respectively. In addition, dark I-V measurement is essential for diagnosing performance issues; we got shunt resistance (Rsh) of 4.97 x 106 Ω which is the highest value that indicates minimal Rs of 0.3 Ω. As a result, it is a potential strategy for n-TOPCon solar cell improvements.

Enhanced fill factor and stability of perovskite solar cells with a multifunctional additive of starch-iodine complex

The efficiency and stability of perovskite solar cells (PSCs) can be greatly affected by various factors such as passivating the perovskite film, oxidizing the hole-transport material of 2,2′,7,7′-tetras(N,N-p-methoxyaniline)-9,9′-spirodifluorene (Spiro-OMeTAD), and inhibiting the iodide migration. Here we introduce a multifunctional starch-iodine complex in the perovskite film to enhance the fill factor and stability of PSCs. Results demonstrate that the starch-iodine complex from the perovskite film can release iodine molecules to gently oxidize the Spiro-OMeTAD, which can significantly increase the PSC's fill factor. Moreover, the remaining starch can effectively passivate the perovskite film to obviously improve the PSC's long-term stability. Furthermore, the starch-iodine complex can absorb and store the iodide ions to generate a starch-triiodide complex, which can release iodide ions to promote iodide defect self-healing and suppress iodide migration in the perovskite films, resulting in a further enhancement of the PSC's long-term stability. As a result, the PSC based on the starch-iodine complex obtains a superior cell efficiency of 22.60% with a high fill factor of 79.54%, and keeps 91.12% of its original efficiency after 1500 h.

Extraction of contact resistivity for a partial contact solar cell

Partial contacts are used in solar cells and other electronic devices. The contact resistivity and contact resistance of these partial contacts play a significant role in the performance optimization of these devices. In this work, we propose a strategy for accurate extraction of the partial contact resistivity (ρPC) of a solar cell with Ohmic (or linear) and Schottky (or non-linear) contacts. We demonstrate how the Cox–Strack method can accurately estimate the ρPC of a solar cell using Sentaurus TCAD-based simulations. Our simulation predicts that for linear contact solar cells, ρPC is approximately constant when the contact fraction is varied, whereas for non-linear contact, ρPC decreases with contact fraction as opposed to the previously reported works. The experimentally reported data is also shown to support the claim for the linear contacts further. Despite the larger full-contact resistivity of non-linear contacts, the contact resistivity and fill factor (FF) of both linear and non-linear partial contact solar cell is almost similar to ∼3.5−5mΩcm−2 and ∼ 75% respectively at a 0.3% contact fraction. This is attributed to the reduction in contact resistivity for non-linear contacts with contact fraction. We finally show the generality of this study for any contact material system. This work can be applied to any device with partial contacts.

Unveiling the mechanism of attaining high fill factor in silicon solar cells

AbstractA world record conversion efficiency of 26.81% has been achieved recently by LONGi team on a solar cell with industry‐grade silicon wafer (274 cm2, M6 size). An unparalleled high fill factor (FF) of up to 86.59% has also been certified in a separated device. The theoretical FF limit has been predicted to be 89.26%, while the practical FF is far below this limit for a prolonged interval due to the constraints of recombination (i.e., SRH recombination) and series resistance. The ideality factor (m) in the equivalent circuit of silicon solar cells is consistently ranging from 1 to 2 and rarely falls below 1, resulting in a relatively lower FF than 85%. Here, this work complements a systematic simulation study to demonstrate how to approach the FF limit in design of silicon solar cells. Firstly, a diode component with an ideality factor equal to 2/3 corresponding to Auger recombination is incorporated in the equivalent circuit for LONGi ultra‐high FF solar cell; Secondly, an advanced equivalent circuit is put forward for comprehensive analysis of bulk recombination and surface recombination on the performance, in which specific ideality factors are directly correlated with various recombination mechanisms exhibiting explicit reverse saturation current density (J0). Finally, we evaluate precisely the route for approaching theoretical FF in practical solar cell fabrication based on electrical design parameters using the developed model.

Boosting the fill factor and open-circuit voltage of carbon-based perovskite solar cells with a graphene co-doped P3HT/NiOx hole-transporting bilayer

A low-temperature and solution-processed graphene co-doped G-P3HT/G-NiOx hole-transporting bilayer with enhanced conductivity and matched cascade band alignment is designed for high-performance carbon electrode perovskite solar cells.

Pressure and temperature effects on the electron transport layer material for solar energy applications: a molecular dynamic approach explores the influence of environmental conditions of biostructure materials in solar cells

This investigation initiated by modelling the crystal structure of perovskite to explore the impact of different temperatures. Researchers modified the perovskite crystal structure and observed its response to temperature variations. The study involved assessing the efficiency and fill factor of perovskite solar cells, incorporating photovoltaic structures without specifying the electron transport layer material. The primary goal of this initiative is to provide power to buildings using environmentally acceptable components in perovskite solar cells. The promising efficiency and cost-effectiveness of manufacturing make perovskite solar cells an intriguing option for generating clean and sustainable energy.

