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Upconverting and downshifting circularly polarized luminescence in a superstructural helix

Science China Chemistry 2024年第8期67卷 2571-2577页

作者： Honghan Ji Bin Wu Enquan Tian Chao Ren Xue Jin Liangliang Zhu Pengfei Duan CAS Key Laboratory of nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology(NCNST)Beijing 100190China State Key Laboratory of Molecular engineering of Polymers Department of Macromolecular ScienceFudan UniversityShanghai 200438China University of Chinese Academy of Sciences Beijing 101408China

The modulation of circularly polarized luminescence(CPL) has become an increasingly prominent area of research. In this study,we propose a unique “one-excitation-to-three-emissions” CPL system through the co-assembly of an upconversion system,incorporating one sensitizer(Pt(II) mesotetraphenyl tetrabenzoporphyrine, Pt TPBP) and two annihilators(R/S-DPA and R/SBDP) within liquid crystals. The chiral nature of the annihilators induces a transformation of the nematic liquid crystal into chiral nematic liquid crystals(N*LC), establishing an excellent chiral matrix. Upon the incorporation of the sensitizer Pt TPBP and subsequent excitation at 635 nm, the system demonstrates two independent triplet–triplet annihilation photon upconversion(TTA-UC) with the emission in blue and yellow, aided by thermally activated triplet–triplet energy transfer(TTET). This is accompanied by the simultaneous generation of upconverting circularly polarized luminescence(UC-CPL) and downshifting near-infrared circularly polarized luminescence(DS-CPL) originating from the residual luminescence of Pt TPBP. Remarkably,fine-tuning the ratio between the two annihilators allows the TTA-UC system to exhibit multicolor CPL emission with an amplified luminescence dissymmetry factor(glum, reaching up to 0.6). Our study unveils a previously unreported “one-excitation-to-three-emissions” system and provides a versatile strategy for modulating CPL emissions, surpassing conventional methodologies.

关键词： circularly polarized luminescence triplet–triplet annihilation upconversion near-infrared emission chiral nematic liquid crystal luminescence dissymmetry factor

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Oligomeric donor with appropriate crystallinity for organic solar cells

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Chinese Chemical Letters 2024年第2期35卷 289-294页

作者： Kaiming Yang Min Lv Yanhong Chang Kun Lu Zhixiang Wei CAS Key Laboratory of nanosystem and Hierarchical Fabrication CAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China department of Environmental Science and engineering University of Science and Technology BeijingBeijing 100083China Beijing Key Laboratory of Resource Treatment of Typical Industrial Pollutants Beijing 100083China

Improving the performance of all-small-molecule organic solar cells(ASM-OSCs)largely depends on the design and application of novel donors with appropriate *** molecular conjugation is an effective method for regulating molecular stacking and *** this work,we successfully designed and synthesized two novel acceptor-donor-donor-donor-acceptor(A-D-D-D-A)type oligomeric donors with three dithieno[2,3-d:2′,3′-d′]benzo[1,2-b:4,5-b']dithiophene(DTBDT)as the central unit,named as 3DTBDT-Cl and 3DTBDT,depending on with and without chlorine substitution on the thiophene side *** found that the introduction of chlorine atoms makes the blend films display stronger crystallinity but with large-scale phase separation morphology and more defects,which eventually leads to a power conversion efficiency(PCE)of only 10.83%,whereas the blend films based 3DTBDT with appropriate crystallinity achieved 13.74%*** with 3DTBDT-Cl/L8-BO,the 3DTBDT/L8-BO films exhibited a nanoscale bi-continuous interpenetrating network morphology with a smaller domain size and more suitable crystallinity,which guarantees the corresponding devices obtained more efficient exciton dissociation,efficient charge transport,reduced bimolecular recombination,and performed more balanced carrier *** results demonstrated that regulating the crystallinity of oligomeric donors to obtain the desired phase separation morphology in the blend films could facilitate further improving the performance of ASM-OSCs.

