Perovskite Nanocrystals Research Articles

Ligand-assisted reprecipitation synthesis of highly luminescent and stable CsPbBr3@SiO2 nanoparticles with formation kinetics analysis

Cesium lead bromide (CsPbBr3) perovskite nanocrystals are becoming a popular alternative to chalcogenide quantum dots because of their bright green fluorescence and high color purity. However, owing to the poor stability caused by their highly ionic nature and the dynamic binding of long-chain capping ligands, their practical applications are limited. Although (3-aminopropyl)triethoxysilane (APTES) is a frequently used insulating material for wrapping CsPbBr3nanocrystals, it often causes surface etching. To address this issue, we introduced oleic acid into the anti-solvent toluene to inhibit the etching effect of APTES using a modified room-temperature ligand-assisted reprecipitation process. We utilized in situ time-dependent photoluminescence measurements to study the formation kinetics of CsPbBr3nanocrystals and determine the optimal ligands ratio. This innovative approach enables precise control over CsPbBr3@SiO2nanoparticles synthesis, yielding uniformly shaped nanocrystals with a silica shell, a consistent size around 10.17 ± 1.6 nm, and enhanced photoluminescence quantum yields ranging from 90% and 100%. The photoluminescence lifetimes of our CsPbBr3@SiO2nanoparticles were significantly prolonged owing to a reduction in non-radiative recombination. This boosts their stability in thermal and polar solvent environments, making them superior candidates for use in photonic devices.

Continuous-flow synthesis of CsPbI3/TiO2 nanocomposites with enhanced water and thermal stability.

The inherent poor stability of CsPbI3 nanocrystals hinders the practical application of this material. Therefore, it is still a challenge to improve the stability of CsPbI3 nanocrystals and realize their large-scale continuous preparation. In this work, we report the preparation of CsPbI3/TiO2 nanocomposites with high stability by a microfluidic method. After the combination of CsPbI3 nanorods with TiO2, the PL intensity increased by 1.3 times under excitation at 577 nm due to the passivating effect of TiO2 on the surface of CsPbI3 nanorods and its carrier transport characteristics. Meanwhile, due to the coating of TiO2, the surface exposure area of CsPbI3 nanorods is reduced, which blocks external environmental effects to some extent and effectively improves the stability of CsPbI3 nanorods. Finally, an LED with a color gamut of 142% NTSC and a color temperature (CCT) of 3952 K was obtained by combining CsPbI1.5Br1.5/TiO2 and CsPbBr3/TiO2 nanocomposites with a blue light chip (455 nm). This study shows that the continuous and controllable synthesis of all inorganic halide perovskite nanocrystals by a microfluidic method is of great significance in the fabrication of high-performance optoelectronic materials and display devices.

Pseudohalide Anion Passivation for Aqueous‐Stable Pure Red Perovskite Nanocrystals

AbstractRecently emerging perovskite nanocrystals (PNCs) have drawn considerable attention due to the superior optoelectronic performances. However, the terrible stability of red emissive PNCs (r‐PNCs) limits their broader application in aqueous media. Despite various encapsulation methods are proposed, the preparation of aqueous r‐PNCs with facile operation and excellent durability is still challenging. Herein, aqueous green emissive PNCs (g‐PNCs) by employing water as an external stimulus to treat oleyamine‐capped CsPbBr3 PNCs are synthesized initially, and then aqueous‐stable pure red emissive PNCs by anion‐exchange reaction and subsequently thiocyanate (SCN‐) passivation treatment (SCN‐r‐PNCs) are prepared. The obtained aqueous‐stable SCN‐r‐PNCs display high brightness, outstanding stability, and extended photoluminescence lifetime. Moreover, by combining aqueous r‐PNCs and portable smartphones, a fluorescence chemosensor for the detection of aqueous SCN− ions is constructed, which exhibits simple operation, high sensitivity, high selectivity, low detection limit, and visualized sensing. This work not only provides a new and facile strategy to prepare aqueous‐stable red emissive PNCs, but also further extends the application of red emissive PNCs in aqueous‐based fields.

