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Effect of normal scratch load and HF etching on the mechanical behavior of annealed and chemically strengthened aluminosilicate glass
摘要： Micro-cracks generated by hard body scratch are a major cause of strength decrease for silicate glass. The influence of normal scratch load on the cracking patterns and flexural strength of annealed glass (AG) and chemically strengthened glass (CSG) were studied. With the increase of the normal load, the load capacity of scratched AG specimens decreased to about 40MPa at 20gf immediately. However, the residual strength of CSG decreased to a steady value of 145MPa as the scratch load increased to 500gf. Then the effect of hydrofluoric acid (HF) etching on the surface morphology and mechanical properties of the 500gf scratched glass were investigated. After 8min (for CSG) and 16 min (for AG) acid treatment, the flexural strength of CSG and AG increased to a considerable value of 900MPa, which is 3.6 and 5.5 times higher than the flexural strength of undamaged specimens. Microscopic observations show that the blunting and eliminating of median cracks as well as the formation of new surfaces are the main causes of strength enhancement.
关键词： morphology,aluminosilicate glass,scratch,flexural strength,HF etching
更新于2025-09-19 17:13:59
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Investigating the influence of the solution-processing method on the morphological properties of organic semiconductor films and their impact on OLED performance and lifetime
摘要： The morphological properties of organic semiconductor films deposited by blade coating and spin coating were investigated. The effect of these solution coating methods in fabricating the hole transport layer (HTL) and emissive layer (EML) of OLEDs was also examined. Transient photoluminescence measurements showed that blade-coated films have longer exciton lifetimes than spin-coated films, indicating that blade coating leads to films with less aggregated and more uniform morphologies. OLEDs with a blade-coated CBP:Ir(ppy)3 EML exhibited an external quantum efficiency (EQE) at 20 mA/cm2 of 8.6 % versus 6.4 % in case of device with the same structure but with a spin-coated EML. Additionally, the blade coated CBP:Ir(ppy)3-based device showed a decrease in electroluminescence emission peak by about 52% from its initial value after 20 min of electrical aging, whereas for the spin-coated device, the decrease was 74%. The higher efficiency and longer lifetime in the blade coated devices is likely a result of a more uniform or less aggregated film morphology. These findings demonstrate that blade coating is a promising solution-based fabrication technique to enable more efficient and longer-lived small molecule, solution-coated OLEDs and organic optoelectronic devices.
关键词： Blade coating,OLEDs,Lifetime,Organic semiconductors,Spin coating,Morphology
更新于2025-09-19 17:13:59
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Oxidized Nickel films as highly transparent HTLs for inverted planar perovskite solar cells
摘要： Inverted planar perovskite solar cells (PSCs) with nickel oxide (NiO) as a hole transporting layer were fabricated in an ambient atmosphere. Nickel (Ni) film synthesized at optimized evaporation conditions using low-cost thermal evaporation were transformed from island-like structure to compact porous thin films of NiO after oxidation at 580 ℃. The formation of highly transparent NiO films without any impurity was confirmed from UV–visible spectroscopy and energy dispersive x-ray analysis. These optically tailored NiO films with island-like morphology conceived minimum absorption to the visible light than that of compact porous thin films. The NiO island-like films coated with single cationic CH3NH3PbI3 perovskite overlayer in ambient conditions via a modified two-step method showed higher hole quenching than the compact porous NiO thin films. PSCs consisting of NiO island-like films showed 39.3% improvement in power conversion efficiency (PCE), and 41.4% enhancement in current density (JSC) compared to the compact porous NiO thin films. Overall, the present approach of utilizing optically engineered island-like inorganic films with single cationic CH3NH3PbI3 perovskite overlayer has opened up a novel approach toward the improvement in high-performance optoelectronic devices fabricated at an ambient atmosphere.
关键词： Thermal evaporation,Perovskite solar cells,Islands morphology,PL,NiO,Ambient process
更新于2025-09-16 10:30:52
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Distribution of Al Element of Ti–6Al–4V Joints by Fiber Laser Welding
摘要： In the process of laser welding, the uneven distribution of solute elements caused by element burning loss and ?ow of molten pool a?ects the quality of joints. In this paper, butt welding experiments were conducted on the 3 mm thick Ti–6Al–4V specimens with di?erent preset ratios of Al and Si powders by using 4 kW ?ber laser. The distribution of Al solute element and its in?uence on the microstructure and mechanical properties of the ?nal weld joint were investigated. The results showed that the self-di?usion of Al element and the ?ow of molten pool a?ects the alloy elements distribution in laser welding. And the microhardness of the welded joint with Ti–6Al–4V and 90% Al + 10% Si powders was signi?cantly higher than that with only Ti–6Al–4V, with the di?erence of about 130HV. At the same time, in the joint with 90% Al and 10% Si powders, the acicular α’ size was ?ner, and basketweave microstructure was present as well. This research is helpful to better understand the distribution of Al solute element and its in?uence on the joint quality during laser welding of Ti–6Al–4V alloy, which provides a certain reference for improving the weld or surface properties of Ti–6Al–4V alloy during laser processing.
