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All-solution-processed UV-IR broadband trilayer photodetectors with CsPbBr3 colloidal nanocrystals as carriers-extracting layer
摘要： Colloidal quantum dots (CQDs) are very promising nanomaterials for optoelectronics due to their tunable bandgap and quantum confinement effect. Especially, all-inorganic CsPbX3 (X=Br, Cl and I) perovskite nanocrystals (NCs) have attracted enormous interests owing to their promising and exciting applications in photovoltaic devices. In this paper, all-solution-processed broadband photodetectors ITO/ZnO/CsPbBr3/PbS/Au with high-performance were presented. The role of CsPbBr3 QDs layer as the carriers-extracting layer in the trilayer devices was discussed. As compared with bilayer device ITO/ZnO/PbS/Au, both the dark currents and photocurrents under illumination from UV-IR broadband trilayer photodetector ITO/ZnO(80nm)/PbS(150nm)/CsPbBr3(50nm)/Au are enhanced, but the trilayer photodetector ITO/ZnO(80nm)/CsPbBr3(50nm)/PbS(150nm)/Au showed a maximum specific detectivity (D*) of 1.73×1012 Jones with a responsivity (R) of 5.31 A/W under 6.8 mW/cm2 405 nm illumination. However, another trilayer photodetector ITO/ZnO(80nm)/PbS(150nm)/CsPbBr3(50nm)/Au showed a maximum D* of 8.3×1012 Jones with a R of 35 A/W under 1.6 mW/cm2 980 nm illumination. Further, the underlying mechanism for the enhanced performance of trilayer photodetectors was discussed. Thus, this strategy of all-solution-processed heterojunction configuration paves a facile way for broadband photodetectors with high-performance.
关键词： broadband photodetectors,all-solution-processed heterojunction,Colloidal quantum dots (CQDs),CsPbBr3 perovskite nanocrystals,carrier-extraction layer
更新于2025-09-12 10:27:22
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Unraveling the Moisture-induced Decomposition Mechanism of Red-Emitting Perovskite CsPbBrI <sub/>2</sub> Nanocrystals and Enhancing their Stability through Copper(II) Substitution
摘要： The red-Emitting perovskite CsPb(BrxI1-x)3 (0<x<1) nanocrystals (NCs) is hindered because of their low structural stability, and the moisture-induced degradation pathways of these red-Emitting perovskite are not well-defined. In the present work, we show that the moisture-induced degradation of CsPbBrI2 NCs spontaneously forms CsPbBr3 (α) and CsPbI3(δ) and other decomposition products. On the other hand, highly stable and luminescent red perovskite CsPbBrI2 NCs were achieved through copper substitution and halide rich passivation strategy. We demonstrated that the incorporation of Cu2+ ions can enhance formation energy, causing a slight lattice contraction, and hence stabilize the cubic phase of these NCs. Cu2+-substituted CsPbBrI2 NCs with higher luminescence were synthesized in a halide-rich passivation method. The highly stable and luminescent Cu2+-substituted CsPbBrI2 NCs can function well as efficient light emitters toward fabrication of the high-performance red perovskite LEDs.
关键词： perovskite nanocrystals,stability,CsPbBrI2,copper-substitution,light-emitting diodes
更新于2025-09-12 10:27:22
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Effects of alkylamine chain length on perovskite nanocrystals after washing and perovskite light-emitting diodes
摘要： Organic-inorganic hybrid lead halide perovskite nanocrystals (PeNCs) have great attention as a light source for perovskite light-emitting diodes (PeLEDs) owing to the superior optical properties. However, PeNCs typically use octylamine (OAm) as capping ligands which have insulating properties. Exploring a desirable short-alkylamine instead of OAm is required for the improvement of PeLEDs. Here, as a one of the strategies to solve this issue, the effects of alkylamine chain length for optical properties of PeNCs and PeLED characteristics are investigated. Pentylamine is an optimal short-alkylamine and precipitate luminescent PeNCs with high PLQY values of 90%. Importantly, pentylamine maintains a relatively high PLQY of 48% after spin-coating, due to the durability pentylamine has to ethyl acetate as a washing solvent. PeNCs capped with pentylamine also demonstrate an external quantum efficiency of over 1% with luminance of over 2000 cd/cm2, indicating that pentylamine has the potential to overcome the insulator properties of PeNC thin film.
