We present a novel numerical model and simulate preliminarily the charging process of a polymer subjected to electron irradiation of several 10 keV. The model includes the simultaneous processes of electron scattering...We present a novel numerical model and simulate preliminarily the charging process of a polymer subjected to electron irradiation of several 10 keV. The model includes the simultaneous processes of electron scattering and ambipolar transport and the influence of a self-consistent electric field on the scattering distribution of electrons. The dynamic spatial distribution of charges is obtained and validated by existing experimental data. Our simulations show that excess negative charges are concentrated near the edge of the electron range. However, the formed region of high charge density may extend to the surface and bottom of a kapton sample, due to the effects of the electric field on electron scattering and charge transport, respectively. Charge trapping is then demonstrated to significantly influence the charge motion. The charge distribution can be extended to the bottom as the trap density decreases. Charge accumulation is therefore balanced by the appearance and increase of leakage current. Accordingly, our model and numerical simulation provide a comprehensive insight into the charging dynamics of a polymer irradiated by electrons in the complex space environment.展开更多
Asymmetric behaviors of capacitance and charging dynamics in the cathode and anode are general for nanoporous supercapacitors.Understanding this behavior is essential for the optimal design of supercapacitors.Herein,w...Asymmetric behaviors of capacitance and charging dynamics in the cathode and anode are general for nanoporous supercapacitors.Understanding this behavior is essential for the optimal design of supercapacitors.Herein,we perform constant-potential molecular dynamics simulations to reveal asymmetric features of porous supercapacitors and their effects on capacitance and charging dynamics.Our simulations show that,counterintuitively,charging dynamics can be fast in pores providing slow ion diffusion and vice versa.Unlike electrodes with singlesize pores,multi-pore electrodes show overcharging and accelerated co-ion desorption,which can be attributed to the subtle interplay between the dynamics and charging mechanisms.We find that capacitance and charging dynamics correlate with how the ions respond to an applied cell voltage in the cathode and anode.We demonstrate that symmetrizing this response can help boost power density,which may find practical applications in supercapacitor optimization.展开更多
Herein,the impact of the independent control of processing additives on vertical phase separation in sequentially deposited (SD) organic photovoltaics (OPVs) and its subsequent effects on charge carrier kinetics at th...Herein,the impact of the independent control of processing additives on vertical phase separation in sequentially deposited (SD) organic photovoltaics (OPVs) and its subsequent effects on charge carrier kinetics at the electron donor-acceptor interface are investigated.The film morphology exhibits notable variations,significantly depending on the layer to which 1,8-diiodooctane (DIO) was applied.Grazing incidence wide-angle X-ray scattering analysis reveals distinctly separated donor/acceptor phases and vertical crystallinity details in SD films.Time-of-flight secondary ion mass spectrometry analysis is employed to obtain component distributions in diverse vertical phase structures of SD films depending on additive control.In addition,nanosecond transient absorption spectroscopy shows that DIO control significantly affects the dynamics of separated charges in SD films.In SD OPVs,DIO appears to act through distinct mechanisms with minimal restriction,depending on the applied layer.This study emphasizes the significance of morphological optimization in improving device performance and underscores the importance of independent additive control in the advancement of OPV technology.展开更多
Despite that organic-inorganic lead halide perovskites have attracted enormous scientific attention for energy conversion applications over the recent years,the influence of temperature and the type of the employed ho...Despite that organic-inorganic lead halide perovskites have attracted enormous scientific attention for energy conversion applications over the recent years,the influence of temperature and the type of the employed hole transport layer(HTL)on the charge carrier dynamics and recombination processes in perovskite photovoltaic devices is still largely unexplored.In particular,significant knowledge is missing on how these crucial parameters for radiative and non-radiative recombinations,as well as for efficient charge extraction vary among different perovskite crystalline phases that are induced by temperature variation.Herein,we perform micro photoluminescence(pPL)and ultrafast time resolved transient absorption spectroscopy(TAS)in Glass/Perovskite and two dierent Glass/ITO/HTL/Perovskite configurations at temperatures below room temperature,in order to probe the charge carrier dynamics of different perovskite crystalline phases,while considering also the effect of the employed HTL polymer.Namely,CH_(3)NH_(3)Pbb films were deposited on Glass,PEDOT:PSS and PTAA polymers,and the developed Glass/CH_(3)NH_(3)PbI_(3)and Glass/ITO/HTL/CH_(3)NH_(3)PbI_(3)architectures were studied from 85 K up to 215 K in order to explore the charge extraction dynamics of the CH_(3)NH_(3)PbI_(3)orthorhombic and tetragonal crystalline phases.It is observed an unusual blueshift of the bandgap with temperature and the dual emission at temperature below of 100 K and also,that the charge carrier dynamics,as expressed by hole injection times and free carrier recombination rates,are strongly depended on the actual pervoskite crystal phase,as well as,from the selected hole transport material.展开更多
Impedance spectroscopy has been increasingly employed in quantum dot light-emitting diodes(QLEDs)to investigate the charge dynamics and device physics.In this review,we introduce the mathematical basics of impedance s...Impedance spectroscopy has been increasingly employed in quantum dot light-emitting diodes(QLEDs)to investigate the charge dynamics and device physics.In this review,we introduce the mathematical basics of impedance spectroscopy that applied to QLEDs.In particular,we focus on the Nyquist plot,Mott-Schottky analysis,capacitance-frequency and capacitance-voltage characteristics,and the d C/d V measurement of the QLEDs.These impedance measurements can provide critical information on electrical parameters such as equivalent circuit models,characteristic time constants,charge injection and recombination points,and trap distribution of the QLEDs.However,this paper will also discuss the disadvantages and limitations of these measurements.Fundamentally,this review provides a deeper understanding of the device physics of QLEDs through the application of impedance spectroscopy,offering valuable insights into the analysis of performance loss and degradation mechanisms of QLEDs.展开更多
