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Carbon Energy 2023年第7期5卷 27-37页

作者： Chang-Mok Oh Sujung park Jihoon Lee sung heum park Shinuk Cho In-Wook Hwang Advanced Photonics Research Institute Gwangju Institute of Science and TechnologyGwangjuRepublic of Korea Department of Physics and Energy Harvest Storage Research Center University of UlsanUlsanRepublic of Korea Department of Physics Pukyong National UniversityBusanRepublic of Korea

Bulk heterojunction(BHJ)composites show improved power conversion efficiencies when optimized in terms of morphology using various film processing methods.A reduced carrier recombination loss in an optimized BHJ was characterized ***,the driving force that leads to this reduction was not clearly *** this study,we focus on the decreased carrier recombination loss and its driving force in optimized nonfullerene acceptor-based PTB7-Th:IEICO-4F BHJ *** demonstrate that the optimized BHJ shows deactivation in the sub-nanosecond nongeminate carrier recombination *** driving force for this deactivation was determined to be the improved interchain hole delocalization between the *** enhanced interchain hole delocalization was observed using steady-state photoinduced absorption(PIA)*** particular,increased splitting between the polaron PIA bands was ***,improved interchain hole delocalization was observed for other state-of-the-art BHJ materials,including D18:Y6 with optimized morphologies.

关键词： bulk heterojunction interchain hole delocalization nonfullerene acceptor photoinduced absorption spectroscopy solar cell

Versatile control of concentration gradients in non-fullerene acceptor-based bulk heterojunction films using solvent rinse treatments

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Green Energy & Environment 2022年第5期7卷 1102-1110页

作者： Chang-Mok Oh Soyeong Jang Jihoon Lee sung heum park In-Wook Hwang Advanced Photonics Research Institute Gwangju Institute of Science and TechnologyGwangju61005Republic of Korea Department of Physics Pukyong National UniversityBusan48513Republic of Korea

Solvent rinse treatments using polar methanol(Me OH)and nonpolar n-hexane have been developed for controlling material concentration gradients along the longitudinal direction of non-fullerene acceptor-based bulk heterojunction(BHJ)films comprised of electron donor polymer,PBDB-T and acceptor,*** the used solvents(chlorobenzene with 1 vol%DIO)were completely evaporated,ITIC-m rich domains were formed at the top surface of the BHJ films after they were rinsed with Me OH,as evidenced by water contact angle,atomic force microscopy,time-of-flight secondary ion mass spectroscopy,which led to enhanced electron transport in the conventional structure of organic solar cells(OSCs).In contrast,after rinsing with n-hexane,ITIC-m rich domains were formed at the bottom surface of the films,which improved electron transport in the inverted structure *** enhanced carrier transports increased the PCEs(11.80%and 11.15%)in both conventional and inverted OSCs by 10.29%and 10.35%compared with control *** versatile control of material concentration gradients is determined to be feasible owing to the chemical interaction of the used substrates(glass,PEDOT:PSS,and Zn O)and rinsing solvents.

关键词： films treatment heterojunction

Understanding the correlation between energy-state mismatching and open-circuit voltage loss in bulk heterojunction solar cells

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Carbon Energy 2024年第5期6卷 164-174页

作者： Hyun-Seock Yang Danbi Kim Chang-Mok Oh Vellaiappillai Tamilavan Pesi MHangoma Hojun Yi Bo RLee Insoo Shin In-Wook Hwang sung heum park Pukyong National University BusanRepublic of Korea Clarendon Laboratory University of OxfordOxfordUK Institute of Energy Transport and Fusion Research Pukyong National UniversityBusanRepublic of Korea Advanced Photonics Research Institute Gwangju Institute of Science and TechnologyGwangjuRepublic of Korea Department of Chemical and Biomolecular Engineering Tandon School of EngineeringNew York UniversityBrooklynNew YorkUSA

