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A Novel Carbazole Based Nonfullerene Acceptor for High‐Efficiency Polymer Solar Cells
摘要： Two novel nonfullerene acceptors 4TFIC-4F and 4TCIC-4F are designed based on fluorene and carbazole. Compared with 4TFIC-4F, 4TCIC-4F exhibited higher LUMO level and narrower optical bandgap. Therefore, Polymer solar cells based on PBDB-T-2Cl:4TCIC-4F achieve a high power conversion efficiency of 13.02%, which is the highest value for the carbazole-containing nonfullerene acceptors based devices.
关键词： Morphology,Nonfullerene acceptors,Donor core,Energy levels,Polymer solar cells
更新于2025-09-11 14:15:04
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Optimizing Microstructure Morphology and Reducing Electronic Losses in 1-cm <sup>2</sup> Polymer Solar Cells to Achieve Efficiency over 15%
摘要： The successful demonstration of high-performance organic solar cells (OSCs) on relatively large-area is vital for their industrial viability and future application. When the device area is enlarged from several mm2 to the scale of >1 cm2, critical losses caused by film inhomogeneity or defects in the photoactive layer strongly restrict the performance and reproducibility of OSCs. In this work, we demonstrate that through delicate optimization of photoactive layer and minimization of optoelectronic losses, an impressive external quantum efficiency maximum up to 88% and an internal quantum efficiency peak of 97% are achieved for non-fullerene OSCs. Further incorporating fullerene as the third component into the photoactive layer optimizes the microstructure morphology, enabling the large-scale devices with an area of >1.1 cm2 surpassing the 15% efficiency milestone. The exciting results demonstrated in this work highlight the strategic priority to minimize losses through both materials and electronic engineering towards high-performance large-area OSCs.
关键词： large-area devices,photoactive layer,non-fullerene acceptors,organic solar cells,electronic losses,microstructure morphology
更新于2025-09-11 14:15:04
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European Microscopy Congress 2016: Proceedings || Nanoparticle Structure and Dynamics Studied Using Controlled Atmosphere Transmission Electron Microscopy
摘要： Nanoparticle and catalysis research makes extensive use of transmission electron microscopy (TEM). In particular, environmental transmission electron microscopy (ETEM) has attracted considerable attention in recent years. This technique allows us to expose samples to gaseous environments at elevated temperatures in order to investigate local structural changes at the atomic level as the environment changes. Recently, the technique has also been used in nanowire, graphene and electron optical lithography research among others. Recent developments in TEM instrumentation include monochromation of the electron source and aberration correction of both condenser and objective lenses. These developments have now been introduced onto the ETEM column. The improved spatial resolution and interpretability provided by these additions are beneficial for imaging the surface structure and dynamics of catalyst nanoparticles and provides exciting new possibilities for investigating chemical reactions. In order to take full advantage of this, an understanding of both the interaction of fast electrons with gas molecules and the effect of the presence of gas on high-resolution imaging is necessary. Using an FEI Titan ETEM equipped with a monochromator and an aberration corrector on the objective lens, we have investigated sintering of supported metal nanoparticles often used in catalysis. A model system consisting of supported gold nanoparticles were prepared by sputter-depositing the metal onto graphene and boron nitride substrates. These samples were imaged under hydrogen at increasing temperatures. Gas was introduced into the environmental cell using digitally controlled mass flow controllers providing accurate and stable control of the pressure in the cell. As the temperature was increased, migrating particles were observed on the support. As they came into contact, a neck was formed between the particles and subsequently, the particles coalesced entirely (Fig. 1). Growth patterns have also been investigated for platinum and palladium nanoparticles supported on silicon oxide substrates. Here, anomalously large particles were observed as the particles were sintered in oxygen atmospheres at temperatures at elevated temparatures. Such large particles have also been observed for industrial catalysts. In this study, we will try to elucidate the mechanisms of metal nanoparticle sintering. The analytical capabilities of the microscope can be further augmented by adding stimuli such as optical or electrical though the sample holder. Using a holder capable of exposing the sample to light, the redox properties of cuprous oxide have been investigated. Cuprous oxide has been identified as an active catalyst for the water splitting and hydrogen evolution from an ethanol solution. However, Cu2O suffers from photocorrosion. This phenomenon was investigated using controlled atmosphere transmission electron microscopy. Fig. 2 shows how the photoinduced degradation of cuprous oxide to metallic copper under an aqueous atmosphere using bright-field imaging, electron diffraction and electron energy-loss spectroscopy. All three techniques show the transformation from oxide to metal. Effects of imaging in various elemental as well as di-molecular gases and their effect on imaging and spectroscopy in the environmental transmission electron microscope will also be discussed.
