Cesium Lead Bromide Perovskite Research Articles

Correlation between Single-Photon Emission and Size of Cesium Lead Bromide Perovskite Nanocrystals.

Emission photon statistics of semiconductor nanocrystal quantum dots (QDs), including lead halide perovskite nanocrystals (PNCs), are important fundamental and practical optical properties. Single QDs exhibit high-probability single-photon emission owing to the efficient Auger recombination between generated excitons. Because the recombination rate depends on QD size, single-photon emission probability should be size-dependent. Previous studies have researched QDs smaller than their exciton Bohr diameters (twice the Bohr radius of excitons). Here, we investigated the relationship between the single-photon emission behavior and size of CsPbBr3 PNCs to elucidate their size threshold. Simultaneous single-nanocrystal spectroscopy and atomic force microscopy observations on single PNCs with approximately 5-25 nm edge length showed that those smaller than approximately 10 nm, which had size-dependent photoluminescence (PL) spectral shifts, exhibited high-probability single-photon emissions, which decreased linearly with PNC volume. Novel single-photon emission, size, and PL peak correlations of PNCs are important for understanding the relationship between single-photon emission and quantum confinement.

Optical and photoelectrical properties of low-concentration-Mn-doped CsPbBr3 nanocrystals

Doping of cesium lead bromide (CsPbBr3) perovskite nanocrystals offers effective control of their optical and optoelectrical properties, leading to possibilities of several new applications. Herein, cesium lead bromide perovskite nanocrystals are synthesized with doping of a low concentration of manganese (Mn) into the perovskite lattice using manganese (II) chloride (MnCl2) as a precursor. The shift in X-ray diffraction peaks toward higher angles indicates that manganese as a dopant is present inside the cesium lead bromide lattice. A change in the manganese (II) chloride precursor concentration from 5 to 10 mmol results in an increment in the atomic percentage of manganese from 0.3 to 0.5% in the cesium lead bromide crystal. Doping of a low concentration of manganese (0.3 at.%) into cesium lead bromide results in enhancement of green emission, while doping with a higher concentration of manganese (0.5 at.%) results in blue emission. The band gap of cesium lead bromide nanocrystals increases from 2.31 to 2.53 eV with an increase in the concentration of manganese. The dark and photoelectrical conductivity of cesium lead bromide nanocrystals is improved in the case of doping with a low concentration (0.3 at.%) of manganese. The ratio of photocurrent against dark current is found to be ∼182 in manganese-doped cesium lead bromide crystal film as compared with ∼101 for undoped cesium lead bromide crystal film. Doping with a low concentration of manganese improves the overall electrical and photoelectrical conductivity of cesium lead bromide perovskite nanocrystals.

Water-induced nucleation growth kinetics enhancement of cesium lead bromide perovskite nanocrystals

Water-induced nucleation growth kinetics enhancement of cesium lead bromide perovskite nanocrystals

Slower Auger Recombination in 12-Faceted Dodecahedron CsPbBr3 Nanocrystals.

Over the past two decades, intensive research efforts have been devoted to suppressions of Auger recombination in metal-chalcogenide and perovskite nanocrystals (PNCs) for the application of photovoltaics and light emitting devices (LEDs). Here, we have explored dodecahedron cesium lead bromide perovskite nanocrystals (DNCs), which show slower Auger recombination time compared to hexahedron nanocrystals (HNCs). We investigate many-body interactions that are manifested under high excitation flux density in both NCs using ultrafast spectroscopic pump-probe measurements. We demonstrate that the Auger recombination rate due to multiexciton recombinations are lower in DNCs than in HNCs. At low and intermediate excitation density, the majority of carriers recombine through biexcitonic recombination. However, at high excitation density (>1018 cm-3) a higher number of many-body Auger process dominates over biexcitonic recombination. Compared to HNCs, high PLQY and slower Auger recombinations in DNCs are likely to be significant for the fabrication of highly efficient perovskite-based photonics and LEDs.

Photostability of amine-free CsPbBr3 perovskite nanocrystals under continuous UV illumination

In this work, we verified that light induces a dynamic equilibrium between ligands and the inorganic surface in amine-free perovskite nanocrystals, and we demonstrated that oleylphosphate ligands can improve the photostability of cesium lead bromide perovskite nanocrystals.