Photoinduced intermolecular charge transfer(PICT)determines the voltage loss in bulk heterojunction(BHJ)organic photovoltaics(OPVs),and this voltage loss can be minimized by inducing efficient PICT,which requires energy-state matching between the donor and acceptor at the BHJ ***,both geometrically and energetically accessible delocalized state matching at the hot energy level is crucial for achieving efficient *** this study,an effective method for quantifying the hot state matching of OPVs was *** degree of energy-state matching between the electron donor and acceptor at BHJ interfaces was quantified using a mismatching factor(MF)calculated from the modified optical density of the ***,the correlation between the open-circuit voltage(Voc)of the OPV device and energy-state matching at the BHJ interface was investigated using the calculated *** OPVs with small absolute MF values exhibited high Voc *** result clearly indicates that the energy-state matching between the donor and acceptor is crucial for achieving a high Voc in *** the MF indicates the degree of energy-state matching,which is a critical factor for suppressing energy loss,it can be used to estimate the Voc loss in OPVs.

关键词： bulk heterojunction open circuit voltage organic photovoltaics photoinduced charge transfer voltage loss

Dual-Functional Light-Emitting Perovskite Solar Cells Enabled by Soft-Covered Annealing Process

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Dual-Functional Light-Emitting Perovskite Solar Cells Enable...

Thermoresponsive Al^(3+)-crosslinked poly(N-isopropylacrylamide)/alginate composite for green recovery of lithium from Li-spiked seawater

第六届新型太阳能电池材料科学与技术学术研讨会

作者： Liu Yanliang Zhang Yuanyuan Ma Yongchao sung heum park Department of Physics Pukyong National University Hybrid Interface Materials Global Frontier Research Group Pusan National University

Solution-processable perovskite semiconductors have demonstrated excellent performance in both perovskite solar cells(PeSCs) and perovskite light emitting diodes(PeLEDs). Their low exciton binding energy and excellent charge transport properties allow the conversion of photons into free electrons and holes and vice versa with minimal energy loss. In addition, planar PeSCs and PeLEDs have similar device architecture. These aspects inspired us to fabricate a dual-functional device with both SC and LED functions, here termed a light-emitting perovskite solar cells(LEPeSCs). However, the absence of an effective fabrication method to control grain size, uniformity, grain boundaries, and coverage of perovskite film inevitably limits device performance of dual-functional LEPeSCs. Here, we have demonstrated an efficient dual-functional LEPeSCs with planar device configuration of ITO/PEDOT:PSS/CHNHPbBrI/PCBM/Ca/Al, which is able to reversibly convert luminous energy to electric energy or electric energy to luminous energy in a single device. By developing a new soft-covered annealing method, we obtained optimized grain morphology with large grain size, high uniformity, and decreased grain boundaries, which is difficult to achieve with conventional fabrication methods. The LEPeSCs exhibits high performance in both PeSCs and PeLEDs modes, with power conversion efficiency of 14.02% in SC mode and bright red-light emission of 1710 cd/cm at 4 V in LED mode.

关键词： dual-functional optoelectronic device perovskite solar cells perovskite LEDs perovskite grain growth grain boundaries

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Green Energy & Environment 2022年第2期7卷 334-344页

作者： sung Ho park Sang Joon Lee Department of Mechanical Engineering Pohang University of Science and Technology(POSTECH)Pohang790-784South Korea

With the rapid increase in the demand for lithium as an energy-critical element,the recovery of Li+ions from seawater is a worldwide challenging ***,we propose a new facile and fast selective recovery approach of Li+using an Al^(3+)-crosslinked poly(N-isopropylacrylamide)(PNIPAAm)/alginate(Alg)(PNP/Alg(Al)) *** in situ TEM images indicate that Alg-Al^(3+)coordination is reorganized via the rearrangement of PNIPAAm and Alg networks,as the temperature *** reorganization eventually leads to the formation of polycrystalline *** in situ FTIR results exhibit that PNP/Alg(Al) composite has peculiar phase transitions,which includes a retrogressive phase change from hydrophobic to *** synergetic effect of the strong repulsion force of Al^(3+) ions and the attractive force of negatively charged polymeric chains enables the efficient adsorption of Li+ions with a low affinity from Li-spiked seawater.7.3% of Li+ions are recovered from Li-spiked seawater although the concentration of Li-spiked seawater is very *** addition,Li+ions can be extracted from PNP/Alg(Al) composite with the use of a small thermal *** proposed thermoresponsive IPN gel provides a strong potential in practical applications for Li+recovery as an innovative energy-material strategy.

