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Two- step synthesis and luminescent properties of BaB <sub/>2</sub> O <sub/>4</sub> :Eu <sup>3+</sup> nano/microphosphors prepared from Ba-B-O:Eu <sup>3+</sup> precursor
摘要： The BaB2O4:Eu3+ nano/microphosphors with sphere‐, rod‐, and granular‐like morphologies were successfully obtained by a two‐step method using Ba‐B‐O:Eu3+ as the precursor. The structure, morphology and photoluminescent properties of the products were characterized by Fourier transfer infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), thermogravimetry‐differential thermal analysis (TG‐DTA), scanning electron microscopy (SEM) and photoluminescence (PL). The formation mechanisms of Ba‐B‐O:Eu3+ and BaB2O4:Eu3+ were proposed. The results show that the BaB2O4:Eu3+ could retain the original morphologies of their respective precursors largely. The BaB2O4:Eu3+ prepared by this two‐step method exhibited better morphology, smaller particle size and better crystallinity than when prepared by a solid‐state method. The granular‐like BaB2O4:Eu3+ red phosphor prepared by this two‐step method exhibited stronger PL intensity and better red color purity than when prepared by a solid‐state method.
关键词： luminescence,nanophosphor,two‐step method,barium borate
更新于2025-09-19 17:15:36
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Water, a green solvent for fabrication of high quality CsPbBr3 films for efficient solar cells
摘要： Water has been labeled as a devil in fabrication and stability of perovskite solar cells. The inherent cognition impels researchers to prepare perovskite films in water-controlled conditions. Herein, water is used as a green solvent to prepare CsPbBr3 films through a two-step spin-coating method. Due to the high solubility of CsBr but low solubility of PbBr2 in water, it provides a possibility to deposit CsBr onto PbBr2 from water solution without destroying the film. Here, high quality CsPbBr3 films are fabricated by spin-coating concentrated CsBr/H2O solution onto the PbBr2 film followed by annealing. As a result, the solar cells basing on a configuration of FTO/TiO2/CsPbBr3/Carbon exhibit a power conversion efficiency of 6.12%. This work provides a simple and easy way to prepare high quality CsPbBr3 films for efficient solar cells. It makes a solid step towards to reducing the solvent toxicity in the fabrication process of perovskite solar cells. It also breaks the forbidden zone for fabricating perovskite films from water, and updates the inherent understanding of water in the research of perovskite solar cells.
关键词： CsPbBr3 film,two-step method,solar cell,green solvent,perovskite
更新于2025-09-12 10:27:22
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Layer-Dependent Dielectric Function of Wafer-Scale 2D MoS <sub/>2</sub>
摘要： Wafer-scale, high-quality, and layer-controlled 2D MoS2 films on c-sapphire are synthesized by an innovative two-step method. The dielectric functions of MoS2 ranging from the monolayer to the bulk are investigated by spectroscopic ellipsometry over an ultra-broadband (0.73–6.42 eV). Up to five critical points (CPs) in the dielectric function spectra are precisely distinguished by CP analysis, and their physical origins are identified in the band structures with the help of first-principles calculations. Results demonstrate that the center energies of these CPs exhibit intriguing layer dependency, which are interpreted by the intrinsic layer-dependent transitions in MoS2. Specially, the change in the imaginary part of the dielectric functions versus the thickness exhibits a “W” like curve, and the two valley bottoms appear at about four-layer and 10-layer respectively. These complex fluctuations are attributed to the alternating domination of the decreasing excitonic effect, the increasing joint density of states, and the mass density increase in relative thick MoS2 samples.
关键词： layer-dependent dielectric function,two-step method,spectroscopic ellipsometry,wafer-scale 2D MoS2
更新于2025-09-10 09:29:36