关键词： Ti–6Al–4V alloy,structure morphology,laser welding,elements distribution,microhardness
更新于2025-09-16 10:30:52
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[Laser Institute of America ICALEO? 2017: 36th International Congress on Applications of Lasers & Electro-Optics - Atlanta, Georgia, USA (October 22–26, 2017)] International Congress on Applications of Lasers & Electro-Optics - Laser metal deposition with 316L stainless wire: Macro morphologies and microstructures
摘要： Laser metal deposition (LMD) with wire as the filler material has demonstrated to be a potential method in addictive manufacturing due to its higher material deposition efficiency, improved surface quality, reduced material wastage and cleaner process environment without metal dust pollution. In this study, single beads samples and block samples of 316L stainless wire were successfully deposited on the surface of 316L stainless steel under optimized depositing conditions using a YLR-4000 S2 CW Fiber Laser, a Fronius MAG arc welding machine and an ABB industrial robot. The macro morphologies, geometric characteristics and microstructures were examined. The influence of process parameters to macro morphologies and geometric characteristics of different samples were carefully studied. A 5*5 block sample was finally deposited with appropriate parameters based on the single bead experiments. The results showed that satisfied single bead samples with smooth surface and high aspect ratio (height-width ratio) can be deposited under appropriate process conditions and parameters during the stable deposit process. Uniform structures of fine equiaxed austenite grains with good metallurgical bonding to the substrate were also obtained. Uniform bond-like microstructures of block samples was also obtained and investigated. All these results will provide guidance for further large study of laser metal-wire deposition with structures.
关键词： Laser metal deposition,macro morphology,geometric characteristic,316L stainless wire,microstructure
更新于2025-09-16 10:30:52
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Morphological Study of Blend Thin Films of Poly(3-hexylthiophene)-<i>block</i>-polyisobutylene-<i>block</i>-poly(3-hexylthiophene):Poly(3-hexylthiophene) and Their Application to Photovoltaics
摘要： The detailed morphological studies of poly(3-hexylthiophene)(P3HT)-b-polyisobutylene(PIB)-b-P3HT:P3HT blend thin films by grazing incidence X-ray scattering (GIXS) were reported. The results of GIXS experiments indicated the formation of phase separation between P3HT and PIB domains even after blending the P3HT homopolymer below 30 wt%. The change in d-spacing values of the phase-separated under strains was suppressed by increasing the weight ratio of the P3HT homopolymer, probably due to the disruption of the microphase separation. The blending the P3HT homopolymer induced the edge-on orientation during the strain process below 75%, probably by improving the interaction between P3HT domains in the blend thin films. The OPV characteristics were obtained with the device structure of ITO/PEDOT:PSS/P3HT-b-PIB-b-P3HT:P3HT:PC61BM/Ca/Al, significantly improving the JSC and FF values by increasing the P3HT homopolymer weight ratio. The excellent elongation behavior of P3HT-b-PIB-b-P3HT:P3HT blend bulk films (P3HT < 30 wt%) could be achieved, probably due to the formation of microphase separation between semi-crystalline P3HT and rubbery PIB domains.
关键词： Organic photovoltaic,Morphology,Block copolymer,π-Conjugated polymer,Elastomer,Synchrotron X-ray scattering
更新于2025-09-16 10:30:52
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Positive effects of side-chain fluorination and polymer additive SBS on the enhanced performance of asymmetric-indenothiophene-based polymer solar cells
摘要： Two new D-A type photovoltaic polymers, namely PITPh-DfQx and PITPhf-DfQx, based on asymmetric indenothiophene (IT) donor units with alkoxyphenyl or fluoroalkoxyphenyl substitutes were designed and synthesized. Effects of the fluorine substitution in the asymmetric IT donor units on the electronic structure, ordering structure, photovoltaic properties, and charge generation and recombination dynamics were investigated. It is found that side-chain fluorination in the asymmetric donor units of the D-A polymers endowed the relative polymers with a deeper HOMO level, higher and more balanced charge mobilites, increased charge dissociation efficiency and reduced bimolecular recombination. As a result, the bulk heterojunction solar cell based on the blend film of PITPhf-DfQx and PC71BM demonstrated an efficiency of 6.10%, whereas the cell efficiency based on PITPh-DfQx was only 3.00%. In addition, a triblock copolymer, poly(styrene-block-butadiene-block-styrene) (SBS), was employed for the first time as a polymer additive into the active layers based on PITPh-DfQx/PC71BM and PITPhf-DfQx/PC71BM devices to promote donor crystallization and tune the extent of phase separation between the donor and acceptor. The presence of SBS obviously improved the molecule packing and induced the crystallization of the two polymers, giving rise to a better phase separation due to enhanced aggregation effect of photovoltaic polymers. Therefore, with a small addition of SBS, the optimal PCE was further increased from 6.10% to 6.60% for PITPhf-DfQx based device and from 3.00% to 5.50% for PITPh-DfQx based device. The positive effects of SBS additive on the performance of photovoltaic polymer/fullerene BHJ solar cells provide a new strategy for developing high performance polymer solar cells.