关键词： optical properties,light-emitting diodes,perovskite nanocrystals,washing process,alkylamine chain length
更新于2025-09-11 14:15:04
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Stability of Sn based inorganic perovskite quantum dots
摘要： Metal halide perovskite crystal structures have emerged as a class of optoelectronic materials, which combine the ease of solution processability with excellent optical absorption and emission qualities. However, the most promising perovskite structures rely on lead as a cationic species, thereby hindering commercial application. The replacement of lead with non-toxic alternatives such as tin has been studied in bulk but not in nanocrystals. In this work, we synthesize Sn and Pb based alloy perovskite nanocrystals by direct synthesis method by of taking mixture of Pb and Sn precursors in the desired ratio leading to quantum dots (QDs) of CsPb1-xSnxBryI3-y with successful Sn incorporation into the host lattice. As colloidal stability of these QDs is a crucial factor for device applications, we have studied the stability of the QDs under different conditions for these Sn based QDs and have found them to degrade faster upon using anti-solvents during washing process. In order to stabilize them, we have devised a purification method that is also discussed. Further, even though the optical and crystal structure stability in some of the inorganic perovskites leaves much room for improvement, so far there has been no studies on the structure property correlation. Here we study their structural purity and their optical stability after understanding the structure property correlation in CsPbI3 and CsPbBr3 perovskite structures. The stability of Sn doped perovskites obtained from a logical understanding of structure property correlations is found to be extremely stable across the series of compounds for upto three months.
关键词： Colloidal synthesis,Sn based perovskite nanocrystals
更新于2025-09-11 14:15:04
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Excitonic Luminescence Engineering in Tervalent Europium Doped Cesium Lead Halide Perovskite Nanocrystals and Their Temperature-Dependent Energy Transfer Emission Properties
摘要： Cesium lead halide (CsPbX3 (X=Cl, Br, I)) perovskite nanocrystals (NCs) have revealed brilliant prospect in lighting, display and lasing fields owing to their excellent photoluminescence properties. To dope rare earth ions into halide perovskite, CsPbX3 (X=Cl, Br, I) NCs hosts not only inherit the excellent narrow linewidth excitonic properties but also yield unique photoluminescence emission. Herein, engineering of such excitonic luminescence is achieved in Eu3+ doped CsPbCl3-xBrx (x=0, 1, 1.5, 2, 3) solid solution NCs for the first time. The single doped-NCs present wide color gamut emission covering whole visible spectrum. Blue to green range (400-520 nm) emission is taken on by tunable excitonic photoluminescence of CsPbX3 NCs. Besides, there is a broad red spectra (590-700 nm) originating from emission of the tervalent europium ions in NCs. Meanwhile, a noticeable spin-polarized 5D0→7F1-6 emission of Eu3+ ions is acquired owing to energy transfer from excitons to dopants. Moreover, the energy transfer is temperature-dependent which originating from the increase of nonradiative transition probability, leading to decrease for the NCs hosts’ PL intensity, but increase for the PL intensity of dopants.
关键词： Eu3+ doped,excitonic luminescence,Cesium lead halide,energy transfer,perovskite nanocrystals
更新于2025-09-10 09:29:36
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Large-scale uniform fabrication and morphology control of ultrafine perovskite nanocrystals
摘要： Nanomaterials are playing more and more important roles in modern industry, while the large-scale fabrication and dispersibility still need to be addressed. This report explores the uniform fabrication and morphology control of ultrafine BaTiO3 (BT) nanocrystals using a "TEG-sol" method. By varying the reactant concentration, the obtained product sols, Ba/Ti ratios, structure and morphology of the nanocrystals are investigated. The results reveal that under low concentrations (0.4 - 0.8 mol/L), transparent sols with uniform BT nanocrystals are obtained. Increasing the concentration to higher than 1.0 mol/L, BT precipitates with abnormal large crystals are obtained. Moreover, the Ba/Ti ratio variation further reveals that the surface organics are critical to the control of crystal size and morphology. This investigation is potential to be extended to the synthesis of various perovskite nanocrystals.
关键词： morphology control,Nanomaterials,BaTiO3,TEG-sol method,perovskite nanocrystals
更新于2025-09-10 09:29:36
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Lead‐Free Semiconductors: Soft Chemistry, Dimensionality Control, and Manganese‐Doping of Germanium Halide Perovskites
摘要： Lead halide perovskites have drawn enormous interest due to their exceptional photovoltaic and optoelectronic properties. However, the toxic heavy metal lead is harmful to humans and the environment resulting in a need for strategies to replace this toxic element. Herein, we report a facile aqueous synthesis of CsGeX3 (X = I, Br) perovskite nanocrystals with size control achieved by varying the cysteammonium halide ligand concentration. We observe a variety of morphologies including pyramidal, hexagonal, and spheroidal. CsGeX3 nanocrystals undergo a lattice expansion due to partial replacement of Cs+ with larger cysteNH3+ cations into the lattice. We successfully dope Mn2+ into the CsGeX3 lattice for the first time with incorporation up to 29% in bulk and 16% in nano samples. XRD peak shifts and EPR hyperfine splitting strongly indicate that Mn2+ is doped into the lattice. Our results introduce a new member to the lead-free halide perovskite family and set the fundamental stage for their use in optoelectronic devices.
