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Lead halide perovskite nanocrystals are attractive for light emitting devices both as electroluminescent and color‐converting materials since they combine intense and narrow emissions with good charge injection and transport properties. However, while most perovskite nanocrystals shine at green and red wavelengths, the observation of intense and stable blue emission still remains a challenging target. In this work, a method is reported to attain intense and enduring blue emission (470–480 nm), with a photoluminescence quantum yield (PLQY) of 40%, originating from very small CsPbBr3 nanocrystals (diameter < 3 nm) formed by controllably exposing Cs4PbBr6 to humidity. This process is mediated by the void network of a mesoporous transparent scaffold in which the zero‐dimensional Cs4PbBr6 lattice is embedded, which allows the fine control over water adsorption and condensation that determines the optimization of the synthetic procedure and, eventually, the nanocrystal size. The approach provides a means to attain highly efficient transparent and stable blue light‐emitting films that complete the palette offered by perovskite nanocrystals for lighting and display applications. [ABSTRACT FROM AUTHOR]

The overexpression of interleukin-17A (IL-17A) is closely associated with the pathogenesis of autoimmune diseases and cancer, rendering precise identification of IL-17A level critical for disease diagnosis and prognosis monitoring. In this study, CsPbBr3 nanoclusters (NCs) were embedded in C16H14Br2O6Pb2 organometallic compound (Pb-MA MOC) via a hot injection approach. Through this way, the issue of CsPbBr3 NCs susceptible to decomposition in water was solved, and the photocurrent intensity that is generated by CsPbBr3 was significantly enhanced. A highly sensitive photoelectrochemical (PEC) sensor for detecting IL-17A in human serum was developed using CsPbBr3/Pb-MA as the photoactive material. The electrode was initially modified with CsPbBr3/Pb-MA. Then, antibody-modified Fe3O4 magnetic nanoparticles (MNs) with target analyte IL-17A captured, and IL-17A antibody-modified Au@CuNi diatomic catalyst (DAC) formed sandwich immune complex structure on the electrode. The existence of CuNi DAC led to a substantial reduction in photoelectric signal intensity due to oxidation of ascorbic acid in the supporting electrolyte. The photocurrent intensity exhibited linear correlation with IL-17A concentration within the range 15-750 pg/mL, and achieving an impressive detection limit of 1 pg/mL. Moreover, the sensor was successfully applied to the determination of IL-17A in human serum, suggesting its potential clinical applications. [ABSTRACT FROM AUTHOR]

Lead halide perovskite quantum dots (PeQDs) have garnered increasing attention due to their extraordinary optoelectronic properties. In recent years, femtosecond (fs) laser direct writing shows to be an effective way of inducing localized crystallization of PeQDs inside glass matrix while remaining their structural stability and optical performance. This article reviews the research progress on fs laser irradiation‐induced nucleation/growth of PeQDs in glass and discusses the latest advancements in the use of the technology for optical data storage, micrometer‐scale light‐emitting diode (LED), information security protection, and other related fields. It offers novel insights and perspectives for exploring new functionality and device application of fs laser‐printed PeQDs glass composite structures. [ABSTRACT FROM AUTHOR]

Through a simple solution method, TiO(Acac)2 was used to in-situ coat the all-inorganic perovskite material CsPbBr3. After heating at 400 ℃, CsPbBr3 @ TiO2 core-shell structure microcrystals were directly prepared. The crystal structure, microscopic morphology, and chemical composition of CsPbBr3 @ TiO2 microcrystals were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). It was confirmed that the in-situ metal oxide coating on the perovskite formed welldispersed spherical shell structures with sizes of 4 ~ 8 μm. A CsPbBr3 @ TiO2 thin film gas sensor was constructed on a fluorine-doped tin oxide (FTO) electrode using spin-coating method. The sensitivity of the sensor to H2 S gas was tested at room temperature. The results show that the sensor has a detection limit of 25 ppb (1 ppb = 10 -9) for H2 S gas, with a response and recovery time of 24/21 s to 100 ppb H2 S, and a sensitivity of 0. 59. The response curve exhibits good cyclic stability. Moreover, the sensor maintains over 90% stability within 30 d of exposure in air and possesses excellent gas selectivity and humidity resistance. Photoluminescence (PL) spectroscopy, time-resolved photoluminescence (TRPL) spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis), and ultraviolet photoelectron spectroscopy (UPS) were employed to analyze the band positions, charge dynamics, and coordination mechanisms. The sensing mechanism was elucidated using the oxygen adsorption principle. This work provides a new approach for the stable monitoring of low concentrations of H2 S gas at room temperature. [ABSTRACT FROM AUTHOR]

Patterning is crucial for advancing perovskite materials into color conversion micro‐display applications, but achieving inkjet‐printed patterns with high performance and precision remains challenging. Here, novel CsPbBr3/PDMS nanoparticles as a promising candidate is proposed for achieving precise and perfect inkjet printing patterns. The as‐prepared nanoparticles ensure exceeding brightness, exceptional stability, uniform fluorescence emission, and high resolution reaching the highest performance of drop‐on‐demand inkjet printing. Specifically, the performance and stability of CsPbBr3/PDMS nanoparticles are enhanced through a two‐step optimization involving dodecyl benzene sulfonic acid (DBSA) ligand modification and polydimethylsiloxane (PDMS) in situ coating, resulting in the highest photoluminescence quantum yield (PLQY) of 92% among CsPbBr3/polymer core‐shell composites so far. The branched structure of DBSA and the PDMS shell provide steric hindrance and effectively prevent agglomeration during storage or patterning. The viscous PDMS coating inhibits the coffee ring effect, not only leading to excellent near‐unity uniform emission but also promoting the formation of smaller and more elaborate droplets, increasing the printing resolution by up to surprisingly 300%. Importantly, the impeccably displayed, high‐resolution patterns formed by versatile CsPbBr3/PDMS nanoparticles have demonstrated significant potential for high pixel density Micro‐LED displays, enabling efficient and stable color conversion. [ABSTRACT FROM AUTHOR]