Continuous nanomanufacturing of Mn2+-doped inorganic lead halide nanocrystals with high-concentration precursors

Microscale flow synthesis is a prominent large-scale method for producing inorganic perovskite nanocrystals (NCs), yet its application in one-pot synthesis of Mn-doped NCs is rare. Here, an optimized microscale flow method is used to prepare Mn2+-doped CsPb(Cl/Br)3 NCs by increasing the cesium precursor concentration to 25 mmol/L to improve the synthesis efficiency. The photoluminescence quantum yield of Mn2+ ions emission exhibits an enhancement with reaction temperature, reaching 39 % at 200 °C. Additionally, high-concentration precursors favor obtaining superior photoluminescence properties at a higher reaction temperature. There is a disparity in the shape of the NCs obtained at 100 and 200 °C, presumably due to the existence of extra rhombohedral phase. The molar ratio of Mn-to-Pb influences the emission characteristics of these NCs, with an optimal value of 3:1 under the above two reaction temperatures. These Mn2+-doped NCs possess promising applications in LEDs and anti-counterfeiting patterns, and the Mn2+ ions emission has remarkable resistance when exposed to oxygen. Furthermore, these NCs may also serve as probes for higher temperatures (>80 °C).

(Keynote) Engineering Lead Halide Perovskite Nanocrystals for Fast Single-Particle and Collective Light Emission

Colloidal lead halide perovskite (LHP) nanocrystals (NCs), with bright and spectrally narrow photoluminescence (PL) tunable over the entire visible spectral range, are of immense interest as classical and quantum light sources. Fast (bright) and pure single-photon emission is key for many quantum technologies, from optical quantum computing to quantum key distribution and quantum imaging.The brightness of an emitter is ultimately described by Fermi’s golden rule, with a radiative rate proportional to its oscillator strength (intrinsic emitter property) times the local density of photonic states (photonic engineering, i.e. cavity). With perovskite NCs, we present a record-low sub-100 ps radiative decay time for CsPb(Br/Cl)3, almost as short as the reported exciton coherence time, by the NC size increase to 30 nm. The characteristic dependence of radiative rates on QD size, composition, and temperature suggests the formation of giant transition dipoles, as confirmed by effective-mass calculations for the case of the giant oscillator strength. Importantly, the fast radiative rate is achieved along with the single-photon emission despite the NC size being ten times larger than the exciton Bohr radius. NC self-assembly is a versatile platform for materials engineering, particularly for attaining collective phenomena with perovskite NCs, such as superfluorescence in perovskite NC superlattices. Thus far, LHP NCs have been co-assembled with building blocks that acted solely as spacers to promote the tuning of the mutual arrangement of LHP nanocubes [2]. However, the functionality of the second SL component can give rise to the enhancement of the LHP NCs properties or the emergence of new collective effects. We present the formation of multicomponent SLs made from the CsPbBr3 NCs of two different sizes. The diversity of obtained SLs encompassed the binary ABO6-, ABO3-, and NaCl-type structures, all of which contained orientationally and positionally confined NCs. For the selected model system, the ABO6-type SL, we observed efficient NC coupling and Förster-like energy transfer from strongly confined 5.3 nm CsPbBr3 NCs to weakly confined 17.6 nm CsPbBr3 NCs. Exciton spatiotemporal dynamics measurements reveal that binary SLs exhibit enhanced exciton diffusivity compared to one-component SLs across the entire temperature range (from 5 K to 298 K). Observed incoherent NC coupling and controllable excitonic transport within the solid NC SLs hold promise for potential applications in optoelectronic devices.[1]C. Zhu, S. C. Boehme, L. G. Feld, A. Moskalenko, D. N. Dirin, R. F. Mahrt, T. Stöferle, M. I. Bodnarchuk, A. L. Efros, P. C. Sercel, M. V. Kovalenko, G. Rainò. In review.[2] Ihor Cherniukh et al. Nature, 2021, 593, 535–542. [3] T. Sekh et al. Submitted

