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Rooma??Temperature Partial Conversion of ?±a??FAPbI <sub/>3</sub> Perovskite Phase via PbI <sub/>2</sub> Solvation Enables Higha??Performance Solar Cells
摘要： The two-step conversion process consisting of metal halide deposition followed by conversion to hybrid perovskite has been successfully applied toward producing high-quality solar cells of the archetypal MAPbI3 hybrid perovskite, but the conversion of other halide perovskites, such as the lower bandgap FAPbI3, is more challenging and tends to be hampered by the formation of hexagonal nonperovskite polymorph of FAPbI3, requiring Cs addition and/or extensive thermal annealing. Here, an efficient room-temperature conversion route of PbI2 into the α-FAPbI3 perovskite phase without the use of cesium is demonstrated. Using in situ grazing incidence wide-angle X-ray scattering (GIWAXS) and quartz crystal microbalance with dissipation (QCM-D), the conversion behaviors of the PbI2 precursor from its different states are compared. α-FAPbI3 forms spontaneously and efficiently at room temperature from P2 (ordered solvated polymorphs with DMF) without hexagonal phase formation and leads to complete conversion after thermal annealing. The average power conversion efficiency (PCE) of the fabricated solar cells is greatly improved from 16.0(±0.32)% (conversion from annealed PbI2) to 17.23(±0.28)% (from solvated PbI2) with a champion device PCE > 18% due to reduction of carrier recombination rate. This work provides new design rules toward the room-temperature phase transformation and processing of hybrid perovskite films based on FA+ cation without the need for Cs+ or mixed halide formulation.
关键词： FAPbI3,two-step conversion,high performance,hybrid perovskite solar cells,quartz-crystal microbalance,in situ grazing incidence wide angle x-ray scattering
更新于2025-09-16 10:30:52
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Implementation of a tunable hybrid system with coupled high Q-factor resonators based on mode localization for sensing purposes
摘要： There has been a growing interest in the development of MEMS devices based on Anderson mode localization to increase the sensitivity to mass perturbation in the last decade [1–7]. Mode localization occurs within an array of weakly coupled identical resonators in which a mass or sti?ness perturbation is introduced. The main strengths of mode localization are its high sensitivity to the perturbation and the common mode rejection [8]. However, taking advantage of this phenomenon requires to have an array of perfectly identical resonators and a low coupling sti?ness, but high enough to avoid mode aliasing [9]. As a consequence, microfabrication defects are often an obstacle to the implementation of such sensitive sensors. In addition, the devices geometry and the chosen excited mode are limited by the implementation of the coupling (for instance the ?rst mode of double-ended tuning forks [4] or cantilevers [5]). Therefore, we hereby suggest an alternative with a system based on a ?rst mechanical resonator coupled to a second resonator having a di?erent physical nature that allows to tune it. Such a hybrid approach has already been investigated for MEMS characterization using electrical resonators [10] having a Q-factor of 1000 and we previously demonstrated the possibility to generate modes in a system made of an electrical resonator having a Q-factor of 20 and a digital device [11]. In this work and for the ?rst time to our knowledge, we set up a two-degree-of-freedom (DoF) coupled system made of piezoelectric resonators (QCM) with Q-factors exceeding 105. The coupling and one of the coupled resonators are replaced by their digital equivalent (based on dynamic equations) and implemented in a hardware performing real time calculations. This method enables to tune the design parameters of one resonator and the coupling coe?cient in order to reach the optimal conditions for mode localization, and to get rid of the geometric constraints imposed by the design of the coupling (thus allowing to work with a QCM for instance). Since such piezoelectric resonators are broadly used the ?eld of mass sensors for agro-food, environment, safety or health applications [12], these results pave the way to a new generation of ultrasensitive biosensors.
