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Ultrafast laser-annealing of perovskite films for efficient perovskite solar cells
摘要： Perovskite solar cells have attracted much attention recently for their high efficiency, ease of preparation and low cost. Here, we report a novel laser-annealing method for perovskite films at a low substrate temperature by scanning laser spots on the film surfaces. An ultrafast crystallization process within a few seconds is realized under a laser with a high intensity and a fast scanning speed. Because the crystalline perovskite phase has a stronger light absorption than the amorphous phase, the fast laser annealing can induce a higher temperature in the former and lead to the selective growth of large perovskite grains. Under optimum conditions, perovskite films with high crystallinity are successfully fabricated, resulting in perovskite solar cells with high power conversion efficiency and good stability. Moreover, a faster laser-annealing process of perovskite films is achieved by using a linear laser beam, which is expected to be a promising technique for the mass production of large-scale perovskite solar cells.
关键词： Perovskite solar cells,ultrafast crystallization,laser-annealing,large-scale production,power conversion efficiency
更新于2025-09-11 14:15:04
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Exploring alkylthiol additives in PBDB-T:ITIC blended active layers for solar cell applications
摘要： Bulk heterojunction, non-fullerene PBDB-T:ITIC blend polymer solar cells have been fabricated. The active layers consisting of PBDB-T as a donor and ITIC as an acceptor are optimized using a series of alkylthiol additives (1,3-propanedithiol, 1,4-butanedithiol, and 1,8-octanedithiol). It is found that the donor and acceptor are phase separated with different crystalline domains. The additives effectively re-organize the morphology and extend the molecule ordering in lamellar structure with increased correlation length in ITIC domain, bene?ting the generation and dissociation of exciton and reducing charge recombination. A substantial improvement in power conversion ef?ciency of the devices from 8.13% to 9.44% is observed. This study shows that the application of alkylthiol additives is a simple and effective approach to improve the device performance in solar cells based on polymer/non-fullerene blend system.
关键词： solvent additive,bulk heterojunction (BHJ) polymer/non-fullerene solar cells,morphology,crystallization
更新于2025-09-11 14:15:04
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In vivo real‐time diagnosis of endoscopic ultrasound‐guided needle‐based confocal laser endomicroscopy in gastric subepithelial lesions
摘要： Although great success has been achieved in perovskite solar cells (PSCs), it still suffers from several drawbacks in terms of stability and higher ef?ciency. Doping as an effective method to modify the optical and electronic properties of the materials is extensively studied in lead halide perovskites (LHPs). Herein, Pb-site doping in organic–inorganic hybrid perovskites (OIH-LHPs) and inorganic CsPbX3-based materials is discussed. Doping has three functions toward PSCs: participating in the crystalline process, modifying the energy states in LHPs, and contributing to the stability of PSCs. Issues about further improvements are raised, and perspectives for further investigation are presented.
关键词： perovskite solar cells,crystallization,stability,doping,energy structures
更新于2025-09-11 14:15:04
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Methylammonium-Mediated Crystallization of Cesium-Based 2D/3D Perovskite toward High-Efficiency Light-Emitting Diodes
摘要： 2D/3D perovskites have been successfully applied to high-efficiency light-emitting diodes (LEDs) due to their large exciton binding energy (Eb) caused by the quantum and dielectric confinements. Thermal annealing and antisolvent treatments are usually executed in order to promote the crystallization and film quality of perovskites, which add complexity to the device fabrication process. Here, the Cesium-based 2D/3D perovskite was prepared by introducing an ammonium halide benzamidine hydrochloride (BMCl) as the additive. By further introducing an appropriate amount of MABr and PbBr2, BM2(Cs1-xMAxPbBr3)n-1PbBr4 crystals can be formed rapidly without any additional treatments, whilst inhibiting the formation of unfavorable Cs4PbBr6 phase. The optimized 2D/3D perovskite based LEDs achieved a maximum luminance of 12367 Cd/m2, current efficiency of 17.4 Cd/A, and EQE of 5.2%. Our results suggest that appropriate perovskite crystallization can be achieved at room temperature by the regulation of precursor solution, making the perovskite crystallization process easier to control with reduced processing complexity.