Selective Detection of Folic Acid Using a Water-Stable Fluorescent CsPbBr3/Cs4PbBr6 Perovskite Nanocrystal Probe

A water-stable cesium lead bromide (CsPbBr3/Cs4PbBr6) perovskite nanocrystal (PNC) was synthesized and studied as a fluorescence probe for the selective detection of folic acid (FA). The as-prepared PNCs emitted strong green fluorescence at 525 nm, and their structure was systematically characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. The interaction between the PNCs and small biological molecules was investigated and the results indicated that the fluorescence of the PNCs could be selectively quenched by FA. The quenching rate has a linear relationship with the concentration of FA in the concentration range from 10 to 800 μM, with a correlation coefficient R2 of 0.9841, and a limit of detection (LOD, 3σ) of 1.69 μM. The mechanism of the interaction between the PNCs and FA was discussed, and the reliability of the method for real sample detection was also verified by the standard addition method. The method proposed here, using a fluorescence PNCs probe, provided a simple alternative strategy for detecting FA that will play an important role in biochemical analysis.

Synthesis and characterization of cesium lead bromide perovskite quantum dots with photovoltaic applications

Synthesis and characterization of cesium lead bromide perovskite quantum dots with photovoltaic applications

Mechanochemistry-driven engineering of 0D/3D heterostructure for designing highly luminescent Cs–Pb–Br perovskites

Embedding metal-halide perovskite particles within an insulating host matrix has proven to be an effective strategy for revealing the outstanding luminescence properties of perovskites as an emerging class of light emitters. Particularly, unexpected bright green emission observed in a nominally pure zero-dimensional cesium–lead–bromide perovskite (Cs4PbBr6) has triggered intensive research in better understanding the serendipitous incorporation of emissive guest species within the Cs4PbBr6 host. However, a limited controllability over such heterostructural configurations in conventional solution-based synthesis methods has limited the degree of freedom in designing synthesis routes for accessing different structural and compositional configurations of these host–guest species. In this study, we provide means of enhancing the luminescence properties in the nominal Cs4PbBr6 powder through a guided heterostructural configuration engineering enabled by solid-state mechanochemical synthesis. Realized by an in-depth study on time-dependent evaluation of optical and structural properties during the synthesis of Cs4PbBr6, our target-designed synthesis protocol to promote the endotaxial formation of Cs4PbBr6/CsPbBr3 heterostructures provides key insights for understanding and designing kinetics-guided syntheses of highly luminescent perovskite emitters for light-emitting applications.

Stabilizing and accessing across ternary phase cesium lead bromide perovskite nanocrystals: thermodynamic and kinetic controls

Lead halide perovskites with fascinating optoelectronic properties have enabled rapid advancement and development in photovoltaics and light-emitting diodes. However, accessing and stabilizing the complex ternary phase space diagram (Cs-Pb-Br) of perovskites including 3 D nanocrystals, 2 D nanoplatelets, and 0 D hexagonal platelets with desirable optoelectronic properties further requires a deeper understanding of the thermodynamic and kinetic aspects regarding the growth of lead halide perovskite nanocrystals. In this work, we have mapped out the multivariant synthetic design spaces observed in the ternary phase diagram of Cs-Pb-Br to evaluate the effect of controlling thermodynamic equilibrium state (e.g. chemical potentials of the Cs:Pb ratio) and growth kinetics with ligand concentration (oleylamine). Further in-situ tracking of reversible phase transformation with the addition of oleylamine (forward) and PbBr2 (reverse) exhibiting distinctive spectroscopic signatures between 3 D and 0 D phases (vice versa) can provide insight into the reversible phase transformation mechanism and important role of PbBr2 species that can modify the bonding motif and connectivity of [PbBr6]4- octahedral frameworks.

