Lead-free copper-based halides have attracted significant attention for optoelectronic applications due to their excellent photophysical properties, good stability, and environmental friendliness. However, current synthesis methods for copper-based halide nanocrystals either require high-temperature inert protection or rely on insulating long-chain ligands, limiting their practical applications. In this study, we report a facile one-pot room-temperature synthesis of Cs3Cu2X5 (X = Cl, Br) and CsCu2I3 nanocrystals using an anti-solvent method. Short-chain propionic acid (PA) is introduced as a surface passivation ligand, significantly enhancing photoluminescence through defect passivation. The PA-coated Cs3Cu2Cl5 nanocrystals exhibit good resistance to ethanol but poor stability in water. To improve thermal stability, PMMA encapsulation is employed, with the composite film retaining ∼90% of initial PL intensity at 80∼90 °C and two-thirds at 150 °C. Time-resolved PL decay measurements confirm that both PA coating and PMMA encapsulation prolong the exciton lifetime. This work provides a green and effective strategy for the synthesis and surface engineering of copper-based halide nanocrystals for environmentally friendly optoelectronic applications.

The research on low-temperature lead-free glass is of great significance for the miniaturization, integration and intelligence of current electronic products, as well as environmental protection. In this article, we report the preparation of low-temperature lead-free B2O3-BaO-ZnO-SiO2-Al2O3-TeO2 glasses by a melt-quenching technique. With the increase of TeO2 content in glass, the glass transition temperature and melting temperature of sintered glass powder decrease, while its wettability and acid corrosion resistance show an increasing trend. The application of glass powder in the sintering experiment of terminal electrode slurry further proves this viewpoint. Compared with the poor sintering performance of the slurry with TeO2-free glass powder, the slurry containing TeO2 glass powder forms a very dense sintered solid, and the sintered slurry is tightly bonded to the ceramic substrate.

The research on low-temperature lead-free glass is of great significance for the miniaturization, integration and intelligence of current electronic products, as well as environmental protection. In this article, we report the preparation of low-temperature lead-free B2O3-BaO-ZnO-SiO2-Al2O3-TeO2 glasses by a melt-quenching technique. With the increase of TeO2 content in glass, the glass transition temperature and melting temperature of sintered glass powder decrease, while its wettability and acid corrosion resistance show an increasing trend. The application of glass powder in the sintering experiment of terminal electrode slurry further proves this viewpoint. Compared with the poor sintering performance of the slurry with TeO2-free glass powder, the slurry containing TeO2 glass powder forms a very dense sintered solid, and the sintered slurry is tightly bonded to the ceramic substrate.

Organic-inorganic perovskite materials have shown excellent performance and strong competitiveness in high-performance photovoltaic and optoelectronic devices. Besides the color-tunable and narrow-band emissions realized in hybrid perovskites, broadband emission from lead-halide perovskites has also attracted strong interest for applications in the next generation of solid-state lighting. Although great progress has been made in lead halide perovskites, a very important aspect that hinders their commercial exploitation is the severe lead toxicity. In this research, a lead-free copper(I)-iodine hybrid was synthesized by a solution evaporation method at room temperature. Single crystal X-ray diffraction shows that this hybrid possesses the chemical formula of C6H5CH2CH2NH3CuI2. The C6H5CH2CH2NH3CuI2 belongs to the monoclinic phase with the C2/c space group, where the edge-sharing [CuI4] tetrahedral chains are separated by organic C6H5CH2CH2NH3 thorn ions, exhibiting one-dimensional (1D) crystal structure. The optical band-gap of C6H5CH2CH2NH3CuI2 was determined to be 4.02 eV. The photoluminescence (PL) spectrum shows a broadband emission ranging from 380 nm to 780 nm and peaks at 542 nm together with a small peak at 336 nm, which can be attributed to the emission of self-trapped exciton (STE) and free exciton (FE), respectively. The large Stokes shift of 230 nm between the PL and photoluminescence excitation (PLE) as well as the broad emission was ascribed to the Jahn-Teller lattice distortion of [CuI4] tetrahedra. The reduced 1D characteristic facilitates the tetrahedral distortion. PL decay analysis shows that the average lifetime of STE is about 66.9 ns? Temperature and time-dependent PL measurements show that the normal working temperature of this luminescent material should be no higher than 100 degrees C. Theoretical calculations were performed to better understand this compound. The successful synthesis and preliminary optical investigations on C6H5CH2CH2NH3CuI2 can be of great significance for offering more environmental-benign options in both solid-state lighting and other perovskite opto-electronic devices.(c) 2023 Elsevier Ltd. All rights reserved.

