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Effect of Side-Chain Variation on Single-Crystalline Structures for Revealing the Structurea??Property Relationships of Organic Solar Cells
摘要： The molecular stacking assembly in the active layer plays a significant role in the photovoltaic performance of organic solar cells (OSCs). Here, we report two new small molecular donors with different side chains, FBT-O and FBT-H, and their corresponding fullerene-based OSCs. A slight change in the side chains led to a big difference in the power conversion efficiencies (PCEs). Although the molecular structures of the two donors are similar to each other, PCEs of the devices based on FBT-O were almost three times higher than those of the devices based on FBT-H, with manifold short-circuit current density, fill factor, as well as three orders of magnitude enhancement in the hole mobility. The difference in their single crystal structures was thoroughly investigated, whereby the FBT-O exhibited better planarity leading to appropriate phase separation and domain size. Furthermore, two-dimensional grazing-incidence wide-angle X-ray scattering results of the blend films revealed that the two donors retained a similar stacking structure as compared to the single-crystal structures, thus, establishing a clear relationship between the molecular stacking structure and the device performance.
关键词： side-chain modification,hole mobility,single crystal,molecular stacking structure
更新于2025-09-19 17:13:59
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Structure and property relationship of methoxy substituted novel organic crystals for photonic applications
摘要： In the present work, a promising non-centrosymmetric chalcone derivative 3-(2, 4, 6-trimethoxyphenyl)-1-(thiophen-2-yl)-prop-2-en-1-one (2TM) was investigated to define their potential for photonic applications through various characterization techniques. Therefore 2TM has been synthesized and single crystals have been grown using slow evaporation solution growth technique. The UV–Vis-NIR spectrum reveals the transparency of the crystal for the entire visible region. The thermal stability and phase transition of the compound was studied by thermo gravimetric and differential thermal analysis and found to be stable up to 132 °C. For structural conformation, the Fourier transform infrared spectral tests were performed on 2TM. For nonlinear optical studies of the third order, the Z-scan experiment was conducted. The material had reverse saturation absorption and self-defocusing properties and therefore, 2TM showed strong nonlinear absorption coefficients and optical limiting behavior, under continuous wave diode-pumped solid state laser. Second harmonic generation efficiency of 2TM crystal is 1.12 times the urea efficiency. The single crystal x-ray diffraction studies of the crystal showed that the crystal system of 2TM is orthorhombic with space group P n a 21. The structural and property relationship studies are carried out for the methoxy substituted organic crystals. Thus, the reported crystal can be used for photonic applications due to its excellent optical properties.
关键词： Single crystal,Chalcones,Z-scan,Second harmonic generation,Structure–property relationship
更新于2025-09-19 17:13:59
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Facile synthesis of ZnO microrod photodetectors by solid-state reaction
摘要： In this study, ZnO microrods were directly synthesized via a single-step solid-state reaction using ZnO powders mixed with graphite without a catalyst under an air atmosphere, instead of using vacuum systems and flowing gases. The structure, growth mechanism, and electrical and optical properties of the microrods were investigated under varying growth conditions. The high-resolution transmission electron microscopy images confirmed the formation of single-crystal ZnO microrods. The photoluminescence spectra of the microrods showed green emission, suggesting the formation of non-stoichiometric ZnO microrods due to the formation of oxygen vacancies during sintering. The length and width of the ZnO microrods could be modulated by controlling the graphite content, sintering temperature, and residual time. A simple photodetector consisting of a single-crystal ZnO microrod on a SiO2-coated Si substrate was fabricated. The photodetector exhibited a linear current–voltage curve in visible light. The slope of the curve increased under ultraviolet (UV) irradiation, maintaining a linear shape of the curve. The curve reversibly returned to the initial shape in the absence of UV illumination. The UV on-off current ratio increased because of the decrease in the off-current by compensating for the oxygen vacancies through annealing in an oxygen atmosphere. Thus, in this study, we proposed a simple and efficient approach to fabricate single-crystal ZnO microrods for application in low-cost photodetectors.
