Cesium Lead Bromide Research Articles

CsPbBr3 NCs Confined and In Situ Grown in ZIF-8: A Stable, Sensitive, Reliable Fluorescent Sensor for Evaluating the Acid Value of Edible Oils.

Rapidly and sensitively evaluating the acid value (AV) of edible oils is significant to ensuring food quality and safety. Cesium lead bromide perovskite nanocrystals (CsPbBr3 NCs) are an effective candidate for AV detection; however, their instability restricts wide applications. Herein, CsPbBr3@ZIF-8 was prepared by confining and growing CsPbBr3 NCs in situ into zeolitic imidazolate framework-8 (ZIF-8) to improve the stability, and a fluorescence sensor was established to evaluate the AV of edible oils. The results present that CsPbBr3 NCs (below 5 nm) with excellent optical properties were confined and grown in situ in micropores and mesopores of ZIF-8. Meanwhile, CsPbBr3@ZIF-8 had better long-term storage, ultraviolet-irradiation, and water-exposure stabilities, compared with CsPbBr3 NCs. Given the fact that free fatty acids (the major contributor of AV) decrease the fluorescence of CsPbBr3 NCs, the fluorescence intensities of CsPbBr3@ZIF-8 were negative-linearly related to oil AV (R2 = 0.9902) in 0.04-6.00 mg of KOH/g with a 0.06 mg of KOH/g limit of detection. Besides, the practical AV recovery was 92-101% with an average relative standard deviation of 2%. Furthermore, the detection time was 20 min. The response mechanism revealed that free fatty acids could remove surface ligands and increase surface defects to prompt the aggregation of CsPbBr3 NCs and the formation of lattice fringe dislocations, inducing a decrease in the fluorescence. Thus, a stable, sensitive, reliable sensor was established to evaluate the AV of edible oils.

Controlled Morphological Growth and Photonic Lasing in Cesium Lead Bromide Microcrystals.

Morphology plays a crucial role in defining the optical, electronic, and mechanical properties of halide perovskite microcrystals. Therefore, developing strategies that offer precise control over crystal morphology during the growth process is highly desirable. This work presents a simple scheme to simultaneously grow distinct geometries of cesium lead bromide (CsPbBr3) microcrystals, including microrods (MR), microplates (MP), and microspheres (MS), in a single chemical vapor deposition (CVD) experiment. By strategically adjusting precursor evaporation temperatures, flux density, and the substrate temperature, we surpass previous techniques by achieving simultaneous yet selective growth of multiple CsPbBr3 geometries at distinct positions on the same substrate. This fine growth control is attributed to the synergistic variation in fluid flow dynamics, precursor substrate distance, and temperature across the substrate, offering regions suitable for the growth of different morphologies. Pertinently, perovskite MR are grown at the top, while MP and MS are observed at the center and bottom regions of the substrate, respectively. Structural analysis reveals high crystallinity and an orthorhombic phase of the as-grown perovskite microcrystals, while persistent photonic lasing manifests their nonlinear optical characteristics, underpinning their potential application for next-generation photonic and optoelectronic devices.

Pressure-dependent band gap engineering with structural, electronic, mechanical, optical, and thermal properties of CsPbBr3: first-principles calculations.

In the renewable industry, pressure-dependent CsPbBr3 perovskite has a lot of potential due to its exceptional properties. Present work revealed the mechanical stability of CsPbBr3 between 0 to 50GPa. The bandgap of unstressed CsPbBr3 is 2.90eV, indicating a direct bandgap. Band gap values decrease by increasing external pressure. CsPbBr3 structure showed a direct band gap from 0 to 35GPa and in-direct from 40 to 50GPa. The unit cell volume and lattice constants are substantially decreased. Mechanical parameters, i.e., Young's modulus, bulk modulus, anisotropy factor, shear modulus, and poison's ratio are obtained. Under ambient conditions, the mechanical properties of CsPbBr3 showed ductile behavior and with induced pressure, their ductility has significantly improved. By applying stresses ranging from 0 to 50GPa, the considerable fluctuation in values of dielectric function (imaginary and real), absorption, reflectivity, loss function, refractive index (imaginary and real), and conductivity (imaginary and real), was also identified. When pressure rises, the optical parameters increase and drag in the direction of high energies. Response functions are used to predict the density of states and the phonon lattice dispersion to study the phonon properties. By using the quasi-harmonic Debye model, the thermal effect on the free energy, entropy, enthalpy, and heat capacity were predicted and compared. These results would be useful for theoretical research and indicate how external pressure significantly affects the physical characteristics of CsPbBr3 perovskites, which may open up new possibilities for use in optoelectronic, photonic, and solar cell applications. The structural, electrical, mechanical, optical, and thermal properties of cesium lead bromide (CsPbBr3) are investigated by applying external pressure from 0 to 50GPa, using generalized gradient approximations (GGA) and Perdew-Burke-Ernzerhof (PBE) with CASTEP code built-in material studio by density functional theory (DFT).