Van der Waals(VDW)heterojunctions in a 2D/2D contact provide the highest area for the separation and transfer of charge carriers.In this work,a top-down strategy with a gas erosion process was employed to fabricate a ...Van der Waals(VDW)heterojunctions in a 2D/2D contact provide the highest area for the separation and transfer of charge carriers.In this work,a top-down strategy with a gas erosion process was employed to fabricate a 2D/2D carbon nitride VDW heterojunction in carbon nitride(g-C_(3)N_(4))with carbon-rich carbon nitride.The created 2D semiconducting channel in the VDW structure exhibits enhanced electric field exposure and radiation absorption,which facilitates the separation of the charge carriers and their mobility.Consequently,compared with bulk g-C_(3)N_(4)and its nanosheets,the photocatalytic performance of the fabricated carbon nitride VDW heterojunction in the water splitting reaction to hydrogen is improved by 8.6 and 3.3 times,respectively,while maintaining satisfactory photo-stability.Mechanistically,the finite element method(FEM)was employed to evaluate and clarify the contributions of the formation of VDW heterojunction to enhanced photocatalysis,in agreement quantitatively with experimental ones.This study provides a new and effective strategy for the modification and more insights to performance improvement on polymeric semiconductors in photocatalysis and energy conversion.展开更多
As an alternative power solution for low-power devices, harvesting energy from the ambient mechanical vibration has received increasing research interest in recent years. In this paper we study the transient dynamic c...As an alternative power solution for low-power devices, harvesting energy from the ambient mechanical vibration has received increasing research interest in recent years. In this paper we study the transient dynamic characteristics of a piezoelectric energy harvesting system including a piezoelectric energy harvester, a bridge rectifier, and a storage capacitor. To accomplish this, this energy harvesting system is modeled, and the charging process of the storage capacitor is investigated by employing the in-phase assumption The results indicate that the charging voltage across the storage capacitor and the gathered power increase gradually as the charging process proceeds, whereas the charging rate slows down over time as the charging voltage approaches to the peak value of the piezoelectric voltage across the piezoelectric materials. In addition, due to the added electrical damping and the change of the system natural frequency when the charging process is initiated, a sudden drop in the vibration amplitude is observed, which in turn affects the charging rate. However, the vibration amplitude begins to increase as the charging process continues, which is caused by the decrease in the electrical damping (i.e., the decrease in the energy removed from the mechanical vibration). This electromechanical coupling characteristic is also revealed by the variation of the vibration amplitude with the charging voltage.展开更多
As the adoption of Electric Vehicles(EVs)intensifies,two primary challenges emerge:limited range due to battery constraints and extended charging times.The traditional charging stations,particularly those near highway...As the adoption of Electric Vehicles(EVs)intensifies,two primary challenges emerge:limited range due to battery constraints and extended charging times.The traditional charging stations,particularly those near highways,exacerbate these issues with necessary detours,inconsistent service levels,and unpredictable waiting durations.The emerging technology of dynamic wireless charging lanes(DWCLs)may alleviate range anxiety and eliminate long charging stops;however,the driving speed on DWCL significantly affects charging efficiency and effective charging time.Meanwhile,the existing research has addressed load balancing optimization on Dynamic Wireless Charging(DWC)systems to a limited extent.To address this critical issue,this study introduces an innovative eco-driving speed control strategy,providing a novel solution to the multi-objective optimization problem of speed control on DWCL.We utilize mathematical programming methods and incorporate the longitudinal dynamics of vehicles to provide an accurate physical model of EVs.Three objective functions are formulated to tackle the challenges at hand:reducing travel time,increasing charging efficiency,and achieving load balancing on DWCL,which corresponds to four control strategies.The results of numerical tests indicate that a comprehensive control strategy,which considers all objectives,achieves a minor sacrifice in travel time reduction while significantly improving energy efficiency and load balancing.Furthermore,by defining the energy demand and speed range through an upper operation limit,a relatively superior speed control strategy can be selected.This work contributes to the discourse on DWCL integration into modern transportation systems,enhancing the EV driving experience on major roads.展开更多
Photocatalytic conversion of CO_(2) to high-value products plays a crucial role in the global pursuit of carbon–neutral economy.Junction photocatalysts,such as the isotype heterojunctions,offer an ideal paradigm to n...Photocatalytic conversion of CO_(2) to high-value products plays a crucial role in the global pursuit of carbon–neutral economy.Junction photocatalysts,such as the isotype heterojunctions,offer an ideal paradigm to navigate the photocatalytic CO_(2) reduction reaction(CRR).Herein,we elucidate the behaviors of isotype heterojunctions toward photocatalytic CRR over a representative photocatalyst,g-C_(3)N_(4).Impressively,the isotype heterojunctions possess a significantly higher efficiency for the spatial separation and transfer of photogenerated carriers than the single components.Along with the intrinsically outstanding stability,the isotype heterojunctions exhibit an exceptional and stable activity toward the CO_(2) photoreduction to CO.More importantly,by combining quantitative in situ technique with the first-principles modeling,we elucidate that the enhanced photoinduced charge dynamics promotes the production of key intermediates and thus the whole reaction kinetics.展开更多
A repeated interdiffusion method is described for phase-stable and high-quality (FA,MA)PbI3 film. The crys- tallization and growth of the perovskite films can be well controlled by adjusting the reactant concentrati...A repeated interdiffusion method is described for phase-stable and high-quality (FA,MA)PbI3 film. The crys- tallization and growth of the perovskite films can be well controlled by adjusting the reactant concentrations. With this method, dense, smooth perovskite films with large crystals have been obtained. Finally, a PCE of 16.5% as well as a steady-state efficiency of 16.3% is achieved in the planar perovskite solar cell.展开更多