关键词： CsPbBr3,light-emitting diodes,perovskite,fast crystallization,2D/3D
更新于2025-09-11 14:15:04
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Use of Aggregation-Induced Emission for Selective Detection of Phase Transformation during Evaporative Crystallization of Hexaphenylsilole
摘要： Crystallization of organic molecules is quite complicated because the crystallization process is governed by the weak intermolecular interactions. By exploiting the aggregation-induced emission (AIE), we attempted to realize the selective detection of phase transformation during the evaporative crystallization of hexaphenylsilole (HPS), which shows different fluorescence colors in the amorphous and crystalline phases. No fluorescence emission was observed in the HPS solution immediately after dropping on the glass substrate due to the non-radiative deactivation induced by intramolecular rotational or vibrational motion, suggesting that HPS exists as a monomer in solution. As time elapsed after dropping, green emission first appeared, which changed to blue after solvent evaporation, because of phase transformation from the amorphous state to the crystalline state. This phenomenon supports not only the two-step nucleation model involving an intermediate such as a liquid-like cluster prior to nucleation, but also the real time-detection of Ostwald’s rule of stages during evaporative crystallization.
关键词： molecular interaction,amorphous-crystal phase transformation,AIE,Ostwald’s rule of stages,evaporative crystallization
更新于2025-09-10 09:29:36
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Crystallization kinetics and the dielectric properties of SrO-BaO-Nb2O5-B2O3 glass-ceramics
摘要： Glass-ceramics materials of SrO-BaO-Nb2O5-B2O3 system have been prepared by conventional melt-casting followed by controlled crystallization. The crystallization kinetics, phase evolution, microstructure, breakdown strength and dielectric properties have been explored by differential scanning calorimetry (DSC), X-ray diffractometer (XRD), scanning electron microscope (SEM), and multifunction LCR meter. The results reveal that crystallization mechanism of this glass is believed to be three-dimensional interfacial growth. It was observed that predominant crystalline phase is Ba0.39Sr0.61Nb2O6 in these glass-ceramics crystallized at 750 °C, and the grain size increases with increase in crystallization time. The uniform microstructure can be seen clearly in glass-ceramics crystallized at 750 °C for 3 h, and the obtained glass-ceramics was found to possess optimal properties. Moreover, glass-ceramic with a dielectric constant of 58, the dielectric loss of 0.007 and breakdown strength of 1010 kV/cm could be achieved. In addition, energy storage density of glass-ceramics reached a maximal value of 2.62 J/cm3. To our knowledge, studies on SrO-BaO-Nb2O5-B2O3 glass-ceramics without SiO2 as a glass network former are few, and the melting temperature of the B2O3-based glass is lower than that of SiO2-based glass, which is conducive to the purpose of energy saving. These findings indicate that this glass may be a candidate for high energy-storage capacitors.
关键词： Energy storage density,Glass-ceramics,Crystallization,Dielectric properties
更新于2025-09-10 09:29:36
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A crystallization method for preparation of anatase-based glass-ceramic glaze
摘要： Developing a way to prepare effective, durable and high-temperature stable anatase-based photocatalytic ceramic is of great significance. In this work, we report a crystallization method for the preparation of anatase-based glass-ceramic glaze. The raw materials were made into frit and glazed on ceramic bodies. The glazed ceramics were sintered at 1180oC and soaked at 700oC. The effect of soaking temperature on the crystallization process was investigated. The photocatalytic property of the glazed tiles was evaluated by degradation of methyl orange. Experimental results show that after sintering and soaking at 700 oC, nanosized anatase grains crystallize in glaze. The crystallization of anatase nanograins is attributed to the relative high viscosity at crystallization temperature. HF etching makes more anatase grains exposed on the surface. The sample etched for 45 seconds shows the highest photocatalytic activity and the methyl orange is decomposed by about 90% after illumination for 35 h.