关键词： Dynamics,ETEM,Nanoparticles,Morphology,Catalysis
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing THE 7TH INTERNATIONAL CONFERENCE ON APPLIED SCIENCE AND TECHNOLOGY (ICAST 2019) - Karbala City, Iraq (27–28 March 2019)] THE 7TH INTERNATIONAL CONFERENCE ON APPLIED SCIENCE AND TECHNOLOGY (ICAST 2019) - Structure, morphology and optical properties of thermally evaporated Cu2S thin films annealed at different temperatures
摘要： In the present work the preparation of Cu2S alloy was done throughout mixing the sulphur and copper elements according to the proper atomic weight and then put in an evacuated quartz ampoule which then sealed and heated at 1273 K for five hours and left to cool. Thin films from Cu2S powder thicknesses of ~300nm were prepared by thermal evaporation technique on a glass substrate and under vacuum of 10-5 mbar with rate of deposition 25nm/sec. The prepared thin films subjected to heat treatment at different temperatures(300, 373 , 473 and 573 K)for half an hour. The structures of Cu2S powder and films have been studied by X–ray diffraction technique. The result reveals that the prepared alloy has cubic structure and coincides with slandered cards while the prepared thin films have amorphous structure. The optical measurement shows that the Cu2S films have direct and indirect energy gap energy gap (Eg opt) for allowed transition. The energy gap (Eg opt) increases slightly with the increase annealing temperature and retune to increase with further increases of annealing temperature. The energy gap (Eg opt) increases from 2.55 to 2.6 eV and then decreases. The transmittance and optical constants such as refractive index (n), extinction coefficient (k) and dielectric constant (εr, εi) have been calculated. The optical constants decrease in the first and then return to increase with annealing temperature.
关键词： Cu2S thin films,optical properties,structural morphology,thermal evaporation,annealing temperature
更新于2025-09-11 14:15:04
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Solvent influence on the surface morphology of P3HT thin films revealed by photoemission electron microscopy
摘要： Only rigorous understanding of the relationship between the nano-scale morphology of organic thin films and the performance of the devices built from them will ultimately lead to design rules that can guide a structured development on the field of organic electronics. Despite great effort, unraveling the nanoscale structure of the films is still a challenge in itself. Here we demonstrate that photoemission electron microscopy can provide valuable insights into the chain orientation, domains size and grain boundary characteristics of P3HT films spun cast from different solvents at room as well as at elevated temperatures.
关键词： surface morphology,photoemission electron microscopy,organic electronics,solvent influence,P3HT
更新于2025-09-11 14:15:04
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Heteroepitaxial Growth of High-Quality and Crack-Free AlN Film on Sapphire Substrate with Nanometer-Scale-Thick AlN Nucleation Layer for AlGaN-Based Deep Ultraviolet Light-Emitting Diodes
摘要： High-quality and crack-free aluminum nitride (AlN) film on sapphire substrate is the foundation for high-efficiency aluminum gallium nitride (AlGaN)-based deep ultraviolet light-emitting diodes (DUV LEDs). We reported the growth of high-quality and crack-free AlN film on sapphire substrate with a nanometer-scale-thick AlN nucleation layer (NL). Three kinds of nanometer-scale-thick AlN NLs, including in situ low-temperature AlN (LT-AlN) NL, oxygen-undoped ex situ sputtered AlN NL, and oxygen-doped ex situ sputtered AlN NL, were prepared for epitaxial growth of AlN films on sapphire substrates. The influence of nanoscale AlN NL thickness on the optical transmittance, strain state, surface morphology, and threading dislocation (TD) density of the grown AlN film on sapphire substrate were carefully investigated. The average optical transmittance of AlN film on sapphire substrate with oxygen-doped sputtered AlN NL was higher than that of AlN films on sapphire substrates with LT-AlN NL and oxygen-undoped sputtered AlN NL in the 200–270 nm wavelength region. However, the AlN film on sapphire substrate with oxygen-undoped sputtered AlN NL had the lowest TD density among AlN films on sapphire substrates. The AlN film on sapphire substrate with the optimum thickness of sputtered AlN NL showed weak tensile stress, a crack-free surface, and low TD density. Furthermore, a 270-nm AlGaN-based DUV LED was grown on the high-quality and crack-free AlN film. We believe that our results offer a promising and practical route for obtaining high-quality and crack-free AlN film for DUV LED.