(Invited) A Polaron Paradigm for Perovskite Nanocrystal Emitting States

Perovskite NCs such as CsPbBr3 have numerous uses. Most involve exploiting their light emission and are motivated by their defect tolerance and large, as-made emission quantum yields. Absent, though, is a fundamental understanding of perovskite NC emitting states, central to these applications. Of particular note are observations of near-universal, size-, temperature-, and composition-dependent absorption/emission Stokes shifts where observed energy differences are between absorbing and emitting states.Very little is known about the origin of these shifts. Moreover, little is known about the exact identity of the emitting state. This is to be contrasted to more conventional NCs such as CdSe where band edge exciton fine structure quantitatively accounts for both global and resonant Stokes shifts, with emission emerging from a dark exciton. Although similar perovskite NC fine structure might account for their shifts, both theory and experiment predict bright/dark fine structure splittings easily an order of magnitude too small to account for experiment.We now propose that perovskite NC emitting states are polarons, which result from the lattice accommodation of photogenerated charges. Polaron binding energies and lifetimes are, in turn, suggested to be the origin of observed size-, temperature-, and composition-dependent absorption/emission Stokes shifts and excited state lifetimes. This represents a significant departure from more conventional descriptions of NC band edge states, which exclusively involve exciton fine structure and dark exciton emitting states.

(Invited) Exploring and Manipulating Luminescence Centers in Lead Halide Perovskites through Hydrostatic Pressure

The application of hydrostatic pressure to materials induces changes in lattice constants, vibrational spectra, and electron-phonon interactions, thereby altering the optoelectronic properties of semiconductors. Consequently, hydrostatic pressure has become a widely utilized tool for investigating and enhancing the optical properties of organic/inorganic halide perovskites and their nanostructures. In this presentation, I will discuss the impact of hydrostatic pressure on two distinct types of luminescence centers in perovskite materials. The first type of luminescence centers originates from excitons within perovskite nanocrystals. I will discuss how hydrostatic pressure serves as a valuable tool for elucidating the origin of luminescence in low-dimensional perovskites, including 2D CsPb2Br5, 0D Cs4PbBr6, and 2D Ruddlesden-Popper Hybrid Perovskite Crystals. The second type of luminescence centers exhibit broadband optical emission from self-trapped excitons in low-dimensional perovskites. I will present our findings on the observation of strong exciton-phonon coupling and demonstrate how hydrostatic pressure can be employed to modulate electron-phonon coupling, offering a means to finely tune the broad emission spectrum.

Solution Processable Carbon Nanotube-Perovskite Nanohybrids

Carbon nanotubes (CNTs) based nanohybrids have attracted considerable interest for their potential in the design of innovative low-dimensional heterostructures. These nanohybrids can offer unique properties, including enhanced electronic transport and tunability, with a diverse range of optoelectronic applications.Here we present a novel approach for the synthesis of solution-processable nanohybrids made of single-walled carbon nanotubes (SWCNTs) and methylammonium-lead-iodide (MAPI) perovskites, where the CNTs act as templates for the facile and tuneable formation of anisotropic perovskite nanocrystals.We will present the structural characterization and electronic properties of the developed CNT-perovskite nanohybrids and demonstrate their integration (from solution) in field-effect transistor device configurations. By harnessing the synergistic properties of carbon nanotubes and perovskite nanocrystals, we will discuss pathways for the development of photoresponsive devices displaying sensitivity to a broad range of illumination wavelengths.The strategy presented here is of general applicability for the templated synthesis of perovskite nanocrystals toward the fabrication of solution processable in nanoscale optoelectronic devices.

(Invited) Dynamics of Photoluminescence in Mn-Doped Pb-Halide Perovskite Nanocrystals

Nanocrystals of lead halide perovskites have been shown to have extraordinary photoluminescence properties, spanning the entire visible range achieved by the composition tuning via solid solutions at the halide site. Taking cues from Mn doping of traditional Group II-VI semiconductor quantum dots, Mn doping of the lead halide perovskites has been extensively explored by the community, establishing intense Mn-dopant induced emission that is significantly Stokes shifted from the excitonic emissions of the host. While all reports agree on the essential features of this emission, such as the peak position and the width of the Mn photoluminescence, there appears to be little agreement on the microscopic processes by which the host sensitizes Mn following its photoexcitation and the steps that control the deexcitation leading to the Mn emission. There are even reports of disagreement between different reports on the temperature dependence of the Mn emission and its origin. I shall discuss the present status of this field and establish, with the help of new experimental data as well as the already reported ones, what appears to be the microscopic processes controlling the excited dynamics in the Mn-doped lead halide perovskites.

