Search Results (13)

Semiconductor photonic nanowires are critical components for nanoscale light manipulation in integrated photonic and electronic devices. Optimizing their optical performance requires enhanced photon conversion efficiency, for which a promising solution is to combine semiconductors with noble metals, using the surface plasmon resonance of noble metals to enhance the photon absorption efficiency. Here, we report plasmon-enhanced light emission in a hybrid nanowire device composed of perovskite semiconductor nanowires and silver nanoparticles formed using superfluid helium droplets. A cesium lead halide perovskite-based four-layer structure (CsPbBr₃/PMMA/Ag/Si) effectively reduces the metal’s plasmonic losses while ensuring efficient surface plasmon–photon coupling at moderate power. Microphotoluminescence and time-resolved spectroscopy techniques are used to investigate the optical properties and emission dynamics of carriers and excitons within the hybrid device. Our results demonstrate an intensity enhancement factor of 29 compared with pure semiconductor structures at 4 K, along with enhanced carrier recombination dynamics due to plasmonic interactions between silver nanoparticles and perovskite nanowires. This work advances existing approaches for exciting photonic nanowires at low photon densities, with potential applications in optimizing single-photon excitations and emissions for quantum information processing. Full article

Amidst the rapid advancements in the fields of photovoltaics and optoelectronic devices, CsPbBr₃ nanosheets (NSs) have emerged as a focal point of research due to their exceptional optical and electronic properties. This work explores the application potential of CsPbBr₃ NSs in photonic and catalytic domains. Utilizing an optimized hot-injection method and a ZnBr₂-assisted in situ passivation strategy, we successfully synthesized CsPbBr₃ NSs with controlled dimensions and optical characteristics. Comprehensive characterization revealed that the nucleation environment and thickness significantly influenced the structure and optical performance of the materials. The results indicate that the optimized synthesis method enables control over the lateral dimensions of the nanoparticles, ranging from 9.1 ± 0.06 nm to 334.5 ± 4.40 nm, facilitating the tuning of the excitation wavelength from 460 nm (blue) to 510 nm (green). Further analyses involving photoresponse and electrochemical impedance spectroscopy demonstrated the substantial potential of these NSs in applications such as photocatalysis and energy conversion. Full article

Over the last decade, the attractive properties of CsPbBr₃ nanoparticles (NPs) have driven ever-increasing progress in the development of synthetic procedures to obtain high-quality NPs at high concentrations. Understanding how the properties of NPs are influenced by the composition of the reaction mixture in combination with the specific synthetic methodology is crucial, both for further elucidating the fundamental characteristics of this class of materials and for their manufacturing towards technological applications. This work aims to shed light on this aspect by synthesizing CsPbBr₃ NPs by means of two well-assessed synthetic procedures, namely, hot injection (HI) and ligand-assisted reprecipitation (LARP) in non-polar solvents, using PbBr₂ and Cs₂CO₃ as precursors in the presence of already widely investigated ligands. The overall goal is to study and compare the properties of the NPs to understand how each synthetic method influences the NPs’ size and/or the optical properties. Reaction composition and conditions are purposely tuned towards the production of nanocubes with narrow size distribution, high emission properties, and the highest achievable concentration. As a result, the formation of bulk crystals as precipitate in LARP limits the achievement of a highly concentrated NP solution. The size of the NPs obtained by LARP seems to be poorly affected by the ligands’ nature and the excess bromide, as consequence of bromide-rich solvation agents, effectively results in NPs with excellent emission properties. In contrast, NPs synthesized by HI exhibit high reaction yield, diffusion growth-controlled size, and less striking emission properties, probably ascribed to a bromide-deficient condition. Full article

Novel and high-security anti-counterfeiting technology has always been the focus of attention and research. This work proposes a nanocomposite combination of upconversion nanoparticles (UCNPs) and perovskite quantum dots (PeQDs) to achieve color-adjustable dual-mode luminescence anti-counterfeiting. Firstly, a series of NaGdF₄: Yb/Tm UCNPs with different sizes were synthesized, and their thermal-enhanced upconversion luminescence performances were investigated. The upconversion luminescence (UCL) intensity of the samples increases with rising temperature, and the UCL thermal enhancement factor rises as the particle size decreases. This intriguing thermal enhancement phenomenon can be attributed to the mitigation of surface luminescence quenching. Furthermore, CsPbBr₃ PeQDs were well adhered to the surfaces and surroundings of the UCNPs. Leveraging energy transfer and the contrasting temperature responses of UCNPs and PeQDs, this nanocomposite was utilized as a dual-mode thermochromic anti-counterfeiting system. As the temperature increases, the color of the composite changes from green to pink under 980 nm excitation, while it displays green to non-luminescence under 365 nm excitation. This new anti-counterfeiting material, with its high security and convenience, has great potential in anti-counterfeiting applications. Full article