In contrast with three-dimensional perovskites, their two-dimensional (2D) analogues have been demonstrated to effectively improve the moisture tolerance due to the hydrophobicity of the long-chain organic layers. However, the insulating property of the long-chain organic layers will deteriorate the charge transport properties of the materials, limiting their applications in photovoltaics and optoelectronics. Short-chain organic cation with less carbon atoms may be a good substitution for the preparation of 2D perovskites with superior environmental stability and optoelectronic properties. In this research, quasi-2D (C3H7NH3)(2)(MA)(n-1)PbnBr3n+1 perovskite nanocrystals with an average size smaller than 10 nm were synthesized by a one-pot method, showing tunable emissions in the range of 406-524 nm for n = 1 similar to infinity, with corresponding band-gaps of 3.63-2.30 eV. Time -resolved photoluminescence (PL) decays show that (C3H7NH3)(2)PbBr4 has the shortest average PL lifetime of 4.4 ns with the fast decay process occupying weighting proportion of 87.3%. When the nominal perovskite layers increases up to 2-4, the average PL lifetime raises up to 10.1-41.7 ns, with the slow decay process taking up most weighting percentage of >70%. MAPbBr(3) possesses the longest PL lifetime of 151.2 ns. The perovskite nano-crystals were then attempted to modify with oleic acid or to embed in PMMA matrix in order to improve their environmental stability. Results show that the stability of oleic acid and PMMA encapsulated nanocrystals im-proves greatly in comparison with bare nanocrystals.

A simple low-temperature (< 100 °C) hot-water treatment was used to synthesize Fe–N co-doped anatase nanocrystals which were uniformly dispersed in micro–mesoporous SiO2 host film for the first time. The Fe–N co-doped TiO2–SiO2 (FNTS) film exhibited stable photocatalytic activities. A NO removal efficiency of 56.1% was achieved under simulated solar light irradiation without any obvious inactivation in 30 min. The transient photocurrent response of FNTS film is approximately six times higher than that of non-doped TiO2–SiO2 film, indicating the superior charge separation of photo-generated electron–hole pairs. Electron spin resonance analysis showed that the ·OH and ·O2− radicals were key species to remove NO. Combined with quantitative reaction intermediates, the possible photocatalytic degradation mechanism of NO over FNTS film was proposed. In addition, the FNTS thin films exhibited intrinsic super-hydrophilicity and durable self-cleaning property even after 6 months of storage in the dark. This work provides a facile method to load the catalyst on thermal labile substrates, such as soda–lime glass and organic polymer for more practical applications. A simple low-temperature (< 100 °C) hot-water treatment was used to synthesize micro–mesoporous TiO2–SiO2 composite film, which shows good self-cleaning ability and superior photodegradation activity for NO removal under solar light.

Organic-inorganic lead halide single crystals have shown great promise for their unique properties and potential applications in next-generation optoelectronic devices. In this paper, solution syntheses of single-crystalline ethylammonium lead halide microstructures were reported. The Br-containing product grown at a low C2H5NH3Br concentration exhibits an interesting crossed-plate morphology and possesses a chemical formula of (C2H5NH3)(4)Pb3Br10, yet the product synthesized at a high C2H5NH3Br concentration shows a block-like morphology and adopts a chemical formula of (C2H5NH3)(2)PbBr4. The I-containing product shows a rod or polyhedron shape and has the chemical formula of (C2H5NH3)PbI3. Time dependent experiments were carried out to reveal their growth mechanisms. The optical absorption spectra show that the (C2H5NH3)(4)Pb3Br10 and (C2H5NH3)(2)PbBr4 possess exciton absorptions at 2.95 eV and 3.19 eV, respectively. And the C2H5NH3PbI3 shows a much sharper exciton absorption at 2.61 eV.

