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Low-energy spin dynamics in a Kitaev material Na_(3)Ni_(2)BiO_(6) investigated by nuclear magnetic resonance
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作者 史昕雨 崔祎 +11 位作者 上官艳艳 徐霄宇 吴占龙 胡泽 李硕 杜柯帆 陈颖 马龙 刘正鑫 温锦生 张金珊 于伟强 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第6期518-524,共7页
We perform ^(23)Na nuclear magnetic resonance(NMR) and magnetization measurements on an S=1,quasi-2D honeycomb lattice antiferromagnet Na_(3)Ni_(2)BiO_(6).A large positive Curie-Weiss constant of 22.9 K is observed.Th... We perform ^(23)Na nuclear magnetic resonance(NMR) and magnetization measurements on an S=1,quasi-2D honeycomb lattice antiferromagnet Na_(3)Ni_(2)BiO_(6).A large positive Curie-Weiss constant of 22.9 K is observed.The NMR spectra at low fields are consistent with a zigzag magnetic order,indicating a large easy-axis anisotropy.With the field applied along the c*axis,the NMR spectra confirm the existence of a 1/3-magnetization plateau phase between 5.1 T and 7.1 T.The transition from the zigzag order to the 1/3-magnetization plateau phase is also found to be a first-order type.A monotonic decrease of the spin gap is revealed in the 1/3-magnetization plateau phase,which reaches zero at a quantum critical field H_(C)≈8.35 T before entering the fully polarized phase.These data suggest the existence of exchange frustration in the system along with strong ferromagnetic interactions,hosting the possibility for Kitaev physics.Besides,well below the ordered phase,the 1/T_(1) at high fields shows either a level off or an enhancement upon cooling below 3 K,which suggests the existence of low-energy fluctuations. 展开更多
关键词 one–third magnetization plateau phase nuclear magnetic resonance honeycomb-lattice antiferromagnet Kitaev interaction
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Effective model for rare-earth Kitaev materials and its classical Monte Carlo simulation
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作者 Mengjie Sun Huihang Lin +9 位作者 Zheng Zhang Yanzhen Cai Wei Ren Jing Kang Jianting Ji Feng Jin Xiaoqun Wang Rong Yu Qingming Zhang zhengxin liu 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第8期509-517,共9页
Recently,the family of rare-earth chalcohalides were proposed as candidate compounds to realize the Kitaev spin liquid(KSL)[Chin.Phys.Lett.38047502(2021)].In the present work,we firstly propose an effective spin Hamil... Recently,the family of rare-earth chalcohalides were proposed as candidate compounds to realize the Kitaev spin liquid(KSL)[Chin.Phys.Lett.38047502(2021)].In the present work,we firstly propose an effective spin Hamiltonian consistent with the symmetry group of the crystal structure.Then we apply classical Monte Carlo simulations to preliminarily study the model and establish a phase diagram.When approaching to the low temperature limit,several magnetic long range orders are observed,including the stripe,the zigzag,the antiferromagnetic(AFM),the ferromagnetic(FM),the incommensurate spiral(IS),the multi-Q,and the 120°ones.We further calculate the thermodynamic properties of the system,such as the temperature dependence of the magnetic susceptibility and the heat capacity.The ordering transition temperatures reflected in the two quantities agree with each other.For most interaction regions,the system is magnetically more susceptible in the ab-plane than in the c-direction.The stripe phase is special,where the susceptibility is fairly isotropic in the whole temperature region.These features provide useful information to understand the magnetic properties of related materials. 展开更多
关键词 Monte Carlo methods Kitaev materials quantum spin liquids rare-earth ions DM interaction
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A review on flexible solar cells
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作者 Shenglei Huang Cheng Qian +13 位作者 Xingting liu Liping Zhang Fanying Meng Zhu Yan Yinuo Zhou Junlin Du Bin Ding Jianhua Shi Anjun Han Wenjie Zhao Jian Yu Xin Song zhengxin liu Wenzhu liu 《Science China Materials》 SCIE EI CAS CSCD 2024年第9期2717-2736,共20页
