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Elimination of Light-Soaking Effect in Hysteresis-Free Perovskite Solar Cells by Interfacial Modification
摘要： The hysteresis and light-soaking effect have been observed in organo-metal halide perovskite solar cells (PSCs) under operating conditions, which inhibit the precise evaluation of power output. The mechanisms leading to these effects are little understood. Here, our studies have demonstrated that the light-soaking effect is related to the electron selective layer/perovskite interface in hysteresis-free PSCs. The introduction of [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) doped with CH3NH3I molecules as the interfacial layer can effectively release or eliminate this effect due to the efficient charge transfer, accompanied with the best stable output efficiency of 19% and an ultrahigh fill factor over 84%. Capacitance -voltage and capacitance -frequency curves derived from electrochemical impedance spectroscopy demonstrate that the light-soaking effect in PSCs mainly originates from the charge accumulation at the PC61BM/perovskite interface. The CH3NH3I doped in PC61BM forestalls the ion movement among the perovskite and thus eliminate the light-soaking effect. Furthermore, a model that combines ion migration and charge accumulation process to interpret the light-soaking effect and performance improvement in PSCs is proposed.
关键词： perovskite solar cells,light-soaking effect,hysteresis,charge transfer,interfacial modification
更新于2025-09-12 10:27:22
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Strontium Chloride Passivated Perovskite Thin Films for Efficient Solar Cells with Power Conversion Efficiency over 21% and Superior Stability
摘要： Industrialization of perovskite solar cells (PSCs) is constrained by adverse stability in the air. Herein, we report an effective strontium chloride (SrCl2) passivation upon the HC(NH2)2-CH3NH3 (FA-MA) based perovskite thin films for the suppression of non-radiative recombination. Moreover, the recombination dynamics, crystallinity, carrier transport, morphology and the elemental stoichiometry of this film were systematically studied. By optimizing the concentration of SrCl2, the corresponding devices exhibited an increased open-circuit voltage (1.00 V vs 1.09 V), in consistent with the enhanced photoluminescence lifetime. The champion passivated device showed a ascendant power conversion efficiency (PCE) about 21.11% , with over 90% retention of the primal PCE in dry air after 1000 h aging with 20% ~ 30% humidity. A superior stability and an accelerated eletron/hole extraction ability were futher observed by time-resolved photoluminescence (TRPL) spectroscopy.
关键词： Charge-transport,High-performance,Spin coating,Crystallzation,Hysteresis,Ion migration
更新于2025-09-12 10:27:22
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Doped but stable: spirobisacridine hole transporting materials for hysteresis-free and stable perovskite solar cells
摘要： Four spirobisacridine (SBA) hole-transporting materials were synthesized and employed in perovskite solar cells (PSC). The molecules bear electronically inert alkyl chains of different length and bulkiness, attached to in-plane N-atoms of nearly orthogonal spiro-connected acridines. Di-p-methoxyphenylamine (DMPA) substituents tailored to the central SBA-platform define electronic properties of the materials mimicking the structure of the benchmark 2,2’,7,7’-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9’-spirobifluorene (spiro-MeOTAD), while the alkyl pending groups affect molecular packing in thin film and affect long-term performance of PSCs. Devices with SBA-based hole transporting layers (HTL) attain efficiencies on par with spiro-MeOTAD. More importantly, solar cells with the new HTMs are hysteresis-free and demonstrate good operational stability, despite being doped as spiro-MeOTAD. The best performing MeSBA-DMPA retained 88% of the initial efficiency after 1000 h ageing test under a constant illumination. The results clearly demonstrate: SBA-based compounds are potent candidates for a design of new HTMs for PSCs with improved longevity.
