- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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A unified figure of merit for interband and intersubband cascade devices
摘要： By exploring a semi-empirical model, the saturation current density J0 is identified to manifest the significant difference in carrier lifetime between interband cascade devices (ICDs) and intersubband quantum cascade devices (QCDs). Based on this model, the values of J0 have been extracted for a large number of ICDs and QCDs from their current-voltage characteristics at room temperature. By analyzing and comparing available ICD and QCD data, we demonstrate how J0 can be used as a unified figure of merit to evaluate both interband and intersubband cascade configurations for their device functionality. The significance of J0 on the performances of mid-infrared detectors and photovoltaic cells is illustrated by comparing the measured detectivity (D*) and the estimated open-circuit voltage (Voc), respectively. From extracted values of J0, which are more than one order of magnitude lower in ICDs than that in QCDs with similar transition energies in active regions, and discussion of the consequences on device performance, the advantages of interband cascade configurations over intersubband quantum cascade configurations have been clearly revealed based on the same framework. The overall picture for both QCDs and ICDs sheds light from the perspective of a united figure of merit, which will provide useful guidance and stimulation to the future development of both ICDs and QCDs.
关键词： Saturation current density,Interband cascade,Quantum cascade,Open-circuit voltage
更新于2025-09-23 15:22:29
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Sputtered and selenized Sb2Se3 thin-film solar cells with open-circuit voltage exceeding 500??mV
摘要： Antimony selenide (Sb2Se3) is a potential absorber material for environment-friendly and cost-efficient photovoltaics and has achieved considerable progress in recent years. However, the severe open-circuit voltage (Voc) deficit ascribed to the interface and/or bulk defect states has become the main obstacle for further efficiency improvement. In this work, Sb2Se3 absorber layer was prepared by an effective combination reaction involving sputtered and selenized Sb precursor thin films. The self-assembled growth of Sb2Se3 thin films with large crystal grains, benign preferential orientation, and accurate chemical composition were successfully fulfilled under an appropriate thickness of Sb precursor and an optimized selenization scenario. Substrate structured Sb2Se3 thin-film solar cells, a champion device with a power-conversion efficiency of 6.84%, were fabricated. This device is comparable to state-of-the-art ones and represents the highest efficiency of sputtered Sb2Se3 solar cells. Importantly, the high Voc of 504 mV is closely related to the reduced deep level defect density for the Sb2Se3 absorber layer, the passivated interfacial defects for Sb2Se3/CdS heterojunction interface, and the additional heterojunction heat treatment-induced Cd and S inter-diffusion. This significantly improved Voc demonstrates remarkable potential to broaden its scope of applications for Sb2Se3 solar cells.
关键词： Open-circuit voltage,Selenization,Sb2Se3 solar Cell,Elemental inter-diffusion,Sputtering
更新于2025-09-23 15:21:01
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[IEEE 2020 IEEE 11th Latin American Symposium on Circuits & Systems (LASCAS) - San Jose, Costa Rica (2020.2.25-2020.2.28)] 2020 IEEE 11th Latin American Symposium on Circuits & Systems (LASCAS) - Advancing Uncooled Infrared Imagers Using An Open-Circuit Voltage Pixel
摘要： A topology leveraging a photodetector in the forward bias region generating an open-circuit voltage is proposed. Connecting the anode of the photodetector to the gate of a MOSFET device operating in the subthreshold region provides the basis for a new open-circuit voltage pixel (VocP). Theoretical analysis outlining the effective photodetector response and performance benefits is described. An integrated circuit (IC) with direct-injection pixels modified to support the VocP front-end and analog output readout fabricated in a CMOS 0.18 μm technology is also presented. The IC allows testing of mid-wave infrared (IR) photodiodes operating in both the photocurrent and VocP modes. The VocP pixel is compared to a traditional reverse bias current mode photodetector configuration. Simulation, modeling, and measurement show improved sensitivity and faster response time for the VocP over direct photocurrent detection.