Underwater wireless optical communication (UWOC) has attracted increasing attention due to its advantages in bandwidth, latency, interference resistance, and security. Photodetectors, as a crucial part of receivers, have been continuously developed with the great progress that has been made in advanced materials. Metal halide perovskites emerging as promising optoelectronic materials in the past decade have been used to fabricate various high-performance photodetectors. In this work, high-performance CsPbBr3 perovskite PDs were realized via solution process, with low noise, a high responsivity, and a fast response. Based on these perovskite PDs, a cost-efficient UWOC system was successfully demonstrated on an FPGA platform, achieving a data rate of 6.25 Mbps with a low bit error rate of 0.36%. Due to lower background noise under environment illumination, perovskite PDs exhibit better communication stability before reaching a data rate threshold; however, the BER increases rapidly due to the long fall time, resulting in difficulty in distinguishing switching signals. Reducing the fall time of perovskite PDs and using advanced coding techniques can help to further improve the performance of the UWOC system based on perovskite PDs. This work not only demonstrates the potential of perovskite PDs in the application of UWOC, but also improves the development of a cost-effective UWOC system based on FPGAs. [ABSTRACT FROM AUTHOR]

With their exceptional optoelectronic properties, CsPbBr3 perovskite nanocrystals (NCs) are promising materials for light‐emitting devices. Elucidating their stimulated emission mechanisms is fundamental to grasp the limitations hindering their use as electrically pumped lasers. In particular, two questions remain open: why the Amplified Spontaneous Emission (ASE) band is significantly shifted from the fluorescence one, and why the former seems to suddenly emerge from, and coexist with, the latter. Here, these questions are addressed through experimental ASE measurements, combined with numerical simulations and a comprehensive assessment of the performance of different analytical expressions used in the literature to retrieve the optical gain from these experiments. This multi‐facet study shows that the ASE behavior in CsPbBr3 NCs thin films stems from four distinctive processes: reabsorption due to a large overlap between the absorption and fluorescence spectra, a strong contribution of excited state absorption within the fluorescence window, the excitation of differently polarized waveguide modes, and the coexistence of short‐ and long‐lived localized excitons. The results in this work delineate the best practices to analyze the optical gain in perovskite samples, help to understand their ASE mechanisms, and provide insights to boost their lasing efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • Highly stable perovskite nanocrystals in water were obtained by modifing wool keratin (WK) and crosslinking agent (PAPI). • CPB/WK-PAPI nanocrystals show excellent photoluminescence retention over time even after 512 days (>40 %). • Portable, low cost, and visualize test strips for amines were successfully made from these nanocrystals. Perovskite nanocrystals (PNCs) have emerged as promising candidates for fluorescent probes owing to their outstanding photoelectric properties. However, the conventional CsPbBr 3 (CPB) NCs are extremely unstable in water, which has seriously limited their sensing applications in water environment. Herein, we present a powerful ligand engineering strategy for fabricating highly water-stable CPB NCs by using a biopolymer of wool keratin (WK) as the passivator and the polyaryl polymethylene isocyanate (PAPI) as the cross-linking agent. In particular, WK with multi-functional groups can serve as a polydentate ligand to firmly passivate CPB NCs by the ligand exchange process in hot toluene; and then the addition of PAPI can further encapsulate CPB NCs by the crosslinking reaction between PAPI and WK. Consequently, the as-prepared CPB/WK-PAPI NCs can maintain ∼ 80 % of their relative photoluminescence (PL) intensity after 60 days in water, and they still maintain ∼ 40 % of their relative PL intensity even after 512 days in the same environment, which is one of the best water stabilities compared previously reported polymer passivation methods. As a proof-of their application, the portable CPB/WK-PAPI NCs-based test strips are further developed as a fluorescent nanoprobe for real-time and visual monitoring amines and food freshness. Among various amine analytes, the as-prepared test strips exhibit higher sensitivity towards conjugated amines, achieving a remarkable detection limit of 18.3 nM for pyrrole. Our research not only introduces an innovative strategy involving natural biopolymers to enhance the water stability of PNCs, but also highlights the promising potential of PNCs for visually and portably detecting amines and assessing food freshness. [ABSTRACT FROM AUTHOR]

Understanding the properties of the precursor can provide deeper insight into the crystallization and nucleation mechanisms of perovskites, which is vital for the solution‐process device performance. Herein, we conducted a detailed investigation into the photophysics properties of CsPbBr3 precursors in a broad concentration and various solvents. The precursor transformed from the solution state into the colloidal state and exhibited aggregation‐induced emission character as the concentration increased. The aggregative luminescence from the precursors originates from the polybromide plumbous that is formed through the coordination of solvent molecules to the lead metal center. Two adducts with monodentate (PbBr2 ⋅ solvent) and bidentate (PbBr2 ⋅ 2solvent) ligands can be obtained, accompanied by emission with photoluminescence at 610 and 565 nm, respectively. Furthermore, the aggregative luminescence intensity and color could be regulated by changing the solvent and precursor ratio. Besides, we discussed the difference between the molecular aggregate in the organic system and the ionic aggregate in the inorganic system: the ionic aggregate is composed of solvated ions rather than individual molecules as in organic systems, which could possess properties that ions do not have. The fluorescence that is sensitive to Pb2+ coordination reported here could be applied to screen perovskite additives and judge the precursor aging. [ABSTRACT FROM AUTHOR]

The achievement of complete conversion of PbBr 2 films presents a significant challenge in the development of CsPbBr 3 films with consistent growth, comprehensive coverage, and controllable components. To address this challenge, introducing a porous structure in the planar PbBr 2 film is advantageous for facilitating the immersion of CsBr precursor, thereby reducing impurity phase formation and mitigating strain caused by the film volume expansion. In order to accomplish this, indium tribromide (InBr 3) was employed as an additive and the InBr 3 (DMF) 3 adduct was utilized to expedite the release of organic molecules in PbBr 2 (DMF), resulting in the transformation of planar PbBr 2 film into porous structures. The growth orientation of PbBr 2 crystals was altered by this transformation, effectively suppressing the generation of metallic Pb impurities in the film. Additionally, it not only optimizes the morphology of CsPbBr 3 film but also reduces impurity phase. As a result, the InBr 3 :CsPbBr 3 perovskite solar cell achieved an efficiency of 7.28 %. The majority of In3+ ions were concentrated near the buried interface between SnO 2 and InBr 3 :CsPbBr 3 , leading to significant improvements in both non-radiative recombination defect states within the perovskite film and electron injection and collection capabilities within the device. [ABSTRACT FROM AUTHOR]

Metal-halide perovskite (MHP) nanocrystals (NCs) have unique advantages in the gas sensing field, but the poor stability restricts their widespread applications. In this work, the CsPbBr 3 @Fe 2 O 3 heterojunction NCs were synthesized successfully by simple solution process and subsequent surface modification strategy for constructing a gas sensor. The Fe 2 O 3 shell layer was obtained through thermal decomposition of acetylacetone iron (AAI) at 400 °C. The resulting CsPbBr 3 @Fe 2 O 3 heterostructured NCs exhibit a higher gas-sensing performance to H 2 S than pure CsPbBr 3 and Fe 2 O 3 , respectively. Upon exposure to 10 ppm H 2 S, the response value of 4.12 was obtained at a moderate working temperature of 350 °C, while the response was fast both in terms of response time and recovery time, i.e. , 1.84 s and 24.20 s, respectively. This might be the best performance for MHP sensors, to the best of our knowledge. The excellent gas-sensitive response might be attributed to the formation of a heterojunction which promotes the electron migration from CsPbBr 3 to Fe 2 O 3. [ABSTRACT FROM AUTHOR]