Lead-free double perovskite Cs_(2)AgBiBr_(6) has gained increasing attention recently.However,the power conversion efficiency(PCE)of Cs_(2)AgBiBr_(6) perovskite solar cells(PSCs)is still low compared with their lead-b...Lead-free double perovskite Cs_(2)AgBiBr_(6) has gained increasing attention recently.However,the power conversion efficiency(PCE)of Cs_(2)AgBiBr_(6) perovskite solar cells(PSCs)is still low compared with their lead-based counterparts.Here,by using photoluminescence(PL),time-resolved photoluminescence(TRPL),and ultrafast transient absorption(TA)measurements,the unbalance between the electron and hole in diffusion and transfer,which limits the performance of the Cs_(2)AgBiBr_(6) PSCs,was further revealed.Considering this issue,a strategy of using the mesoporous TiO_(2) electron transport layer(ETL)to construct a bulk heterojunction in Cs_(2)AgBiBr_(6) PSCs was proposed.Consequently,the PCE had improved by over 24%comparing with that only used compact TiO_(2) ETL.Moreover,based on mesoporous TiO_(2),the unencapsulated Cs_(2)AgBiBr_(6) PSCs maintained 90%of their initial performance after approximately 1200 h of storage in a desiccator(humidity~30%).This work gives further understanding of Cs_(2)AgBiBr_(6) perovskite and demonstrates that a proper design of balancing the electron and hole diffusion can improve device performance.展开更多
Amid escalating energy crises and environmental pressures,electric vehicles(EVs)have emerged as an effective measure to reduce reliance on fossil fuels,combat climate change,uphold sustainable energy and environmental...Amid escalating energy crises and environmental pressures,electric vehicles(EVs)have emerged as an effective measure to reduce reliance on fossil fuels,combat climate change,uphold sustainable energy and environmental development,and strive towards carbon peaking and neutrality goals.This study introduces a nonlinear integer programming model for the deployment of dynamic wireless charging lanes(DWCLs)and EV charging strategy joint optimization in highway networks.Taking into account established charging resources in highway service areas(HSAs),the nonlinear charging characteristics of EV batteries,and the traffic capacity constraints of DWCLs.The model identifies the deployment of charging facilities and the EV charging strategy as the decision-making variables and aims to minimize both the DWCL construction and user charging costs.By ensuring that EVs maintain an acceptable state of charge(SoC),the model combines highway EV charging demand and highway EV charging strategy to optimize the DWCL deployment,thus reducing the construction cost of wireless charging facilities and user charging expenses.The efficacy and universality of the model are demonstrated using the classical Nguyen-Dupius network as a numerical example and a real-world highway network in Guangdong Province,China.Finally,a sensitivity analysis is conducted to corroborate the stability of the model.The results show that the operating speed of EVs on DWCLs has the largest impact on total cost,while battery capacity has the smallest.This comprehensive study offers vital insights into the strategic deployment of DWCLs,promoting the sustainable and efficient use of EVs in highway networks.展开更多
This paper proposes the design concept of a dynamic charging system for electric vehicles using multiple transmitter coils connected to a common radio frequency(RF)feeder driven by a pair of two power supplies.Using a...This paper proposes the design concept of a dynamic charging system for electric vehicles using multiple transmitter coils connected to a common radio frequency(RF)feeder driven by a pair of two power supplies.Using a common RF feeder for multiple transmitter coils reduces the power electronic redundancy compared to a conventional system,where each transmitter coil is individually driven by one switched-mode power supply.Currently,wireless charging of electric vehicles is recommended to operate in the frequency range of 85 kHz and beyond.In this frequency range,the signal wavelength is shorter than about 3.5 km.Therefore,a charging pad longer than several hundred meters is subject to the standing wave effect.In such a case,the voltage significantly varies along the RF feeder,resulting in a variation in the received power level when the receiver moves.Specifically,the received power significantly deteriorates when the receiver is nearby a node of the voltage standing wave.In this paper,we employ a pair of two power sources which are electrically separated by an odd-integer number of the quarter wavelength to drive the RF feeder.As a result,the voltage standing wave generated by one power source is complemented by that of the other,leading to stable received power and transmission efficiency at all the receiver’s positions along with the charging pad.Simulation results at the 85 kHz frequency band verify the output power stabilization effect of the proposed design.It is worth noting that the proposed concept can also be applied to simultaneous wireless information and power transfer(SWIPT)for passive radio frequency identification(RFID)tags by raising the operation frequency to higher industrial,scientific and medical(ISM)bands,e.g.,13.56 MHz and employing similar modulation methods as in the current RFID technology.展开更多
The change in the coordination environment of the active sites of a fuel cell cathode catalyst provides a new modulation strategy for stimulating the catalyst’s oxygen reduction reaction activity.The thermodynamic an...The change in the coordination environment of the active sites of a fuel cell cathode catalyst provides a new modulation strategy for stimulating the catalyst’s oxygen reduction reaction activity.The thermodynamic and electronic properties of the FeCoN5A and FeCoN6A catalyst structures with nonmetallic A-doped(A=B,N,O,P,and S)coordination were calculated and analyzed based on density functional theory.The modulation order of G*OH by different A-doped FeCo bimetal pairs(BMPs)was as follows:S>P>O>N/C>B.There was a dynamic distribution of charges in the coordination environment during the adsorption of OH,which resulted in inversely proportional relationship with the charge transfer between the adsorbate OH,active site,first coordination layer,and second coordination layer in turn.Descriptors of the orbital energy levels of neighboring nonmetal atoms were constructed based on the p-electron number and electronegativity of the doped nonmetal A.The change of the orbital energy levels of the first coordination atom during the adsorption process caused the structure to exhibit different adsorption energies.This study provides new insights on the non-metallic modulation of the M-N-C coordination environment to improve the oxygen reduction reaction activity.展开更多