With the gradual progression of the carbon neutrality target,the future of our electricity supply will experience a massive increase in solar generation,and approximately 50%of the global electricity generation will c... With the gradual progression of the carbon neutrality target,the future of our electricity supply will experience a massive increase in solar generation,and approximately 50%of the global electricity generation will come from solar generation by 2050.This provides the opportunity for researchers to diversify the applications of photovoltaics(PVs)and integrate for daily use in the future.Flexible solar cell technology is the next frontier in solar PV and is the key way to achieve CO_(2)neutrality.The integration of PV technology with other fields will greatly broaden the development areas for the PV industry,providing products with higher added value.In this paper,we reviewed the latest research progress on flexible solar cells(perovskite solar cells,organic solar cells,and flexible silicon solar cells),and proposed the future applications of flexible solar cell technology. 展开更多
关键词 carbon neutrality flexible PVs perovskite solar cells organic solar cells flexible silicon solar cells
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A novel silver-doped nickel oxide hole-selective contact for crystalline silicon heterojunction solar cells
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作者 Junfeng Zhao Xudong Yang +6 位作者 Zhongqing Zhang Shengpeng Xie Fangfang liu Anjun Han zhengxin liu Yun Sun Wei liu 《Frontiers of Chemical Science and Engineering》 SCIE EI CSCD 2024年第2期93-101,共9页
Based on its band alignment,p-type nickel oxide(NiO_(x))is an excellent candidate material for hole transport layers in crystalline silicon heterojunction solar cells,as it has a smallΔEV and largeΔEC with crystalli... Based on its band alignment,p-type nickel oxide(NiO_(x))is an excellent candidate material for hole transport layers in crystalline silicon heterojunction solar cells,as it has a smallΔEV and largeΔEC with crystalline silicon.Herein,to overcome the poor hole selectivity of stoichiometric NiO_(x) due to its low carrier concentration and conductivity,silver-doped nickel oxide(NiO_(x):Ag)hole transport layers with high carrier concentrations were prepared by co-sputtering high-purity silver sheets and pure NiO_(x) targets.The improved electrical conductivity of NiO_(x) was attributed to the holes generated by the Ag^(+)substituents for Ni^(2+),and moreover,the introduction of Ag^(+)also increased the amount of Ni^(3+)present,both of which increased the carrier concentration in NiO_(x).Ag^(+)doping also reduced the c-Si/NiO_(x) contact resistivity and improved the hole-selective contact with NiO_(x).Furthermore,the problems of particle clusters and interfacial defects on the surfaces of NiO_(x):Ag films were solved by UV-ozone oxidation and high-temperature annealing,which facilitated separation and transport of carriers at the c-Si/NiO_(x) interface.The constructed c-Si/NiO_(x):Ag solar cell exhibited an increase in open-circuit voltage from 490 to 596 mV and achieved a conversion efficiency of 14.4%. 展开更多
关键词 band alignment nickel oxide hole transport layer silver-doped nickel oxide UV-ozone
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Silvaco TCAD模拟应用三层氢化纳晶硅薄膜改善IBC-SHJ太阳电池的电学性能并扩大其工艺窗口
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作者 姜铠 张洪华 +9 位作者 张丽平 孟凡英 高彦峰 虞祥瑞 赵东明 李睿 黄海威 郝志丹 刘正新 刘文柱 《Science China Materials》 SCIE EI CAS CSCD 2023年第12期4891-4896,共6页
叉指式背接触硅异质结(IBC-SHJ)太阳电池由于其优异的光学性能备受关注,但是较低的填充因子(FF)限制了其转换效率.本文中,我们用Silvaco TCAD软件模拟了IBC-SHJ太阳电池,发现p-n结和高低结收集载流子的能力有很大差异.高低结内建电场较... 叉指式背接触硅异质结(IBC-SHJ)太阳电池由于其优异的光学性能备受关注,但是较低的填充因子(FF)限制了其转换效率.本文中,我们用Silvaco TCAD软件模拟了IBC-SHJ太阳电池,发现p-n结和高低结收集载流子的能力有很大差异.高低结内建电场较弱,难以收集电子是FF较低的主要原因.因此,我们用氢化纳晶硅(nc-Si:H)薄膜来代替氢化非晶硅(a-Si:H)薄膜,并且在nc-Si:H薄膜表面覆盖一层超薄高掺杂层进一步提高了载流子传输效率,获得了高达85.3%的FF.此外,三层nc-Si:H薄膜还提高了工艺生产中对掺杂层厚度的容错性,这大大扩展了IBCSHJ太阳电池的工艺窗口.这项工作为解决IBC-SHJ太阳电池的电学问题提供了一条有效的途径,对工艺生产中IBC-SHJ太阳电池的设计具有指导意义. 展开更多