Syntheses of 2D propylammonium lead halide perovskite microstructures are reported. The I-containing perovskite exhibits a flower-like hierarchical morphology and possesses the chemical formula (C3H7NH3)6Pb4I14. The hydrogen-bonding interactions between organic group C3H7NH3+ and bilateral nearest-neighboring perovskite sheets are deemed to be responsible for this structure.

采用溶胶-凝胶结合低温(<100℃)热水后处理法,在塑料衬底上制得N-Fe共掺杂锐钛矿TiO2-SiO2复合薄膜.采用多种技术手段对薄膜样品进行了表征,并考察了薄膜样品在可见光下对罗丹明B的降解能力.研究结果表明,有机衬底上形成了锐钛矿T iO2纳米晶弥散分布的复合薄膜,薄膜具有较高的可见光催化效率,150min后对罗丹明B的降解效率达到77.4％,其中矿化率达61％.

Borosilicate glasses doped with PbSe quantum dots (QDs) were prepared by a conventional melt-quenching process followed by heat treatment, which exhibit good thermal, chemical, and mechanical stabilities, and are amenable to fiber-drawing. A broad near infrared (NIR) photoluminescence (PL) emission (1070-1330 nm) band with large full-width at half-maximum (FWHM) values (189-266 nm) and notable Stokes shift (100-210 nm) was observed, which depended on the B2O3 concentration. The PL lifetime was about 1.42-2.44 mu s, and it showed a clear decrease with increasing the QDs size. The planar [BO3] triangle units forming the two-dimensional (2D) glass network structure clearly increased with increasing B2O3 concentration, which could accelerate the movement of Pb2+ and Se2- ions and facilitate the growth of PbSe QDs. The tunable broadband NIR PL emission of the PbSe QD-doped borosilicate glass may find potential application in ultra-wideband fiber amplifiers.

针对物理专业学生开设高等化学课程教育进行调查和研究.第一,对国内外著名高校物理系开设化学类课程教育的情况进行了调研;第二,论述了物理专业学生开设高等化学课程教育的重要性;最后给出了实施高等化学课程教育的建议.

Organic–inorganic hybrid perovskites attract considerable attention owing to their applications in high-efficiency solar cells and light emission. Compared with three-dimensional perovskites, two-dimensional (2D) layered hybrid perovskites have a higher exciton binding energy and potentially higher light-emission efficiency. The growth of high-quality crystalline 2D perovskites with a well-defined nanoscale morphology is desirable because they can be suitable building blocks for integrated optoelectronics and (nano)photonics. Herein, we report the facile solution growth of single-crystal microplates of 2D perovskites based on a 2-phenylethylammonium (C6H5CH2CH2NH 3 + , PEA) cation, (PEA)2PbX4 (X = Br, I), with a well-defined rectangular geometry and nanoscale thickness through a dissolution–recrystallization process. The crystal structures of (PEA)2PbX4 are first confirmed using single-crystal X-ray diffraction. A solution-phase transport-growth process is developed to grow microplates with a typical size of tens of micrometers and thickness of hundreds of nanometers on another clean substrate different from the substrate coated with lead-acetate precursor film. Surface-topography analysis suggests that the formation of the 2D microplates is likely driven by the wedding-cake growth mechanism. Through halide alloying, the photoluminescence emission of (PEA)2Pb(Br,I)4 perovskites with a narrow peak bandwidth is readily tuned from violet (~410 nm) to green (~530 nm).

Single ZnO nanowire (NW)-based Au/ZnO NW/Au memristors were fabricated by a one step shadow mask technique.The devices show nonpolar memristive switching behavior with an on/off ratio ＞105.The low resistance state of the materials exhibits semiconducting behavior.It is inferred that the memristive switching may be attributed to the formation/rupture of discontinuous oxygen vacancy filaments at the surfaces of ZnO NWs.The one step shadow mask technique is an effective method for the fabrication of NW devices due to the facile process and less contaminants introduced into devices compared to lithography techniques.