All-inorganic CsPbBr3 perovskite solar cells have garnered extensive attention in the photovoltaic domain due to their remarkable environmental stability. Nevertheless, CsPbBr3 prepared using the conventional sequential deposition method suffers from issues such as inferior crystallinity, low phase purity, and poor film morphology. Herein, we propose a pre-crystallization methodology by introducing a minute quantity of CsBr into the PbBr2 precursor solution to generate a small amount of CsPb2Br5 crystals within the PbBr2 film, leading to a porous PbBr2 film with enhanced crystallinity. Under the influence of more pores and CsPb2Br5 crystals as nucleation sites for inducing growth, a CsPbBr3 film with a larger crystal size, lower grain boundary density, stronger crystallinity, and higher phase purity is formed. Compared with untreated devices, photovoltaic devices prepared using the pre-crystallization method achieved a champion photovoltaic conversion efficiency (PCE) of 8.62%. Furthermore, pre-crystallized devices demonstrate higher stability than untreated ones and can still retain 94% of the original PCE after being exposed to air for 1000 h without encapsulating. [ABSTRACT FROM AUTHOR]

To address challenges such as signal interference and crosstalk, the development of novel materials with the ability of electromagnetic absorption (EMA) is imperative. In this study, the composition of the B‐site of CsPbBr3 was fixed for all samples Pb0.2Fe0.2Co0.2Ni0.2Mn0.2 with varying A/B ratios of 1:1, 1:2, and 1:3. We achieved good EMA properties for the Cs1(Pb0.2Fe0.2Co0.2Ni0.2Mn0.2)3O3, including a minimum reflection loss of 75 dB at 10.2 GHz and a 2.5 mm thickness, accompanied by an exceptionally wide effective bandwidth of 8.8 GHz. X‐ray diffraction, transmittance electron microscopy, and X‐ray photoelectron spectroscopy, etc. were used to characterize the structure, morphology, and EMA‐associated properties of CsMBr3. The presence of high entropy was validated through meticulous analysis using Rietveld and grazing‐incidence wide‐angle scattering patterns. The magnetic permeability, dielectric constant, polarization, and attenuation loss were improved with a high‐entropy ratio of 3 within the 30–50 nm crystals. Notable lattice distortion within PbBr6 and phase transition within high‐entropy alloying are the driving forces behind these enhanced EMA characteristics. [ABSTRACT FROM AUTHOR]

The inorganic cesium lead bromide (CsPbBr3) perovskite solar cell (PSC) is considered as an attractive option for new solar cells due to its outstanding stability. Preparing CsPbBr3 PSCs with H2O can effectively save costs and reduce the harm of toxic solvents to the environment. However, the poor contact property of the PbBr2 layer to the CsBr/H2O solution and the ability of water to dissolve the CsPbBr3 phase has a significant impact on the performance of the CsPbBr3 devices. In this article, isobutyramide is introduced into the PbBr2 film in the first step to improve the wettability of the PbBr2 film to CsBr/H2O solution, followed by spin‐coating of the 150 mg mL−1 CsBr/H2O solution on the PbBr2 film. Using this strategy, the fabricated PSCs with the architecture of FTO/compact‐TiO2/mesoporous‐TiO2/CsPbBr3 film/carbon demonstrate outstanding performance with a maximum efficiency of 9.59%. Furthermore, after 45 days of storage at ambient temperatures, the unencapsulated device retains more than 96% of its original efficiency. Therefore, this work provides a good demonstration for the preparation of high‐efficiency and eco‐friendly CsPbBr3 PSCs. [ABSTRACT FROM AUTHOR]

BACKGROUND: The development of new scintillation materials based on fluorescent nanocrystals with a perovskite structure of CsPbBr3 composition and CdSe/ZnS quantum dots is a pressing topic that is being pursued by numerous scientific groups [1–4]. Both of these materials have a high potential for application in this role due to their excellent fluorophore properties, with a quantum yield of luminescence of approximately 100%. Additionally, they possess high values of the effective atomic Zeff number. The photoelectric cross section is dependent on Zeff as (Zeff)5, while the magnitude of X-ray absorption is dependent on Zeff as (Zeff)4/(AE3), where A is the atomic mass of the substance absorbing the γ-quantum and E is the energy of the X-ray photon [5]. AIM: The aim of the study was to develop a technique for fabricating scintillators based on quantum dots and polymer matrices with a high degree of transparency, high temporal stability of luminescence quantum yield, and short luminescence decay times (time of illumination or average lifetime of the substance in the excited state) for gamma-ray registration. MATERIALS AND METHODS: A HAMAMAMATSU R7400U-6 photomultiplier tube was employed to register scintillation signals. A 137Cs source with a γ-quantum energy of 661.7 keV was used as a source of ionizing radiation. RESULTS: At irradiation with γ-quanta of 137Cs isotope samples based on poly(para-methylstyrene) matrix cross-linked with divinylbenzene molecules (10% wt%), activated with naphthalene (10%, primary acceptor), anthracene (1%) and quantum dots/perovskite nanocrystals (0, 1–1.0%, re-emitter), the energy spectrum showed effective Compton scattering of gamma-quanta in matter on atoms included in quantum dots/perovskite nanocrystals. The study revealed that samples devoid of inorganic elements, including quantum dots and perovskite nanocrystals, do not exhibit the Compton effect for gamma-quanta. Furthermore, the paramethylstyrene matrix serves to safeguard perovskite nanocrystals from external influences. The photoluminescence quantum yield of bulk composite materials based on perovskite nanocrystals of the CsPbBr3 composition and poly(paramethylstyrene) remains constant over an extended period, with minimal fluctuations within the margin of error. CONCLUSIONS: Experimental evidence has demonstrated that quantum dots and perovskite nanocrystals encapsulated in various polymer matrices exhibit scintillator properties when subjected to ionizing radiation. The fabricated samples of perovskite nanocrystals/quantum dots and various polymers have been identified as the most promising candidates for use as scintillation material for the registration of X-ray and gamma radiation.