关键词 太阳电池 填充因子 转换效率 氢化非晶硅 载流子传输 工艺窗口 硅薄膜 电学性能
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High-quality industrial n-type silicon wafers with an efficiency of over 23% for Si heterojunction solar cells 被引量:3
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作者 Fanying MENG Jinning liu +8 位作者 Leilei SHEN Jianhua SHI Anjun HAN Liping ZHANG Yucheng liu Jian YU Junkai ZHANG Rui ZHOU zhengxin liu 《Frontiers in Energy》 SCIE CSCD 2017年第1期78-84,共7页
n-type CZ-Si wafers featuring longer minority carrier lifetime and higher tolerance of certain metal contamination can offer one of the best Si-based solar cells. In this study, Si heterojuction (SHJ) solar cells wh... n-type CZ-Si wafers featuring longer minority carrier lifetime and higher tolerance of certain metal contamination can offer one of the best Si-based solar cells. In this study, Si heterojuction (SHJ) solar cells which was fabricated with different wafers in the top, middle and tail positions of the ingot, exhibited a stable high efficiency of〉 22% in spite of the various profiles of the resistivity and lifetime, which demonstrated the high material utilization of n-type ingot. In addition, for effectively converting the sunlight into electrical power, the pyramid size, pyramid density and roughness of surface of the Cz-Si wafer were investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM). Furthermore, the dependence of SHJ solar cell open- circuit voltage on the surface topography was discussed, which indicated that the uniformity of surface pyramid helps to improve the open-circuit voltage and conversion efficiency. Moreover, the simulation revealed that the highest efficiency of the SHJ solar cell could be achieved by the wafer with a thickness of 100 μm. Fortunately, over 23% of the conversion efficiency of the SHJ solar cell with a wafer thickness of 100 μm was obtained based on the systematic optimization of cell fabrication process in the pilot production line. Evidently, the large availability of both n-type ingot and thinner wafer strongly supported the lower cost fabrication of high efficiency SHJ solar cell. 展开更多
关键词 n-type Cz-Si thinner wafer surface texture high efficiency SHJ solar cell
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Review of DC-DC Converter Topologies Based on Impedance Network with Wide Input Voltage Range and High Gain for Fuel Cell Vehicles 被引量:2
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作者 Xiaogang Wu Jiulong Wang +3 位作者 Yun Zhang Jiuyu Du zhengxin liu Yu Chen 《Automotive Innovation》 EI CSCD 2021年第4期351-372,共22页
The development of fuel cell vehicles(FCVs)has a major impact on improving air quality and reducing other fossil-fuel-related problems.DC-DC boost converters with wide input voltage ranges and high gains are essential... The development of fuel cell vehicles(FCVs)has a major impact on improving air quality and reducing other fossil-fuel-related problems.DC-DC boost converters with wide input voltage ranges and high gains are essential to fuel cells and DC buses in the powertrains of FCVs,helping to improve the low voltage of fuel cells and“soft”output characteristics.To build DC-DC converters with the desired performance,their topologies have been widely investigated and optimized.Aiming to obtain the optimal design of wide input range and high-gain DC-DC boost converter topologies for FCVs,a review of the research status of DC-DC boost converters based on an impedance network is presented.Additionally,an evaluation system for DC-DC topologies for FCVs is constructed,providing a reference for designing wide input range and high-gain boost converters.The evaluation system uses eight indexes to comprehensively evaluate the performance of DC-DC boost converters for FCVs.On this basis,issues about DC-DC converters for FCVs are discussed,and future research directions are proposed.The main future research directions of DC-DC converter for FCVs include utilizing a DC-DC converter to realize online monitoring of the water content in FCs and designing buck-boost DC-DC converters suitable for high-power commercial FCVs. 展开更多