Copper(I) Induced Phase Transition and 1D Growth in Cesium Lead Bromide Cubic Nanocrystals

Lead halide perovskites have been explored ardently in the past decade owing to their excellent photophysical properties. High‐temperature cation exchange reactions have been employed to improve the stability and performance in perovskite lattice, but lacks control over size, shape, and stoichiometry. Herein, the solution phase interaction of cesium lead bromide (CsPbBr3) nanocrystals with monovalent and bivalent copper ions, under ambient conditions is systematically investigated. The introduction of Cu1+ explicitly initiates a one‐dimensional growth with a distinct phase transition, that is from cubic to orthorhombic, while Cu2+ induces a partial exchange with Pb2+ with no phase change. DFT calculations suggest that Cu1+ induces structural distortion via Cs1+ substitution, altering the Goldschmidt tolerance factor and perovskite octahedral tilting, leading to the phase transition. Additionally, the oleic acid/amine ligands used to stabilize the nanocrystals, are preferentially etched away to form complexes with Cu1+, initializing an oriented growth of the nanocubes to nanorods. A mechanistic investigation of the evolution of the nanorods gave insights on tuning the tolerance factor via room temperature modifications and cation exchanges in perovskites for anisotropy and morphology tuning. This effortlessly obtained perovskite nanorods with Cu1+ could find effective applications in optoelectronics, and as novel photocatalysts.

Study of charge transport in cesium lead bromide perovskite quantum dots and PCPDTBT composites: an application to photosensitive FETs

This work investigates the optical, structural, and photo-physical properties of PCPDTBT/cesium lead bromide (CsPbBr3) perovskite quantum dots (QDs) composite for optoelectronic devices. The composite was prepared by processing the PCPDTBT and CsPbBr3 QDs via the solution blending method. Incorporating CsPbBr3 QDs with different weight % (wt%) ratio in PCPDTBT influences its optoelectronic properties. UV–vis absorption spectroscopy, photoluminescence (PL), and atomic force microscopy measurements were used to analyze their optical and morphological properties. We observed that incorporating 4 wt% QDs in PCPDTBT enhanced its light absorption and charge transfer properties. Increased carrier lifetime for PCPDTBT/QDs (4 wt%) was observed from PL decay measurements. Further, we fabricated the field effect transistors (FETs) of pristine PCPDTBT and PCPDTBT/CsPbBr3 QDs composite (4 wt%) to study their electronic and charge transfer features. Significant variation in source-to-drain current (IDS) and carrier mobility has been observed. A substantial increased output current was observed for composite FET than pristine PCPDTBT-based FET due to charge transfer from QDs to PCPDTBT. Both PCPDTBT and PCPDTBT/CsPbBr3 QDs-based FET show enhanced current with illumination, which could be attributed to the photo-generated charge carriers.

Brightly Luminescent and Color‐Tunable CsPbBr3 Nanocrystals with Enhanced Stability and Room Temperature Cubic Structure through Codoping with MnCl2

Lead halide perovskites have attracted much attention from the scientific community in recent years due to their attractive properties and their proven potential in many applications. Nevertheless, their stability and lead toxicity have remained a problem. Herein, the potential of manganese as a divalent dopant to offer better stability and replace a fraction of the toxic lead ions is investigated. Moreover, the reverse microemulsion method is used to obtain tunability in emission and bandgap by doping cesium lead bromide. Furthermore, cubic cesium lead bromide particles are managed to obtain at room temperature as a result of doping.