关键词： Morphology,Polymer additive SBS,Charge transport,Side-chain fluorination,Polymer solar cells,Asymmetric-indenothiophene
更新于2025-09-16 10:30:52
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A pre-solution mixing precursor method for improving the crystallization quality of perovskite films and electroluminescence performance of perovskite light-emitting diodes
摘要： Quasi-two-dimensional (Q-2D) perovskites are one kind of efficient luminescent material with fast energy transfer and radiative decay of excitons due to the energy cascade formed by the mixed perovskite phase. However, the existence of monolayer or bilayer nanosheets in the Q-2D perovskite film results in poor charge transport, high trap density and rough film surface because of the high ratio of ligands, which leads to poor performance of Q-2D perovskite light-emitting diodes (PeLEDs). Herein, we proposed a new strategy of a pre-solution mixing (PSM) precursor to inhibit the formation of ultrathin perovskite nanosheets, which significantly enhanced the charge carrier mobility, reduced the concentration of defects and improved the film morphology. The PeLEDs based on the PSM precursor achieved the maximum luminescence of 7832.1 cd m?2 (～218% enhancement) and the peak current efficiency of 6.0 cd A?1 (～131% enhancement). By introducing mixed cations in the PeLED, the maximum brightness of 14 211.0 cd m?2 and current efficiency of 14.6 cd A?1 were realized, demonstrating the generality of our PSM method for the preparation of high performance PeLEDs.
关键词： charge transport,pre-solution mixing,Quasi-two-dimensional perovskites,film morphology,light-emitting diodes
更新于2025-09-16 10:30:52
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High-efficiency non-halogenated solvent processable polymer/PCBM solar cells <i>via</i> fluorination-enabled optimized nanoscale morphology
摘要： PNTz4T-based polymers have been extensively employed in high-efficiency fullerene-based polymer solar cells (PSCs) with a power conversion efficiency (PCE) of approximately 10.0% due to the high crystallinity of these polymers. The introduction of two fluorine atoms into PNTz4T to synthesize the PNTz4T-2F polymer has boosted the PCE to 10.6%, but the introduction of four fluorine atoms to synthesize the PNTz4T-4F polymer negatively affects the efficiency (PCE ? 6.5%), implying that the number of fluorine atoms is not yet optimized. We have developed a new synthetic route for a novel monofluoro-bithiophene monomer and successfully synthesized a novel PNTz4T-1F polymer. The fullerene-based PSCs based on our novel PNTz4T-1F polymer processed using a halogen-free solvent system demonstrated an outstanding PCE of 11.77% (11.67% certified), representing the highest PCE reported thus far in the literature. Due to the optimum molecular ordering/packing, improved interaction with PC71BM and interconnectivity between photoactive material domains, PNTz4T-1F-based PSCs exhibit lower charge carrier recombination and enhanced charge carrier mobility levels, leading to a substantially high photocurrent density (20.37 mA cm(cid:2)2). These results create new means to tune the structural properties of polymers, ultimately leading to the realization of this class of solar cells for practical applications.
关键词： polymer solar cells,nanoscale morphology,halogen-free solvent,power conversion efficiency,fluorination
更新于2025-09-16 10:30:52
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Inorganic perovskite engineering through incorporation of a carboxylic acid containing ligand for performance enhancement in perovskite light-emitting diodes
摘要： Inorganic cesium lead halide perovskites (such as CsPbBr3) are emerging as one kind of promising optoelectronic material with good stability, narrow color spectrum and facile bandgap tunability. However, the morphology issue of CsPbBr3 film limits its applications in perovskite light-emitting diodes (PeLEDs). Here, we present an effective strategy of perovskite structure engineering by incorporating a long chain cation ligand (HOOC-PMA-Br) into CsPbBr3, aiming to optimize perovskite morphology and thereby improve device performance. It is found that the HOOC-PMA-Br ligand plays a key role in controlling the dimension and crystal growth of perovskites, attributed to the formation of hydrogen bond networks induced by the carboxylic acid unit. With an optimized doping ratio of HOOC-PMA-Br, (HOOC-PMA)2CsPb2Br7 perovskite not only maintains a 3D structure but also presents excellent morphology with a uniform distribution of smaller grain size, smoother surface and better coverage like that of a quasi-2D structure, along with a much higher photoluminescence quantum yield than that of pure CsPbBr3. Significantly, (HOOC-PMA)2CsPb2Br7 endows PeLEDs with remarkably higher luminance and efficiencies than that of CsPbBr3 based devices.
关键词： morphology,inorganic perovskite,carboxylic acid,performance enhancement,light-emitting diodes
更新于2025-09-16 10:30:52