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First-principles study of the band gap tuning and doping control in CdSexTe1-x alloy for high efficiency solar cell

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Chinese Physics B 2019年第8期28卷 16-21页

作者： Jingxiu Yang Su-huai wei Department of Materials Science and Engineering Jilin Jianzhu UniversityChangchun 130118China Beijing Computational Science Research Center Beijing 100193China

CdTe is one of the leading materials for low cost,high efficiency thin-film solar cells with a nearly ideal band gap of 1.48 ***,its solar to electricity power conversion efficiency(PCE)is hindered by the relatively low open circuit voltage(VOC)due to intrinsic defect related ***,we propose that alloying CdTe with CdSe could possibly improve the solar cell performance by reducing the"ideal"band gap of CdTe to gain more short-circuit current from long-wavelength absorption without sacrificing much *** the hybrid functional calculation,we find that the minimum band gap of the CdTe1-xSex alloy can be reduced from 1.48 eV at x=0 to 1.39 eV at x=0.32,and most of the change come from the lowering of the conduction band *** also show that the formation of the alloy can improve the p-type doping of CuCdimpurity based on the reduced effective formation energy and nearly constant effective transition energy level,thus possibly enhance VOC,thus PCE.

关键词： alloy bowing effect doping Ⅱ-Ⅵsemiconductors

Overcoming doping bottleneck by using surfactant and strain

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Frontiers of Materials Science 2011年第4期5卷 335-341页

作者： Junyi ZHU Su-huai wei National Renewable Energy Laboratory Golden Colorado 80401 USA

Overcoming the doping bottleneck in semiconductors, especially in wide band gap semiconductors, has been a challenge in semiconductor physics for many years. In this paper, we review some recent progresses in enhancing doping by surfactant and strain. We show that surfactant and strain are two effective approaches to enhance dopant solubility in epitaxial growth. The surfactant can introduce an energy level deep inside the band gap, making the host compound less stable, thus lower the formation energy of the intentional dopant. The strain enhanced doping is based on the observation that dopant induces volume change in the host. If the external strain is in the same direction as the dopant induced volume change, the formation energy of the dopant is reduced. This effect can be used to tune doping sites, thus doping type, in a host. A hybrid method to both include strain and surfactant is proposed, which can be a promising general method to further enhance doping.

关键词： semiconductor surfactant strain doping band gap

First-principles study of defect control in thin-film solar cell materials

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Science China(Physics,Mechanics & Astronomy) 2021年第3期64卷 28-45页

作者： Hui-Xiong Deng RuYue Cao Su-huai wei State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Beijing Computational Science Research Center Beijing 100193China

A solar cell is a photovoltaic device that converts solar radiation energy to electrical energy, which plays a leading role in alleviating global energy shortages and decreasing air pollution levels typical of conventional fossil fuels. To render solar cells more efficient, high visible-light absorption rates and excellent carrier transport properties are required to generate high carrier levels and high output voltage. Hence, the core material, i.e., the absorption layer, should have an appropriate direct band gap and be effectively doped by both p-and n-types with minimal carrier traps and recombination centers. Consequently, defect properties of absorbers are critical in determining solar cell efficiency. In this work, we review recent first-principles studies of defect properties and engineering in four representative thin-film solar cells, namely CdTe, Cu(In,Ga)Se2, Cu2ZnSnS4, and halide perovskites. The focal points include basic electronic and defect properties, existing problems, and possible solutions in engineering defect properties of those materials to optimize solar cell efficiency.

关键词： first-principles study thin-film solar cells defect engineering energy conversion efficiency

Inhomogeneous strain-induced half-metallicity in bent zigzag graphene nanoribbons

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npj Computational Materials 2017年第1期3卷 189-193页

作者： Dong-Bo Zhang Su-huai wei Beijing Computational Science Research Center Beijing 100193P.R.China

Realization of half-metallicity in low dimensional materials is a fundamental challenge for nano spintronics,which is a critical component for next-generation information *** the method of generalized Bloch theorem,we show that an in-plane bending can induce inhomogeneous strains,which in turn lead to spin-splitting in zigzag graphene nanoribbons and results in the highly desired half-metallic *** the previously proposed scheme that requires unrealistically strong external electric fields,the obtained half-metallicity with sizeable half-metallic gap and high energetic stability of magnetic order of edge states requires only relatively low-level strain in the in-plane *** the superior structural flexibility of graphene and the recent experimental advances in controllable synthesis of graphene nanoribbons,our design provides a hitherto most practical approach to the realization of half-metallicity in low dimensional *** work,thus paves a way towards the design of nanoscale spintronic devices through strain engineering.