Polymer optical fiber amplifier based on all-inorganic perovskite quantum dots

The proliferation of polymer optical fibers (POFs) has opened multiple avenues of optical-based networks and sensing applications in the visible spectral range. However, the lack of efficient amplifiers significantly hinders their utilization in practical scenarios. As emerging gain media, halide perovskites have attracted considerable attention in exploring their practical applications. In this Letter, we investigated the optical gain properties of cesium lead bromide quantum dots (CsPbBr3 QDs), and by facet dip-coating, we realized a polymer optical fiber amplifier. Under a 400-nm, 163-fs Ti:Sapphire laser pumping, the amplified spontaneous emission (ASE) thresholds of 1.6 and 20.1 μJ/cm2 were achieved through stripe pumping of a QDs-thin-film and end-pumping of a polymer-fiber facet dip-coated with the QDs, respectively. A gain coefficient of 232.2 ± 22.8 cm−1 was obtained using the variable stripe length method. By coupling a broadband continuous-wave light source into the POF as the signal, the optical gain behavior was studied with varying pump fluence and signal power density. More than 20 dB optical gain was achieved within the ASE wavelength region of 530–540 nm with a predicted theoretical maximum gain of 33.6 dB. The research verifies the feasibility of amplifying continuous-wave signals in the visible spectrum and potentially closing the research gap in visible-light optical-to-optical amplifiers. This opens the avenue for further research and innovations in practical polymer-based optical amplification for a plethora of applications, including all optical processing chips and short-range interconnects, as well as visible-light and underwater communications.

Ab-initio investigation of the structural, electronic and optical properties of CsPbBr3 perovskite under pressure using the DFT-1/2 method

Pressure-induced phase transitions in metal halide perovskites lead to significantly different material properties and offer great potential for diverse applications. The electronic, structural, and optical properties of Cesium lead bromide (CsPbBr3) crystals are investigated using density functional theory (DFT) to draw an integrated picture of orbital morphology, absorption spectra, and band gap values. Spin-orbit coupling and DFT-1/2 correction are used to gain a better insight into electronic properties and band splitting in the cubic phase. Calculations of pressure-induced phase transitions, electronic band gap engineering, and manipulation of optical absorption edges of CsPbBr3 are conducted. In the cubic and tetragonal crystal lattices, a band gap closure and opening occurs demonstrating a Dirac cone upon application and increase of pressure. Indeed, in the tetragonal lattice of CsPbBr3, a topological band occurs. Orthorhombic perovskite crystal lattice undergoes successive direct-indirect and indirect-direct band gap transitions, followed by a space group change at extreme pressures. However, under pressure, orthorhombic non-perovskite lattice experiences a sudden band gap breakdown. Phase and band gap transitions are explained by orbital hybridizations and structural symmetry evolution (e.g., bond length contraction/dilation and octahedral cage rotation/distortion). These results provide comprehensive guidelines for further experimental studies on pressure engineering, advanced photovoltaic and optoelectronic applications, discovering and understanding new topological band structures of perovskite materials.

Room Temperature Polariton Condensation from Whispering Gallery Modes in CsPbBr3 Microplatelets.

Room temperature (RT) polariton condensate holds exceptional promise for revolutionizing various fields of science and technology, encompassing optoelectronics devices to quantum information processing. Using perovskite materials, like all-inorganic cesium lead bromide (CsPbBr3) single crystal, provides additional advantages, such as ease of synthesis, cost-effectiveness, and compatibility with existing semiconductor technologies. In this work, the formation of whispering gallery modes (WGM) in CsPbBr3 single crystals with controlled geometry is shown, synthesized using a low-cost and efficient capillary bridge method. Through the implementation of microplatelets geometry, enhanced optical properties and performance are achieved due to the presence of sharp edges and a uniform surface, effectively avoiding non-radiative scattering losses caused by defects. This allows not only to observe strong light matter coupling and formation of whispering gallery polaritons, but also to demonstrate the onset of polariton condensation at RT. This investigation not only contributes to the advancement of the knowledge concerning the exceptional optical properties of perovskite-based polariton systems, but also unveils prospects for the exploration of WGM polariton condensation within the framework of a 3D perovskite-based platform, working at RT. The unique characteristics of polariton condensate, including low excitation thresholds and ultrafast dynamics, open up unique opportunities for advancements in photonics and optoelectronicsdevices.

Surface-Engineered Cesium Lead Bromide Perovskite Nanocrystals for Enabling Photoreduction Activity.