A novel and effective method to improve scintillation properties of glass-ceramics, such as intensity enhancement and decay-time shortening, is reported in this work. Compared with crystal scintillators, glass scintillators always have the problems of low efficiency and long decay; how to solve them has always been a scientific puzzle in the field of scintillation glass-ceramics. The plasma enhancement effect can be predicted to solve the above problems. Ag⁺ ions were diffused into glasses by ion exchange, and then Ag nanoparticles and CsPbBr₃ quantum dots were formed by heat treatment. The structure of the CsPbBr₃ perovskite consists of a series of shared corner PbBr₆ octahedra with Cs ions occupying the cuboctahedral cavities. By using Ag and the plasma resonance effect, the photoluminescence intensity of CsPbBr₃ quantum dot glasses was enhanced by 3 times, its radioluminescence intensity increased by 6.25 times, and its decay time was reduced by a factor of more than one. Moreover, the mechanism of photoluminescence and radioluminescence enhanced by Ag and plasma was discussed based on the experimental results and finite-difference time-domain method. We concluded that the increase in radioluminescence intensity was related to plasma enhancements and the energy exchange between Ag nanoclusters and CsPbBr₃ quantum dots. Doping Ag is a valid means to improve the scintillation luminescence of CsPbBr₃ quantum dot glasses, which can be applied in the field of scintillation. Full article

All-inorganic metal halide perovskite nanocrystals (IPeNCs) have become one of the most promising luminescent materials for next-generation display and lighting technology owing to their excellent color expression ability. However, research on IPeNCs with stable blue emission is limited. In this paper, we report stable blue emissive all-bromide IPeNCs obtained through a modified ligand-assisted reprecipitation method using an ultraviolet (UV)-curable prepolymer as the anti-solvent at a low temperature. We found that the blue emission originates from quantum-confined CsPbBr₃ nanoparticles formed together with the colorless wide-bandgap Cs₄PbBr₆ nanocrystals. When the temperature of the prepolymer was increased from 0 to 50 °C, CsPbBr₃ nanoparticles became larger and more crystalline, thereby altering their emission color from blue to green. The synthesized all-bromide blue-emitting IPeNC solution remained stable for over 1 h. It also remained stable when it was mixed with the green-emitting IPeNC solution. By simply exposing the as-synthesized IPeNC–prepolymer solutions to UV light, we formed water-stable composite films that emitted red, green, blue, and white colors. We believe that this synthetic method can be used to develop color-emitting composite materials that are highly suitable for application as the color conversion films of full-color liquid crystal display backlight systems and lighting applications. Full article

Perovskite nanocrystals (PNCs) have witnessed unprecedented development in optoelectronic fields over the past few years. However, their intrinsic ionic structural instability still dramatically hinders their practical applications. Reliably improving the stability of PNCs while retaining their colloidal dispersity remains a grand challenge. Herein, we report a new strategy whereby CsPbBr₃ nanoparticles are grown in situ in an entropy ligand-functionalized SiO₂ nanoreactor. Consequently, the as-obtained CsPbBr₃@SiO₂ NPs show outstanding stability and colloidal dispersity in various non-polar solvents and have good solution processability, which are unattainable by conventional template-assisted methods. Full article

Materials and processing of transparent electrodes (TEs) are key factors to creating high-performance translucent perovskite solar cells. To date, sputtered indium tin oxide (ITO) has been a general option for a rear TE of translucent solar cells. However, it requires a rather high cost due to vacuum process and also typically causes plasma damage to the underlying layer. Therefore, we introduced TE based on ITO nanoparticles (ITO-NPs) by solution processing in ambient air without any heat treatment. As it reveals insufficient conductivity, Ag nanowires (Ag-NWs) are additionally coated. The ITO-NPs/Ag-NW (0D/1D) bilayer TE exhibits a better figure of merit than sputtered ITO. After constructing CsPbBr₃ perovskite solar cells, the device with 0D/1D TE offers similar average visible transmission with the cells with sputtered ITO. More interestingly, the power conversion efficiency of 0D/1D TE device was 5.64%, which outperforms the cell (4.14%) made with sputtered-ITO. These impressive findings could open up a new pathway for the development of low-cost, translucent solar cells with quick processing under ambient air at room temperature. Full article