The solar-driven reduction of CO_(2) into valuable products is a promising method to alleviate global environmental problems and energy crises.However,the low surface charge density limits the photocatalytic conversio...The solar-driven reduction of CO_(2) into valuable products is a promising method to alleviate global environmental problems and energy crises.However,the low surface charge density limits the photocatalytic conversion performance of CO_(2).Herein,a polymeric carbon nitride(PCN)photocatalyst with Zn single atoms(Zn1/CN)was designed and synthesized for CO_(2) photoreduction.The results of the CO_(2) photoreduction studies show that the CO and CH_(4) yields of Zn1/CN increased fivefold,reaching 76.9 and 22.9μmol/(g·h),respectively,in contrast to the unmodified PCN.Ar+plasma-etched X-ray photoelectron spectroscopy and synchrotron radiation-based X-ray absorption fine structure results reveal that Zn single atom is mainly present in the interlayer space of PCN in the Zn–N_(4) configuration.Photoelectrochemical characterizations indicate that the interlayer Zn–N_(4) configuration can amplify light absorption and establish an interlayer charge transfer channel.Light-assisted Kelvin probe force microscopy confirms that more photogenerated electrons are delivered to the catalyst surface through interlayer Zn–N_(4) configuration,which increases its surface charge density.Further,in-situ infrared spectroscopy combined with density functional theory calculation reveals that promoted surface charge density accelerates key intermediates(*COOH)conversion,thus achieving efficient CO_(2) conversion.This work elucidates the role of internal single atoms in catalytic surface reactions,which provides important implications for the design of single-atom catalysts.展开更多
Quantum batteries are energy storage devices that satisfy quantum mechanical principles.How to improve the battery’s performance such as stored energy and power is a crucial element in the quantum battery.Here,we inv...Quantum batteries are energy storage devices that satisfy quantum mechanical principles.How to improve the battery’s performance such as stored energy and power is a crucial element in the quantum battery.Here,we investigate the charging and discharging dynamics of a three-level counterdiabatic stimulated Raman adiabatic passage quantum battery via shortcuts to adiabaticity,which can compensate for undesired transitions to realize a fast adiabatic evolution through the application of an additional control field to an initial Hamiltonian.The scheme can significantly speed up the charging and discharging processes of a three-level quantum battery and obtain more stored energy and higher power compared with the original stimulated Raman adiabatic passage.We explore the effect of both the amplitude and the delay time of driving fields on the performances of the quantum battery.Possible experimental implementation in superconducting circuit and nitrogen–vacancy center is also discussed.展开更多
In this work, we demonstrated the successful construction of metal-free zero- dimensional/two-dimensional carbon nanodot (CND)-hybridized protonatedg=C3N4 (pCN) (CND/pCN) heterojunction photocatalysts b; means o...In this work, we demonstrated the successful construction of metal-free zero- dimensional/two-dimensional carbon nanodot (CND)-hybridized protonatedg=C3N4 (pCN) (CND/pCN) heterojunction photocatalysts b; means of electrostatic attraction. We experimentally found that CNDs with an average diameter of 4.4 nm were uniformly distributed on the surface of pCN using electron microscopy analysis. The CND/pCN-3 sample with a CND content of 3 wt.% showed thehighest catalytic activity in the CO2 photoreduction process under visible and simulated solar light. This process results in the evolution of CH4 and CO. Thetotal amounts of CH4 and CO generated by the CND/pCN-3 photocatalyst after 10 h of visible-light activity were found to be 29.23 and 58.82 molgcatalyst-1, respectively. These values were 3.6 and 2.28 times higher, respectively, than thearn*ounts generated when using pCN alone. The corresponding apparent quantum efficiency (AQE) was calculated to be 0.076%. Furthermore, the CND/pCN-3 sample demonstrated high stability and durability after four consecutive photoreaction cycles, with no significant decrease in the catalytic activity.展开更多
The formation of chemical bonds between metal ions and their supports is an effective strategy to achieve good catalytic activity.However,both the synthesis of active metal species on a support and control of their co...The formation of chemical bonds between metal ions and their supports is an effective strategy to achieve good catalytic activity.However,both the synthesis of active metal species on a support and control of their coordination environment are still challenging.Here,we show the use of an organic compound to produce tubular carbon nitride(TCN)as a support for Pd nanoparticles(NPs),creating a composite material(NP-Pd-TCN).It was found that Pd ions preferentially bind with the electron-rich N atoms of TCN,leading to strong metal-support interactions that benefit charge transfer from g-C_(3)N_(4)to Pd.X-ray absorption spectroscopy further revealed that the metal-support interactions resulted in the formation of Pd-N bonds,which are responsible for the improvement in the charge dynamics as evidenced by the results from various techniques including photoluminescence(PL)spectroscopy,photocurrent measurements,and electrochemical impedance spectroscopy(EIS).Owing to the good dynamical properties,NP-Pd-TCN was used for photocatalytic hydrogen evolution under visible-light irradiation(λ>420 nm)and an excellent evolution rate of~381μmol·h^(-1)(0.02 g of the photocatalyst)was attained.This work aims to promote a strategy to synthesize efficient photocatalysts for hydrogen production by controllably introducing metal nanoparticles on a support and in the meantime forming chemical bonds to achieve intimate metal-support contact.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11175140)the Fundamental Research Funds for the Central Universities
文摘We present a novel numerical model and simulate preliminarily the charging process of a polymer subjected to electron irradiation of several 10 keV. The model includes the simultaneous processes of electron scattering and ambipolar transport and the influence of a self-consistent electric field on the scattering distribution of electrons. The dynamic spatial distribution of charges is obtained and validated by existing experimental data. Our simulations show that excess negative charges are concentrated near the edge of the electron range. However, the formed region of high charge density may extend to the surface and bottom of a kapton sample, due to the effects of the electric field on electron scattering and charge transport, respectively. Charge trapping is then demonstrated to significantly influence the charge motion. The charge distribution can be extended to the bottom as the trap density decreases. Charge accumulation is therefore balanced by the appearance and increase of leakage current. Accordingly, our model and numerical simulation provide a comprehensive insight into the charging dynamics of a polymer irradiated by electrons in the complex space environment.