In recent years, colloidal lead halide perovskite (LHP) nanocrystals (NCs) have exhibited such intriguing light absorption properties to be contemplated as promising candidates for photocatalytic conversions. However, for effective photocatalysis, the light harvesting system needs to be stable under the reaction conditions propaedeutic to a specific transformation. Unlike photoinduced oxidative reaction pathways, photoreductions with LHP NCs are challenging due to their scarce compatibility with common hole scavengers like amines and alcohols. In this contribution, it is investigated the potential of CsPbBr3 NCs protected by a suitably engineered bidentate ligand for the photoreduction of quinone species. Using an in situ approach for the construction of the passivating agent and a halide excess environment, quantum-confined nanocubes (average edge length = 6.0 ± 0.8 nm) are obtained with a low ligand density (1.73 ligand/nm2) at the NC surface. The bifunctional adhesion of the engineered ligand boosts the colloidal stability of the corresponding NCs, preserving their optical properties also in the presence of an amine excess. Despite their relatively short exciton lifetime (τAV = 3.7 ± 0.2 ns), these NCs show an efficient fluorescence quenching in the presence of the selected electron accepting quinones (1,4-naphthoquinone, 9,10-phenanthrenequinone, and 9,10-anthraquinone). All of these aspects demonstrate the suitability of the NCs for an efficient photoreduction of 1,4-naphthoquinone to 1,4-dihydroxynaphthalene in the presence of triethylamine as a hole scavenger. This chemical transformation is impracticable with conventionally passivated LHP NCs, thereby highlighting the potential of the surface functionalization in this class of nanomaterials for exploring new photoinduced reactivities.

Isobutyramide Additive to Improve the Performance of CsPbBr3 Perovskite Solar Cells Prepared by Green Solvent

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.

P-Thiocresol Functionalized Cesium Lead Bromide (PTC@CsPbBr3): A Fluorometric Sensing Probe for the Detection of Cholesterol.

Inorganic halide-based perovskites (e.g., cesium lead bromide) are tremendously useful semiconducting materials due to their unique optoelectronic properties. However, degradation of these perovskites under humid conditions is one of the major drawbacks to prevent their wide applications. Herein, passivated cesium lead bromide nanoparticles are synthesized using p-thiocresol as a passivating ligand, and this stable version of perovskite is later applied successfully as a sensor probe towards cholesterol detection. The designed sensor can detect cholesterol with a lower detection limit of 0.24 ppm and a fast response time of 10 s. The mechanism of quenching PTC@CsPbBr3 upon the gradual addition of cholesterol is discussed. Further, the sensor is successfully applied in the detection of cholesterol in real samples (blood serum). This work presents PTC@CsPbBr3 as a novel sensing platform for detecting cholesterol well in biomedical applications.

Quantum‐Defect‐Minimized, Three‐Photon‐Pumped Ultralow‐Threshold Perovskite Excitonic Lasing

AbstractThree‐photon‐pumped (3PP) excitonic lasing in inorganic semiconductor quantum dots (QDs) is of particular importance for near‐infrared biophotonics and optical communications. However, the implementation of such lasers has been hindered severely by the required high pump thresholds. Here, 3PP excitonic lasing of all‐inorganic cesium lead bromide perovskite QDs (CsPbBr3 PQDs) embedded in a whispering‐gallery microcavity is demonstrated, and achieving a record low threshold of 3 mJ cm−2 by tuning the 3P pump energy in resonance with the S exciton state. Wavelength‐dispersive Z‐scan spectroscopy reveals that such reduced lasing threshold is attributed to the exciton resonance enhanced multiphoton absorption, which, as disclosed by the kinetics analysis of transient absorption spectroscopy (TAS), leads to the appearance of net gain at a pump fluence as low as 2.2 mJ cm−2, corresponding to an average S exciton population of 1.5. A microscopic model incorporating the quantum master equation reproduces the TAS results and provides the intrinsic parameters of biexciton relaxation for lasing. The 3PP resonant excitonic transition is the most favored multiphoton pumping process that minimizes quantum defect (6.8% of the pump photon energy) to realize optical gain at low threshold, marking a major step toward using all‐inorganic perovskite QDs for on‐chip integrated microlasers and multiphoton bioimaging.