关键词： oxygen vacancies,solid-state reaction,single-crystal,ZnO microrods,photodetector
更新于2025-09-19 17:13:59
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Formation of thioglucoside single crystals by coherent molecular vibrational excitation using a 10-fs laser pulse
摘要： Compound crystallization is typically achieved from supersaturated solutions over time, through melting, or via sublimation. Here a new method to generate a single crystal of thioglucoside using a sub-10-fs pulse laser is presented. By focusing the laser pulse on a solution in a glass cell, a single crystal is deposited at the edge of the ceiling of the glass cell. This finding contrasts other non-photochemical laser-induced nucleation studies, which report that the nucleation sites are in the solution or at the air-solution interface, implying the present crystallization mechanism is different. Irradiation with the sub-10-fs laser pulse does not heat the solution but excites coherent molecular vibrations that evaporate the solution. Then, the evaporated solution is thought to be deposited on the glass wall. This method can form crystals even from unsaturated solutions, and the formed crystal does not include any solvent, allowing the formation of a pure crystal suitable for structural analysis, even from a minute amount of sample solution.
关键词： crystallization,coherent molecular vibrations,single crystal,thioglucoside,laser-induced nucleation
更新于2025-09-19 17:13:59
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Ultrafast Photodetector by Integrating Perovskite Directly on Silicon Wafer
摘要： Single crystal (SC) perovskite is currently a promising material due to its high quantum efficiency and long diffusion length. However, the reported perovskite photodection range (< 800 nm) and response time (> 10 μs) are still limited. Here, to promote the development of perovskite-integrated optoelectronic devices, this work demonstrates wider photodection range and shorter response time perovskite photodector by integrating the SC CH3NH3PbBr3 (MAPbBr3) perovskite on silicon (Si). The Si/MAPbBr3 heterojunction photodetector with an improved interface exhibits high performances including high speed, broad spectrum, and long-term stability. To our best knowledge, the measured detectable spectrum (405 nm-1064 nm) largely expands the widest response range reported in previous perovskite-based photodetectors. In addition, the rise time is as fast as 520 ns, which is comparable with commercial germanium photodetectors. Moreover, the Si/MAPbBr3 device can maintain excellent photo-current performance up to 3 months. Furthermore, typical grey-scale face imaging is realized by scanning the Si/MAPbBr3 single-pixel photodetector. This work of ultrafast photodetector by directly integrating perovskite on Si can promote advances in next-generation integrated optoelectronic technology.
关键词： photodetectors,integrations,single crystal perovskites,CH3NH3PbBr3,ultrafast
更新于2025-09-19 17:13:59
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Enhanced Ona??Off Ratio Photodetectors Based on Leada??Free Cs <sub/>3</sub> Bi <sub/>2</sub> I <sub/>9</sub> Single Crystal Thin Films
摘要： Hybrid organic–inorganic lead halide perovskite single crystal thin film (SCTF) recently has attracted enormous interest in the field of optoelectronic devices, since it efficiently resolves the trade-off between thickness and carrier diffusion length. However, the toxicity of lead element and the instability induced by organic component still hinder its future developments. In this work, lead-free all-inorganic Cs3Bi2I9 SCTF with a high orientation along (00h) has been in situ grown on indium tin oxide (ITO) glass via a space-limited solvent evaporation crystallization method. The trap density of Cs3Bi2I9 SCTF (5.7 × 1012 cm?3) is 263 folds lower than that of the polycrystalline thin film (PCTF) counterpart, together with a 5-order-of-magnitude higher carrier mobility. These superior charge transfer properties enable a photoresponse on–off ratio as high as 11 000, which far surpasses that of the PCTF device by 460 folds, comparable to the lead halide perovskite. Furthermore, the Cs3Bi2I9 SCTF photodetector exhibits outstanding stability even without any encapsulation, whose initial performance is well maintained after aging 1000 h in humid air of 50% RH or continuous on–off light illumination for 20 h. This work will pave the way to produce new families of high-performance, stable, and nontoxic perovskite SCTF for future optoelectronic applications.
关键词： stability,photodetectors,perovskites,Cs3Bi2I9,single crystal thin films
更新于2025-09-19 17:13:59
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Controlled Growth of Single‐Crystal Graphene Films
摘要： Grain boundaries produced during material synthesis affect both the intrinsic properties of materials and their potential for high-end applications. This effect is commonly observed in graphene film grown using chemical vapor deposition and therefore caused intense interest in controlled growth of grain-boundary-free graphene single crystals in the past ten years. The main methods for enlarging graphene domain size and reducing graphene grain boundary density are classified into single-seed and multiseed approaches, wherein reduction of nucleation density and alignment of nucleation orientation are respectively realized in the nucleation stage. On this basis, detailed synthesis strategies, corresponding mechanisms, and key parameters in the representative methods of these two approaches are separately reviewed, with the aim of providing comprehensive knowledge and a snapshot of the latest status of controlled growth of single-crystal graphene films. Finally, perspectives on opportunities and challenges in synthesizing large-area single-crystal graphene films are discussed.