All-inorganic perovskite materials have gained enormous attention in photodetectors (PDs) due to their high charge carrier mobility, cost-effectiveness, and tunable bandgap. However, instability and corresponding performance degradation of perovskite PDs when exposed to surrounding humidity persist as challenges. In this work, a composite PD was fabricated by combining CsPb2Br5 nanowires and CsPbBr3 thin-film perovskites as an example to address these problems. The CsPb2Br5 nanowires were prepared by a facile water-bath method to improve the water resistance, and the subsequent evaporation of the CsPbBr3 film formed a type-I heterostructure to enhance its photosensitivity of PDs. As a result, the device exhibits a 10 times higher responsivity of 206 mA/W than that of the bare CsPbBr3 thin film device and maintains 92.85% of its original detectivity after being exposed to a humid environment (RH = 75%) for 144 h. Furthermore, the corresponding fundamental characterization was also performed to reveal the role of CsPb2Br5 nanowires in enhancing the overall performance of the PD. This work provides a simple and efficient approach to enhancing the durability and performance of all-inorganic halide perovskite devices through the embedding of CsPb2Br5 perovskite nanowires. [ABSTRACT FROM AUTHOR]

The wettability of precursor solution on substrates is the critical factor for fabricating quality film. In this work, superwetting nanofluids (NFs) of non‐stoichiometric nickel oxide (NiOx) nanocrystals (NCs)‐CsBr solution are first utilized to fabricate quality NiOx‐CsPbBr3 hybrid film with gradient‐distributed NiOx NCs in the upper part for constructing hole transport ladder in carbon‐based perovskite solar cells (C‐PSCs). As anticipated, the crystalline properties (improved crystalline grain diameters and reduced impurity phase) and hole extraction/transport of the NiOx‐CsPbBr3 hybrid film are improved after incorporating NiOx NCs into CsPbBr3. This originates from the superb wettability of NiOx‐CsBr NFs on substrates and the excellent hole‐transport properties of NiOx. Consequently, the C‐PSCs with the structure of FTO/SnO2/NiOx‐CsPbBr3/C displays a power conversion efficiency of 10.07%, resulting in a 23.6% improvement as compared with the pristine CsPbBr3 cell. This work opens up a promising strategy to improve the absorber layer in PSCs by incorporating NCs into perovskite layers through the use of the superwettability of NFs and by composition gradient engineering. [ABSTRACT FROM AUTHOR]

Titanium dioxide ( TiO 2 ) is a commonly employed electron transport layer in perovskite solar cells (PSCs) due to its exceptional attributes such as high mobility, a wide bandgap and remarkable stability against moisture and high temperatures. This holds particularly true for inorganic PSCs. Nevertheless, the substantial hysteresis and elevated trap defect levels following annealing present challenges to enhance the efficiency of the PSCs. Herein, we proposed a chemical bath deposition (CBD) method to fabricate the TiO 2 layer, serving as the electron transport layer in CsPbBr 3 solar cells. This method is coupled with KCl, which supplies an ample quantity of K ions capable of diffusing into the CsPbBr 3 perovskite film during the annealing process. The inclusion of K ions significantly diminishes the solar cell hysteresis and enhances the crystalline quality of the perovskite material, thereby enhancing the performance of CsPbBr 3 solar cells. By implementing the TiO 2 and KCl treatments, we achieved an impressive efficiency of 9.49%. Furthermore, the device also exhibited excellent stability in air for 30 days. We introduced KCl as a buffer layer to improve the quality of the TiO 2 films, which was used as the electron transport layer in CsPbBr 3 perovskite solar cells. This strategic addition of K ions serves not only to alleviate hysteresis in the perovskite solar cells, but also to enhance the crystallinity of the perovskite material. These cells have achieved an impressive champion efficiency of 9.49%, while maintaining their performance for over 30 days in ambient conditions. [ABSTRACT FROM AUTHOR]

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AbstractThe impact of CsPbBr3, known for its high atomic number and cross section with neutrons, on the gamma-ray and neutron shielding properties of CsPbBr3-polypropylene (PP) composite material was investigated in this study. Critical shielding parameters, including linear attenuation coefficient μ, mass attenuation coefficient μm, half-value thickness, tenth-value layer, and mean free path (MFP), were calculated using Phy-X/PSD software. Additionally, two types of gamma-ray buildup factors, i.e., exposure buildup factor and energy absorption buildup factor, were computed within the range of 0.015 to 15 MeV for depths up to 40 MFP. Furthermore, the neutron shielding ability was evaluated by determining the neutron total effective removal cross section. The results demonstrate that the incorporation of CsPbBr3 enhances the gamma-ray and neutron shielding characteristics of the CsPbBr3-PP composite material. [ABSTRACT FROM AUTHOR]

The exceptional optical properties and good temperature stability of inorganic halide perovskites make them appealing materials for photoelectrochemical water splitting. However, their instability towards water molecules is a serious challenge. Our solution to this issue is to use waste carbon-based toner from cartridge printers to protect CsPbBr 3 -based photoanodes in aqueous electrolytes in an environmentally friendly, cost-effective, and efficient way. Waste carbon toner: graphite (WCTG) protective layer is a novel approach that we present here to recycle these environmentally harmful pollutants. Through adjustment of WCTG ratios, we discovered that the CsPbBr 3 photoanodes' photocurrent densities for water oxidation achieved 3.6 and 4.6 mA cm−2 at 1.23 vs reversible hydrogen electrode at pH 7 and pH 12, respectively. After 5 h, the most stable electrodes still maintained their photocurrent density, a critical step towards the circular economy of waste toners and the use of inorganic halide perovskites for solar water splitting. [Display omitted] • The photoanode device is prepared using the CsPbBr 3 perovskite structure as a light absorber. • Waste carbon-based toner was used on CsPbBr 3 perovskite photoanodes as a protective layer against water molecules. • The PEC water oxidation performance of the CsPbBr 3 photoanodes strikingly improves with increasing graphite. • Increasing the amount of waste carbon-based toner increases the stability of CsPbBr 3 photoanodes in aqueous electrolytes. [ABSTRACT FROM AUTHOR]