基金funding support from the National Natural Science Foundation of China(51876072)the Hubei Provincial Natural Science Foundation of China(2019CFA002,2020CFA093)supported by the Program for HUST Academic Frontier Youth Team
文摘Asymmetric behaviors of capacitance and charging dynamics in the cathode and anode are general for nanoporous supercapacitors.Understanding this behavior is essential for the optimal design of supercapacitors.Herein,we perform constant-potential molecular dynamics simulations to reveal asymmetric features of porous supercapacitors and their effects on capacitance and charging dynamics.Our simulations show that,counterintuitively,charging dynamics can be fast in pores providing slow ion diffusion and vice versa.Unlike electrodes with singlesize pores,multi-pore electrodes show overcharging and accelerated co-ion desorption,which can be attributed to the subtle interplay between the dynamics and charging mechanisms.We find that capacitance and charging dynamics correlate with how the ions respond to an applied cell voltage in the cathode and anode.We demonstrate that symmetrizing this response can help boost power density,which may find practical applications in supercapacitor optimization.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.RS-2023-00213920,NRF-2021R1A4A1031761).
文摘Herein,the impact of the independent control of processing additives on vertical phase separation in sequentially deposited (SD) organic photovoltaics (OPVs) and its subsequent effects on charge carrier kinetics at the electron donor-acceptor interface are investigated.The film morphology exhibits notable variations,significantly depending on the layer to which 1,8-diiodooctane (DIO) was applied.Grazing incidence wide-angle X-ray scattering analysis reveals distinctly separated donor/acceptor phases and vertical crystallinity details in SD films.Time-of-flight secondary ion mass spectrometry analysis is employed to obtain component distributions in diverse vertical phase structures of SD films depending on additive control.In addition,nanosecond transient absorption spectroscopy shows that DIO control significantly affects the dynamics of separated charges in SD films.In SD OPVs,DIO appears to act through distinct mechanisms with minimal restriction,depending on the applied layer.This study emphasizes the significance of morphological optimization in improving device performance and underscores the importance of independent additive control in the advancement of OPV technology.
文摘Despite that organic-inorganic lead halide perovskites have attracted enormous scientific attention for energy conversion applications over the recent years,the influence of temperature and the type of the employed hole transport layer(HTL)on the charge carrier dynamics and recombination processes in perovskite photovoltaic devices is still largely unexplored.In particular,significant knowledge is missing on how these crucial parameters for radiative and non-radiative recombinations,as well as for efficient charge extraction vary among different perovskite crystalline phases that are induced by temperature variation.Herein,we perform micro photoluminescence(pPL)and ultrafast time resolved transient absorption spectroscopy(TAS)in Glass/Perovskite and two dierent Glass/ITO/HTL/Perovskite configurations at temperatures below room temperature,in order to probe the charge carrier dynamics of different perovskite crystalline phases,while considering also the effect of the employed HTL polymer.Namely,CH_(3)NH_(3)Pbb films were deposited on Glass,PEDOT:PSS and PTAA polymers,and the developed Glass/CH_(3)NH_(3)PbI_(3)and Glass/ITO/HTL/CH_(3)NH_(3)PbI_(3)architectures were studied from 85 K up to 215 K in order to explore the charge extraction dynamics of the CH_(3)NH_(3)PbI_(3)orthorhombic and tetragonal crystalline phases.It is observed an unusual blueshift of the bandgap with temperature and the dual emission at temperature below of 100 K and also,that the charge carrier dynamics,as expressed by hole injection times and free carrier recombination rates,are strongly depended on the actual pervoskite crystal phase,as well as,from the selected hole transport material.
基金supported by National Key Research and Development Program of China(Nos.2021YFB3602703,2022YFB3606504,and 2022YFB3602903)Shenzhen Key Laboratory for Advanced Quantum Dot Displays and Lighting(No.ZDSYS201707281632549)Shenzhen Science and Technology Program(No.JCYJ20220818100411025)。
文摘Impedance spectroscopy has been increasingly employed in quantum dot light-emitting diodes(QLEDs)to investigate the charge dynamics and device physics.In this review,we introduce the mathematical basics of impedance spectroscopy that applied to QLEDs.In particular,we focus on the Nyquist plot,Mott-Schottky analysis,capacitance-frequency and capacitance-voltage characteristics,and the d C/d V measurement of the QLEDs.These impedance measurements can provide critical information on electrical parameters such as equivalent circuit models,characteristic time constants,charge injection and recombination points,and trap distribution of the QLEDs.However,this paper will also discuss the disadvantages and limitations of these measurements.Fundamentally,this review provides a deeper understanding of the device physics of QLEDs through the application of impedance spectroscopy,offering valuable insights into the analysis of performance loss and degradation mechanisms of QLEDs.
基金the National Natural Science Foundation of China(51676096)supported by the Australian Research Council(DP170104264 and DP190103548).
