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- 2018
- Inorganic perovskite quantum dots
- Stability
- Light-emitting diodes
- Optoelectronic Information Materials and Devices
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Predicting the structure and stability of titanium oxide electrides
摘要： The search for new inorganic electrides has attracted significant attention due to their potential applications in transparent conductors, battery electrodes, electron emitters, as well as catalysts for chemical synthesis. However, only a few inorganic electrides have been successfully synthesized thus far, limiting the variety of electride examples. Here, we show the stabilization of inorganic electrides in the Ti-rich Ti–O system through first-principles calculations in conjunction with swarm-intelligence-based CALYPSO method for structure prediction. Besides the known Ti-rich stoichiometries of Ti2O, Ti3O, and Ti6O, two hitherto unknown Ti4O and Ti5O stoichiometries are predicted to be thermodynamically stable at certain pressure conditions. We found that these Ti-rich Ti–O compounds are primarily zero-dimensional electrides with excess electrons confined in the atom-sized lattice voids or between the cationic layers playing the role as anions. The underlying mechanism behind the stabilization of electrides has been rationalized in terms of the excess electrons provided by Ti atoms and their accommodation of excess electrons by multiple cavities and layered atomic packings. The present results provide a viable direction for searching for practical electrides in the technically important Ti–O system.
关键词： first-principles calculations,inorganic electrides,Ti-rich Ti–O system,structure prediction,CALYPSO method
更新于2025-09-04 15:30:14
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Additive-Manufacturing of 3D Glass-Ceramics down to Nanoscale Resolution
摘要： Fabrication of a true-3D inorganic ceramic with resolution down to nanoscale (～ 100 nm) using sol-gel resist precursor is demonstrated. The method has an unrestricted free-form capability, control of the ?ll-factor, and high fabrication throughput. A systematic study of the proposed approach based on ultrafast laser 3D lithography of organic-inorganic hybrid sol-gel resin followed by a heat treatment enabled formation of inorganic amorphous and crystalline composites guided by the composition of the initial resin. The achieved resolution of 100 nm was obtained for 3D patterns of complex free-form architectures. Fabrication throughput of 50 × 103 voxels/s is achieved; voxel - a single volume element recorded by a single pulse exposure. A post-exposure thermal treatment was used to form a ceramic phase which composition and structure were dependent on the temperature and duration of the heat treatment as revealed by Raman micro-spectroscopy. The X-ray diffraction (XRD) showed a gradual emergence of the crystalline phases at higher temperatures with a signature of cristobalite SiO2, a high-temperature polymorph. Also, a tetragonal ZrO2 phase known for its high fracture strength was observed. This 3D nano-sintering technique is scalable from nanoscale to millimeter dimensions and opens a conceptually novel route for optical 3D nano-printing of various crystalline inorganic materials de?ned by an initial composition for diverse applications for microdevices designed to function in harsh physical and chemical environments and at high temperatures.
关键词： ultrafast 3D laser nanolithography,3D nanoscale optical printing,inorganic 3D structures,high-temperature glass-ceramic materials,calcination
更新于2025-09-04 15:30:14
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The First 2D Hybrid Perovskite Ferroelectric Showing Broadband White-Light Emission with High Color Rendering Index
摘要： Luminescent ferroelectrics have attracted considerable attention in terms of integrated photoelectronic devices, most of which are focused on the multicomponent systems of rare-earth doping ferroelectric ceramics. However, bulk ferroelectricity with coexistence of strong white-light emission, especially in the single-component system, remains quite rare. Here, a new organic–inorganic hybrid ferroelectric of (C4H9NH3)2PbCl4 (1) is reported, adopting a 2D layered perovskite architecture, which exhibits an unprecedented coexistence of notable ferroelectricity and intrinsic white-light emission. Decent above-room-temperature spontaneous polarization of ≈2.1 μC cm?2 is confirmed for 1. Particularly, it also exhibits brilliant broadband white-light emission with a high color-rendering-index up to 86 under UV excitation. Structural analyses indicate that ferroelectricity of 1 originates from molecular reorientation of dynamic organic cations, as well as significant structural distortion of PbCl6 octahedra that also contribute to its white-light emission. This work paves an avenue to design new hybrid ferroelectrics for multifunctional application in the photoelectronic field.
关键词： organic–inorganic hybrids,ferroelectrics,white-light emissions,perovskites,2D materials
更新于2025-09-04 15:30:14
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Creation of Photoactive Inorganic/Organic Interfaces Using Occlusion Electrodeposition Process of Inorganic Nanoparticles During Electropolymerization of 2,2′:5′,2′′-Terthiophene
摘要： Photoactive (IOI) inorganic/organic interface assemblies were prepared using an occlusion electrodeposition method. Poly-2,2′:5′,2′′-Terthiophene (PTTh) were the organic thin films that occluded each of CdS, TiO2, and Zn-doped WO3 nanoparticles. The energy band gap structures were investigated using spectroscopic and electrochemical techniques. The obtained assemblies were investigated in aqueous solutions under both dark and illuminated conditions. The results were compared with the behavior of PTTh thin film. Oxygen played an important role in minimizing electron/hole recombination as was evident by observed very low photocurrent when oxygen was removed by nitrogen purge. Results show that PTTh/CdS gave the greatest photocurrent, followed by PTTh/Zn-WO3 and PTTh/TiO2.
关键词： Occlusion,Interface,Organic semiconductors,Photoelectrochemistry,Inorganic
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
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Multiple Resistive Switching Behaviours of CH3NH3PbI3 Perovskite film with Different Metal Electrodes
摘要： The utilization of defects in organic-inorganic hybrid perovskite materials such as CH3NH3PbI3 is beneficial for memory applications. In this work, a simple CH3NH3PbI3 memory device with various commonly used electrodes such as aluminium (Al), silver (Ag), and gold (Au) yielded different switching behaviours. Using Al in ITO/CH3NH3PbI3/Al device reveals Resistive Random Access Memory (ReRAM) behaviour with a SET voltage of 4.5 V and can be RESET by applying a negative sweep voltage above 1.3 V due to the formation of iodide vacancy filament. Interestingly, by using Ag and Au cathodes to replace Al, yielded Write-Once-Read-Many (WORM) resistive switching characteristics. The conversion process from OFF to ON occur at around 4.7 V and 4.0 V for Ag and Au, respectively. The “shorting effect” remains even though a reverse voltage was applied indicating data retention. These fabricated devices could contribute to further understanding of selecting the right electrodes and open up new possibility of studies in the direction of resistive switching memory applications.
关键词： organic-inorganic perovskite,resistive switching,filamentary conduction,charge trapping
更新于2025-09-04 15:30:14