关键词： Linked donor unit Oligomeric donors Crystallinity regulation Organic solar cells

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Carbon nanotube films with ultrahigh thermal-shock and thermalshock-fatigue resistance characterized by ultra-fast ascending shock testing

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Nano Research 2024年第8期17卷 6777-6784页

作者： Mingquan Zhu Shijun Wang Yunxiang Bai Feng Gao Zhenxing Zhu Congying Wang Peng Zhang Hao Jin Hui Zhang Luqi Liu Zhiping Xu Xinghong Zhang Fei Wei Zhong Zhang CAS Key Laboratory of nanosystem and Hierarchical Fabrication CAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Beijing Key Laboratory of Green Chemical Reaction engineering and Technology Department of Chemical EngineeringTsinghua UniversityBeijing 100084China department of engineering Mechanics Tsinghua UniversityBeijing 100084China National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Center for Composite Materials and StructuresHarbin Institute of TechnologyHarbin 150001China CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsUniversity of Science and Technology of ChinaHefei 230027China

The exploration of material failure behavior not only involves defining its limits and underlying mechanisms but also entails devising strategies for improvement and protection in extreme ***'ve pioneered an advanced multi-scale,high-speed ascending thermal shock testing platform capable of inducing unprecedented heat shocks at rates surpassing 105℃/*** meticulous examination of the thermal shock responses of carbon nanotube(CNT)films,we've achieved remarkable *** employing an innovative macro-scale synchronous tightening and relaxing approach,we've attained a critical temperature differential in CNT films that exceeds an exceptional 2500℃—surpassing any previously reported metric for highperformance,thermal-shock-resistant ***,these samples have demonstrated exceptional resilience,retaining virtually unchanged strength even after enduring 10,000 thermal shock cycles at temperatures exceeding 1000℃.Furthermore,our research has revealed a novel thermal shock/fatigue failure mechanism that fundamentally diverges from conventional theories centered on thermal stress.

关键词： carbon nanotubes failure behavior thermal shock characterization

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Fabricating bio-inspired high impact resistance carbon nanotube network films for multi-protection under an extreme environment

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Nano Research 2024年第9期17卷 7793-7802页

作者： Mingquan Zhu Kailu Xiao Wei Zhang Xudong Lei Yunxiang Bai Shijun Wang Peng Zhang Feng Gao Congying Wang Wenqiang Xu Huiyong Li Xianqian Wu Chao Wang Hui Zhang Luqi Liu Zhong Zhang CAS Key Laboratory of nanosystem and Hierarchical Fabrication CAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China department of Materials Science and engineering Texas A&M UniversityCollege StationTexas 77840USA Institute of Mechanics Chinese Academy of SciencesBeijing 100190China School of Astronautics Harbin Institute of TechnologyHarbin150001China CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsUniversity of Science and Technology of ChinaHefei 230027China

The fabrication of light-weight,highly impact-resistant,and energy-absorbent materials is urgently demanded in many facets of the society from body armor to aerospace engineering,especially under an extreme *** nanotubes(CNTs),one of the strongest and toughest materials ever found,also have good conductivity,chemical stability,and thermal stability,etc,making them a competitive candidate as building blocks to help achieve the above *** this work,a kind of CNT network was prepared by using chlorosulfonic acid(CSA)to release the internal stress of super-aligned carbon nanotube films(SA-CNTF)and dendritic polyamide amine(PAMAM)to further introduce multiple hydrogen bonds and interlocking *** fabricated bioinspired carbon nanotube network films(PAMAM@C-CNTF)have a high toughness of 45.97 MJ/m3,showing an increase of 420%compared to neat *** importantly,the anti-impact performance of the films(e.g.,with a maximum specific energy absorption of 1.40 MJ/kg under 80-100 m/s projectile impact)is superior to that of conventional protective materials from steel and Kevlar fiber,and also exceeds that of any other reported carbon-based *** hierarchical energy dissipation mechanism was further revealed through experiment and *** functions including intelligent heating/anti-icing,ultraviolet protection,as well as electromagnetic interference shielding properties make these network films have great potential in practical multi-protection applications,especially under an extreme environment.