关键词 Fuel cell vehicles DC-DC boost converter Evaluation systems and indexes High gain topology
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Cross-linked hole transport layers for high-efficiency perovskite tandem solar cells 被引量:1
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作者 Yurui Wang Shuai Gu +11 位作者 Guoliang liu Liping Zhang Zhou liu Renxing Lin Ke Xiao Xin Luo Jianhua Shi Junling Du Fanying Meng Ludong Li zhengxin liu Hairen Tan 《Science China Chemistry》 SCIE EI CSCD 2021年第11期2025-2034,共10页
Perovskite tandem solar cells have recently received extensive attention due to their promise of achieving power conversion efficiency(PCE)beyond the limits of single-junction cells.However,their performance is still ... Perovskite tandem solar cells have recently received extensive attention due to their promise of achieving power conversion efficiency(PCE)beyond the limits of single-junction cells.However,their performance is still largely constrained by the widebandgap perovskite solar cells which show considerable open-circuit voltage(VOC)losses.Here,we increase the VOCand PCE of wide-bandgap perovskite solar cells by changing the hole transport layer(HTL)from commonly used poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine)(PTAA)to in-situ cross-linked small molecule N_(4),N_(4)′-di(naphthalen-1-yl)-N_(4),N_(4)′-bis(4-vinylphenyl)biphenyl-4,4′-diamine(VNPB).The stronger interaction and lower trap density at the VNPB/perovskite interface improve the PCE and stability of wide-bandgap perovskite solar cells.By using the cross-linked HTL for front wide-bandgap subcells,PCEs of 24.9%and 25.4%have been achieved in perovskite/perovskite and perovskite/silicon tandem solar cells,respectively.The results demonstrate that cross-linkable small molecules are promising for high-efficiency and cost-effective perovskite tandem photovoltaic devices. 展开更多
关键词 perovskite solar cells tandem solar cells hole transport layer CROSS-LINKED
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Derivation of Non-Integration Induced Pluripotent Stem Cells from Fibroblast of Severe Deafness Patients with GJB2 Mutation 被引量:1
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作者 Xiaofeng Jin Rui Fu +7 位作者 Wanwan Zhu zhengxin liu Tiantian Gu Guanyi Jiao Hua Yang Qi Zhou Zhiqiang Gao Xiao-Yang Zhao 《Journal of Genetics and Genomics》 SCIE CAS CSCD 2015年第8期455-458,共4页
In all the connexin-associated human diseases, deafness is one of the most important diseases with high frequency. The mu- tations of GJB2 (gap junction protein β2, also called connexin 26, Cx26) gene link with non... In all the connexin-associated human diseases, deafness is one of the most important diseases with high frequency. The mu- tations of GJB2 (gap junction protein β2, also called connexin 26, Cx26) gene link with nonsyndromic or syndromic senso- rineural hearing loss and were shown to account for a large proportion of congenital deaf cases in many studied populations (del Castillo and del Castillo, 2011). For example, the 235de1C mutation in GJB2 shows the frequency of approximately 1% and is the most frequent mutation in East Asian population (Yan et al., 2003). Many efforts have been put to study the function of Gjb2 gene in both mouse model and human. In mouse, extensive deletion of Gjb2 causes embryo lethal due to the decreased transplacental glucose uptake, which was not found in human (Takata and Hirano, 1997; Gabriel et al., 1998). In human, GJB2 deficiency is not able to cause embryo lethal (D'Andrea et al., 2002). However, the study of GJB2-associated hearing loss is hampered by many difficulties, such as unobtainable human cochlea and acoustic nerve tissues, and therefore the GJB2-associated hearing loss are underlying mechanisms of still remaining unclear. 展开更多
关键词 GJB In PSCs
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