关键词： metallic zigzag bending

Advances and challenges in DFT-based energy materials design

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Chinese Physics B 2022年第10期31卷 34-52页

作者： Jun Kang Xie Zhang Su-huai wei Beijing Computational Science Research Center Beijing 100193China

The growing worldwide energy needs call for developing novel materials for energy *** initio density functional theory(DFT)calculations allow the understanding and prediction of material properties at the atomic scale,thus,play an important role in energy materials *** to the fast progress of computer power and development of calculation methodologies,DFT-based calculations have greatly improved their predictive power,and are now leading to a paradigm shift towards theory-driven materials *** aim of this perspective is to introduce the advances in DFT calculations which accelerate energy materials *** first present state-of-the-art DFT methods for accurate simulation of various key properties of energy *** we show examples of how these advances lead to the discovery of new energy materials for photovoltaic,photocatalytic,thermoelectric,and battery *** challenges and future research directions in computational design of energy materials are highlighted at the end.

关键词： density functional theory materials design energy applications

Band structure engineering and defect control of oxides for energy applications

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Chinese Physics B 2018年第11期27卷 112-119页

作者： Hui-Xiong Deng Jun-wei Luo Su-huai wei State Key Laboratory of Superlattices and Microstructures Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China University of Chinese Academy of Sciences Beijing 100049 China Beijing Computational Science Research Center Beijing 100193 China

Metal oxides play an essential role in modern optoelectronic devices because they have many unique physical properties such as structure diversity, superb stability in solution, good catalytic activity, and simultaneous high electron conductivity and optical transmission. Therefore, they are widely used in energy-related optoelectronic applications such as photovoltaics and photoelectrochemical（PEC） fuel generation. In this review, we mainly discuss the structure engineering and defect control of oxides for energy applications, especially for transparent conducting oxides（TCOs） and oxide catalysts used for water splitting. We will review our current understanding with an emphasis on the contributions of our previous theoretical modeling, primarily based on density functional theory. In particular, we highlight our previous work：（i） the fundamental principles governing the crystal structures and the electrical and optical behaviors of TCOs;（ii） band structures and defect properties for n-type TCOs;（iii） why p-type TCOs are difficult to achieve;（iv） how to modify the band structure to achieve p-type TCOs or even bipolarly dopable TCOs;（v） the origin of the high-performance of amorphous TCOs; and（vi） band structure engineering of bulk and nano oxides for PEC water splitting. Based on the understanding above, we hope to clarify the key issues and the challenges facing the rational design of novel oxides and propose new and feasible strategies or models to improve the performance of existing oxides or design new oxides that are critical for the development of next-generation energy-related applications.

关键词： band-structure engineering defect control oxides density functional theory

水下冲击波载荷作用下复合材料层合板的动态失效机理

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火炸药学报 2024年第8期47卷 730-737,I0004页

作者：蔡泽喆朱小龙王鹤然黄怀纬龙舒畅姚小虎华南理工大学土木与交通学院广东广州510641 中航成飞民用飞机有限责任公司四川成都610073

为了研究复合材料层合结构的水下抗冲击特性,基于水下爆炸冲击波等效加载装置,结合三维数字图像相关方法,开展了碳纤维增强复合材料层合板动态响应以及失效特征的试验研究;讨论了水下冲击波载荷下复合材料层合板计及流固耦合效应的动态... 详细信息

