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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Sensitivity of PV Plant Performance to Tracker Error
摘要： Photovoltaic (PV) power plants are financed – and later evaluated – based on a modeled energy prediction. However, any unaccounted-for losses or other model inaccuracies may cause plants to underperform expectation, resulting in large sums of lost revenue for plant owners. For example, while tracking systems have the potential to increase plant energy significantly over fixed tilt designs, any deviation from the optimum tracking angle can create large additional losses. This work investigates two real world case studies where tracking errors resulted in significant lost generation. Further modeling work uses the new electrical shading and time series tracking input features in PlantPredict to demonstrate the range of potential losses under tracker error scenarios for both CdTe and cSi various technologies.
关键词： energy loss,tracking errors,PV power plants,cSi,CdTe,Photovoltaic
更新于2025-09-19 17:13:59
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Tuning the hybridization of local exciton and chargea??transfer states in highly efficient organic photovoltaic cells
摘要： Decreasing the energy loss is one of the most feasible ways to improve the efficiencies of organic photovoltaic (OPV) cells. Recent studies have suggested that non-radiative energy loss ( ) is the dominant factor that hinders further improvements in state-of-the-art OPV cells. However, there is no rational molecular design strategy for OPV materials with suppressed . In this work, taking molecular surface electrostatic potential (ESP) as a quantitative parameter, we establish a general relationship between chemical structure and intermolecular interactions. The results reveal that increasing the ESP difference between donor and acceptor will enhance the intermolecular interaction. In the OPV cells, the enhanced intermolecular interaction will increase the charge transfer (CT) state ratio in its hybridization with local exciton to facilitate the charge generation but simultaneously result in a larger . These results suggest that finely tuning the ESP of OPV materials is a feasible method to further improve the efficiencies of OPV cells.
关键词： hybridization,charge transfer state,intermolecular interaction,organic photovoltaic cells,non-radiative energy loss
更新于2025-09-19 17:13:59
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High Resolution Characterization of Plasmonic Hybridization in Silver Nanostructures
摘要： Surface plasmon resonances (SPR) in metallic nanostructures arise from the collective oscillation of conduction electrons, which create strong confined electric fields around the nanostructures. This confinement of electromagnetic (EM) energy at nanoscale dimensions holds potential towards the miniaturization of photonic devices [1]. Tremendous effort has been devoted towards optimization and design of nanostructures for several applications [2,3,4]. Most of these applications involve arrays of closely-spaced nanostructures: the plasmonic properties of the array differ from those of its isolated parts due to the interaction of evanescent fields. The study of SPR in these arrays, in particular the coupling of resonant modes, requires a characterization technique with both high spatial and energy resolution. Electron energy loss spectroscopy (EELS) meets these requirements, but has previously been limited to energies in the range of visible light or higher, mainly because of the relative intensities of the zero loss peak (ZLP) and low energy loss signal.
关键词： electron energy loss spectroscopy,metallic nanostructures,Surface plasmon resonances,hybridization,silver nanostructures
更新于2025-09-19 17:13:59
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ITC‐2Cl: a Versatile Middle‐Bandgap Nonfullerene Acceptor for High‐Efficiency Panchromatic Ternary Organic Solar Cells
摘要： An effective way to improve the power conversion efficiency of organic solar cells (OSCs) is to use the ternary architecture consisting of a donor, an acceptor, and a third component. Identifying the proper third component for successful ternary OSCs, however, is not an easy task. Here, we demonstrate that a middle-bandgap acceptor, ITC-2Cl, functions as a successful third component for several wide-bandgap donor: ultra-narrow bandgap acceptor binary systems (PBDB-T-2F: F8IC, PBDB-T-2F: IOIC-2Cl, PBDB-T-2Cl: IOIC-2Cl). Photovoltaic parameters, including VOC, JSC, FF, and PCE, are effectively improved by incorporating ITC-2Cl, which lies in the complementary absorption of ITC-2Cl and host binary system, high-lying LUMO level of ITC-2Cl, and the inhibition of bimolecular recombination. The ternary device based on PBDB-T-2Cl: ITC-2Cl: IOIC-2Cl achieves a champion PCE of 14.75% (certified as 13.78%) with a very low energy loss of 0.48 eV. These results provide critical insight into the ternary strategy and encourage re-evaluation and re-study of the photoactive materials previously reported with moderate performance.