Unraveling the role of hydrogen bromide in the growth of cesium lead bromide perovskite nanocrystals

Hydrogen bromide (HBr) could substantially improve the quality of cesium lead bromide perovskite (CsPbBr3) nanocrystals (NCs) and greatly enhance their optoelectronic performance. However, clarifying the role of HBr in the growth of CsPbBr3 NCs has been a substantial challenge thus far. Herein, we design an in situ cryogenic photoluminescence system using liquid nitrogen to unravel the role played by HBr in the growth of CsPbBr3 NCs. Compared with no HBr (∼40 s), HBr improves the nucleation rate of CsPbBr3 NCs about two times (∼20 s), and its emission peak also exhibits a redshift of ∼30 nm. Thus, we conclude that HBr accelerates the nucleation rate of CsPbBr3 NCs and extends their growth stage, affording the generation of large grains. Perovskite light-emitting diodes based on CsPbBr3 NCs with added HBr also exhibit an outstanding performance. These outcomes provide new insights into the role of HBr in CsPbBr3 NCs and help prepare high-quality CsPbBr3 NCs for use in the fabrication of efficient CsPbBr3 NC-based optoelectronic devices.

Colorimetric paper test strips based on cesium lead bromide perovskite nanocrystals for rapid detection of ciprofloxacin hydrochloride

The detection of drugs containing hydrochloric salt with conventional methods is time consuming and expensive. In this work, upon exposure to ciprofloxacin hydrochloride at different concentrations, the emission from CsPbBr3 NCs shifts to the blue from 513 nm to 442 nm. CsPbBr(3−x)Cl x NCs are formed by the ion exchange and substitution of Br− and Cl− ions from surface to core of NCs. The first-principles calculations suggest that the substitution of Br− by Cl− ions plays a critical role in the tuning of the energy bandgap. The color of paper test strips changes immediately after exposure to different Ciproxan solutions. We propose that this rapid and portable method has a high potential application in other chloride salts for food safety.

Wavelength Tunable Aqueous CsPbBr3-Based Nanoprobes with Ultrahigh Photostability for Targeted Super-Resolution Bioimaging.

Single molecule localization microscopy (SMLM) is indispensable in the visualization of cellular microstructures. However, current SMLM imaging materials, from organic fluorophores to quantum dots, still lack the requirement of increasing need for multiple targets of interest due to their broad emission. Here, by one-step encapsulating hydrophilic cesium lead bromide perovskite nanocrystals (CsPbBr3 NCs) into functionalized polyethylene glycol (PEG), a core-shell nanocomposite of CsPb(Cl(1-x)/Brx)3@PEG (0 < x < 1) was presented as a wavelength-tunable fluorescent probe with the narrow full width at half-maximum (fwhm) as 11 nm. The layer of functionalized PEG endows CsPbBr3 NCs with a broad spectral tunability from 521 to 431 nm, superior photostability for several years, and the ability to be further surface functionalized. The CsPb(Cl(1-x)/Brx)3@PEG exhibits a sub-10 nm localization precision and 10-fold enhanced spatial resolution. Using exosomes with small sizes less than 150 nm as the imaging target, CsPb(Cl(1-x)/Brx)3@PEG realized the distinction of two adjacent exosomes by SMLM. Moreover, after being modified with biotin, CsPb(Cl(1-x)/Brx)3@PEG was universally used for SMLM imaging of cellular microstructures. The excellent photostability and narrow fwhm indicated that such a CsPbBr3-based nanoprobe has great potential as a commercial dye for multitarget super-resolution bioimaging applications.

Low-temperature synthesis of stable blue Cesium lead bromide perovskite nanoplates with high quantum efficiency for display applications

Despite heavy research, the efficiencies of blue perovskite light-emitting diodes (LEDs) lag behind those of their green and red cousins. One of the most critical problems is the lack of technology to obtain both high blue emission and spectral stability of perovskite in thin films. Herein, we employ low-temperature synthesis of CsPbBr3 nanoplates (NPLs) by anti-solvent assisted crystallization method using green ethylacetate anti-solvent, which show high absolute photoluminescence quantum yield (PLQY = 90.2%), blue emission at 464 nm with a narrow emission line width (15 nm), small Stokes shift (5 nm) and the average PL decay lifetime (6.91 ns). Significantly, there is no obvious QY loss at different storage conditions. Furthermore, the PL can be tuned from blue to green (457–513 nm) by controlling the amount of precursor injected into anti-solvent. For the first time, we utilize all-bromide-based inorganic perovskites to fabricate ultraviolet-pumped white LEDs (UV-WLEDs) and optimize the chromaticity coordinate of WLEDs, whose CIE color temperature (CCT) is 6083 K. Finally, highly efficient blue LED device using CsPbBr3 nanoplates (464 nm) with high external quantum efficiency (EQE) of 2.03% was fabricated and spectral stability of CsPbBr3 nanoplates under constant current density was demonstrated. This work will be expected to facilitate the development of the blue light source for WLEDs and displays.

