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Ultrasonication-assisted synthesis of CsPbBr <sub/>3</sub> and Cs <sub/>4</sub> PbBr <sub/>6</sub> perovskite nanocrystals and their reversible transformation
摘要： We demonstrate an ultrasonication-assisted synthesis without polar solvent of CsPbBr3 and Cs4PbBr6 perovskite nanocrystals (PNCs) and their reversible transformation. The as-prepared CsPbBr3 PNCs and Cs4PbBr6 PNCs exhibit different optical properties that depend on their morphology, size, and structure. The photoluminescence (PL) emission and quantum yield (QY) of the CsPbBr3 PNCs can be tuned by changing the ultrasound power, radiation time, and the height of the vibrating spear. The optimized CsPbBr3 PNCs show a good stability and high PL QY of up to 85%. In addition, the phase transformation between CsPbBr3 PNCs and Cs4PbBr6 PNCs can be obtained through varying the amount of oleylamine (OAm) and water. The mechanism of this transformation between the CsPbBr3 PNCs and Cs4PbBr6 PNCs and their morphology change are studied, involving ions equilibrium, anisotropic growth kinetics, and CsBr-stripping process.
关键词： ultrasonication,polar-solvent-free,CsPbBr3 PNCs,Cs4PbBr6 PNCs,reversible transformation
更新于2025-11-19 16:46:39
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A Single Non-blinking Cs4PbBr6 Nanoparticle as a Nano-thermometer
摘要： Inorganic perovskite materials have attracted broad interest in the last several years due to their stability and promising applications as photovoltaic and light-emitting materials. In this work, we prepared Cs4PbBr6 nanoparticles showing stable photoluminescence (PL) without blinking and studied the PL properties of individual Cs4PbBr6 nanoparticles in the biology temperature range. We found that both PL intensity and lifetime of a single Cs4PbBr6 particle strongly depends on the temperature. The PL intensity and lifetime decrease almost linearly with the increasing of the temperature. The slope of the PL intensity and lifetime versus temperature were as high as 2% and 3% per degree centigrade, respectively. The photo stability and thermal stability were also checked for individual particles. With these results, we proposed that the sensitivity of PL intensity and lifetime of a single Cs4PbBr6 nanoparticle on temperature showed the potential application of a single particle as a nano-thermometer for thermal detection in a local environment.
关键词： Cs4PbBr6,Thermometer,Perovskite,Photoluminescence,Nanoparticle
更新于2025-09-23 15:23:52
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Consecutive Interfacial Transformation of Cesium Lead Halide Nanocubes to Ultrathin Nanowires with Improved Stability
摘要： Although all-inorganic CsPbX3 (X=Cl, Br, I) nanocrystals (NCs) have been considered as a promising material for photoelectronic devices, their applications are still limited because of their poor stability and the lack of in-depth understanding. Here, we demonstrate a post-treatment method for the preparation of ultrathin CsPbX3 nanowires (NWs) by treating CsPbBr3 nanocubes with thiourea solution. A systematic study showed a consecutively interfacial transformation process, in which CsPbBr3 nanocubes were first converted to Cs4PbBr6 NCs in the presence of thiourea, followed by a further transformation to CsPbBr3 NCs through an interfacial CsX-stripping process. To reduce the surface energy, an oriented attachment process has been realized and CsPbBr3 NCs aggregated to form ultrathin NWs. The ultrathin CsPbBr3 NWs exhibited high photoluminescence quantum yield (PLQY, up to 60%) and high resistance to water treatment, which can be attributed to the surface passivation by thiourea. In addition to thiourea, cysteine and thioacetamide that contain thiol group can also be used to trigger this transformation. This work can not only offer a facile method for the synthesis of efficient and stable ultrathin CsPbBr3 NWs, but also help to reveal the in-depth mechanisms which may be very useful in the field of metal halide perovskite NCs.