关键词： ternary organic solar cells,non-fullerene acceptor,panchromatic,energy loss
更新于2025-09-19 17:13:59
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Ternary organic solar cells with NC70BA as a third component material exhibit high open-circuit voltage and small energy losses
摘要： The ternary organic solar cells (OSCs) were fabricated with PBDB-T as donor and a blend of IEICO-4F and NC70BA as the acceptor and the power conversion efficiency (PCE) reaches 10.92%. Due to good compatibility and cascade LUMO level among PBDB-T, a large amount of IEICO-4F and a small amount of NC70BA (the ratio of IEICO-4F:NC70BA is 85:15), which beneficial for adjusting lowest unoccupied molecular orbital (LUMO) levels of blend acceptor and wide energy offset between the donor and acceptor materials, leading to the enhancement of the open-circuit voltage (VOC). The optimized ternary PBDB-T:IEICO-4F:NC70BA films is more efficient exciton dissociation and suppress charge carrier recombination than that of binary PBDB-T:IEICO-4F and PBDB-T:NC70BA films, leading to small energy losses. In addition, this approach maintains PCE without sacrificing short-circuit current density (JSC) and fill factor (FF), even if the weak long and near-infrared wavelength photon harvesting. A more than 10% PCE improvement is achieve by employing a ternary strategy in comparison to PBDB-T:IEICO-4F-based binary OSCs with a PCE of 9.87%. Simultaneously, the optimized ternary PBDB-T:IEICO-4F:NC70BA OSCs exhibit the excellent thermal stability and 78.8% initial PCE under thermal annealing treatment at 80°C for 20 h.
关键词： Energy loss,Charge carrier recombination,Exciton dissociation
更新于2025-09-16 10:30:52
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Nitrogen plasma treatment of ZnO and TiO2 nanowire arrays for polymer photovoltaic applications
摘要： This work reports on a simple, yet unique approach to improving the opto-electronic properties of vertically-aligned arrays of rutile TiO2 and Wurzite ZnO nanowires by means of controlled nitrogen doping during exposure to highly kinetic radio-frequency generated N2 plasma radicals. Morphologically, the plasma treatment causes a distortion of the vertical alignment of the nanowires due to a dissociation of the weak Van der Waals force clustering the nanowires. Optical spectroscopy show that plasma treatment increases the light transmission of TiO2 arrays from 48% to 90%, with the ZnO arrays exhibiting an increase from 70% to 90% in the visible to UV range. The as-synthesized TiO2 array has an indirect band gap of 3.13 eV, which reduces to 3.03 eV after N2 treatment, with the ZnO equivalent decreasing from 3.20 to 3.17 eV post plasma exposure. A study of the 3d transition metal near edge fine structure of both Ti and Zn show that the N2 plasma treatment of the nanowires results in nitrogen doping of both TiO2 and ZnO lattices; this is confirmed by scanning transmission electron microscopy coupled with energy dispersive spectroscopy x-ray maps collected of single nanowires, which show a clear distribution of nitrogen throughout the metal-oxide. Application of these structures in P3HT:PCBM polymer blends shows progressive improvement in the photoluminescence quenching of the photoactive layer when incorporating both undoped and nitrogen-doped nanowires.
关键词： Electron energy loss spectroscopy,RF plasma nitrogen doping,One-dimensional nanowire arrays,Hydrothermal synthesis
更新于2025-09-16 10:30:52
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Fluorine Tuning of Morphology, Energy Loss, and Carrier Dynamics in Perylenediimide Polymer Solar Cells
摘要： We investigate backbone fluorination effects in bulk-heterojunction (BHJ) polymer solar cells (PSCs) with the fluorine-poor PBDTT-FTTE and fluorine-rich PBDTTF-FTTE donor polymers, paired with the perylenediimide (PDI) 3D “propeller acceptor” Ph(PDI)3. The PBDTTF-FTTE:Ph(PDI)3 devices exhibit a > 50 % power conversion efficiency (PCE, up to 9.1%) increase versus PBDTT-FTTE:Ph(PDI)3. This enhancement reflects structurally optimized phase separation due to templating effects, affording reduced energy loss, higher electron mobility, greater free charge lifetimes and yields, and lower bimolecular recombination, as quantified by UPS, AFM, TEM, GIWAXS, SCLC, light intensity dependence measurements, and fs/ns transient absorption (TA) spectroscopy. In PBDTTF-FTTE, the DFT-computed dipole orientations of the ground and excitonic states is nearly antiparallel, explaining the longer free charge lifetimes, minimized recombination, and lowered exciton binding energy. The PBDTTF-FTTE:Ph(PDI)3 performance enhancement vs. that of the fluorine-poor PBDTT-FTTE:Ph(PDI)3 analogue as well as the overall PSC performance exceeds that of the corresponding PC71BM- and ITIC-Th-based cells.