文摘Van der Waals(VDW)heterojunctions in a 2D/2D contact provide the highest area for the separation and transfer of charge carriers.In this work,a top-down strategy with a gas erosion process was employed to fabricate a 2D/2D carbon nitride VDW heterojunction in carbon nitride(g-C_(3)N_(4))with carbon-rich carbon nitride.The created 2D semiconducting channel in the VDW structure exhibits enhanced electric field exposure and radiation absorption,which facilitates the separation of the charge carriers and their mobility.Consequently,compared with bulk g-C_(3)N_(4)and its nanosheets,the photocatalytic performance of the fabricated carbon nitride VDW heterojunction in the water splitting reaction to hydrogen is improved by 8.6 and 3.3 times,respectively,while maintaining satisfactory photo-stability.Mechanistically,the finite element method(FEM)was employed to evaluate and clarify the contributions of the formation of VDW heterojunction to enhanced photocatalysis,in agreement quantitatively with experimental ones.This study provides a new and effective strategy for the modification and more insights to performance improvement on polymeric semiconductors in photocatalysis and energy conversion.
基金Project supported by the National Natural Science Foundation of China(Grant No.10476019)the Fundamental Research Funds for the Central Universities(Grant No.K5051304011)
文摘As an alternative power solution for low-power devices, harvesting energy from the ambient mechanical vibration has received increasing research interest in recent years. In this paper we study the transient dynamic characteristics of a piezoelectric energy harvesting system including a piezoelectric energy harvester, a bridge rectifier, and a storage capacitor. To accomplish this, this energy harvesting system is modeled, and the charging process of the storage capacitor is investigated by employing the in-phase assumption The results indicate that the charging voltage across the storage capacitor and the gathered power increase gradually as the charging process proceeds, whereas the charging rate slows down over time as the charging voltage approaches to the peak value of the piezoelectric voltage across the piezoelectric materials. In addition, due to the added electrical damping and the change of the system natural frequency when the charging process is initiated, a sudden drop in the vibration amplitude is observed, which in turn affects the charging rate. However, the vibration amplitude begins to increase as the charging process continues, which is caused by the decrease in the electrical damping (i.e., the decrease in the energy removed from the mechanical vibration). This electromechanical coupling characteristic is also revealed by the variation of the vibration amplitude with the charging voltage.
基金funded by the National Natural Science Foundation of China(72201149)Xinjiang Key Laboratory of Green Mining of Coal resources,Ministry of Education(KLXGY-KB2420)Guangzhou Basic and Applied Basic Research(SL2023A04J00802).
文摘As the adoption of Electric Vehicles(EVs)intensifies,two primary challenges emerge:limited range due to battery constraints and extended charging times.The traditional charging stations,particularly those near highways,exacerbate these issues with necessary detours,inconsistent service levels,and unpredictable waiting durations.The emerging technology of dynamic wireless charging lanes(DWCLs)may alleviate range anxiety and eliminate long charging stops;however,the driving speed on DWCL significantly affects charging efficiency and effective charging time.Meanwhile,the existing research has addressed load balancing optimization on Dynamic Wireless Charging(DWC)systems to a limited extent.To address this critical issue,this study introduces an innovative eco-driving speed control strategy,providing a novel solution to the multi-objective optimization problem of speed control on DWCL.We utilize mathematical programming methods and incorporate the longitudinal dynamics of vehicles to provide an accurate physical model of EVs.Three objective functions are formulated to tackle the challenges at hand:reducing travel time,increasing charging efficiency,and achieving load balancing on DWCL,which corresponds to four control strategies.The results of numerical tests indicate that a comprehensive control strategy,which considers all objectives,achieves a minor sacrifice in travel time reduction while significantly improving energy efficiency and load balancing.Furthermore,by defining the energy demand and speed range through an upper operation limit,a relatively superior speed control strategy can be selected.This work contributes to the discourse on DWCL integration into modern transportation systems,enhancing the EV driving experience on major roads.
基金This work was financially supported in part by the National Natural Science Foundation of China(Grant Nos.12047564,52071041,12074048)the Project for Fundamental and Frontier Research in Chongqing(cstc2020jcyj-msxmX0777 and cstc2020jcyj-msxmX0796)+1 种基金the Fundamental Research Funds for the Central Universities(cqu2018CDHB1A09,106112016CDJZR308808)Open access funding provided by Shanghai Jiao Tong University
文摘Photocatalytic conversion of CO_(2) to high-value products plays a crucial role in the global pursuit of carbon–neutral economy.Junction photocatalysts,such as the isotype heterojunctions,offer an ideal paradigm to navigate the photocatalytic CO_(2) reduction reaction(CRR).Herein,we elucidate the behaviors of isotype heterojunctions toward photocatalytic CRR over a representative photocatalyst,g-C_(3)N_(4).Impressively,the isotype heterojunctions possess a significantly higher efficiency for the spatial separation and transfer of photogenerated carriers than the single components.Along with the intrinsically outstanding stability,the isotype heterojunctions exhibit an exceptional and stable activity toward the CO_(2) photoreduction to CO.More importantly,by combining quantitative in situ technique with the first-principles modeling,we elucidate that the enhanced photoinduced charge dynamics promotes the production of key intermediates and thus the whole reaction kinetics.
基金supported by the National Key Basic Research Program (No.2012CB932903)Natural Science Foundation of China (Nos. 51402348,51421002,91433205,21173260,11474333 and 91233202)
文摘A repeated interdiffusion method is described for phase-stable and high-quality (FA,MA)PbI3 film. The crys- tallization and growth of the perovskite films can be well controlled by adjusting the reactant concentrations. With this method, dense, smooth perovskite films with large crystals have been obtained. Finally, a PCE of 16.5% as well as a steady-state efficiency of 16.3% is achieved in the planar perovskite solar cell.