Dipoles and defects caused by CO2 plasma improve carrier transport of silicon solar cells

AbstractCarrier‐selective contact is a fundamental issue for solar cells. For silicon heterojunction (SHJ) solar cells, it is important to improve hole transport because of the low doping efficiency of boron in amorphous silicon and the barrier stemming from valence band offset. Here, we develop a carbon dioxide (CO2) plasma treatment (PT) process to form dipoles and defect states. We find a dipole moment caused by longitudinal distribution of H and O atoms. It improves hole transport and blocks electron transport and thus suppresses carrier recombination. In the meantime, the CO2 PT process also results in defect states, which reduce passivation performance but improve hole hopping in the intrinsic amorphous layer. As a balance, an appropriate CO2 PT process at the i/p interface increases fill factor and power conversion efficiency of SHJ solar cells. We emphasize, based on sufficient evidences, this work finds a distinct role of the CO2 plasma in SHJ solar cells opposed to reported mechanisms.

Predicting and analyzing the fill factor of non-fullerene organic solar cells based on material properties and interpretable machine-learning strategies

In recent years, encouraging progress in non-fullerene acceptors-based organic solar cells (NFAs-OSCs) has been made in the field of clean-energy technologies. Nevertheless, achieving a high fill factor (FF) for NFAs-OSCs is a great challenge due to the FF value can be dramatically affected by various factors. An accurate prediction (based on empirical data) of how inherent characteristics of polymer-NFA combinations (e.g., frontier molecular orbitals (FMO) and charge-carrier mobilities) affects the FF in NFAs-OSCs is therefore urgently needed for the future commercialization prospect. The presented work demonstrates an outperforming predictive model using the optimized Gradient-boosting decision tree (GBDT) machine learning (ML) algorithm to accurately predict the FF value, which is based on a dataset consisting of > 180 unique donor/NFA blends with reported FF from previously published publications and experimental physical descriptors (FMO and charge-carrier mobilities). In addition, the SHapley Additive exPlanations (SHAP) strategy is further applied to not only gain the interpretability of the GBDT model prediction but also directly map the relationship between the FF value and experimental physical descriptors by systematic interpretable explanations (e.g., global and local). The SHAP analysis qualitatively reveals that the highest occupied molecular orbital (HOMO) of the donor and the HOMO of the acceptor are the two most important features associated with FF value prediction, which is in good agreement with previous experimental facts. Furthermore, the ML strategies explore the key requirements (e.g., small HOMO offset (<0.3 eV), high hole and electron mobilities (>1.0 × 10–4 cm2 V−1 s−1), and desired μh/μe ratio (in the range of 1.8–3.3)) for enhancing the FF values of NFAs-OSCs. This study provides novel insights into the possible physical mechanisms of FF enhancement, thus facilitating research efforts (e.g., rational design of energy level tuning in donor/NFA blend) for high-performance NFAs-OSCs.

Investigation into fill factor and open-circuit voltage degradations in silicon heterojunction solar cells under accelerated life testing at elevated temperatures

There are many reports on open-circuit voltage (VOC) degradation but limited reports on fill factor (FF) degradation in silicon heterojunction (SHJ) solar cells which are either subjected to an accelerated testing condition or to a field condition. The factors contributing to FF loss and VOC loss due to aging required a thorough investigation to gain insight into potential loss mechanisms and the approaches to mitigate them. In this context, we subjected SHJ solar cells of the same structure to varying accelerated testing conditions (i.e. exposure temperature of 90 °C versus 120 °C, under 1-sun illumination) in experiment 1 to 3 of this work. The SHJ cells exposed to a temperature of 90 °C were nearly stable in performance even after 2000 h while those exposed to 120 °C degraded significantly in FF. Device measurements and analysis revealed that the FF degradation was due to an increase in series resistance (Rs) and hole collection barrier. In experiment 4, the effect of device structure was investigated by subjecting cells with only front-side indium tin oxide (ITO) and those with both-sides ITO to the same accelerated testing conditions at a temperature of 90 °C under 1-sun illumination. The result obtained revealed that SHJ cells with both sides ITO were nearly stable in electrical performance while those with only front ITO degraded in performance, dominated by VOC loss. The VOC loss was perhaps due to loss of passivation at the rear-side of the cells.

Enhanced performance of lead sulfide quantum dot-sensitized solar cells by controlling the thickness of metal halide perovskite shells

The metal halide perovskite CH3NH3PbI3 (MAP) can be applied as the shell layer of lead sulfide quantum dots (PbS QDs) for improving solar power conversion efficiency. However, basic physics for this PbS core/MAP shell QD system is still unclear and needs to be clarified to further improve efficiency. Therefore, in this study, we investigate how MAP shell thickness affects device performance and dynamics of charge carriers for PbS QD-sensitized solar cells. Covering the PbS QDs with the MAP shell layers of an appropriate thickness around 0.34 nm greatly suppresses charge carrier recombination at surface defects along with improved carrier transport to neighboring oxide and polymer layers. Therefore, this MAP shell thickness provides the highest open-circuit voltage, short-circuit current density, and fill factor for solar cells. Overall power conversion efficiencies of these solar cells reached about 4.1%, which is about six-fold higher than that for solar cells without MAP (about 0.7%). Additionally, use of the MAP shell layers can prevent oxidation of PbS QDs and, therefore, makes a degradation of solar cell performance slower in air.