Inorganic halides perovskite CsPbX₃ (X = Cl, Br, and I or mixed halide systems Cl/Br and Br/I) nanoparticles are efficient light-conversion objects that have attracted significant attention due to their broadband tunability over the entire visible spectral range of 410–700 nm and high quantum yield of up to 95%. Here, we demonstrate a new method of recrystallization of CsPbBr₃ nanoparticles inside the electrospun fluoropolymer fibers. We have synthesized nonwoven tetrafluoroethylene mats embedding CsPbBr₃ nanoparticles using inexpensive commercial precursors and syringe electrospinning equipment. The fabricated nonwoven mat samples demonstrated both down-conversion of UV light to 506 nm and up-conversion of IR femtosecond laser radiation to 513 nm green photoluminescence characterized by narrow emission line-widths of 35 nm. Nanoparticle formation inside nonwoven fibers was confirmed by TEM imaging and water stability tests controlled by fluorimetry measurements. The combination of enhanced optical properties of CsPbBr₃ nanoparticles and mechanical stability and environmental robustness of highly deformable nonwoven fluoropolymer mats is appealing for flexible optoelectronic applications, while the industry-friendly fabrication method is attractive for commercial implementations. Full article

The surface modification of perovskite nanocrystals (NCs) (i.e., their decoration with noble metals) holds great promise with respect to the tailoring of their properties but has remained a challenge because perovskite NCs are extremely sensitive to water and alcohols. In this study, Au or Pt@CsPbBr₃ NCs were successfully synthesized by photoreduction at the water/hexane interface. First, Cs₄PbBr₆ NCs were synthesized through the hot-injection method. Then, Cs₄PbBr₆ was transformed into CsPbBr₃ and subjected to noble metal modification, both at the interface. The synthesized CsPbBr₃ NCs exhibited a cubic perovskite phase and had an average size of approximately 13.5 nm. The deposited Au and Pt nanoparticles were crystalline, with a face-centered cubic lattice and average diameters of approximately 3.9 and 4.4 nm, respectively. The noble metal modification process had almost no effect on the steady-state photoluminescence (PL) emission wavelength but affected the charge-recombination kinetics of the CsPbBr₃ NCs. Time-resolved PL decay spectral analysis indicated that the fluorescence lifetimes of the Au and Pt@CsPbBr₃ NCs were shorter than those of the pure CsPbBr₃ NCs, probably owing to the quenching of the free charges because of electron transfer from the perovskite to the noble metal nanoparticles. Full article

In this study, the electrically driven perovskite light-emitting diodes (PeLEDs) were investigated by hybridizing the organic polyethylene oxide, 1,3,5-tris (N-phenylbenzimiazole-2-yl) benzene (TPBi), and bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl) iridium III (FIrpic) with CsPbBr₃ in the emission layer and adopting the colloidal NiO_x nanoparticle (NP) hole transport layer. The synthesized NiO_x NPs, having an average size of ~5 nm, can be spin-coated to become a smooth and close-packed film on the indium–tin–oxide anode. The NiO_x NP layer possesses an overall transmittance of ~80% at 520 nm, which is about the peak position of electroluminescence (EL) spectra of CsPbBr₃ emission layer. The coating procedures of NiO_x NP and CsPbBr₃ layers were carried out in ambient air. The novel PeLED turned on at 2.4 V and emitted bright EL of 4456 cd/m² at 7 V, indicating the remarkable nonradiative-related defect elimination by organic additive addition and significant charge balance achieved by the NiO_x NP layer. Full article

We demonstrate a method to enhance the power conversion efficiency (PCE) of MAPbI₃ perovskite solar cells through localized surface plasmon (LSP) coupling with gold nanoparticles:CsPbBr₃ hybrid perovskite quantum dots (AuNPs:QD-CsPbBr₃). The plasmonic AuNPs:QD-CsPbBr₃ possess the features of high light-harvesting capacity and fast charge transfer through the LSP resonance effect, thus improving the short-circuit current density and the fill factor. Compared to the original device without Au NPs, a 27.8% enhancement in PCE of plasmonic AuNPs:QD-CsPbBr₃/MAPbI₃ perovskite solar cells was achieved upon 120 μL Au NP solution doping. This improvement can be attributed to the formation of surface plasmon resonance and light scattering effects in Au NPs embedded in QD-CsPbBr₃, resulting in improved light absorption due to plasmonic nanoparticles. Full article

Recent microstructural studies on lead halide perovskite nanocrystals have consistently reported the coexistence of byproduct nanoparticles (NPs). However, the nature of these NPs and their formation mechanism are still a matter of debate. Herein, we have investigated the structure and compositions of the NPs located on colloidal cesium lead bromide nanocrystals (CsPbBr₃ NCs), mainly through aberration-corrected transmission electron microscopy and spectroscopy. Our results show that these NPs can be assigned to PbBr₂ and CsPb₂Br₅. The new CsPb₂Br₅ species are formed by reacting CsPbBr₃ NCs with the remaining PbBr₂ during the drying process. In addition, observation of the metallic Pb NPs are ascribed to the electron damage effect on CsPbBr₃ NCs during transmission electron microscopy imaging. Full article