关键词： ?eld programmable gate array,Tunable hybrid system,weak coupling,quartz crystal microbalance,mode localization,digital resonator
更新于2025-09-12 10:27:22
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A model for real time, <i>in situ</i> estimation of cesium coverage on metal substrate using infrared imaging under vacuum
摘要： The present work is to develop an infra-red (IR) camera based in situ diagnostic tool for the determination of cesium (Cs) coverage suitable for ion source applications. Cs seeding is done to reduce the surface work function that enhances the surface assisted negative hydrogen ion production. The temporal Cs deposition on a metal surface (for, e.g., tungsten or molybdenum) follows Langmuir adsorption isotherm (LAI) kind of behavior. The surface temperature varies while the Cs deposition is reflected in the IR camera temperature measurements for a constant surface emissivity value. In this paper, a model on the relationship between Cs coverage in correlation with surface emissivity and temperature variation based on the theory of LAI is presented. A surface ionization probe (SIP) in the form of a cathode-anode assembly together with an IR camera viewing arrangement is designed to measure the Cs flux and the surface temperature simultaneously to test our model. In the present experiment, the Cs flux measurement using SIP is validated with a standard quartz crystal microbalance (QCM). The proposed model would be useful to correlate Cs coverage on plasma grid-like surface conditions under negative ion source relevant vacuum conditions.
关键词： surface ionization probe,infra-red camera,cesium coverage,quartz crystal microbalance,Langmuir adsorption isotherm
更新于2025-09-12 10:27:22
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Nucleation mechanism of metal-vapor atoms on photochromic diarylethene surface with a low glass transition temperature
摘要： Metal pattern formation on organic surfaces is essential in organic electronics. Selective metal-vapor deposition using photochromic diarylethene (DAE) is a promising method to prepare ?ne metal patterns by maskless evaporation. Metal-vapor atoms are adsorbed, di?used, and then desorbed from the colorless surface with a low glass transition temperature. We, however, found that metal deposition started at a speci?c time (deposition-threshold time, tth) even on the colorless surface by continuous evaporation. tth was investigated using a quartz crystal microbalance. We elucidated that metal-nucleation sites were generated by chemical reactions between metal atoms and surface DAE molecules. The number of nucleation sites increases during metal evaporation and when the sites are located in the di?usion range of surface metal atoms, metal-atom nucleation for ?lm-formation starts. This is the origin of tth. This result would provide important knowledge for the preparation of electrodes for organic devices based on selective metal-vapor deposition.
关键词： organic electronics,nucleation mechanism,photochromic diarylethene,quartz crystal microbalance,metal-vapor deposition
更新于2025-09-10 09:29:36
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Detection of Benzene and Volatile Aromatic Compounds by Molecularly Imprinted Polymer Coated Quartz Crystal Microbalance Sensor
摘要： The detection of benzene and its analogues are important but difficult without using expensive extremely analytical instruments. The present work reports the detection of aromatic hydrocarbons like benzene, toluene and isomers of xylene using quartz crystal microbalance (QCM) sensor. The surface of a silver-coated quartz crystal was coated with a simple solution drop coating method and thermally polymerized in an inert atmosphere for the formation of the sensing film. The polymer was synthesized by copolymerization of the optimum ratio of styrene, divinylbenzene and tung oil at 90°C with template. 1, 2, 3 trimethoxybenzene as template performed most efficiently for all the hydrocarbons. Linear calibration curves were observed for all the vapors in the concentration range between approximately as 1.645 to 2.605 Hz/ppm. For benzene, the sensitivity is 2.605 Hz /ppm which is the highest amongst the reported literature. Thus minimum concentration of benzene that can be detected is 0.98 ppm. The molecularly imprinted polymer structure and surface morphology were analyzed by FTIR spectroscopy, FESEM and AFM. The sensitivity of detection of aromatic molecule in this work by the molecularly imprinted polymer film is found to be the best amongst the reported literatures.
关键词： molecular imprinting technique,thermal polymerization,vegetable oil,Quartz Crystal Microbalance (QCM),aromatic hydrocarbons
更新于2025-09-10 09:29:36
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Thermal atomic layer deposition of Sn metal using SnCl <sub/>4</sub> and a vapor phase silyl dihydropyrazine reducing agent
摘要： This work explores a novel, thermal atomic layer deposition (ALD) process to deposit tin metal at a low temperature. The authors employ 1,4-bis(trimethylsilyl)-1,4-dihydropyrazine (DHP) to reduce SnCl4 on silicon substrates. The authors explored a range of temperatures between 130 and 210 °C to determine the ALD window, which was found to be 170–210 °C. The authors show that this process yields a growth rate of ～0.3 ? per cycle at 190 °C. Furthermore, X-ray photoelectron spectroscopy results showed that the ?lm impurities are reduced for depositions within the ALD window. The reaction mechanism was explored using in situ mass spectrometry and in situ quartz crystal microbalance (QCM). Within the ALD temperature window, the QCM results showed a saturated mass gain during the SnCl4 exposure and a net mass loss during the DHP dose. Consistent with the QCM results, in situ mass spectroscopy data indicate that the DHP exposure step removes surface Cl via formation of volatile trimethylsilyl chloride and pyrazine by-products, effectively reducing the oxidation state of surface-bound Sn. This work is the ?rst thermal Sn metal ALD process to be reported in literature and the oxidation/reduction chemistry presented here may be applied to other metal precursors, increasing the applicability of metal ALD use in industry.