Cesium lead bromide (CsPbBr3) is a representative material of the emerging class of lead halide perovskite semiconductors that possess remarkable optoelectronic properties. Its optical properties in the vicinity of the bandgap energy are greatly contributed by excitons, which form exciton polaritons due to strong light–matter interactions. Exciton–polaritons in solution‐grown CsPbBr3 crystals are examined by means of circularly polarized reflection spectroscopy measured in high magnetic fields up to 60 T. The excited 2P exciton state is measured by two‐photon absorption. Comprehensive modeling and analysis provides detailed quantitative information about the exciton–polariton parameters: exciton binding energy of 32.5 meV, oscillator strength characterized by longitudinal–transverse splitting of 5.3 meV, damping of 6.7 meV, reduced exciton mass of 0.18m0, exciton diamagnetic shift of 1.6 μeV T−2, and exciton Landé factor gX = +2.35. It is shown that the exciton states can be described within a hydrogen‐like model with an effective dielectric constant of 8.7. From the measured exciton longitudinal–transverse splitting, Kane energy of Ep = 15 eV is evaluated, which is in reasonable agreement with values of 11.8–12.5 eV derived from the carrier effective masses. [ABSTRACT FROM AUTHOR]

Hole transport material free carbon‐based all‐inorganic CsPbBr3 perovskite solar cells (PSCs) are promising for commercialization due to its low‐cost, high open‐circuit voltage (Voc) and superior stability. Due to the different solubility of PbBr2 and CsBr in conventional solvents, CsPbBr3 films are mainly obtained by multi‐step spin‐coating through the phase evolution from PbBr2 to CsPb2Br5 and then to CsPbBr3. The scalable fabrication of high‐quality CsPbBr3 films has been rarely studied. Herein, an inkjet‐printing method is developed to prepare high‐quality CsPbBr3 films. The formation of long‐range crystalline CsPb2Br5 phase can effectively improve phase purity and promote regular crystal stacking of CsPbBr3. Consequently, the inkjet‐printed CsPbBr3 C‐PSCs realized PCEs up to 9.09%, 8.59% and 7.81% with active areas of 0.09, 0.25, and 1 cm2, respectively, demonstrating the upscaling potential of our fabrication method and devices. This high performance is mainly ascribed to the high purity, strong crystal orientation, reduced surface roughness and lower trap states density of the as‐printed CsPbBr3 films. This work provides insights into the relationship between the phase evolution mechanisms and crystal growth dynamics of cesium lead bromide halide films. [ABSTRACT FROM AUTHOR]

Artificial synapse inspired by the biological brain has great potential in the field of neuromorphic computing and artificial intelligence. The memristor is an ideal artificial synaptic device with fast operation and good tolerance. Here, we have prepared a memristor device with Au/CsPbBr3/ITO structure. The memristor device exhibits resistance switching behavior, the high and low resistance states no obvious decline after 400 switching times. The memristor device is stimulated by voltage pulses to simulate biological synaptic plasticity, such as long-term potentiation, long-term depression, pair-pulse facilitation, short-term depression, and short-term potentiation. The transformation from short-term memory to long-term memory is achieved by changing the stimulation frequency. In addition, a convolutional neural network was constructed to train/recognize MNIST handwritten data sets; a distinguished recognition accuracy of ∼96.7% on the digital image was obtained in 100 epochs, which is more accurate than other memristor-based neural networks. These results show that the memristor device based on CsPbBr3 has immense potential in the neuromorphic computing system.

Underwater wireless optical communication (UWOC) has attracted increasing attention due to its advantages in bandwidth, latency, interference resistance, and security. Photodetectors, as a crucial part of receivers, have been continuously developed with the great progress that has been made in advanced materials. Metal halide perovskites emerging as promising optoelectronic materials in the past decade have been used to fabricate various high-performance photodetectors. In this work, high-performance CsPbBr3 perovskite PDs were realized via solution process, with low noise, a high responsivity, and a fast response. Based on these perovskite PDs, a cost-efficient UWOC system was successfully demonstrated on an FPGA platform, achieving a data rate of 6.25 Mbps with a low bit error rate of 0.36%. Due to lower background noise under environment illumination, perovskite PDs exhibit better communication stability before reaching a data rate threshold; however, the BER increases rapidly due to the long fall time, resulting in difficulty in distinguishing switching signals. Reducing the fall time of perovskite PDs and using advanced coding techniques can help to further improve the performance of the UWOC system based on perovskite PDs. This work not only demonstrates the potential of perovskite PDs in the application of UWOC, but also improves the development of a cost-effective UWOC system based on FPGAs.

The low stability and high toxicity of CsPbBr3 perovskite nanocrystals (PNCs) greatly limit their application in the biological field. Here, six different CsPbBr3 PNCs were prepared by ligand-assisted reprecipitation (LARP) and hot injection using oleic acid (OA), oleamine (OAm), (3-Aminopropyl) triethoxysilane (APTES) modification and SiO2 coating, respectively. Different ligands, shells, and synthesis methods give CsPbBr3 PNCs diverse optical properties, stability, and biocompatibility. Among them, OA-OAm-APTES-CsPbBr3@SiO2 has the highest photoluminescence quantum yield (PLQY) (80.74%) and higher stability (fluorescence intensity remains 70% after 15 days in an atmospheric environment). OA-OAm-APTES-CsPbBr3@SiO2 (30 μg/mL) was cocultured with liver cancer cells for 12 h, and the survival rate was 80%, indicating high biocompatibility. Under the observation of the microplate reader, bright green fluorescence appeared in the cytoplasm, indicating that OA-OAm-APTES-CsPbBr3@SiO2 has great application potential in the field of bioimaging. [ABSTRACT FROM AUTHOR]

The photoluminescence (PL) spectra of CsPbBr3 perovskite nanocrystals grown in a fluorophosphate glass matrix exhibit phonon replicas of the exciton line. The dependence of intensity of the phonon replica on its number is simulated taking into account the difference in the curvature of the excited and ground adiabatic potentials. The Raman spectra of CsPbBr3 nanocrystals are measured. Calculations based on the density functional theory is performed to obtain the spectrum of phonon states of these crystals in the orthorhombic phase. The phonon frequencies observed in the PL and Raman spectra are compared with the calculation results. [ABSTRACT FROM AUTHOR]

Perovskite quantum dots (PQDs) are inherently unstable under environmental conditions, making it difficult to form patterns using conventional techniques. Herein, a unique approach is reported for patterning PQDs by the nonuniform photopolymerization of the liquid monomer. The demonstrated approach employs a PQD‐dispersed photocurable liquid, which is illuminated with the patterned light formed using a digital micromirror device (DMD). As the monomers are photopolymerized, the PQDs in the solution are patterned by diffusion (migration), and eventually, their pattern is imprinted on the film after photopolymerization. The migration process of the PQDs is in situ observed using an inverted‐type confocal microscope, and the patterning principle is examined by fine‐tuning the spatial distribution of the light intensity using the DMD. These findings will promote the generation of clear nanocrystal patterns with high contrasts and narrow line widths on films. [ABSTRACT FROM AUTHOR]