An approach using molecular dynamics to connect biomaterials with solar systems to increase the amount of renewable energy: Application in built environments

In this work, the LAMMPS software was utilized for molecular dynamics to model perovskite crystal structure. Researchers aimed to understand behavior of perovskite layer at different temperatures and pressures. By exposing it to various temperature settings, they observed and examined characteristics of perovskite structure. The study also investigated volume growth of perovskite structure under influence of heat, as atoms inside material became more active with increasing temperature, resulting in volume expansion. Understanding these thermal effects is crucial for developing perovskite solar cells capable of withstanding extreme temperatures. To further explore application of perovskites in solar cells, researchers integrated Spiro-OMeTAD as a hole-transport layer (HTL) within perovskite solar cell structure. Spiro-OMeTAD is a widely used material in construction of biostructures. Its impact on total efficiency and fill factor of perovskite solar cells was investigated. The efficiency of a solar cell indicates its ability to convert sunlight into electrical energy, while fill factor evaluates cell's capacity to utilize available light effectively. The ultimate objective of this study is to utilize perovskite solar cells to contribute to advancement of sustainable energy alternatives. These cells have shown great promise for harnessing solar energy and can serve as an environmentally friendly option for powering buildings.

Achieved 18.9% Efficiency by Fine-Tuning Non-Fullerene Acceptor Content to Simultaneously Increase the Short-Circuit Current and Fill Factor of Organic Solar Cells.

In this study, using PM6:L8-BO as the main system and non-fullerene acceptor IDIC as the third component, a series of ternary organic solar cells (TOSCs) are fabricated. The results reveal that IDIC plays a significant role in enhancing the performance of TOSCs by optimizing the morphology of blended films and forming interpenetrating nanostructure. The improved film morphology facilitates exciton dissociation and collection in TOSCs, which causes an increase in the short-circuit current density (JSC ) and fill factor (FF). Further, by optimizing the IDIC content, the power conversion efficiency (PCE) of TOSCs reaches 18.9%. Besides, the prepared TOSCs exhibit a JSC of 27.51mAcm-2 and FF of 76.64%, which are much higher than those of PM6:L8-BO-based organic solar cells (OSCs). Furthermore, the addition of IDIC improves the long-term stability of the OSCs. Meanwhile, TOSCs with a large effective area of 1.00cm2 have been prepared, which exhibit a PCE of 12.4%. These findings suggest that modifying the amount of the third component can be a useful strategy to construct hight-efficiencyTOSCs with practical application potential.

Fundamentals of solar cell physics revisited: Common pitfalls when reporting calculated and measured photocurrent density, open-circuit voltage, and efficiency of solar cells

Very often, articles are found in the international literature reporting solar cells (single junction) with efficiencies above the Shockley-Queisser limit. In other similar papers, the short-circuit current density (Jsc) of solar cells are also reported with values that are above the maximum that a single absorber semiconductor can provide (without multiple-exciton generation), under the solar spectrum. For example, it will be easy to find both experimental and simulation reports for CdTe solar cells with Jsc values above 40 mA/cm2, under the AM1.5 solar spectrum. Unfortunately, in a pattern of perpetuating unsound analysis, recent articles with such parameter values cite old erroneous articles to justify their results. This fact reveals that some of the solar cell’s basic physics fundamentals have been forgotten or are not known by many researchers in the field. In this work, some of the solar cell physics basic concepts that establish limits for the efficiency, the short-circuit current density, the open-circuit voltage and even the fill factor for solar cells are reviewed. All these parameter limits will be shown as a function of the active semiconductor bandgap for single junction cells under the AM1.5 solar spectrum. Finally, it is explained what experimental and theoretical errors are typically made, causing the erroneous report of cell parameters, when the fundamental limits are not considered.

Performance analysis of c-Si & CdS solar cells

Solar energy is one of the best non-conventional energy resources which can be converted into electrical energy by means of solar cells. Solar cells are generally made up of silicon semi- conductor. But due to high power loss the efficiency of solar cell reduces. At present, the efficiency of solar cell is nearly 20–21%, which needs to be addressed to increase efficiency. So, the main aim of this work is to study the characterization of different solar cells and suggest an appropriate method to increase efficiency. Increase of efficiency can be achieved by doping various substrate or alloys of silicon, and the doped elements on solar cells are compared for further investigation. The parameters like short circuit current (ISC), open circuit voltage (VOC) and fill factor(ff) of solar cell will be analyzed using scanning electron microscope and Corescan.