关键词： ultrathin nanowires,oriented attachment,Cs4PbBr6,CsPbBr3,thiourea
更新于2025-09-23 15:23:52
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Synthesis of thermally stable and highly luminescent spherical shaped ligand-free Cs4PbBr6 nanospheres with a single polar solvent
摘要： We demonstrate a simple method to synthesis thermally stable and green luminescent ligand-free Cs4PbBr6 nanospheres (NS) with a polar solvent. In this approach, a single polar solvent, N,N-dimethylformamide (DMF) is sufficient enough to convert precursors into cubic shaped ligand-free Cs4PbBr6 crystals. Further, the morphology of cubic shaped Cs4PbBr6 crystals is reformed into spherical shaped Cs4PbBr6 NS by prolonged DMF washing (overnight stirring, 15 h). Besides, the reduction in average particle size of spherical shaped Cs4PbBr6 NS (~70 nm) to one-fourth to the original size of cubic Cs4PbBr6 crystals (~310 nm). The ligand-free spherical shaped Cs4PbBr6 NS showed a high photoluminescence quantum yield of 42.5%, which could compete the conventional ligand mediated Cs4PbBr6 crystals. Moreover, spherical shaped Cs4PbBr6 NS exhibited a high thermal stability even at 200 °C without sacrificing luminescence intensity. Hence, it is foreseen that this approach brings a new strategy to prepare ligand-free Cs4PbBr6 NS as a promising material in optoelectronic devices.
关键词： Perovskites,Single solvent,Nanospheres,Ligand-free,Cs4PbBr6
更新于2025-09-19 17:15:36
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Cs <sub/>4</sub> PbBr <sub/>6</sub> /CsPbBr <sub/>3</sub> perovskite composites for WLEDs: pure white, high luminous efficiency and tunable color temperature
摘要： Cs4PbBr6/CsPbBr3 perovskite composites are fabricated by room-temperature one-pot mixing synthesis, which is short in time, free from inert gases and delivers a high product yield. Temperature-dependent photoluminescence shows that a larger exciton binding energy of 291.1 meV exhibits better thermal stability compared with that of pure Cs4PbBr6 and CsPbBr3 materials. The CIE chromaticity coordinates (0.1380, 0.7236) of green LEDs designed with Cs4PbBr6/CsPbBr3 perovskite composites show almost no variation under driving current changing from 5 to 30 mA. Furthermore, the ground Cs4PbBr6/CsPbBr3 perovskite composites mixed with red emitting K2SiF6:Mn4+ phosphor are dropped and casted on a blue-emitting InGaN chip. The white light emitting diodes (WLEDs) are presented, which have good luminous e?ciency of 65.33 lm W(cid:1)1 at 20 mA, a correlated color temperature of 5190 K, and the white gamut with chromaticity coordinate of (0.3392, 0.3336). According to the state of art, these excellent characteristics observed are much superior to the reported results of conventional perovskite-based WLEDs, which demonstrate the immense potential and great prospect of Cs4PbBr6/CsPbBr3 perovskite composites to replace conventional phosphors in lighting devices.
关键词： WLEDs,luminous efficiency,tunable color temperature,Cs4PbBr6/CsPbBr3 perovskite composites
更新于2025-09-16 10:30:52
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Light Emitting Diodes Based on Inorganic Composite Halide Perovskites
摘要： CsPbBr3 is a promising type of light-emitting halide perovskite with inorganic composition and desirable thermal stability. The luminescence efficiency of pristine CsPbBr3 thin films, however, appears to be limited. In this work, light emitting diodes based on CsPbBr3|Cs4PbBr6 composites are demonstrated. Both quantum efficiency and emission brightness are improved significantly compared with similar devices constructed using pure CsPbBr3. The high brightness can be attributed to the enhanced radiative recombination from CsPbBr3 crystallites confined in the Cs4PbBr6 host matrix. The unfavorable charge transport property of Cs4PbBr6 can be circumvented by optimizing the ratio between the host and the guest components and the total thickness of the composite thin films. The inorganic composition of the emitting layer also leads to improved device stability under the condition of continuous operation.
关键词： stability,conductivity,composite perovskite,light emitting diode,Cs4PbBr6
更新于2025-09-04 15:30:14