为了研究复合材料层合结构的水下抗冲击特性,基于水下爆炸冲击波等效加载装置,结合三维数字图像相关方法,开展了碳纤维增强复合材料层合板动态响应以及失效特征的试验研究;讨论了水下冲击波载荷下复合材料层合板计及流固耦合效应的动态响应过程;分析了水下冲击波载荷水压峰值、衰减时间以及板厚度变化对复合材料层合板失效特征产生的影响。结果表明,水下冲击波载荷作用下层合板的动态响应过程因涉及板的面内弯剪波传播与流体空化二次加载的相互作用,响应阶段可划分为面内波传播、边界控制响应、二次加载3个阶段;当层合板发生破坏,层合板边界处纤维剪切破坏及靠近边界范围的纤维拉伸破坏均出现在响应第一阶段,响应第二阶段中破坏现象不明显,响应第三阶段则受板厚和载荷的影响可能在板中心因弯折出现纤维断裂;当层合板受较小冲量水下冲击波加载时,外表面不会出现明显失效,但响应过程中结构内部的纤维及基体破坏引起了气背面的残余变形,也降低了结构剩余强度影响承载能力。

关键词：爆炸力学水下冲击波复合材料动态响应失效机理水下抗冲击特性

Electronic origin of the unusual thermal properties of copper-based semiconductors:The s-d coupling-induced large phonon anharmonicity

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Science China(Physics,Mechanics & Astronomy) 2023年第7期66卷 112-119页

作者： Kaike Yang huai Yang Yujia Sun Zhongming wei Jun Zhang Ping-Heng Tan Jun-wei Luo Shu-Shen Li Su-huai wei Hui-Xiong Deng State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Key Laboratory for Matter Microstructure and Function of Hunan ProvinceSynergetic Innovation Center for Quantum Effects and ApplicationsDepartment of PhysicsHunan Normal UniversityChangsha 410081China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Beijing Computational Science Research Center Beijing 100193China

Copper(Cu)-based materials(such as cuprates,Cu chalcogenides,and Cu halides)often exhibit unusual properties such as superconductivity,ultralow thermal conductivity,and ***,the electronic origin of these unusual behaviors remains *** this study,we demonstrate that the high-lying occupied 3d orbital of Cu causes a strong s-d coupling with its unoccupied 4s state when local symmetry is *** leads to strong phonon anharmonicity and is responsible for these intriguing *** example,during thermal transport,symmetry-controlled s-d coupling can substantially lower the lattice potential barrier,thereby enhancing the anharmonicity and scattering between phonons and ultimately significantly reducing lattice thermal *** confirmed this understanding with Raman spectra measurements,which demonstrated a remarkable red shift in the phonon vibrational frequency with an increase in the temperature of Cu-based *** study shows that the cause of phonon anharmonicity is related to the fundamental electronic structures,which can also explain other unusual physical properties of the Cu compounds.

关键词： anharmonicity copper-based semiconductor electronic structure thermal conductivity

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改良的双极射频溶脂技术在形体雕塑中的应用

中国医疗器械信息 2024年第12期30卷 38-40页

作者：祝顺武汪锋廖怀伟南昌科颜美医疗美容门诊部美容外科江西南昌330038 南昌大学第一附属医院整形外科江西南昌330006

目的:探讨改良的双极射频溶脂技术在形体雕塑中的应用效果。方法:研究对象为2020年12月~2021年12月在本院行形体塑造的患者110例,采用双盲法将患者分成两组,即对照组与观察组各55例,前者实施常规的负压吸脂手术,后者实施改良的双极射频... 详细信息

目的:探讨改良的双极射频溶脂技术在形体雕塑中的应用效果。方法:研究对象为2020年12月~2021年12月在本院行形体塑造的患者110例,采用双盲法将患者分成两组,即对照组与观察组各55例,前者实施常规的负压吸脂手术,后者实施改良的双极射频溶脂技术,对比两组取得的效果、满意度调查结果及并发症发生情况。结果:观察组总有效率为94.55%,与对照组的78.18%对比差异显著(P0.05)。结论:改良的双极射频溶脂技术用于形体雕塑中,可获得良好的紧致皮肤效果,且并发症少,患者满意度高。

关键词：改良的双极射频溶脂技术形体雕塑满意度并发症