关键词： carbon nanotubes composites mechanical properties multi-function

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Characteristics of machined surface controlled by cutting tools and conditions in machining of brittle material

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中国有色金属学会会刊：英文版 2009年第B9期19卷 194-201页

作者： Yong-Woo KIM Soo-Chang CHOI Jeung-Woo PARK Deug-Woo LEE department of Nano Fusion Technology Pusan National University department of Mechanical Design engineering Chosun University department of nanosystem and nanoprocess engineering Pusan National University

One of the ultra-precision machining methods was adapted for brittle material as well as soft material by using multi-arrayed diamond tips and high speed spindle. Conventional machining method is too hard to control surface roughness and surface texture against brittle material because the particles of grinding tools are irregular size and material can be fragile. Therefore, we were able to design tool paths and machine controlled pattern on surface by multi-arrayed diamond tips with uniform size made in MEMS fabrication and high speed spindle, and the maximum speed was about 3×105 r/min. We defined several parameters that can affect the machining surface. Those were multi-array of diamond tips (n×n), speed of air spindle and feeding rate. The surface roughness and surface texture can be controlled by those parameters for micro machining.

关键词：加工表面脆性材料条件控制刀具路径表面粗糙度特征高速主轴加工方法

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Epitaxial quasi-2D/3D hybrid perovskite heterojunctions for photodetector with enhanced detectivity and stability

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Nano Research 2024年第7期17卷 6594-6602页

作者： Yifu Chen Lin Zhang Xinxin Peng Weiran Qin Shiqing Li Yingwei Wang Zhihui Chen Si Xiao Bin Yang Biao Liu Junliang Yang Han Huang Yun Lin Jun He Liming Ding Yongbo Yuan Hunan Key Laboratory of Super Microstructure and Ultrafast Process School of PhysicsCentral South UniversityChangsha 410083China Hunan Key Laboratory of Nanophotonics and Devices School of PhysicsCentral South UniversityChangsha 410083China College of Materials Science and engineering Hunan UniversityChangsha 410082China department of Photoelectric Information School of PhysicsCentral South UniversityChangsha 410083China Center for Excellence in Nanoscience Key Laboratory of Nanosystem and Hierarchical FabricationNational Center for Nanoscience and TechnologyChinese Academy of ScienceBeijing 100190China

Although numerous metal halide perovskite materials have been investigated in the field of optoelectronic,the development of perovskite heterojunctions with exotic structures is still ***,we report the epitaxial growth of quasi-two-dimensional(Q-2D)perovskites on methylammonium lead iodide(MAPbI_(3))single crystals to form perovskite heterojunctions with interfacial *** MAPbI_(3)adjacent to epitaxial Q-2D perovskite shows blue shifted photoluminescence with shortened lifetime,which becomes significant with the reduced layer number of the Q-2D *** findings suggest the presence of an interfacial strain gradient leading to enhanced photocarrier ***,compared to the MAPbI_(3)single crystal detector,the BA_(2)MAPb_(2)I_(7)/MAPbI_(3)(BA:n-butylamine)heterojunction-based photodetector demonstrates a bandpass detecting property and exhibits 5 times enhanced external quantum efficiency and 83 times enhanced specific detectivity(D*=3.26×10^(11)Jones).Remarkably,the unencapsulated BA_(2)MAPb_(2)I_(7)/MAPbI_(3)heterojunction is stable in ambient condition for>300 *** Q-2D/3D heterojunction shows suppressed ion inter-diffusion due to the presence of Q-2D phase.

关键词： epitaxial growth interfacial strain quasi-two-dimensional/three-dimensional(Q-2D/3D)heterojunctions ion inter-diffusion

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Attaching single carbon nanotube on tip's apex using dielectrophoresis of DC-pulse voltage

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中国有色金属学会会刊：英文版 2009年第B9期19卷 280-283页

作者： Hee-Jin JEONG Yoong-Ho JUNG Deug-Woo LEE Gyeongbuk Hybrid Technology Institute School of Mechanical engineering Pusan National University department of nanosystem and nanoprocess engineering Pusan National University

Single carbon nanotubes (CNTs) are candidates for a number of electronics and sensing applications, provided that single CNTs can be separated from a bundle of CNTs in suspension. Dielectrophoresis has recently been demonstrated as one route for the extraction of desired CNTs. However, previous methods using dielectrophoresis have found it difficult to extract single nanotubes from bundles of CNTs in solution. Here, we show that this restriction can be overcome by using pulsed DC voltage of an electric field, instead of regular AC and DC voltages.