关键词： structure seawater lithium

Empathic Responses of Behavioral-Synchronization in Human-Agent Interaction

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Computers, Materials & Continua 2022年第5期71卷 3761-3784页

作者： sung park Seongeon park Mincheol Whang Savannah College of Art and Design SavannahGA31401USA Sangmyung University Seoul03016Korea

Artificial entities,such as virtual agents,have become more *** long-term presence among humans requires the virtual agent’s ability to express appropriate emotions to elicit the necessary empathy from the *** empathy involves behavioral mimicry,a synchronized co-movement between dyadic ***,the characteristics of such synchrony between humans and virtual agents remain unclear in empathic *** study evaluates the participant’s behavioral synchronization when a virtual agent exhibits an emotional expression congruent with the emotional context through facial expressions,behavioral gestures,and *** viewed an emotion-eliciting video stimulus(negative or positive)with a virtual *** participants then conversed with the virtual agent about the video,such as how the participant felt about the *** virtual agent expressed emotions congruent with the video or neutral emotion during the *** participants’facial expressions,such as the facial expressive intensity and facial muscle movement,were measured during the dialog using a *** results showed the participants’significant behavioral synchronization(i.e.,cosine similarity≥.05)in both the negative and positive emotion conditions,evident in the participant’s facial mimicry with the virtual ***,the participants’facial expressions,both movement and intensity,were significantly stronger in the emotional virtual agent than in the neutral virtual *** particular,we found that the facial muscle intensity of AU45(Blink)is an effective index to assess the participant’s synchronization that differs by the individual’s empathic capability(low,mid,high).Based on the results,we suggest an appraisal criterion to provide empirical conditions to validate empathic interaction based on the facial expression measures.

关键词： Facial emotion recognition facial expression virtual agent virtual human embodied conversational agent empathy human-computer interaction

Exploration of cobalt selenite-carbon composite porous nanofibers as anode for sodium-ion batteries and unveiling their conversion reaction mechanism

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Journal of Materials Science & Technology 2021年第30期89卷 24-35页

作者： Jin-sung park Gi Dae park Yun Chan Kang Department of Materials Science and Engineering Korea UniversityAnam-DongSeongbuk-GuSeoul136-713Republic of Korea

Efforts have been made to develop a promising anode material with a novel composition for sodiumion batteries(SIBs).In this study,the sodium-ion storage mechanism of transition metal selenite that comprises transition metal cation coupled with two anions is *** cobalt selenite(CoSeO_(3))-carbon composite nanofibers containing numerous pores are synthesized via electrospinning *** heat treatment of the electrospun nanofibers containing selenium,CoSe_(2)nanoclusters are *** the subsequent oxidation,CoSe_(2)transformed into amorphous CoSeO_(3)and some part of carbon was oxidized into CO_(2),leaving the pores inside the *** unveil the electrochemical reaction mechanism,analytical methods including cyclic voltammetry,ex-situ X-ray photoelectron spectroscopy,ex-situ transmission electron microscopy,and in-situ electrochemical impedance spectroscopy techniques were *** on the analyses,the following conversion reaction from the second cycle onward is suggested:CoO+xSeO_(2)+(1-x)Se+4(x+1)Na^(+)+4(x+1)e~-?Co+(2x+1)Na_(2)O+Na_(2)***,the electrochemical properties of porous CoSeO_(3)-carbon composite nanofibers are analyzed in *** anode material exhibited stable cycle stability up to 200 cycles at 0.5 A g^(-1)and high rate performance up to 5 A g^(-1).