(Invited) Designing Photocatalytic Membrane to Direct Electron and Hole Transport

Surface interaction of chromophore or redox active molecule which dictate the efficiency of energy/electron transfer, plays an important role in realizing photocatalytic and optoelectronic applications. Metal halide perovskite nanocrystals are interesting in the sense that they can either transfer energy or selectively transfer electrons or holes to the adsorbed molecules.1,2 The presentation will focus on two specific scenarios of the flow of energy and electron processes in CsPbX3 (X= Br, I) nanocrystal-molecular hybrids. The energy transfer is probed through three moleculr acceptors – rhodamine B (RhB), rhodamine isothiocyanate (RhB-NCS), and rose Bengal (RoseB), which contain an increasing degree of heavy atom pendant groups. Electron and/or hole transfer from excited CsPbX3 nanocrystals to a molecular relay present near the interface offers another avenue to directly convert light energy into chemical energy. Such interfacial electron transfer of semiconductor nanocrystals has been widely explored in photocatalytic processes. A basic understanding of the fundamental differences between the two excited deactivation processes (energy and charge transfer) and ways to modulate them should enable design of more efficient light harvesting assemblies with semiconductor and molecular systems.

Chirality of CsPbBr3 Nanocrystals with Varying Dimensions in the Presence of Chiral Molecules.

Chiral lead halide perovskite (LHP) nanocrystals (NCs) have been attracting considerable interest for circularly polarized luminescence (CPL)-based optoelectronic applications. This study combined experimental and computational analyses to investigate how the dimensionality of 3D (cubic) to 0D (quantum dots) influences the tunable chiral emission of CsPbBr3 LHP NCs. The circular dichroism (CD) spectra have a significant blue shift from 508 to 406 nm. The dissymmetry factors for CD (gCD) change from ±2.5 × 10-3 to ±7.5 × 10-3 as dimensionality varies from 3D to 0D in the presence of the chiral molecule (cyclohexylethylamine, CHEA). A significant luminescence dissymmetry factor (glum) of ±5.6 × 10-4 is observed in the 0D CsPbBr3 NCs. Theoretical calculations using structural distortion parameters, the extent of charge transfer, and electrostatic potential profiles have revealed that the most significant enhancement of the chirality transfer occurs from the CHEA molecules to 0D NCs, and the order of chirality transfer from CHEA to CsPbBr3 NCs is 0D (quantum dots) > 2D (nanoplatelet) > 3D (cubic).

Deep Blue CsPbBr3 Quantum Wires with Tailored Shapes.

Low-dimension metal halide perovskites are attractive for bandgap tunable optoelectronic materials. Among them, 1-D CsPbBr3 quantum wires (QWs) are emerging as promising deep-blue luminescent material. However, the growth dynamics of 1-D perovskite QWs are intricate, making the study and control of 1-D QWs highly challenging. In this study, a strategy for controlling both the length and width of the CsPbBr3 QWs was realized. The temperature-dependent isotropic growth mechanism was revealed and employed as the main tool for the oriented growth of 1-D CsPbBr3 QWs for various aspect ratios. Our results pave the way for the controlled synthesis of ultrasmall perovskite nanocrystals.

Surface Structure of Lecithin-Capped Cesium Lead Halide Perovskite Nanocrystals Using Solid-State and Dynamic Nuclear Polarization NMR Spectroscopy.

