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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Room-Temperature Synthesis of Cesium Lead Halide Perovskite Nanorods
摘要： Low-dimensional materials attract much attention because of their unique and outstanding properties in optical and electronic products, giving a promising class of materials for optoelectronic applications. A facile synthesis method of CsPbBr3 nanorods (NRs) was presented in this paper. The nanorods have a one-dimensional (1D) scale, a high photoluminescence quantum yield (PLQY, 60%) and a narrow FWHM. By tuning the ratio of organic ligands, the CsPbBr3 NRs with the diameter of less than 20 nm and length up to several hundred nanometers were obtained. Moreover, because of the quantum confinement effects, a large blue-shift have happened in PL spectra. A light-emitting diode (LED) device was fabricated with our synthesized CsPbBr3 NRs. The LED device showed a strong green emission. All of these shows the ability of halide perovskite nanocrystals for applications on photoelectron, such as optical communication, display, lightning and so on.
关键词： formation mechanism,cesium lead halide perovskite nanorods,light-emitting diode
更新于2025-09-09 09:28:46
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Switching excitonic recombination and carrier trapping in cesium lead halide perovskites by air
摘要： All-inorganic cesium lead halide perovskites have been emerging as the promising semiconductor materials for next-generation optoelectronics. However, the fundamental question of how the environmental atmosphere affects their photophysical properties, which is closely related to the practical applications, remains elusive. Here, we report the dynamic switching between radiative exciton recombination and non-radiative carrier trapping in CsPbBr3 by controlling the atmospheric conditions. Specifically, we show that the photoluminescence (PL) intensity from the CsPbBr3 crystals can be boosted by ~ 60 times by changing the surrounding from vacuum to air. Based on the comprehensive optical characterization, near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) as well as density functional theory (DFT) calculations, we unravel that the physisorption of oxygen molecules, which repairs the trap states by passivating the PL-quenching bromine vacancies, is accountable for the enhanced PL in air. These results are helpful for better understanding the optical properties of all-inorganic perovskites.
关键词： trap states,bromine vacancies,oxygen physisorption,photoluminescence,all-inorganic cesium lead halide perovskites
更新于2025-09-09 09:28:46
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Structural Characterization and Room Temperature Low Frequency Raman Scattering from MAPbI3 Halide Perovskite Films Rigidized by Cesium Incorporation
摘要： The structural instability of organometal halide perovskites (OHP) is one of the major issues concerning commercialization of perovskite solar cells. Probing this intrinsic instability is one of the major milestones and challenging tasks towards enhancing the lifespan of the material. Here we have incorporated Cs ions into methylammonium lead iodide (MAPbI3) films and studied the thin film structural and optical properties. Incorporation of Cs into MAPbI3 leads to formation of both α-CsPbI3 and ?-CsPbI3 phases, black and yellow respectively, as indicated by the evolution of the optical band edge and X-Ray diffraction (XRD) spectrum. At a concentration of 20% Cs ions, we observe existence of a stable α-CsPbI3 phase. Incorporating 59% or more Cs ions yields the yellow phase of CsPbI3, due to alloying of Cs with the MAPbI3 matrix. The structural transformations observed in absorption spectra and XRD are confirmed by Low Frequency Raman Spectroscopy. The thermally induced structural fluctuations in pure MAPbI3 films are damped upon Cs incorporation, thus bringing long range stabilized order to the perovskite structure and enabling for the first time observation of Low Frequency Raman Scattering at room temperature for OHPs. In addition to this, Cs incorporation rigidizes the perovskite film and sharpens all low frequency vibrational peaks.
关键词： Cesium incorporation,Low Frequency Raman,Perovskite Stability,Phonon Damping,Hybrid Perovskite
更新于2025-09-04 15:30:14
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[IEEE 48th European Solid-State Device Research Conference (ESSDERC 2018) - Dresden (2018.9.3-2018.9.6)] 2018 48th European Solid-State Device Research Conference (ESSDERC) - Electric Double Layer Esaki Tunnel Junction in a 40-nm-Length, WSe2 Channel Grown by Molecular Beam Epitaxy on Al203
摘要： An electric-double-layer (EDL) Esaki junction is demonstrated for the first time in a molecular beam epitaxy-grown WSe2 thin-film field-effect transistor (FET). By carefully engineering the strength and spatial extent of the electron-cation and hole-anion EDLs at the WSe2/solid polymer electrolyte polyethylene oxide: cesium perchlorate (PEO:CsClO4) interface, degenerate and abrupt doping profiles are obtained, which are key to enable interband tunneling operations. Gate-tunable negative differential resistance (NDR) is measured at temperatures up to 140 K, with a maximum peak-to-valley current ratio (PVCR) of 3.5 at 110 K, in a 40 nm-long channel device.
关键词： tunnel diode,Esaki tunneling,electric double layer,tungsten diselenide,cesium perchlorate,polyethylene oxide
更新于2025-09-04 15:30:14
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Cs Oleate Precursor Preparation for Lead Halide Perovskite Nanocrystal Synthesis: The Influence of Excess Oleic Acid on Achieving Solubility, Conversion, and Reproducibility.
摘要： In the colloidal synthesis of inorganic perovskite materials, cesium oleate (CsOL) is the most commonly used Cs precursor. Yet despite its ubiquitous use in literature, CsOL has been observed to be insoluble at room temperature and leads to surprisingly inconsistent results in CsPbX3 nanocrystal synthesis depending on the Cs salt from which the precursor is derived. We show that under the conditions used in most reports, the amount of oleic acid (OA) added, while stoichiometrically sufficient, still leads to incomplete conversion of the Cs salts to CsOL. This results in a mixture of Cs sources being present during the reaction, causing decreased homogeneity and reproducibility. When a 1:5 Cs:OA ratio is used, complete conversion is readily obtained even under mild conditions, resulting in a precursor solution that is soluble at room temperature and yields identical synthetic results regardless of the initial Cs source. Further, 1H nuclear magnetic resonance (NMR) of solutions prepared using varying Cs:OA ratios shows that the maximum ratio of Cs:OA obtainable in solution is 1:5, with any excess Cs present in the precipitate. We believe the use of a soluble, fully converted CsOL reagent will improve reproducibility for Cs-based perovskite synthesis and directly benefit synthetic methods based on microfluidics.
关键词： reproducibility,inorganic perovskite materials,microfluidics,CsPbX3 nanocrystal synthesis,colloidal synthesis,oleic acid,solubility,cesium oleate
更新于2025-09-04 15:30:14