Owing to the absence of organic cations, all‐inorganic perovskite exhibits superior thermal and irradiation stability compared to organic‐inorganic perovskite. However, it is difficult for the traditional solution method to produce pinhole‐free and phase‐pure all‐inorganic perovskite films, which hinders its application. Here, a method of in situ A‐site cation exchange to synthesize CsPbBr3 films is introduced. The MAPbBr3 films are treated with CsAc solution to initiate cation exchange, where the intermediate product MAAc plays a crucial role in guiding grain growth during evaporation, resulting in the production of pinhole‐free and phase‐pure CsPbBr3 films. The self‐powered photodetector, based on compact and pinhole‐free CsPbBr3 film, exhibits excellent performance with an LDR of 126.7 dB, a detectivity of 1.1 × 1013 Jones, and a rise/decay time of 2.9/25.1 µs. Furthermore, the photodetector maintains over 90% of its original performance after a 2500 s irradiation test and a 30‐day air exposure test. Benefiting from the exceptional device performance and stability, the photodetector proves to be a valuable component in the laser eavesdropping system. [ABSTRACT FROM AUTHOR]

Achieving high‐quality, frequency‐upconversion single‐mode lasing output is an important requirement for developing new nonlinear optoelectronic devices, such as on‐chip optical communication, nonlinear optical switches, and optical parametric amplifiers. Here, an individual CsPbBr3 microwire prepared by the anti‐solvent method is served as both gain media and microresonator to achieve two‐photon pumped frequency upconversion single‐mode lasing with the side‐mode suppression ratio of 18 dB. Meanwhile, the refractive index of orthorhombic perovskite is theoretically calculated based on first principles, and determining its square whispering‐gallery oscillation type by combining with the plane wave model and the steady‐state oscillation conditions of laser. The extracted exciton binding energy of 33.15 meV higher than the thermal ionization energy of room temperature (≈26 meV) suggests that the as‐grown CsPbBr3 microwires possess the capacity to achieve two‐photon pumped lasing output, as well further gaining deeper insights into the role of exciton‐phonon coupling in light emission. [ABSTRACT FROM AUTHOR]

A photoelectrochemical (PEC) immunosensor was designed based on MgIn2S4-decorated inorganic halide perovskite CsPbBr3 combined with the signal polarity conversion strategy for neuron-specific enolase (NSE) detection. CsPbBr3 was applied as the basic photoactive material owing to its excellent optical and electronic properties, which provide a good PEC performance for sensor construction. In order to improve the stability of this perovskite, the three-dimensional flower-like MgIn2S4 with a desirable direct band gap was applied to enhance the PEC response. Also, the excellent structure of MgIn2S4 provides large surface-active sites for CsPbBr3 loaded. For enhancing the detection sensitivity of PEC immunosensor, p-type CuInS2 was used as a signal probe which fixed on detection antibody (Ab2). When the target NSE was present, the photogenerated electrons produced by CuInS2 were transferred to the test solution, and the polarity of PEC signal changes. Based on the above photosensitive materials and signal conversion strategy, the proposed PEC immunosensor showed favorable detection performance, and the linear detection range is 0.0001 ~ 100 ng/mL with a 38 fg/mL of detection limit. The proposed strategy improved the adhibition of CsPbBr3 in the analytical chemistry field as well as provided a reference method for other protein detections. [ABSTRACT FROM AUTHOR]

A photoelectrochemical (PEC) immunosensor was designed based on MgIn2S4-decorated inorganic halide perovskite CsPbBr3 combined with the signal polarity conversion strategy for neuron-specific enolase (NSE) detection. CsPbBr3 was applied as the basic photoactive material owing to its excellent optical and electronic properties, which provide a good PEC performance for sensor construction. In order to improve the stability of this perovskite, the three-dimensional flower-like MgIn2S4 with a desirable direct band gap was applied to enhance the PEC response. Also, the excellent structure of MgIn2S4 provides large surface-active sites for CsPbBr3 loaded. For enhancing the detection sensitivity of PEC immunosensor, p-type CuInS2 was used as a signal probe which fixed on detection antibody (Ab2). When the target NSE was present, the photogenerated electrons produced by CuInS2 were transferred to the test solution, and the polarity of PEC signal changes. Based on the above photosensitive materials and signal conversion strategy, the proposed PEC immunosensor showed favorable detection performance, and the linear detection range is 0.0001 ~ 100 ng/mL with a 38 fg/mL of detection limit. The proposed strategy improved the adhibition of CsPbBr3 in the analytical chemistry field as well as provided a reference method for other protein detections. [ABSTRACT FROM AUTHOR]

Low‐temperature, ambient processing of high‐quality CsPbBr3 films is demanded for scalable production of efficient, low‐cost carbon‐electrode perovskite solar cells (PSCs). Herein, we demonstrate a crystal orientation engineering strategy of PbBr2 precursor film to accelerate its reaction with CsBr precursor during two‐step sequential deposition of CsPbBr3 films. Such a novel strategy is proceeded by adding CsBr species into PbBr2 precursor, which can tailor the preferred crystal orientation of PbBr2 film from [020] into [031], with CsBr additive staying in the film as CsPb2Br5 phase. Theoretical calculations show that the reaction energy barrier of (031) planes of PbBr2 with CsBr is lower about 2.28 eV than that of (020) planes. Therefore, CsPbBr3 films with full coverage, high purity, high crystallinity, micro‐sized grains can be obtained at a low temperature of 150 °C. Carbon‐electrode PSCs with these desired CsPbBr3 films yield the record‐high efficiency of 10.27% coupled with excellent operation stability. Meanwhile, the 1 cm2 area one with the superior efficiency of 8.00% as well as the flexible one with the champion efficiency of 8.27% and excellent mechanical bending characteristics are also achieved. [ABSTRACT FROM AUTHOR]

By using the method of low‐temperature crystallization, CsPbBr3 perovskite nanocrystals (PNCs) coated with trifluoroacetyl lysine (Tfa‐Lys) and oleamine (Olam) were synthesized in aqueous solution. The structure of the CsPbBr3 PNCs was characterized by many methods, such as ultraviolet (UV)‐visible absorption spectrophotometer, fluorescence spectrophotometer, transmission electron microscopy (TEM), and X‐ray diffraction (XRD) pattern. The fluorescence emission of the CsPbBr3 PNCs is stable in water for about 1 day at room temperature. It was also found that the fluorescence of the PNCs could be obviously and selectively quenched after the addition of mercury ion (Hg2+), allowing a visual detection of Hg2+ by the naked eye under UV light illumination. The fluorescence quenching rate (I0/I) has a good linear relationship with the addition of Hg2+ in the concentration range 0.075 to 1.5 mg/L, with a correlation coefficient (R2) of 0.997, and limit of detection of 0.046 mg/L. The fluorescence quenching mechanism of the PNCs was determined by the fluorescence lifetime and X‐ray photoelectron spectroscopy (XPS) of the PNCs. Overall, the synthesis method for CsPbBr3 PNCs is simple and rapid, and the as‐prepared PNCs are stable in water that could be conveniently used for selective detection of Hg2+ in the water environment. [ABSTRACT FROM AUTHOR]