关键词：碳纳米管直流脉冲脉冲电压介电顶点消息电子号码 CNTs

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Regulation of the quantum barrier and carrier transport toward high-efficiency quasi-2D Dion-Jacobson tin perovskite solar cells

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Journal of Energy Chemistry 2024年第8期95卷 200-207,I0005页

作者： Huanhuan Yao Chang Shi Tai Wu Shurong Wang Mingyu Yin Liming Ding Yong Hua Feng Hao School of Materials and Energy University of Electronic Science and Technology of ChinaChengdu 611731SichuanChina College of Chemistry and Molecular engineering Peking UniversityBeijing 100871China Yunnan Key Laboratory for Micro/Nano Materials&Technology School of Materials and EnergyYunnan UniversityKunming 650091YunnanChina Center for Excellence in Nanoscience(CAS) Key Laboratory of Nanosystem and Hierarchical Fabrication(CAS)National Center for Nanoscience and TechnologyBeijing 100190China

Quasi-2D Dion-Jacobson(DJ)tin halide perovskite has attracted much attention due to its elimination of Van der Waals gap and enhanced environmental ***,the bulky organic spacers usually form a natural quantum well structure,which brings a large quantum barrier and poor film quality,further limiting the carrier transport and device ***,we designed three organic spacers with different chain lengths(ethylenediamine(EDA),1,3-propanediamine(PDA),and 1,4-butanediamine(BDA))to investigate the quantum barrier *** and experimental characterizations indicate that EDA with short chain can reduce the lattice distortion and dielectric confinement effect,which is beneficial to the effective dissociation of excitons and the inhibition of trap-free non-radiative *** addition,EDA cation shows strong interaction with the inorganic octahedron,realizing large aggregates in precursor solution and high-quality films with improved structural ***,femtosecond transient absorption proves that EDA cations can also weaken the formation of small n-phases with large quantum barrier to achieve effective carrier transport between different ***,the quasi-2D DJ(EDA)FA_(9)Sn_(10)I_(31)solar cells achieves a 7.07%power conversion efficiency with good environment ***,this work sheds light on the regulation of the quantum barrier and carrier transport through the chain length of organic spacer for qua si-2D DJ lead-free perovskites.

关键词： Chain lengths Organic spacers Quantum well Carrier transport Lattice distortion

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Finite element and experimental analysis of Vickers indentation testing on Al_2O_3 with diamond-like carbon coating

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Journal of Central South University 2012年第5期19卷 1175-1181页

作者： ZHAI Jian-guang WANG Yi-qi KIM Tae-gyu SONG Jung-il department of Mechanical engineering Changwon National University Changwon 641-773 Korea department of nanosystem and nanoprocess engineering Pusan National University Pusan 609-735 Korea

Numerical simulation and experimental study of the Vickers indentation testing of the Al2O3 ceramic coated by diamond-like carbon(DLC) layer were *** numerical analysis was implemented by a two-dimensional finite element(FE) axis symmetry *** analysis results gave insight into the fracture mechanism of DLC films coated on brittle ceramic(Al2O3) *** maximum principal stress field was used to locate the most expected area for crack formation and propagation during the Vickers indentation *** results show that the median crack initiates in the interface under indenter,before ring crack occurs as the indenter presses ***,the plastic deformation appears when the indenter penetrates into the *** thicker DLC coating increases the Vickers hardness and fracture toughness.

关键词： Vickers indentation testing finite element diamond-like carbon Al2O3 fracture toughness

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engineering fibrillar morphology for highly efficient organic solar cells

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Journal of Semiconductors 2024年第2期45卷 7-9页

作者： Chengcheng Xie Bin Zhang Menglan Lv Liming Ding engineering Research Center for Energy Conversion and Storage Technology of Guizhou School of Chemistry and Chemical EngineeringGuizhou UniversityGuiyang 550025China Center for Excellence in Nanoscience(CAS) Key Laboratory of Nanosystem and Hierarchical Fabrication(CAS)National Center for Nanoscience and TechnologyBeijing 100190China

The power conversion efficiency(PCE)for single-junction organic solar cells(OSCs),wherein the photoactive layer is a typical bulk-heterojunction containing donor and acceptor materials,has surpassed 19%[1−4].The advance is ascribed to the development of Y-series non-fullerene acceptors(NFAs)[5,6]and polymer donors[7−13],and the refined control of the blend film morphology.

关键词： morphology refined donor

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