关键词： Perylenediimide,Energy loss,Fluorine tuning,Carrier dynamics,Morphology,Polymer solar cells
更新于2025-09-16 10:30:52
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13.7% Efficiency Small‐Molecule Solar Cells Enabled by a Combination of Material and Morphology Optimization
摘要： Compared with the quick development of polymer solar cells, achieving high-efficiency small-molecule solar cells (SMSCs) remains highly challenging, as they are limited by the lack of matched materials and morphology control to a great extent. Herein, two small molecules, BSFTR and Y6, which possess broad as well as matched absorption and energy levels, are applied in SMSCs. Morphology optimization with sequential solvent vapor and thermal annealing makes their blend films show proper crystallinity, balanced and high mobilities, and favorable phase separation, which is conducive for exciton dissociation, charge transport, and extraction. These contribute to a remarkable power conversion efficiency up to 13.69% with an open-circuit voltage of 0.85 V, a high short-circuit current of 23.16 mA cm?2 and a fill factor of 69.66%, which is the highest value among binary SMSCs ever reported. This result indicates that a combination of materials with matched photoelectric properties and subtle morphology control is the inevitable route to high-performance SMSCs.
关键词： morphology,energy loss,power conversion efficiency,small-molecule solar cells,nonfullerene acceptors
更新于2025-09-12 10:27:22
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Plasmonic Oligomers with Tunable Conductive Nanojunctions
摘要： Engineering plasmonic hot-spots is essential for applications of plasmonic nanoparticles. A particularly appealing route is to weld plasmonic nanoparticles together to form more complex structures sustaining plasmons with symmetries targeted to given applications. However, the control of the welding and subsequent hotspot characteristic is still challenging. Herein, we demonstrate an original method that connects gold particles to their neighbors by another metal of choice. We first assemble gold bipyramids in a tip-to-tip configuration, yielding short chains of variable length and grow metallic junctions in a second step. We follow the chain formation and the deposition of the second metal (i.e. silver or palladium) via UV/Vis spectroscopy and we map the plasmonic properties using electron energy loss spectroscopy. The formation of silver bridges leads to a huge redshift of the longitudinal plasmon modes into the mid-infrared region, while the addition of palladium results in a redshift accompanied by significant plasmon damping.
关键词： UV/Vis spectroscopy,Tunable conductive nanojunctions,Palladium,Plasmonic oligomers,Gold bipyramids,Electron Energy Loss Spectroscopy,Silver bridges
更新于2025-09-12 10:27:22
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New Conjugated Polymers Based on Dithieno[2,3‐e:3′,2′‐g]Isoindole‐7,9(8H)‐Dione Derivatives for Applications in Nonfullerene Polymer Solar Cells
摘要： We have designed two new wide bandgap A1-D1-A2-D1 conjugated polymers with same dithieno[2,3-e:3’,2’-g]isoindole-7,9(8H)-dione (DTID) acceptor (A1) and D1 (thiophene donor) and different A2 acceptor units i.e. benzothiadiazole (BT) and fluorinated benzothiadiazole (f-BT) denoted as P113 and P114 and investigated the effect of fluorination the benzothiadiazole acceptor unit on photovoltaic properties of polymer solar cells using non-fullerene acceptor. We found that the incorporation of fluorine atom into the benzothiadiazole acceptor unit increases the absorption coefficients and the relative dielectric constant. The increase in the photoluminescence quenching, reduction in charge recombination loss and improvement in the charge carrier life are observed for the P114. These all factors resulted in dramatically improved the power conversion efficiency of P114:ITIC-m based polymer solar cell to 10.42 % with small energy loss of 0.56 eV as compared to P113 counterpart (8.74 % with energy loss of 0.69 eV) under identical conditions. The low energy loss is beneficial to overcome the trade-off between open circuit voltage and short circuit current.
关键词： low energy loss,dielectric constant,Polymer solar cells,power conversion efficiency,fluorinated backbone
更新于2025-09-12 10:27:22