基金financial support from Macao Science and Technology Development Fund,China(FDCT-0044/2020/A1,FDCT-091/2017/A2,FDCT-014/2017/AMJ)University of Macao Research Grant,China(MYRG2018-00148-IAPME,MYRG2018-00142-IAPME)from University of Macao+2 种基金the Natural Science Foundation of China,China(91733302,61935017)Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials(2019B121205002)Natural Science Foundation of Guangdong Province,China(2019A1515012186).
文摘Lead-free double perovskite Cs_(2)AgBiBr_(6) has gained increasing attention recently.However,the power conversion efficiency(PCE)of Cs_(2)AgBiBr_(6) perovskite solar cells(PSCs)is still low compared with their lead-based counterparts.Here,by using photoluminescence(PL),time-resolved photoluminescence(TRPL),and ultrafast transient absorption(TA)measurements,the unbalance between the electron and hole in diffusion and transfer,which limits the performance of the Cs_(2)AgBiBr_(6) PSCs,was further revealed.Considering this issue,a strategy of using the mesoporous TiO_(2) electron transport layer(ETL)to construct a bulk heterojunction in Cs_(2)AgBiBr_(6) PSCs was proposed.Consequently,the PCE had improved by over 24%comparing with that only used compact TiO_(2) ETL.Moreover,based on mesoporous TiO_(2),the unencapsulated Cs_(2)AgBiBr_(6) PSCs maintained 90%of their initial performance after approximately 1200 h of storage in a desiccator(humidity~30%).This work gives further understanding of Cs_(2)AgBiBr_(6) perovskite and demonstrates that a proper design of balancing the electron and hole diffusion can improve device performance.
基金supported by the Natural Science Foundation of Guangdong Province(Grant No.2023A1515011322).
文摘Amid escalating energy crises and environmental pressures,electric vehicles(EVs)have emerged as an effective measure to reduce reliance on fossil fuels,combat climate change,uphold sustainable energy and environmental development,and strive towards carbon peaking and neutrality goals.This study introduces a nonlinear integer programming model for the deployment of dynamic wireless charging lanes(DWCLs)and EV charging strategy joint optimization in highway networks.Taking into account established charging resources in highway service areas(HSAs),the nonlinear charging characteristics of EV batteries,and the traffic capacity constraints of DWCLs.The model identifies the deployment of charging facilities and the EV charging strategy as the decision-making variables and aims to minimize both the DWCL construction and user charging costs.By ensuring that EVs maintain an acceptable state of charge(SoC),the model combines highway EV charging demand and highway EV charging strategy to optimize the DWCL deployment,thus reducing the construction cost of wireless charging facilities and user charging expenses.The efficacy and universality of the model are demonstrated using the classical Nguyen-Dupius network as a numerical example and a real-world highway network in Guangdong Province,China.Finally,a sensitivity analysis is conducted to corroborate the stability of the model.The results show that the operating speed of EVs on DWCLs has the largest impact on total cost,while battery capacity has the smallest.This comprehensive study offers vital insights into the strategic deployment of DWCLs,promoting the sustainable and efficient use of EVs in highway networks.
基金JSPS KAKENHI under Grant Nos.20K14736 and 19K04376.
文摘This paper proposes the design concept of a dynamic charging system for electric vehicles using multiple transmitter coils connected to a common radio frequency(RF)feeder driven by a pair of two power supplies.Using a common RF feeder for multiple transmitter coils reduces the power electronic redundancy compared to a conventional system,where each transmitter coil is individually driven by one switched-mode power supply.Currently,wireless charging of electric vehicles is recommended to operate in the frequency range of 85 kHz and beyond.In this frequency range,the signal wavelength is shorter than about 3.5 km.Therefore,a charging pad longer than several hundred meters is subject to the standing wave effect.In such a case,the voltage significantly varies along the RF feeder,resulting in a variation in the received power level when the receiver moves.Specifically,the received power significantly deteriorates when the receiver is nearby a node of the voltage standing wave.In this paper,we employ a pair of two power sources which are electrically separated by an odd-integer number of the quarter wavelength to drive the RF feeder.As a result,the voltage standing wave generated by one power source is complemented by that of the other,leading to stable received power and transmission efficiency at all the receiver’s positions along with the charging pad.Simulation results at the 85 kHz frequency band verify the output power stabilization effect of the proposed design.It is worth noting that the proposed concept can also be applied to simultaneous wireless information and power transfer(SWIPT)for passive radio frequency identification(RFID)tags by raising the operation frequency to higher industrial,scientific and medical(ISM)bands,e.g.,13.56 MHz and employing similar modulation methods as in the current RFID technology.
基金funded by the National Natural Science Foundation of China(Nos.61701288 and 51706128)the basic research plan of natural science in Shaanxi province(No.2021JM-485)the key scientific research project of Shaanxi provincial education department(No.20JS019).
文摘The change in the coordination environment of the active sites of a fuel cell cathode catalyst provides a new modulation strategy for stimulating the catalyst’s oxygen reduction reaction activity.The thermodynamic and electronic properties of the FeCoN5A and FeCoN6A catalyst structures with nonmetallic A-doped(A=B,N,O,P,and S)coordination were calculated and analyzed based on density functional theory.The modulation order of G*OH by different A-doped FeCo bimetal pairs(BMPs)was as follows:S>P>O>N/C>B.There was a dynamic distribution of charges in the coordination environment during the adsorption of OH,which resulted in inversely proportional relationship with the charge transfer between the adsorbate OH,active site,first coordination layer,and second coordination layer in turn.Descriptors of the orbital energy levels of neighboring nonmetal atoms were constructed based on the p-electron number and electronegativity of the doped nonmetal A.The change of the orbital energy levels of the first coordination atom during the adsorption process caused the structure to exhibit different adsorption energies.This study provides new insights on the non-metallic modulation of the M-N-C coordination environment to improve the oxygen reduction reaction activity.