关键词： Germanium Halide Perovskites,Manganese(II) Doping,Perovskite Phases,Lead Substitution,Perovskite Nanocrystals
更新于2025-09-09 09:28:46
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Room-temperature synthesis of Mn2+-doped cesium lead halide perovskite nanocrystals via a transformation doping method
摘要： Currently, Mn2+-doped cesium lead halide perovskite nanocrystals have attracted research interests. Here, we report a novel room-temperature transformation doping method for the synthesis of Mn2+-doped CsPbCl3 and CsPb(Br/Cl)3 nanocrystals. Innovatively, the transformation of Cs4PbX6 (X=Cl, Br) phase which has no excitation emission to CsPbX3 phase which has strong luminescence was used in this mechanism. Simply injecting MnCl2 precursor into Cs4PbX6 solution could result in the full transformation of Cs4PbX6 phase to CsPbX3 phase and Mn2+-doped CsPbCl3 or CsPb(Br/Cl)3 were obtained. The basic idea for the transformation doping method is that MnCl2 can not only drive the transformation of the two structures but also Mn2+ can substitute Pb2+. In this reaction, the concentration of Mn precursor is a key influence factor. Moreover, instead of the ligand of OA, the acetic acid was used in our method. Through the adjustment of the ligand in precursor, not just the photoluminescence quantum yields of as-prepared Mn2+-doped CsPbCl3 nanocrystals were improved from 7.8 to 32.6% (Mn2+-doped CsPb(Br/Cl)3 nanocrystals even could reach to 42.7%), the nanocrystals also retained outstanding stability. We propose a combination of structure transformation and ion doping as a perovskite doping mechanism. Our doping method is a novel strategy for lead halide perovskite nanocrystals doping project and it could provide more possibilities in the future.
关键词： photoluminescence quantum yields,Cs4PbX6,Mn2+-doped cesium lead halide perovskite nanocrystals,CsPbX3,room-temperature transformation doping method
更新于2025-09-09 09:28:46
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Lead-Free Direct Bandgap Double Perovskite Nanocrystals with Bright Dual-Color Emission
摘要： Lead-free double perovskite nanocrystals (NCs), i.e. Cs2AgInxBi1?xCl6 (x = 0, 0.25, 0.5 0.75 and 0.9), that can be tuned from the indirect bandgap (x = 0, 0.25 and 0.5) to the direct bandgap (x = 0.75 and 0.9) are designed. Direct-bandgap NCs exhibit 3 times greater absorption cross-section, lower sub-bandgap trap states, and >5 times photoluminescence quantum efficiency (PLQE) compared with those observed for indirect bandgap NCs (Cs2AgBiCl6). A PLQE of 36.6% for direct bandgap NCs is comparable to those observed for lead-perovskite NCs in the violet region. Besides the band edge violet emission, the direct bandgap NCs exhibit bright orange (570 nm) emission. Density functional theory calculations suggesting forbidden transition is responsible for the orange emission, which is supported by time resolved PL and PL excitation spectra. The successful design of lead-free direct bandgap perovskite NCs with superior optical properties opens the door for high performance lead-free perovskite optoelectronic devices.
关键词： dual-color emission,direct bandgap,Lead-free,photoluminescence quantum efficiency,double perovskite nanocrystals
更新于2025-09-09 09:28:46
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Aqueous synthesis of lead halide perovskite nanocrystals with high water stability and bright photoluminescence
摘要： Lead halide perovskites nanocrystals (NCs) have attracted intense attentions because of their excellent optoelectronic properties. The ionic nature of halide perovskites makes them highly vulnerable to water. Encapsulation of perovskite NCs with inorganic or organic materials have been reported to enhance the stability, however they often suffer from large aggregation size, low water-solubility and difficulty for further surface functionalization. Here, we report a facile aqueous process to synthesize water-soluble CsPbBr3/Cs4PbBr6 NCs with the assistance of fluorocarbon agent, which features a novel mechanism of the perovskite crystallization at oil/water interface and direct perovskite NCs/fluorocarbon agent self-assembly in aqueous environment. The products exhibit a high absolute photoluminescence quantum yield (PLQY) of ~80% in water with the photoluminescence lasting for weeks. Through successive ionic layer adsorption and reaction (SILAR), BaSO4 was further applied to encapsulate the NCs, and greatly enhanced their stability in phosphate buffered saline solutions. The high stability in water and saline solution, high PLQY and tunable emission wavelength, together with the successful demonstration of brain tissue labelling and photoluminescence under X-ray excitation, make our perovskite NCs a promising choice for X-ray fluorescent bio-labels.
关键词： CsPbBr3,water soluble,multicolor,perovskite,nanocrystals
更新于2025-09-09 09:28:46