关键词： crystal quality,tensile stress,nucleation layer,surface morphology,DUV LED
更新于2025-09-11 14:15:04
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Multicomponent multiphase modeling of dissimilar laser cladding process with high-speed steel on medium carbon steel
摘要： During a laser cladding process, the transport phenomena in the molten pool, including rapid solidification, strong fluid convection, and species diffusion are complex, and determine the microstructure and composition of the cladding layer. In this study, a three-dimensional transient multicomponent multiphase model was proposed to simulate the dissimilar laser cladding process with T15 powder and T15/CeO2 mixed powder on 42CrMo substrate. The position and expression of the source terms on energy and mass were clearly defined. The model was validated by comparing the morphology of the cross section with single-track cladding experiments. The simulation results indicate that the molten pool is dominated by a strong Marangoni flow that results in a fully mixed cladding layer and a narrow transition zone at the bottom. The molten pool exhibits an inward flow pattern with pure T15 powder and an outward flow pattern with T15-CeO2 mixed powder. The content of the elements and the microstructure of the cladding layer were investigated by using an electron probe micro-analyzer and a scanning electron microscope. The microstructure evolves from planar to cellular, and to equiaxed dendrites from the substrate–clad interface to the top surface. The transition zone comprised of planar and cellular grains. The solidification characteristics calculated from the numerical model were associated to the grain morphology.
关键词： Transport phenomena,Grain morphology,Laser cladding,Multiphase modeling,Marangoni flow
更新于2025-09-11 14:15:04
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Solution-Processable All-Small-Molecule for High-Performance Nonfullerene Organic Solar Cells with High Crystallinity Acceptor
摘要： In this work, two small molecule acceptors (IDIC and IDIC-4F) with different crystallinity and energy level have been successfully applied in nonfullerene-based all-small molecule organic solar cells (NFASM-OSCs). The donor of DFDT(DPP)2 was chosen because of complementary absorption with IDIC and IDIC-4F. As acceptor, IDIC-4F exhibited a higher PCE than IDIC due to better crystallinity. This work not only shows us how to balance the relationship between Voc and Jsc, but also suggests us how to get a good phase separation morphology. Moreover, Increased crystallinity helps to inhibit bimolecular recombination and increase charge mobility. By optimizing device preparation conditions, the best PCE of 9.43% for DFDT(DPP)2 : IDIC-4F as active layer was achieved with excitable Jsc (16.83 mA cm-2) and FF (0.65). The FF and Jsc of resultant device show a significant increased which is among the top efficiencies based on DPP as terminal acceptor groups of NFSM-OSCs reported in document up to now.
关键词： crystallinity,small molecule acceptors,phase separation morphology,nonfullerene organic solar cells,charge mobility
更新于2025-09-11 14:15:04
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Influence of different post-annealing temperatures on physical properties of La0.72Ca0.28MnO3:Ag0.2 thin films by pulsed laser deposition technique
摘要： La0.72Ca0.28MnO3:Ag0.2/LaAlO3 (100) thin ?lms, prepared by pulsed laser deposition, were post-annealed at di?erent temperatures in air. X-ray di?raction technique were used to analysize the orientation and lattice parameter, atomic force microscope (AFM) and scanning electronic microscope (SEM) were employed to characterize the surface morphology of the thin ?lms. Resistance vs. temperature (R-T) behaviors of the thin ?lms were tested with standard four-probe technique. The surface morphology results show that the grain size increases and crystalline quality of the ?lms are improved with increased annealing temperature up to 1200 °C, while the amount of grains also increases; R-T results illustrate that both the temperature coe?cient of resistance (TCR) and metal-insulator transition temperature (TMI) of the ?lms, increase with annealing temperature. In particular, TCR of thin ?lm (post-annealing at 1200 °C) reaches 28.8%·K?1, which makes such ?lms be promisingly applicated in thermal detectors near the room temperature.
关键词： Pulsed laser deposition technique,Electrical properties,La0.72Ca0.28MnO3:Ag0.2 thin ?lms,Surface morphology
更新于2025-09-11 14:15:04
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Production of carbon dots during the liquid phase exfoliation of MoS2 quantum dots
摘要： In the long-distance migration of reindeer in winter, furs of reindeer foot, as the part in direct contacting with the external environment, can play the role of protection and heat preservation. With furs on different parts of the right posterior foot (fibular side, tibial side and planta pedis) as research objects, the microstructure of reindeer foot furs was observed with a scanning electron microscope. The image displayed that the reindeer foot furs was divided into 3 layers, namely cuticular layer, cortical layer and medulla layer. It was observed from the fur surface that the scales of fur on tibial side had smooth edge, with the scale structure in mosaic and coronary types. The scale structure of furs on the other parts showed the irregular waves due to abrasion to different degrees. From the cross-section view of fur, there was a non-medullated segment on the medial part of fur on planta pedis. The medulla layer of fibular and tibial sides showed a porous foam structure. The medulla index (MI) of fur on fibular side and tibial side at distal part was 70.35% and 81.79%, respectively, and MI at medial part was higher than that on other parts. The composition of reindeer foot fur was measured through infrared spectroscopy and energy spectrum analysis respectively. The element contents of foot fur varied on different parts. The content of sulfur of the furs on planta pedis was higher than that on other parts. The research results can provide foundations for the functional study and bionic design of reindeer foot furs during long distance migration and swimming.
关键词： structure and morphology,furs of reindeer foot,composition,functional analysis,experimental measurement
更新于2025-09-11 14:15:04