关键词： model,ROIC,open-circuit voltage,readout,MWIR,Mid-wave,Voc
更新于2025-09-23 15:21:01
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Reduced Non-radiative Recombination Energy Loss Enabled Efficient Polymer Solar Cells via Tuning Alkyl Chain Positions on Pendent Benzene Units of Polymers
摘要： Non-radiative recombination energy loss (ΔE3) plays a key role in enhancing device efficiencies for polymer solar cells (PSCs). Up to now, there is no clear resolution for reducing ΔE3 via molecular design. Herein, we report two conjugated polymers, PBDB-P-p and PBDB-P-m, which are integrated from benzo[1,2-b:4,5-b′]dithiophene (BDT) with alkylthio chain substituted at para- or meta- position on pendent benzene and benzo[1,2-c:4,5-c′]dithiophene-4,8-dione (BDD). Two polymers have different temperature-dependent aggregation properties, but similar molecular energy levels. When BO-4Cl was used as acceptor to fabricate PSCs, the device of PBDB-P-p:BO-4Cl displayed a maximal power conversion efficiency (PCE) of 13.83%, while the best device of PBDB-P-m:BO-4Cl exhibited a higher PCE of 14.12%. The close JSCs and FFs in both PSCs are attributed to their formation of effective nanoscale phase-separation as confirmed by atomic force microscopy (AFM) measurements. We find that the PBDB-P-m-based device has one order of magnitude higher of electroluminescence quantum efficiency (EQEEL) than that in PBDB-P-p-based one, which could arise from the relatively weak aggregation in PBDB-P-m-based film. Thus, the PBDB-P-m-based device has a remarkably enhanced VOC of 0.86 V in contrast to 0.80 V in PBDB-P-p-based device. This study offers a feasible structural optimization way on the alkylthio side chain substitute position on the conjugated polymer to enhance VOC by reducing non-radiative recombination energy loss in resulting PSCs.
关键词： polymer solar cells,open-circuit voltage,non-radiative recombination energy loss,polymer donor,alkylthio substituted position
更新于2025-09-23 15:21:01
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Indenea??C <sub/>60</sub> Bisadduct Electron Transporting Material with the High LUMO Level Enhances Open-Circuit Voltage and Efficiency of Tin-Based Perovskite Solar Cells
摘要： Tin-based halide perovskite materials are promising eco-friendly light absorbers with similar optoelectronic properties to lead-based ones. However, their solar cells have suffered from considerably low open-circuit voltage (VOC) arising from mismatched energy levels between tin-based perovskite and charge-transporting layers because they imitate typical device structures developed for lead-based ones. Herein we report the unoccupied molecular orbital (LUMO) level of electron transporting layer (ETL) significantly affects VOC of tin-based perovskite solar cells (PSCs) in contrast to lead-based ones. The indene?C60 bisadduct (ICBA) ETL with the much higher LUMO level than typical ETLs decreases an energy off-set with the conduction band minimum of mixed formamidinium/phenylethylammonium tin iodide (FA0.9PEA0.1SnI3)-based perovskite material. The resultantly reduced VOC loss at their interface gives a VOC of 0.651 V, the highest to date for FASnI3-based PSCs. An achieved champion PCEs reaches 7.05%. This result highlights the importance of redesigning device structures dedicated to tin-based PSCs.
关键词： open-circuit voltage,electron transportation,perovskite solar cells,lead-free,tin
更新于2025-09-23 15:21:01
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Direct nanoscale mapping of open circuit voltages at local back surface fields for PERC solar cells
摘要： The open circuit voltage (VOC) is a critical and common indicator of solar cell performance as well as degradation, for panel down to lab-scale photovoltaics. Detecting VOC at the nanoscale is much more challenging, however, due to experimental limitations on spatial resolution, voltage resolution, and/or measurement times. Accordingly, an approach based on Conductive Atomic Force Microscopy is implemented to directly detect the local VOC, notably for monocrystalline Passivated Emitter Rear Contact (PERC) cells which are the most common industrial-scale solar panel technology in production worldwide. This is demonstrated with cross-sectioned monocrystalline PERC cells around the entire circumference of a poly-aluminum-silicide via through the rear emitter. The VOC maps reveal a local back surface ?eld extending * 2 lm into the underlying p-type Si absorber due to Al in-diffusion as designed. Such high spatial resolution methods for photovoltaic performance mapping are especially promising for directly visualizing the effects of processing parameters, as well as identifying signatures of degradation for silicon and other solar cell technologies.
关键词： solar cell,nanoscale,Conductive Atomic Force Microscopy,open circuit voltage,PERC cells
更新于2025-09-23 15:21:01
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Ideal alloys of two donor isomers with non-covalently conformational locking for ternary organic solar cells
摘要： Ternary organic solar cells (OSCs) based on the alloy model have great potential in maximizing the improvement of device performance due to the probability of simultaneously enhancing the photocurrent through morphology optimization and improving open circuit voltage (Voc) by energy level adjustment. However, rationally designing compatible materials and constructing an effective alloy remain difficult. In this manuscript, two donor isomers, BT-TO-ID and BT-OT-ID with non-covalently conformational locking of alkoxy groups at different position, were designed and synthesized to obtain an ‘‘ideal alloy’’. A linearly tunable Voc was observed between the Voc limitation of binary blends with the changes of the composition across the full range, indicating the behavior of an ideal alloy in the ternary blends. A face-on molecular packing and an appropriate phase separation was observed in the ternary blends due to the strong interactions between the two isomers, which facilitated charge transport and charge recombination suppression. Notable improvements of 76% and 29% in device performance were obtained for the ternary blends compared with BT-OT-ID based and BT-OT-ID based binary devices, respectively. Therefore, this work provided a probable molecular design strategy to guide the construction of an effective alloy in ternary OSCs.