关键词： Anode materials Sodium-ion batteries Conversion reaction Metal selenite Electrospinning

Local Energy and Planned Ramping Product Joint Market Based on a Distributed Optimization Method

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CSEE Journal of Power and Energy Systems 2021年第6期7卷 1357-1368页

作者： Zhong Zhang Furong Li sung-Won park sung-Yong Son Dalian University of Technology DalianChina Department of Electronic and Electrical Engineering University of BathBathU.K. the University of Bath BathU.K. the Department of Electrical and Electronic Engineering Youngsan UniversitySouth Korea Gachon University SeoulSouth Korea

High penetration of renewable energy generation(REG)in the distribution system increases both the power uncertainty at a given interval and the power variation between two *** markets addressing power uncertainty have been widely ***,there is a lack of market mechanisms regarding the power variation of the load and *** paper thus defines a planned ramping(PR)product to follow the net load variation and extends the local energy market to include the trading of PR *** are economically compensated for their PR *** models of dispatchable generators and flexible load aggregators in the joint market are *** solve the market problem in polynomial time,a distributed market clearing method is developed based on the ADMM *** joint market is tested on a modified IEEE 33-bus *** verifies that introducing the PR market can encourage flexible loads to provide more PR service to accommodate the net load *** such,the ramping cost of dispatchable generators is reduced by 29.09%in the test *** planned energy curtailment from REG is also *** computational efficiency of the proposed distributed clearing method is validated by comparing it with a centralized method.

关键词： Distributed market clearing flexible load aggregator local electricity market planned ramping product renewable energy generation

Variations in dynamic recrystallization behavior and mechanical properties of AZ31 alloy with extrusion temperature

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Journal of Magnesium and Alloys 2023年第7期11卷 2351-2365页

作者： Jae Won Cha sung Hyuk park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

This study investigates the effects of extrusion temperature on the dynamic recrystallization(DRX)behavior of a Mg-3Al-1Zn-0.3Mn(AZ31,wt%)alloy during hot extrusion and on the microstructural characteristics and mechanical properties of materials extruded at 350 and 450℃.An increase in the extrusion temperature causes a decrease in the amount of strain energy accumulated in the material during extrusion,because of promoted activation of pyramidalslip and dynamic *** reduced strain energy weakens the DRX behavior during extrusion,which eventually results in a decrease in the area fraction of recrystallized grains of the extruded *** material extruded at 450℃has coarser grains and a stronger basal fiber texture than that extruded at 350℃.As the extrusion temperature increases from 350 to 450℃,the tensile yield strength(TYS)of the extruded material increases from 191.8 to 201.5 MPa,whereas its compressive yield strength(CYS)decreases from 122.5 to 111.0 MPa;consequently,its tension-compression yield stress ratio(CYS/TYS)decreases from 0.64 to *** increase in the TYS is attributed mainly to the stronger texture hardening and strain hardening effects of the extruded material,and the decrease in the CYS is attributed to the reduced twinning stress resulting from grain coarsening and texture *** microstructural and textural evolutions of the materials during extrusion and the deformation and hardening mechanisms of the extruded materials are discussed in detail.

关键词： Mg-Al-Zn alloy Extrusion Dynamic recrystallization Microstructure Yield asymmetry

Underlying mechanisms of variation in yield asymmetry and strain hardening behavior of extruded pure Mg with Gd addition

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Journal of Magnesium and Alloys 2023年第6期11卷 2165-2181页

作者： Gyo Myeong Lee sung Hyuk park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

Effects of Gd addition on the strain hardening behavior and yield asymmetry of pure Mg are investigated by subjecting extruded pure Mg,Mg–5Gd,and Mg–15Gd(all in wt%)to tension and compression tests along the extrusion direction(ED).As the amount of Gd added to pure Mg increases,the basal texture tilts toward the ED and the distribution of c-axes of grains becomes *** tension,the strain hardening rates of all the materials decrease until ***,under compression,the strain hardening rate increases in the early stage of deformation in pure Mg and Mg–5Gd,whereas it continuously decreases in Mg–*** Mg exhibits considerably high tension-compression yield asymmetry,with a compressive yield strength(CYS)to tensile yield strength(TYS)ratio of *** contrast,Mg–5Gd exhibits excellent yield symmetry with CYS/TYS of 0.9 and Mg–15Gd exhibits reversed yield asymmetry with CYS/TYS of *** mechanisms of these drastically different Gd-addition-induced deformation behaviors of the materials are discussed in terms of the crystallographic distribution of grains and the relative activation stresses of basal slip,prismatic slip,pyramidal slip,and{10–12}twinning under tension and compression.

关键词： Pure Mg Gd addition Texture Yield asymmetry Activation stress