Probing the effect of a glass network on the synthesis and luminescence properties of composite perovskite glasses [Invited

All-inorganic cesium lead bromide perovskite nanocrystals (PNCs) are highly promising candidates for various optoelectronic and photonic devices. However, poor stability upon exposure to moisture and lead toxicity issues significantly limit their applications. A modern and promising strategy on resolving these issues is the encapsulation of highly luminescent (PNCs) within transparent inorganic oxide glasses. While the encapsulation procedure effect on the development and properties of the so-formed PV-Glasses has been explored in detail, there is lack of understanding the influence of the selected glass composition and network type on the outcome of the synthesis. Herein we report on the synthesis and photoluminescence properties of composite perovskite-glasses upon growing all-inorganic lead halide perovskites within three different types of inorganic oxide glasses. When a silver metaphosphate glass matrix is used it is revealed that the low glass transition temperature of the phosphate glass limits significantly the temperature range of the required post-melting annealing treatment, while the lead salt precursors react with the phosphate entities of the network destroying the stoichiometry of the PNCs. As a result the formation of PNCs is hindered. As a consequence, a double network former borophosphate glass was employed as a suitable host. While annealing treatments at higher temperature were facilitated in this case, it is found that the high silver content becomes an obstacle for the perovskite formation. In view of these findings, cesium lead bromide (CsPbBr3) and cesium lead iodide (CsPbI3) composite perovskite borate glasses were synthesized and found to be suitable hosts. Indeed, such composite glasses exhibit interesting photoluminescence properties that are compared with those of PNCs outside the glass matrix.

Solution processed and highly efficient UV-photodetector based on CsPbBr3 perovskite-polymer composite film

All inorganic cesium lead bromide (CsPbBr3) perovskite is being extensively applied to optoelectronics due to its facile solution processability and extraordinary optical properties. However, the expansion of its implementation in optoelectronic devices is being hindered due to the poor surface coverage of its film, inefficient charge transportation, long-term instability, and requirements of complex fabrication techniques. Here, a facile solution-processed composite perovskite film composed of CsPbBr3 polycrystals merged with polymers such as polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) has been introduced to act as a light absorber for efficient ultraviolet (UV) light detection. The as-used polymers in the composite film have improved the surface coverage, surface passivation, light absorption, stability, charge carrier lifetime due to the high UV-Absorption tendency of CsPbBr3 and transport capability strengthened by the good ionic conduction of PEO, which results in an efficient UV-photodetection. Compared to the pristine CsPbBr3 film-based PD, the CsPbBr3-polymer based PD has achieved a high photo-to-dark current ratio, responsivity and specific detectivity of up to 106, 55.71 AW−1 and 8.07 × 1013 Jones, respectively, at a very low bias voltage of 0.2 V using 365 nm light source. The device has shown excellent stability of over 3 weeks under ambient environmental conditions.

High-quality and full-coverage CsPbBr3 thin films via electron beam evaporation with post-annealing treatment for all-inorganic perovskite solar cells