关键词： perovskite solar cells,hysteresis-free,spirobisacridine,operational stability,hole-transporting materials
更新于2025-09-12 10:27:22
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A Bouc–Wen Model-Based Compensation of the Frequency-Dependent Hysteresis of a Piezoelectric Actuator Exhibiting Odd Harmonic Oscillation
摘要： This paper proposes an enhancement of the Bouc–Wen hysteresis model to capture the frequency-dependent hysteretic behavior of a thin bimorph-type piezoelectric actuator which also exhibits odd harmonic oscillation (OHO) at specific input frequencies. The odd harmonic repetitive controller has recently been proposed to compensate for the hysteresis, and attenuates the OHO of the piezoelectric actuator for which the hysteresis nonlinearity is regarded as a disturbance. This paper proposes an alternate treatment of the hysteresis compensation with the attenuation of the OHO observed at some input frequencies. It will be shown that the proposed compensator fully utilizes the mathematical structure of the enhanced Bouc–Wen model proposed in this paper to compensate the hysteresis and to attenuate the OHO. The results of the hysteresis compensation experiment illustrate the excellent performance of the proposed control system, especially at the frequencies where OHO is conspicuous.
关键词： Bouc–Wen model,hysteresis compensation,hysteresis modeling,odd harmonic oscillation,piezoelectric actuator
更新于2025-09-11 14:15:04
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Enhanced Incorporation of Guanidinium in Formamidinium‐Based Perovskites for Efficient and Stable Photovoltaics: The Role of Cs and Br
摘要： Recently, incorporating guanidium (GA) cations into organolead halide perovskites is shown to effectively improve the stability and performance of the solar cells. However, the underlying mechanisms that govern the GA incorporation have remained unclear. Here, FAPbI3 is used as a basic framework to investigate experimentally and theoretically the role of cesium (Cs) and bromine (Br) substitutions in GA+ incorporation. It is found that simultaneous introduction of the small-size Cs+ and Br– in the FAPbI3 lattice is critical to create sufficient space for the large GA+ and that the presence of the Cs+ prevents the formation of a GA-contained low-dimensional phase, which both assist GA+ incorporation. Upon entering the perovskite lattice, the GA+ can stabilize the lattice structure via forming strong hydrogen bonds with their neighboring halide ions. Such structure modification suppresses halide vacancy formation, thus leading to improved material properties. Compared to the GA-free perovskite reference samples, the optimal system GA0.05Cs0.15FA0.8Pb(I0.85Br0.15)3 exhibits substantially improved thermal and photothermal stability, as well as increased photocarrier lifetime. Solar cells fabricated with the optimal material system show an excellent photovoltaic performance, with the champion device reaching a power conversion efficiency of 21.3% and an open circuit voltage of 1.229 V.
关键词： DFT calculations,methylammonium-free,guanidium incorporation,hysteresis
更新于2025-09-11 14:15:04
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Study on Shunt Active Power Filter Control Strategies of Three-phase Grid-connected Photovoltaic Systems
摘要： This paper deals with the improvement of the energy quality using shunt active power filter. The three-phase grid-connected photovoltaic generator consists in solar panels, a three-phase voltage inverter connected to the grid and a nonlinear load constituted by a diode rectifier bridge supplying a resistive load in series with an inductor. In so doing, three main challenges arise from the application context. First, the harmonic currents and the reactive power must be compensated. The second challenge is the injection of active solar energy into the grid. Third, Maximum Power Point Tracking (MPPT) must be found. This paper proposes a method addressing those challenges. For the first and the second one, direct current and power controls is used. For the third challenge, an algorithm is proposed which take in account the electrical variables and the variation of the solar irradiation. Simulation results of the proposed method are shown. The method is illustrated with two different strategies: Hysteresis Control and Direct Power Control (DPC) for a variable load. Obtained results are presented and compared in this paper to confirm the robustness and the superiority of DPC strategy compared to Hysteresis Control strategy. In the same context, the simulation carried out in this article shows promising results with THD approximates 1.33 %.