关键词： Glass-ceramic glaze,Photocatalytic property,Anatase,Crystallization process
更新于2025-09-10 09:29:36
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Selective brookite polymorph formation related to the amorphous precursor state in TiO2 thin films
摘要： A wide variety of brookite TiO2 synthesis methods have been published over the past several decades, but few studies discuss the underlying mechanism that stabilizes brookite over its stable counterparts, rutile and anatase. Here, we investigate of the effect of pulsed laser deposition parameters on the as-deposited amorphous precursor titania thin films, which subsequently crystallize into stable and metastable TiO2 polymorphs upon annealing. We find that oxygen pressure in the deposition chamber strongly influences the non-equilibrium state of the amorphous precursor, which ultimately allows for selective polymorph formation. Rutile forms as the dominant phase at low pO2 < 0.1 mTorr, while anatase is favored at high pO2 > 5 mTorr. Brookite forms primarily at intermediate pO2 (0.5–1.0 mTorr). Controlling the amorphous structure (i.e. Ti—O bonding and polyhedral arrangement) of the precursors via oxygen deficiency is therefore likely for the selective formation of crystalline TiO2 polymorphs from sub-stoichiometric amorphous precursors. Directing phase selectivity by manipulating the structure and internal energy of the precursor amorphous state may have tremendous potential for synthesis of metastable crystalline phases that exhibit more desirable properties in comparison to their stable counterparts.
关键词： Amorphous precursors,Selective crystallization,Polymorphs,Oxygen deficiency,Thin films,TiO2
更新于2025-09-10 09:29:36
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Structural aspects of the high-temperature space charge relaxation in ferroelectric VDF/TFE 94/6 copolymer
摘要： Structural changes in isotropic films of ferroelectric vinylidene fluoride (VDF)/tetrafluoroethylene (TFE) 94/6 copolymers in the metastable state have been studied on heating. The metastable state was ascribed to c-crystals. The dielectric relaxation spectroscopy was employed to study space charge relaxation processes. Two relaxations were observed at high temperatures. One of them was attributed to relaxation of space charge accumulated on the Al electrode which may be partially blocked due to new functional groups formed in the polymer surface. Recrystallization of the film from the melt is accompanied by small a-crystals formation. This results in a decrease in activation energy of the space-charge relaxation process.
关键词： Ferroelectricity,dielectric properties,crystallization,fluoropolymers
更新于2025-09-10 09:29:36
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Isothermal crystallization of poly(glycolic acid) studied by terahertz and infrared spectroscopy and SAXS/WAXD simultaneous measurements
摘要： Isothermal crystallization of poly(glycolic acid) (PGA) has been studied using terahertz (THz) and infrared (IR) spectroscopy and simultaneous small-angle X-ray scattering (SAXS)/wide-angle X-ray diffraction (WAXD) measurements. Changes in the intermolecular interactions in PGA during the isothermal crystallization were monitored using THz spectroscopy, which is an efficient technique for analyzing the higher-order structure of polymers. In the THz spectra, the temporal difference in the intensity observed in the isothermal crystallization is due to the difference in the vibrational origins of two bands at 192 and 65 cm?1. The band at 192 cm?1 primarily originates from the intramolecular vibrational mode (twisting of the local structure of the PGA molecular chain). Furthermore, the band at 65 cm?1 exists due to the intermolecular vibration mode (C = O···H-C hydrogen bonds between polymer chains). In addition, these THz bands appeared after the appearance of the SAXS and WAXD peaks. When a lamellar structure is formed and the molecular chains are oriented, the THz band originating from the intermolecular vibration is observed. It is highly possible that the intermolecular vibration appearing in the THz spectra requires the molecular chains to be oriented.
关键词： Terahertz spectroscopy,Intermolecular interactions,Infrared spectroscopy,Isothermal crystallization,SAXS/WAXD,Poly(glycolic acid)
更新于2025-09-10 09:29:36