There is a growing demand for materials for detecting ionizing radiation, which has led to the expansion of research and development of new scintillators. Typically, scintillators are synthesized by crystallizing materials at high temperatures, and their photoluminescence (PL) is difficult to tune in the visible spectral range. Therefore, composite materials based on CsPbBr3 perovskite nanocrystals (PNCs), which have a high average atomic number and a long charge-carrier diffusion length, are of particular interest and may be used for detecting ionizing radiation. Unlike bulk scintillators, PNCs are synthesized in solution at relatively low temperatures, with the PL tunable throughout the visible spectrum. The main problem limiting the widespread use of PNCs is their low stability upon contact with the environment. This study presents the results of experiments on the encapsulation of PNCs in a polystyrene matrix, the evaluation of the changes in the luminescence quantum yield (QY) over time, and the development of a technique for studying the amplitude characteristics of signals recorded during the interaction of α-particles with composite materials based on CsPbBr3 PNCs and polystyrene. The study has shown that composite samples based on PNCs and polystyrene retain a stable luminescence QY for two weeks. Using a 241Am source with a characteristic α-particle energy of about 4.6 MeV and γ-ray energy of 60 keV, the light output values were calculated for the samples studied. The maximum light output was 20% of that of the standard "fast" plastic scintillator (POPOP) at a volume fraction of PNCs in the composite of less than 1%, which indicates the prospect of PNCs as a basis for composite scintillators and their further use in X-ray diagnosis. [ABSTRACT FROM AUTHOR]

Inorganic perovskite solar cells have attracted considerable interest for their thermal stability. In this study, turmeric and carotene natural dyes as additives for refining CsPbBr3 film crystal structure are explored. These dyes enhance light absorption and carrier transport by increasing CsPbBr3 crystal size and reducing defects. Capitalizing on the dyes' light-absorbing nature and their impact on device energy levels, turmeric and carotene additives elevate efficiency from 5.35% to 9.78% and 7.81%, respectively. Remarkably, device stability extends 90 days without encapsulation. In this work, an eco-friendly, economical method to optimize perovskite crystallization is introduced and optoelectronic properties in inorganic perovskite solar cells are enhanced. [ABSTRACT FROM AUTHOR]

All-inorganic CsPbBr3 perovskite solar cells (PSCs) have attracted more attentions due to the excellent environmental stability, however, the wide bandgap and relatively poor crystallinity of CsPbBr3 have been the main obstacle to improve their power conversion efficiency (PCE). Herein, we proposed an efficient and simple strategy of precursor additive in the two-step aqueous-solution method, the resulted CsPbBr3 film has achieved more uniform grain size, almost pure perovskite phase, smoother surface, less defects, enhanced light absorption and longer carrier lifetime. This is due to the rapid evaporation of additive (IPA and CH3OH) in the CsBr/H2O precursor leads to a relatively higher local CsBr concentration on the surface of PbBr2, which can provide more nucleation sites and accelerate the crystallization of perovskite. Further, when utilizing the optimal additive of 5% (in volume) IPA, the HTM-free carbon-based CsPbBr3 PSCs obtained a PCE improvement from 9.09% to 10.29%, and an ultrahigh fill factor (FF) of 85.21%. What is more, by adding 0.1 mol/L PbCl2 into the PbBr2 solution in the first step, the open circuit voltage of device has increased from 1.36 V to 1.48 V, the champion PCE reached 10.37% (steady output PCE of 10.17%), and the non-encapsulated device could maintain 85% of its initial efficiency after 50 d in the air. This work provides a cost-effective approach to grow CsPbBr3 film and boosts the efficiency benchmark of the CsPbBr3 PSCs to more than 10%, it is desirable that the highly efficient and stable CsPbBr3 PSCs can be developed in future.

Cesium lead bromide (CsPbBr3) nanocrystals (NCs) with nanoplatelet shapes and different crystal structures were synthesized via the ligand-assisted reprecipitation (LARP) method using different pairs of ligands and antisolvents, namely oleic acid (OA) or linoleic acid (LA) as the ligand and toluene or chloroform as the antisolvent. The XRD data revealed that the obtained CsPbBr3 NCs have different crystal structures, namely orthorhombic, tetragonal, and cubic, depending on the ligand and antisolvent pair, which exhibited significantly different photoluminescence (PL) characteristics. From the XPS data, these CsPbBr3 nanoplatelets showed two doublet peaks of the Br-3d orbital at different binding energies, representing two different chemical environments of the Br bonds. The doublet peak apparent at a higher binding energy was associated with the Br chemical states at the crystal surface, which appeared because of the distorted crystal structure resulting from the interaction of the solvent and ligand with Br ions. The PL emission consists of three luminescence centers: a PL band peaked at 520 nm (A band), a PL band peaked at 540 nm (B band), and a PL band tail, which can be discussed in terms of exciton models. Stable and intense luminescence was observed in CsPbBr3 nanoplatelets synthesized using a pair of toluene antisolvent and LA ligand, namely CsPbBr3#(Tl/LA). The orthorhombic crystal structure and distorted crystal surface in this sample may lead to confinement of the photogenerated small exciton-polaron and weak phonon interactions, which effectively hinder exciton dissociation, particularly at the crystal surface, resulting in intense PL. The results of this study may provide additional important insights into the role of the antisolvent and ligand in the formation of CsPbBr3 NCs and the exciton behavior in their PL characteristics, which may also be found in other types of halide perovskites.

Blue-emission (∼480 ​nm) CsPbBr3 nanoparticles with ultra-small size (∼2.1 ​nm) are synthesized using the liquid nitrogen freezing with the ligand of dodecylbenzene sulfonic acid (DBSA). Asymmetric narrow emissions at the low energy side, with the full width at half-maximum of ∼20 ​nm, are observed in solution and film at room temperature. The spectral asymmetry is mainly ascribed to phonon vibronic replica with averaged phonon energy of ∼40 ​meV. Moreover, exciting this CsPbBr3 nanoparticles solution using linearly polarized 6 ns pulsed laser at 355 ​nm, we observe polarized emission with polarization degree (PPL) of ∼7%, and PPL decreases more than 20% in the vibronic progression. However, the PPL goes to zero in frozen solutions as well as in films. Thus we speculate the polarized emission is due to the photoinduced re-alignment of nanoparticles, and the diminished PPL at the phonon side band may be due to the non-adiabatic electronic-to-vibronic transitions. The novel phenomena from the ultra-small CsPbBr3 nanoparticle demonstrated in this work may provide fundamental insights into its photophysics with direct implications for optoelectronics.