Inorganic colloidal cesium lead halide perovskite nanocrystals (NCs) encapsulated by surface capping ligands exhibit tremendous potential in optoelectronic applications, with their surface structure playing a pivotal role in enhancing their photophysical properties. Soy lecithin, a tightly binding zwitterionic surface-capping ligand, has recently facilitated the high-yield synthesis of stable ultraconcentrated and ultradilute colloids of CsPbX3 NCs, unlocking a myriad of potential device applications. However, the atomic-level understanding of the ligand-terminated surface structure remains uncertain. Herein, we use a versatile solid-state nuclear magnetic resonance (NMR) spectroscopic approach, in combination with dynamic nuclear polarization (DNP) and atomistic molecular dynamics (MD) simulations, to explore the effect of lecithin on the core-to-surface structures of CsPbX3 (X = Cl or Br) perovskites, sized from micron to nanoscale. Surface-selective (cross-polarization, CP) solid-state and DNP NMR (133Cs and 207Pb) methods were used to differentiate the unique surface and core chemical environments, while the head-groups {trimethylammonium [-N(CH3)3+] and phosphate (-PO4-)} of lecithin were assigned via 1H, 13C, and 31P NMR spectroscopy. A direct approach to determining the surface structure by capitalizing on the unique heteronuclear dipolar couplings between the lecithin ligand (1H and 31P) and the surface of the CsPbCl3 NCs (133Cs and 207Pb) is demonstrated. The 1H-133Cs heteronuclear correlation (HETCOR) DNP NMR indicates an abundance of Cs on the NC surface and an intimate proximity of the -N(CH3)3+ groups to the surface and subsurface 133Cs atoms, supported by 1H{133Cs} rotational-echo double-resonance (REDOR) NMR spectroscopy. Moreover, the 1H-31P{207Pb} CP REDOR dephasing curve provides average internuclear distance information that allows assessment of -PO4- groups binding to the subsurface Pb atoms. Atomistic MD simulations of ligand-capped CsPbCl3 surfaces aid in the interpretation of this information and suggest that ligand -N(CH3)3+ and -PO4- head-groups substitute Cs+ and Cl- ions, respectively, at the CsCl-terminated surface of the NCs. These detailed atomistic insights into surface structures can further guide the engineering of various relevant surface-capping zwitterionic ligands for diverse metal halide perovskite NCs.

Synthesis and characterization of novel double perovskite K2AgBiBr6

Over the past few years, Lead-free halide double perovskites have attracted a tremendous attention such that it is demonstrated by the power conversion efficiency's sharp increase of over 25 %. It has also stimulated a widespread application of halide metal perovskites in other fields, such as light-emitting diodes, field-effect transistors, detectors, and lasers. Double perovskites have been put forth as an alternative to hybrid lead halide perovskites in the last decade because of their efficiency in doing away with the existing toxicity and instability. It is probably the first attempt, to date, that lead-free halide double perovskite K2AgBiBr6 has been made with a cheap, easy-to-use solution-state reaction method. To determine their structure, single crystal X-ray diffraction and PXRD analysis have been employed. The synthesized K2AgBiBr6 adopts the cubic structure with Fm‾3m symmetry and lattice parameters of a = 6.606 (9) Å at room temperature, according to the diffraction result. Energy dispersive X-ray spectroscopy (EDX), elemental mapping, and scanning electron microscopy (SEM) have all been employed to analyze the morphology and elemental composition. Elements including K, Bi, Ag, and Br have been confirmed to be present in the synthesized sample by the EDX technique. For K2AgBiBr6, the 2.859 eV (indirect) and 3.076 eV (direct) bandgaps have been estimated by employing the UV–Vis absorption spectra. Furthermore, the K2AgBiBr6 double perovskite nanocrystal's thermogravimetric analysis/differential thermal and differential scanning analysis (TG/DTA and DSC) curves at 20–800 °C have been measured. An analysis has been conducted on the mechanism of thermal decomposition of synthesized double perovskite. This work demonstrates great promise for future band gap engineering-based photovoltaic and other optoelectronic applications, and it offers a novel path to obtaining premium K2AgBiBr6 double perovskite.