关键词： Open circuit voltage,Non-covalently conformational locking,Alloy model,Device performance,Molecular packing,Phase separation,Ternary organic solar cells,Donor isomers
更新于2025-09-23 15:21:01
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Energetics and Energy Loss in 2D Ruddlesdena??Popper Perovskite Solar Cells
摘要： 2D Ruddlesden–Popper perovskites (RPPs) are emerging as potential challengers to their 3D counterpart due to superior stability and competitive efficiency. However, the fundamental questions on energetics of the 2D RPPs are not well understood. Here, the energetics at (PEA)2(MA)n?1PbnI3n+1/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) interfaces with varying n values of 1, 3, 5, 40, and ∞ are systematically investigated. It is found that n–n junctions form at the 2D RPP interfaces (n = 3, 5, and 40), instead of p–n junctions in the pure 2D and 3D scenarios (n = 1 and ∞). The potential gradient across phenethylammonium iodide ligands that significantly decreases surface work function, promotes separation of the photogenerated charge carriers with electron transferring from perovskite crystal to ligand at the interface, reducing charge recombination, which contributes to the smallest energy loss and the highest open-circuit voltage (Voc) in the perovskite solar cells (PSCs) based on the 2D RPP (n = 5)/PCBM. The mechanism is further verified by inserting a thin 2D RPP capping layer between pure 3D perovskite and PCBM in PSCs, causing the Voc to evidently increase by 94 mV. Capacitance–voltage measurements with Mott–Schottky analysis demonstrate that such Voc improvement is attributed to the enhanced potential at the interface.
关键词： energy loss,2D Ruddlesden–Popper perovskites,open-circuit voltage,perovskite solar cells,energetics
更新于2025-09-23 15:21:01
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Alternative buffer layers in Sb2Se3 thina??film solar cells to reduce opena??circuit voltage offset
摘要： Antimony Selenide (Sb2Se3) thin-film solar cell configurations with alternative buffer layers are proposed to improve the efficiency by minimizing open‐circuit voltage offset (Voc,offset). The conduction band offsets have been optimized not only at absorber/buffer (ΔEC‐BA) but also at buffer/transparent conductive oxide (ΔEC-TB). Voltage‐independent recombination rates in the quasi‐neutral region (Rb0), and at the absorber/buffer interface (Ri0) of the Sb2Se3 solar cells with various configurations are individually modelled. The development of cell configurations causes to decrease the Ri0, and Rb0, consequently reducing the Voc,offset. It is found that the solar cell configuration of Mo/MoSe2/Sb2Se3/TiO2/ZnO0.4S0.6/Zn0.93Mg0.07O/ZnO:Al is suitable with the ΔEC‐BA of 0.29 eV and ΔEC‐TB of ?0.2 eV, therefore considerably reducing Voc,offset to approximately 0.52 V, and improving the efficiency to 15.46%.
关键词： Recombination rate,Sb2Se3,Open‐circuit voltage offset,Device configuration,Alternative buffer layers
更新于2025-09-23 15:21:01
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Examination of relationship between Urbach energy and open-circuit voltage deficit of flexible Cu(In,Ga)Se <sub/>2</sub> solar cell for its improved photovoltaic performance
摘要： Flexible Cu(In,Ga)Se2 (CIGSe) solar cells on stainless steel (SUS) substrates are developed. The contribution concentrates on the investigation of the correlation between Urbach energy (EU) and open-circuit voltage deficit (VOC,def). The several CIGSe solar cells on soda-lime glass and SUS substrates with various VOC,def values are fabricated through the variations of [Ga]/([Ga]+[In]) ratio (GGI), substrate temperature (TSUB) and Fe concentration of their CIGSe absorbers. The EU is determined based on external quantum efficiency in the long-wavelength edge. It is determined that the EU is influenced by the GGI, TSUB and Fe concentration. The EU is well consistent with the carrier lifetimes and can be an indicator of the CIGSe quality. In addition, the relationship between EU and VOC,def is obviously observed, where the decrease in the EU by 1 meV reduces the VOC,def by 8.6 mV. Through the optimizations of GGI and TSUB as well as the minimization of Fe concentration, the EU is obviously reduced, which implies the improvement of the CIGSe quality. Ultimately, the high η of 17.9% for the flexible CIGSe solar cell on SUS substrate is attained.
关键词： Cu(In,Ga)Se2,stainless steel substrate,TRPL carrier lifetime,Urbach energy,open-circuit voltage deficit
更新于2025-09-23 15:19:57