关键词： quartz crystal microbalance,X-ray photoelectron spectroscopy,ALD window,SnCl4,mass spectrometry,tin metal,thermal atomic layer deposition,DHP
更新于2025-09-04 15:30:14
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Relationship between C=C double bond conversion and dissolution kinetics in cross-linking-type photoresists for display manufacture, studied by real-time Fourier transform infrared spectroscopy and quartz crystal microbalance methods
摘要： Photoresists are an indispensable technology used for manufacturing electronic devices such as displays and semiconductors. In this study, we investigated the relationship between C=C double bond conversion and dissolution kinetics in cross-linking-type photoresists used for display manufacture using real-time Fourier transform infrared spectroscopy (FTIR) and quartz crystal microbalance (QCM) methods. To improve photoresist performance, it is important to understand the development mechanism of photoresists. Two kinds of polymers (a polymer with peeling-type dissolution and a polymer with a dissolution type with Case II diffusion) were used. 1,2-Octanedione-1-[4-(phenylthio)-2-(O-benzoyloxime)] and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide were used as photoinitiators. The dissolution was of the peeling type when the polymers were formulated as a typical cross-linking-type photoresist. With increasing conversion ratio of C=C double bonds, the rate of developer intake decreased and the impregnation threshold before the onset of peeling increased and then decreased. It was also found that the dissolution kinetics were affected by the radicals generated upon the decomposition of photoinitiators.
关键词： C=C double bond conversion,dissolution kinetics,quartz crystal microbalance,Photoresists,real-time Fourier transform infrared spectroscopy
更新于2025-09-04 15:30:14
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Enhanced Photoresponsive Graphene oxide-modified g-C3N4 for Disassembly of Amyloid β Fibrils
摘要： Protein misfolding and abnormal self-assembly lead to the aggregates of oligomer, fibrils, or senior amyloid β plaques, which is associated with the pathogenesis of many neurodegenerative diseases. Progressive cerebral accumulation of amyloid β-protein (Aβ) was widely proposed to explain the cause of Alzheimer's disease, for which one promising direction of preclinical study is to convert the pre-formed β-sheet structure of amyloid β aggregates into innocent structures. However, the conversion is even harder than the modulation of amyloidosis process. Herein, graphene oxide/carbon nitride (GO/g-C3N4) composite was developed as a good photocatalyst for irreversibly disassembling the amyloid β aggregates of Aβ (33-42) under UV. Quartz crystal microbalance, circular dichroism spectrum, atomic force microscopy, fluorescent spectra, and mechanical property analysis were performed to analyze this photo-degradation process from different aspects for fully understanding the mechanism, which may provide an important enlightenment for the relevant research in this field and neurodegenerative disease study.
关键词： Neurodegenerative disease,Amyloid β disassembly,Quartz crystal microbalance,Atomic force microscopy,Photo-degradation
更新于2025-09-04 15:30:14
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Electrodeposition of catalytically active polyporphyrin films of metal complexes of amino-substituted tetraphenylporphyrins
摘要： The process of electrodeposition of polyporphyrin films based on amino-substituted tetraphenylporphyrins and their metal complexes (CuT(p-NH2Ph)P, FeClT(m-NH2Ph)P, MnClT(m-NH2Ph)P) has been studied by the quartz crystal microbalance method. The surfaces of the films have been characterized by the scanning electron microscopy method and the number of electrons taking part in porphyrin electropolymerization has been determined. It has been established that the most intensive film growth is observed for the metal-free porphyrin ligand. The obtained polyporphyrin films have been analyzed for the catalytic ability in oxygen electroreduction reactions.
关键词： electropolymerization,polyporphyrin films,quartz crystal microbalance method,oxygen electroreduction.
更新于2025-09-04 15:30:14