关键词： single-crystal,graphene,grain boundaries,growth,chemical vapor deposition,nucleation
更新于2025-09-19 17:13:59
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Pulsed Laser Deposition Assisted van der Waals Epitaxial Large Area Quasi‐2D ZnO Single‐Crystal Plates on Fluorophlogopite Mica
摘要： There are still challenges in growth of transferable large area orientated ultrathin high-melting-point metal oxide single crystals with conventional methods. Herein, a new pathway to produce high quality single-crystal ZnO nanoplates with more than 400 μm crystal size is revealed by using the van der Waals epitaxy (vdWE) combined with pulsed laser deposition (PLD) method on fluorophlogopite mica. The quasi-2D ZnO plates as thin as 5 nm on fluorophlogopite mica without transition layer are achieved, showing an excellent thickness and orientation control while maintaining the excellent crystalline. ZnO nanoplates grown on conducting graphite and insulating hexagonal boron nitride (h-BN) 2D substrates are also obtained through PLD assisted vdWE. The transfer of 15 nm thick quasi-2D ZnO plates with 8 mm × 8 mm area onto a SiO2/Si substrate is successfully demonstrated. Based on the ZnO nanoplates, semitransparent self-powered ultraviolet (UV) photodetectors and light-emitting diodes centered at 400 nm UV region are demonstrated. This research highlights that the PLD assisted vdWE method is a fascinating way to fabricate high coverage ultrathin 2D ZnO plates with precisely thickness control for optoelectronic applications and may have enormous inspiration for other 2D nanomaterials growth.
关键词： pulsed laser deposition,van der Waals epitaxy,quasi-2D,ZnO single-crystal plate
更新于2025-09-19 17:13:59
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Enhanced dielectric and piezoelectric properties in the [001]-poled 0.25Pb(In <sub/>1/2</sub> Nb <sub/>1/2</sub> )O <sub/>3</sub> -0.43Pb(Mg <sub/>1/3</sub> Nb <sub/>2/3</sub> )O <sub/>3</sub> -0.32PbTiO <sub/>3</sub> single crystal near morphotropic phase boundary by alternating current treatment
摘要： In this paper, temperature dependance of induced dielectric and piezoelectric properties in the [001]-oriented predirect current poling (DCP) of the 0.25Pb(In1/2Nb1/2)O3-0.43Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 (0.25PIN-0.43PMN-0.32PT) single crystals near morphotropic phase boundary was investigated using the alternating current treatment (ACT). By the optimized ACT conditions of 1 kV/mm at 50 Hz over 20 cycles, the dielectric permittivity (ε0) and piezoelectric coefficient (d33) at room temperature of the DCP-ACT crystal were improved to be 7120 and 2610 pC/N, which were 48% and 54% higher than that of the DCP crystal (ε0 = 4800, d33 = 1700 pC/N). Based on the temperature dependence of dielectric permittivity and dielectric loss of the DCP-ACT crystal, the induced monoclinic phases (MA and MC) were involved in the phase transition process from a rhombohedral phase to a tetragonal phase. The phase transition temperatures TR-MA of 116 °C of the DCP-ACT crystal showed about 10 °C higher than that of DCP. Meanwhile, ε0 of the DCP-ACT crystal at TR-MA and in the tetragonal phase region, at around 110 °C and 130 °C, were 160% and 390% higher than those of the DCP crystal, respectively. The ultrahigh ε0 = 17 000 of the DCP-ACT crystal at 130 °C may relate to the nanoscale heterogeneous polar-regions induced by ACT. The ACT is a promising way to enhance the dielectric and piezoelectric performance of the pre-DCP 0.25PIN-0.43PMN-0.32PT single crystals with broadened temperature range for device applications.
关键词： single crystal,piezoelectric properties,morphotropic phase boundary,alternating current treatment,dielectric properties
更新于2025-09-19 17:13:59
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Light-controlled efficient photoluminescence based on an europium β-diketonate complex with single-crystal-to-single-crystal [2+2] cycloaddition
摘要： A brand new europium(III) b-diketonate complex undergoes a single-crystal-to-single-crystal transformation via [2+2] cycloaddition after UV irradiation, triggering strong Eu(III) red emission turn-on, which is highly photostable even after 50 hours of irradiation. A photo-patterning process is successfully conducted for security printing application in materials science.
关键词： lanthanide complexes,single-crystal-to-single-crystal transformation,security printing,UV irradiation,photoluminescent
更新于2025-09-16 10:30:52