Improved photoluminescence stability and defect passivation in SbBr3 post-treated CsPbBr3 quantum dots under ambient conditions.

Inorganic cesium lead halide perovskites have evoked wide popularity because of their excellent optoelectronic properties, high photoluminescence (PL) quantum yield (PLQY), and narrowband emission. Here, cesium lead bromide (CsPbBr3 ) quantum dots (QDs) were synthesized via the ligand-assisted re-precipitation method. Post-synthesis treatment of CsPbBr3 QDs using antimony tribromide improved the PL stability and optoelectronic properties of the QDs. In addition, the PLQY of the post-treated sample was enhanced to 91% via post-treatment, and the luminescence observed was maintained for 8 days. The post-synthesis treatment ensured defect passivation and improved the stability of CsPbBr3 perovskite QDs. High-resolution transmission electron microscopy revealed the presence of more ordered, uniform-sized CsPbBr3 QDs after post-synthesis treatment, and the uniformity of the sample improved as the day passed. The formation of a mixed crystal phase was observed from X-ray diffraction in both as-synthesized, as well as post-treated QDs samples with the possibility of a polycrystalline nature in the post-treated CsPbBr3 QDs as per the selected area electron diffraction pattern. The X-ray photoelectron spectroscopy spectra confirmed the presence of antimony and the possibility of defect passivation in the post-treated samples. These QDs can act as potential candidates in various optoelectronic applications such as photodetectors and light-emitting diodes due to their high PLQY and longer lifetime.

Structure and Charge Carrier Separation Promotion Effects of Antiphase Boundaries in Cesium Lead Bromide.

Defects in lead halide perovskites (LHPs) may have a significant impact on charge carrier separation, but the roles of the defects are not fully understood. Here, using aberration-corrected scanning transmission electron microscopy (STEM), different types of antiphase boundaries (APBs) are discovered in CsPbBr3 platelets. APBs with a displacement vector of 1/4[111] are characterized by double layers of CsBr layers at the (110) or (001) planes, while APBs at the (112) planes are formed through edge sharing of PbBr6 ̵octahedra. Significant lattice distortions are determined at (001) and (110) APBs on the basis of quantitative analyses of STEM images. Density functional theory calculations demonstrate that all three types of APBs can induce band offsets at their valence bands and conduction bands. The APBs are intended to promote the separation of photogenerated charge carriers in LHPs. These findings provide a crystal engineering technique for enhancing the optoelectronic properties of LHPs by controlling defects.

Insight into the Interaction between Perovskite and Water via In Situ PL Measurement

Contrary to widely held view that water induces negative effect on lead halide perovskites, publications on active role of water in photoluminescence (PL) and stability of perovskites have been emerged recently. Until now, comprehensively understanding the interaction between perovskite and water is absolutely necessary for its highly correlation with the practical application and remains a significant challenge. In this study, we utilize in situ PL measurement, ex situ transmission electron microscopy, UV–vis spectroscopy and X-ray photoelectron spectroscopy to track and reveal the interaction of perovskite with water. For the organic-inorganic lead bromide perovskite, water induces amorphization, degradation of MAPbBr3, as well as formation of PbBrOH. As-obtained MAPbBr3@PbBrOH composites exhibit high PL quantum yield (QY) of 41.8–57.0% and robust water stability for the protection from PbBrOH. For cesium lead bromide perovskite, water facilitates the phase transition from non-luminescent Cs4PbBr6 to luminescent CsPbBr3, and could also instigate the formation of PbBrOH. However, the water-induced Ostwald maturation of CsPbBr3 and structure defects brought by the phase transition ultimately lead to the production of large CsPbBr3 crystals or CsPbBr3@PbBrOH composites with ultralow PLQY. This work provides valuable insights into the interaction between perovskite and water, and holds important implications for comprehending the instability of lead halide perovskites.