Due to their superior stability in comparison to organic–inorganic hybrid devices, all-inorganic cesium lead bromide (CsPbBr3) perovskite solar cells (PSCs) have garnered considerable attention. However, the conventional solution process is limited for the preparing of CsPbBr3 films due to the limitation of bromide in solution, resulting in uneven film and low coverage. So, the development of viable evaporation deposition strategies is essential for boosting the power conversion efficiency (PCE) of CsPbBr3-based PSCs. In this work, high-quality and full-coverage CsPbBr3 thin films are fabricated using single-source electron beam evaporation followed with post-annealing treatment. Br-rich condition in evaporation process is realized by using the mixture of CsPbBr3 and Cs4PbBr6 powders as source materials, and the formation of CsPb2Br5 phase is successfully suppressed. Furthermore, the influences of annealing temperature and annealing time on the crystallinity, morphology and optical properties of the films are thoroughly explored. High-quality CsPbBr3 films with good uniformity and crystallinity are achieved by systematic optimization of the annealing parameters. As a result, a device efficiency of 7.81% with an open circuit voltage (VOC) of 1.43 V has been achieved for the PSCs with a planar structure of FTO/c-TiO2/CsPbBr3/carbon.

Low-Temperature Synthesis of Stable Blue Cesium Lead Bromide Perovskite Nanoplates with High Quantum Efficiency for Display Applications

Low-Temperature Synthesis of Stable Blue Cesium Lead Bromide Perovskite Nanoplates with High Quantum Efficiency for Display Applications

The Effects of CsBr Concentration on the Inorganic Cesium Lead Bromide Perovskite Film Properties and the Performances of Carbon-Based HTM-Free Perovskite Solar Cells

Inorganic cesium lead bromide (ICLB) perovskite films were prepared onto an FTO conductive substrate by a two-step spin-dipping method. PbBr2 films were first coated onto the FTO substrate, and then they were immersed into CsBr solutions at various concentrations: 0.04, 0.06, 0.08, 0.10, and 0.12 M, forming the ICLB perovskite films. The surface morphology of the perovskite films prepared from the CsBr concentrations under 0.08 M had a uniform crystalline surface, but the CsBr concentrations above 0.08 M gave the film a non-uniform structure. XRD spectra of all ICLB films compose of mixed phases of monoclinic-CsPbBr3 and tetragonal-CsPb2Br5. The direct optical bandgap of 2.3 eV corresponded to the CsPbBr3 phase, and the indirect optical bandgap of 2.87-3.10 eV corresponded to the CsPb2Br5 phase. Carbon-based hole-transport-material (HTM) free CsPb2Br5 - CsPbBr3 perovskite solar cells were assembled, and the CsPb2Br5 - CsPbBr3 perovskite solar cells prepared from 0.08 M CsBr concentration delivered the highest efficiency of 2.6%. This was because the 0.08 M-perovskite film had good uniformity, low pinhole defect, and low PbBr2 impurities. Good cell stability, with an efficiency reduction of 10.0% of the initial value after 816 h under ambient environment, was achieved from the 0.08 M CsBr concentration cells.

Corrigendum: Cesium Lead Bromide Perovskite Nanocrystals as a Simple and Portable Spectrochemical Probe for Rapid Detection of Chlorides

Corrigendum: Cesium Lead Bromide Perovskite Nanocrystals as a Simple and Portable Spectrochemical Probe for Rapid Detection of Chlorides

A modified hybrid chemical vapor deposition method for the fabrication of efficient CsPbBr3 perovskite solar cells

Due to its outstanding stability, all-inorganic cesium lead bromide (CsPbBr3) perovskite is gaining increasing attention as a functional material in photovoltaics and other optoelectronic applications. However, the preparation of high-quality CsPbBr3 films via solution processing remains a significant challenge due to the cesium precursor’s low solubility in common solvents. As a result, developing viable evaporation deposition strategies is critical for increasing the photovoltaic performance of perovskite solar cells (PSCs) based on CsPbBr3. In this paper, a modified hybrid chemical vapor deposition is applied to fabricate CsPbBr3 films, and the effects of reaction temperature and reaction time on the crystallinity, morphology, and photo-electric properties of the films are investigated. By optimizing the reaction conditions, high-quality CsPbBr3 films with good crystallinity and uniformity are successfully obtained. Based on these films, CsPbBr3 PSCs with a device configuration of fluorine-doped tin oxide/compact-TiO2/CsPbBr3/carbon attained impressive power conversion efficiency of 4.41% with an ultra-high open-circuit voltage (V OC) of 1.39 V. This demonstration suggests that the modified hybrid chemical vapor deposition strategy enables a promising fabrication route suitable for all-inorganic perovskite thin films in photovoltaic application.