关键词： photovoltaic system,MPPT,Direct Power Control,energy quality,Hysteresis Control
更新于2025-09-11 14:15:04
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Two-Step Annealing of NiO Enhances the NiO –Perovskite Interface for High-Performance Ambient-Stable p–i–n Perovskite Solar Cells
摘要： In this study, we applied two-step annealing to nickel oxide (NiOx) films that we then used in perovskite solar cells (PSCs). The optimized annealing process resulted in a change in the structure and chemical composition of the NiOx, leading to a change in the work function and improved conductivity for NiOx-coated ITO substrates. X-ray photoelectron spectroscopy suggested that a change in the Ni2+/Ni3+ ratio of NiO (Ni 2p at 854.0 eV) and the presence of Ni3+ species induced by vacancies in Ni2O3 (Ni 2p at 855.6 eV) and NiOOH (Ni 2p at 856.7 eV) were responsible for the enhanced conductivity of the two-step-annealed NiOx films. The modified NiOx served as an efficient hole transporting layer, enhancing the PL quenching behavior at the perovskite–NiOx interface. Time-resolved photoluminescence measurements provided evidence for efficient carrier extraction. These improvements led to increases in the fill factors and power conversion efficiencies (PCEs) of corresponding PSC devices. The champion device displayed a PCE of 19.04%—a value comparable with those of state-of-the-art NiOx-based PSCs. Furthermore, the devices possessed excellent air-stability, retaining 97% of their PCEs after storage in air for over 672 h (at 25 °C, with a humidity of 40%).
关键词： power conversion efficiency,Perovskite solar cell,nickel oxide,hysteresis
更新于2025-09-11 14:15:04
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High performance perovskites solar cells by hybrid perovskites co-crystallized with poly(ethylene oxide)
摘要： Hybrid perovskite materials have emerged as attractive alternatives for cost-effective solar cells in the past ten years. However, achieving hysteresis-free, stable and efficient solution-processed perovskites solar cells has remained as a significant fundamental challenge. In this study, we report a strategy that utilizes poly(ethylene oxide) to sequester the counter ions in the perovskite lattices to suppress the formation of point defects, reduce the migration of ions/vacancy and to facilitate crystal growth in a more thermodynamically preferred orientation. Systematical investigations indicate that poly(ethylene oxide) indeed form hydrogen bonds with perovskite, which reduces the formation of kinetically-driven point defects, minimize charge carrier recombination and sharpen the density of states distribution. As a result, un-encapsulated solution-processed perovskite solar cells exhibit stabilized power conversion efficiency with hysteresis-free characteristics and significantly improved ambient shelf- and thermal-stability at relative high humidity, in comparison to the reference devices that exhibit unstable power conversion efficiency with dramatically higher hysteresis factor and poorer device lifetime. Our studies demonstrate that development of hybrid perovskite materials co-crystallized with polymers is an efficient approach towards high performance perovskite solar cells.
关键词： photocurrent hysteresis,hydrogen bonding,stability,poly(ethylene oxide),power conversion efficiency,hybrid perovskite
更新于2025-09-11 14:15:04
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Dynamic Hysteresis Based Modeling Of Piezoelectric Actuators
摘要： Piezoelectric actuators are popularly applied as actuators in high precision systems due to their small displacement resolution, fast response and simple construction. However, the hysteresis nonlinear behavior limits the dynamic modeling and tracking control of piezoelectric actuators. This paper studies a dynamic model of a moving stage driven by piezoelectric stack actuator. The Bouc-Wen model is introduced and analyzed to express the nonlinear hysteresis term. Two triangular actuating voltages with frequency of 1 Hz and amplitudes of 80 V and 90 V are applied to drive the piezoelectric stack actuator. The results demonstrate the existence of the hysteresis phenomenon between the input voltage and the output displacement of the piezoelectric stack actuator, and validate the correctness of the model.
关键词： Bouc-Wen model,hysteresis modeling,Piezoelectric actuator
更新于2025-09-11 14:15:04
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Hysteretic modeling and simulation of a bilateral piezoelectric stack actuator based on Preisach model
摘要： A bilateral piezoelectric stack actuator (BPSA) is introduced, and its actuated property is also analyzed. Usually, a piezoelectric stack can only undertake significant compressive loads but cannot tolerate tension, while this new actuator is able to generate obvious bilateral actuated outputs. The actuated principle of the new actuator is analyzed firstly. The linear and nonlinear models are also built up. The latter is to analyze the piezoelectric hysteresis based on the classical Preisach model. Moreover, the effect of the preload on the actuator is considered. By comparison with the experiment results, the Preisach model is valid for the present actuator.
关键词： piezoelectric hysteresis,Preisach model,preload,Bilateral piezoelectric stack actuator
更新于2025-09-11 14:15:04