Inorganic metal halide perovskites have significant interest due to their wide applications in optoelectronics. The effect of substrate immersion angle on the evaporation-induced self-assembly of Cesium lead bromide (CsPbBr3) thin films on a glass substrate is reported in this work. Colloidal CsPbBr3 nano-crystals synthesized through the Ligand Assisted Re-precipitation (LARP) method under ambient conditions are used for self-assembly. Structural, morphological, and optical properties of the self-assembled thin films are investigated using TEM, XRD, FE-SEM, AFM, Raman, UV-visible absorption, and Photoluminescence techniques. Thin films self-assembled on a substrate inclined at 90° show the best crystallinity, larger optical band gap, and minimum grain size relative to films grown with an inclination of 0° and 45°. Self-assembled thin films exhibit preferential growth along the (004) and (220) planes for a substrate inclination angle of 90°. C-axis growth was favored when the substrate was inclined at 450. The optical band gap of the self-assembled 2D material was found to increase as the substrate angle was increased from 0° to 90°. The recombination lifetime in these self-assembled CsPbBr3 thin films was found to be ∼14 ns, exhibiting a 68% reduction relative to that measured for the colloidal nanocrystals. A shelf life of over 6 months for the self-assembled thin films with no significant degradation in their structural and optical properties has been reckoned by us presently.

[Display omitted] All inorganic CsPbX 3 perovskite has aroused broad interests in building efficient light-emitting devices with wide color gamut and flexible fabrication process. So far, the realization of high-performance blue perovskite light-emitting devices (PeLEDs) is still a critical challenge. Herein, we propose an interfacial induction strategy to generate low-dimensional CsPbBr 3 with sky blue emission by employing γ-aminobutyric acid (GABA) modified poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The interaction between GABA and Pb2+ inhibited the formation of bulk CsPbBr 3 phase. Further assisted by the polymer networks, the sky-blue CsPbBr 3 film exhibited much improved stability under both photoluminescence and electrical excitation. This can be ascribed to the scaffold effect and the passivation function of the polymer. Consequently, the obtained sky-blue PeLEDs exhibited an average external quantum efficiency (EQE) of 5.67% (maximum of 7.21%) with a maximum brightness of 3308 cd/m2 and a working lifespan reaching 0.41 h. The strategy in this work provides a new opportunity for exploitation the full potential of blue PeLEDs towards application in lighting and display devices. [ABSTRACT FROM AUTHOR]

After establishing themselves as promising active materials in the field of solar cells, halide perovskites are currently being explored for fabrication of low‐cost, easily processable, and highly efficient light‐emitting diodes (LEDs). Despite this, the highest efficiencies reported for perovskite‐based LEDs (PeLEDs) are achieved through spin coating or vacuum evaporation deposition techniques, which are not adequate, in most of the cases, for an industrial‐scale production. Additionally, the long‐term stability is still a big handicap, even though all inorganic perovskites, such as CsPbBr3, are found to be more stable to external variables. In this context, herein, the fabrication of fully inkjet‐printed (IJP) CsPbBr3‐based PeLEDs in ambient conditions, on rigid and flexible substrates, on a proof‐of‐concept basis, with the successful incorporation of NiO and SnO2 as hole‐ and electron‐selective contacts, respectively, is reported. Despite the moderate luminance (324 cd m−2) value obtained, this result paves the way toward the development of upscalable fabrication of PeLEDs based on deposition techniques with controlled spatial resolution. [ABSTRACT FROM AUTHOR]

1D semiconductor wires have great potential in on‐chip integrated photonics systems. However, it is still challenging to efficiently integrate various semiconductor wires on a large scale for complex functional devices. This study reports a universal route to in‐plane integrate unidirectional metal halide perovskite CsPbBr3 wire arrays with Sb2Se3, PbSeand CdS wires on mica substrates, respectively. It is found that the growth of the unidirectional wire arrays is controlled by a synergistic effect of the promoted initial nucleation on the transferred heterogeneous wires and the thermodynamically favored epitaxy on mica. The optical characterizations show that the CsPbBr3 wire arrays can act as both the light emitting media and waveguide, where the emission in the CsPbBr3 wires can be efficiently guided into the backbone Sb2Se3 wire. Importantly, the constructed CsPbBr3 waveguide arrays/Sb2Se3 wire photodetector system shows 73.4 nA photocurrent with the on/off ratio of 111, by exciting the CsPbBr3 wires at 174 mW cm−2 of 405 nm laser. The frequency dependent photoresponse characterizations exhibit a response capability of 2000 Hz modulated laser pulse and a 3 dB frequency above 300 Hz, indicating the rapid response speed. This study promotes the application of semiconductor wires in on‐chip multifunctional integrated photonic devices. [ABSTRACT FROM AUTHOR]

Metal halide perovskites (MHPs) have garnered significant interest as promising candidates for nanoscale optoelectronic applications due to their excellent optical properties. Axially heterostructured CsPbBr3–CsPb-(Br(1–x)Clx)3 nanowires can be produced by localized anion exchange of pregrown CsPbBr3 nanowires. However, characterizing such heterostructures with sufficient strain and real space resolution is challenging. Here, we use nanofocused scanning X-ray diffraction (XRD) and X-ray fluorescence (XRF) with a 60 nm beam to investigate a heterostructured MHP nanowire as well as a reference CsPbBr3 nanowire. The nano-XRD approach gives spatially resolved maps of composition, lattice spacing, and lattice tilt. Both the reference and exchanged nanowire show signs of diverse types of ferroelastic domains, as revealed by the tilt maps. The chlorinated segment shows an average Cl composition of x = 66 and x = 70% as measured by XRD and XRF, respectively. The XRD measurements give a much more consistent result than the XRF ones. These findings are consistent with photoluminescence measurements, showing x = 73%. The nominally unexchanged segment also has a small concentration of Cl, as observed with all three methods, which we attribute to diffusion after processing. These results highlight the need to prevent such unwanted processes in order to fabricate optoelectronic devices based on MHP heterostructures. [ABSTRACT FROM AUTHOR]