Enhanced Cyan Photoluminescence and Stability of CsPbBr3 Quantum Dots Via Surface Engineering for White Light‐Emitting Diodes

AbstractThe emission of cyan light (470‐500 nm) plays a vital role in the visible light spectrum and is essential for applications such as lighting, displays, and optical communication. Inorganic cesium lead bromide perovskite quantum dots (CsPbBr3 PQDs) have made significant progress in the field of luminescence materials and devices, however, the lack of techniques to obtain highly emissive and stable cyan‐emitting CsPbBr3 PQDs has limited their device applications. Here, it is demonstrated that the complete surface passivation by treatment of didodecyldimethylammonium bromide (DDAB) and lead bromide, which can enhance the photoluminescence and stability of cyan emitting CsPbBr3 PQDs. In particular, the photoluminescence quantum yield of CsPbBr3 QDs can be greatly improved from 10.5% to 83.8%. Through an effective PMMA passivation, the obtained stable and bright CsPbBr3 PQDs composite films as the cyan color converters can effectively emit the cyan light to fill the “cyan gap” of white light‐emitting diode (WLED). The color rendering index value of such WLED is remarkably enhanced from 73.6 to 82.5. This study paves the way for the application of PQD color converters in the next generation of full‐visible‐spectrum WLED lighting.

Strong Light-Matter Coupling in Lead Halide Perovskite Quantum Dot Solids.

Strong coupling between lead halide perovskite materials and optical resonators enables both polaritonic control of the photophysical properties of these emerging semiconductors and the observation of fundamental physical phenomena. However, the difficulty in achieving optical-quality perovskite quantum dot (PQD) films showing well-defined excitonic transitions has prevented the study of strong light-matter coupling in these materials, central to the field of optoelectronics. Herein we demonstrate the formation at room temperature of multiple cavity exciton-polaritons in metallic resonators embedding highly transparent Cesium Lead Bromide quantum dot (CsPbBr3-QD) solids, revealed by a significant reconfiguration of the absorption and emission properties of the system. Our results indicate that the effects of biexciton interaction or large polaron formation, frequently invoked to explain the properties of PQDs, are seemingly absent or compensated by other more conspicuous effects in the CsPbBr3-QD optical cavity. We observe that strong coupling enables a significant reduction of the photoemission line width, as well as the ultrafast modulation of the optical absorption, controllable by means of the excitation fluence. We find that the interplay of the polariton states with the large dark state reservoir plays a decisive role in determining the dynamics of the emission and transient absorption properties of the hybridized light-quantum dot solid system. Our results should serve as the basis for future investigations of PQD solids as polaritonic materials.

Some physical properties of K2TlAsX6 (X = Cl, Br) and CsPbBr3 semiconducting compounds

Some physical properties of K2TlAsX6 (X = Cl, Br) double perovskite compounds have been predicted using the theoretical unit cell parameters and elastic constants computed by Munir et al. (Materials Science and Engineering B 298 (2023) 116830). At equilibrium the Debye temperatures of K2TlAsCl6 and K2TlAsBr6 materials were found to be 193.5 K and 159.6 K, respectively. Furthermore, the mass density, the longitudinal, transverse and mean acoustic wave speeds, the acoustic impedance and the Debye temperature of Cesium Lead Bromide (CsPbBr3) inorganic perovskite compound under high stress up to 15 GPa have been predicted using the theoretical unit cell parameters and elastic constants computed by Junaid Zaidi et al. (Materials Research Express, Vol. 9, No. 12, (2022) 125501). To the best of our knowledge, there is no any data in the literature that can be compared to the findings we’ve achieved on the Debye temperature of K2TlAsX6 (X = Cl, Br) and CsPbBr3 materials.

Photoluminescence and photovoltaic properties of cesium lead bromide nanocrystals with linoleic acid ligand

Cesium lead bromide (CsPbBr3) nanocrystals (NCs) were synthesized using the ligand-assisted reprecipitation (LARP) method, with linoleic acid (LA) and oleylamine (OlAm) as ligands. The crystal structures of the samples depend on the ligand used in the synthesis. Sample-1, with LA-OlAm as the ligand, showed an orthorhombic crystal structure, whereas Sample-2, with OlAm only, showed a tetragonal crystal structure. These samples exhibited slightly different photoluminescence (PL) characteristics, where the PL peak of Sample-1 appeared at 521.4 nm, whereas the PL peak of Sample-2 appeared at 524.1 nm. Sample-1 showed brighter PL than that of Sample-2. These differences are strongly related to their crystal structures and degree of crystallization, which is also evident from the differences in the chemical states of the Br and Pb ions on the NCs surface, as depicted by the X-Ray Photoelectron Spectroscopy (XPS) spectra. In addition, despite exhibiting PL characteristics, these CsPbBr3 NCs also exhibit photovoltaic properties.