基金partially supported by the National Natural Science Foundation of China(22272019)Sichuan Science and Technology Program(2022ZYD0039,2022NSFSC1213,2023NSFSC1069)。
基金supported by Shanghai Pujiang Program(21PJ1400400)Shanghai Municipal Science and Technology Commission(22511103900)+1 种基金the Fundamental Research Funds for the Central Universities(2232023A-02)the National Natural Science Foundation of China(22173017).
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences,China(Nos.XDA23010300 and XDA23010000)the National Natural Science Foundation of China(Nos.51878644 and 41573138)the CAS Youth Interdisciplinary Team.
文摘The solar-driven reduction of CO_(2) into valuable products is a promising method to alleviate global environmental problems and energy crises.However,the low surface charge density limits the photocatalytic conversion performance of CO_(2).Herein,a polymeric carbon nitride(PCN)photocatalyst with Zn single atoms(Zn1/CN)was designed and synthesized for CO_(2) photoreduction.The results of the CO_(2) photoreduction studies show that the CO and CH_(4) yields of Zn1/CN increased fivefold,reaching 76.9 and 22.9μmol/(g·h),respectively,in contrast to the unmodified PCN.Ar+plasma-etched X-ray photoelectron spectroscopy and synchrotron radiation-based X-ray absorption fine structure results reveal that Zn single atom is mainly present in the interlayer space of PCN in the Zn–N_(4) configuration.Photoelectrochemical characterizations indicate that the interlayer Zn–N_(4) configuration can amplify light absorption and establish an interlayer charge transfer channel.Light-assisted Kelvin probe force microscopy confirms that more photogenerated electrons are delivered to the catalyst surface through interlayer Zn–N_(4) configuration,which increases its surface charge density.Further,in-situ infrared spectroscopy combined with density functional theory calculation reveals that promoted surface charge density accelerates key intermediates(*COOH)conversion,thus achieving efficient CO_(2) conversion.This work elucidates the role of internal single atoms in catalytic surface reactions,which provides important implications for the design of single-atom catalysts.
基金The work was supported by the National Natural Science Foundation of China(Grant No.12075193).
文摘Quantum batteries are energy storage devices that satisfy quantum mechanical principles.How to improve the battery’s performance such as stored energy and power is a crucial element in the quantum battery.Here,we investigate the charging and discharging dynamics of a three-level counterdiabatic stimulated Raman adiabatic passage quantum battery via shortcuts to adiabaticity,which can compensate for undesired transitions to realize a fast adiabatic evolution through the application of an additional control field to an initial Hamiltonian.The scheme can significantly speed up the charging and discharging processes of a three-level quantum battery and obtain more stored energy and higher power compared with the original stimulated Raman adiabatic passage.We explore the effect of both the amplitude and the delay time of driving fields on the performances of the quantum battery.Possible experimental implementation in superconducting circuit and nitrogen–vacancy center is also discussed.
文摘In this work, we demonstrated the successful construction of metal-free zero- dimensional/two-dimensional carbon nanodot (CND)-hybridized protonatedg=C3N4 (pCN) (CND/pCN) heterojunction photocatalysts b; means of electrostatic attraction. We experimentally found that CNDs with an average diameter of 4.4 nm were uniformly distributed on the surface of pCN using electron microscopy analysis. The CND/pCN-3 sample with a CND content of 3 wt.% showed thehighest catalytic activity in the CO2 photoreduction process under visible and simulated solar light. This process results in the evolution of CH4 and CO. Thetotal amounts of CH4 and CO generated by the CND/pCN-3 photocatalyst after 10 h of visible-light activity were found to be 29.23 and 58.82 molgcatalyst-1, respectively. These values were 3.6 and 2.28 times higher, respectively, than thearn*ounts generated when using pCN alone. The corresponding apparent quantum efficiency (AQE) was calculated to be 0.076%. Furthermore, the CND/pCN-3 sample demonstrated high stability and durability after four consecutive photoreaction cycles, with no significant decrease in the catalytic activity.
基金This work was supported by the National Key R&D Program of China(No.2018YFE0201704)the National Natural Science Foundation of China(No.21771061)Outstanding Youth Fund of Heilongjiang Province(No.JQ 2020B002)。
文摘The formation of chemical bonds between metal ions and their supports is an effective strategy to achieve good catalytic activity.However,both the synthesis of active metal species on a support and control of their coordination environment are still challenging.Here,we show the use of an organic compound to produce tubular carbon nitride(TCN)as a support for Pd nanoparticles(NPs),creating a composite material(NP-Pd-TCN).It was found that Pd ions preferentially bind with the electron-rich N atoms of TCN,leading to strong metal-support interactions that benefit charge transfer from g-C_(3)N_(4)to Pd.X-ray absorption spectroscopy further revealed that the metal-support interactions resulted in the formation of Pd-N bonds,which are responsible for the improvement in the charge dynamics as evidenced by the results from various techniques including photoluminescence(PL)spectroscopy,photocurrent measurements,and electrochemical impedance spectroscopy(EIS).Owing to the good dynamical properties,NP-Pd-TCN was used for photocatalytic hydrogen evolution under visible-light irradiation(λ>420 nm)and an excellent evolution rate of~381μmol·h^(-1)(0.02 g of the photocatalyst)was attained.This work aims to promote a strategy to synthesize efficient photocatalysts for hydrogen production by controllably introducing metal nanoparticles on a support and in the meantime forming chemical bonds to achieve intimate metal-support contact.