Similar to the three-dimensional perovskites, two-dimensional (2D) layered lead halide perovskites constitute a particular class of semiconductor materials in the family of perovskites. This article reports syntheses of needle-like bundles of 2D perovskite (C6H5CH2NH3)(2)PbI4 by a two-step processing technique. The concentration of C6H5CH2NH3I precursor has a great influence on the product, structural and compositional analyses prove the phase and stoichiometry of 2D perovskite (C6H5CH2NH3)(2)PbI4 with high crystallinity for the needle bundles synthesized with concentration of C6H5CH2NH3I higher than 25 mg/mL. Intensive studies on the growth mechanism of the products were carried out; we believe the involvement of C6H5CH2NH3+ group determines the layered structure and the final morphology of the products. Photoluminescence measurement show that the needles possess a band-edge emission peak centering around 540 nm and a narrow full width at half maximum of about 30 nm. (C) 2016 Elsevier B.V. All rights reserved.

原子物理学作为物理学专业的基础必修课,研究内容抽象深奥,知识点多,思维跨度大,初学者常感到无所适从.本研究提出研究型教学模式的运用,从教学内容、教学方法和教学评价三个方面论述对原子物理学的教学改革.研究型教学模式置"学生为中心,教师为引导",激发了学生学习的积极性和主动性,培养和提高了学生分析问题、解决问题以及科技创新的能力.

美国是世界上高等教育最为发达的国家之一,其研究生教育体系被认为最完整、最规范且具有多样化、灵活性.我国研究生教育取得了长足发展,但研究生数量连续大幅度扩招也使研究生教育中存在的一些问题日益凸显.以美国威斯康星大学和浙江工业大学的物理专业研究生为例,从培养目标、培养过程以及培养评价等方面对两国的研究生培养模式进行了系统的分析和比较.

Understanding crystal growth and improving material quality is important for improving semiconductors for electronic, optoelectronic, and photovoltaic applications. Amidst the surging interest in solar cells based on hybrid organic inorganic lead halide perovskites and the exciting progress in device performance, improved understanding and better control of the crystal growth of these perovskites could further boost their optoelectronic and photovoltaic performance. Here, we report new insights on the crystal growth of the perovskite materials, especially crystalline nanostructures. Specifically, single crystal nanowires, nanorods, and nanoplates of methylammonium lead halide perovskites (CH3NH3PbI3 and CH3NH3PbBr3) are successfully grown via a dissolution-recrystallization pathway in a solution synthesis from lead iodide (or lead acetate) films coated on substrates. These single crystal nanostructures display strong room-temperature photoluminescence and long carrier lifetime. We also report that a solid liquid interfacial conversion reaction can create a highly crystalline, nanostructured MAPbI(3) film with micrometer grain size and high surface coverage that enables photovoltaic devices with a power conversion efficiency of 10.6%. These results suggest that single-crystal perovskite nanostructures provide improved photophysical properties that are important for fundamental studies and future applications in nanoscale optoelectronic and photonic devices.

Silicon micropyramids with n(+)pp(+) junctions are demonstrated to be efficient absorbers for integrated solar-driven hydrogen production systems enabling significant improvements in both photocurrent and onset potential. When conformally coated with MoSxCly, a catalyst that has excellent catalytic activity and high optical transparency, the highest photocurrent density for Si-based photocathodes with earth-abundant catalysts is achieved.

The synthesis of PbSe quantum dots (QDs) in silicate glasses was achieved by a simple melt-annealing technique. Transmission electron microscopy analysis proves the formation of PbSe QDs in glasses. The absorption spectra show that the light absorption originates from the PbSe QDs in glasses mostly, and the energy-integrated molar extinction coefficient for the first exciton transition was deemed to be only about 1/10 of those from colloidal PbSe QDs. The photoluminescence analysis reveals that the Forster energy transfer is responsible for the shape of the PL peak. For the sample with PbSe QDs in a small radius of 5.2 nm, a pronounced Stokes shift of 70 meV was found, and the Huang–Rhys factor was calculated to be 2.1.