Evolution of perovskite nanocrystals in hot injection process with various ligand-rich systems

Evolution of perovskite nanocrystals in hot injection process with various ligand-rich systems

Enhancing exciton-to-Mn2+ energy transfer and emission efficiency in Mn2+-doped CsPbCl3 perovskite nanocrystals via CaCl2 post-treatment

Mn2+-doped CsPbCl3 perovskite nanocrystals (NCs) exhibit a significant Stokes shift and emit bright orange-red light, making them promising candidates for optoelectronic devices. However, these NCs are prone to surface defects during multiple purification steps, which hinder the transfer of energy from excitons to Mn2+ and reduce luminescence efficiency. Herein, we introduce a post-treatment method using a CaCl2 ethanol solution to passivate surface defects in Mn2+-doped CsPbCl3 NCs. This treatment enhances the energy transfer from excitons to Mn2+ and boosts luminescence performance, achieving a photoluminescence quantum yield of up to 96 % and maintaining stability through several washing cycles. In this process, Ca2+ ions, as a Lewis acid, replace oleic acid molecules on NC surfaces, leading to stronger binding. The Cl− from the CaCl2 solution fill vacancies on NC surfaces, effectively passivating surface defects. This reduces non-radiative recombination centers, increases energy transfer efficiency from 83 % to 87 %, and accelerates the radiative recombination rates of excitons and Mn2+. The post-treated NCs also retain their PL against continuous heat and ultraviolet irradiation. The passivation of surface defects on perovskite NCs achieved through this post-processing strategy enhances the energy transfer from excitons to doped ions, providing guidance for achieving efficient and stable doped perovskite NCs.

Impedance dynamics in tandem solar cells based on c-Si with upper layers of CsPbBr3 (CsPbI3) perovskite nanocrystals

The application of an additional nanoparticle layer is a common practice for enhancing the optical and electrical properties of third-generation solar cells. In this study, we present the results of impedance spectroscopy (IS) for modified solar cells using Nyquist and Bode diagrams. The structure investigated consists of a conventional double junction based on crystalline silicon (c-Si) coated with thin films of inorganic perovskite nanocrystals (NC) of lead halides CsPbI3 and CsPbBr3. The latter are characterized by a significant phonon disorder, which leads to unique electron-phonon interactions and dielectric responses. The IS results indicate that, under the same conditions, the measured Nyquist plots align well with the simulated ones. An equivalent circuit model is proposed, featuring ohmic resistance, recombination resistance, and geometric capacitance. These elements arise due to charge accumulation, charge transfer resistance, and/or additional interfacial electronic states. The study finds that the introduction of a CsPbI3 layer enhances the photoresponse under bias conditions, but this photoresponse leads to a decrease in DC conductivity. In contrast, the addition of a CsPbBr3 layer obstructs the photoresponse under bias while slightly improving the photoresponse in the absence of an applied voltage. The results obtained contribute to the improvement of tandem solar cell characteristics featuring top layers of perovskite nanocrystals.

Thermal management towards ultra-bright and stable perovskite nanocrystal-based pure red light-emitting diodes

Despite the promising candidacy of perovskite nanocrystals for light-emitting diodes, their pure red electroluminescence is hindered by low saturated luminance, severe external quantum efficiency roll-off, and inferior operational stability. Here, we report ultra-bright and stable pure red light-emitting diodes by manipulating Joule heat generation in the nanocrystal emissive layer and thermal management within the device. Diphenylphosphoryl azide-mediated regulation of the nanocrystal surface synergistically enhances the optical properties and carrier transport of the emissive layer, enabling reduced Joule heat generation and thus lowering the working temperature. These merits inhibit ion migration of the CsPb(Br/I)3 nanocrystal film, promising excellent spectra stability. Combined with the highly thermal-conductive sapphire substrates and implementation of pulse-driving mode, the pure red light-emitting diodes exhibit an ultra-bright luminance of 390,000 cd m−2, a peak external quantum efficiency of 25%, suppressed efficiency roll-off, an operational half-life of 20 hours, and superior spectral stability within 15 A cm−2.

Exploring the Effects of Structural and Surface Modifications of Lead Halide Perovskite Nanocrystals on Photocatalytic CO2 Reduction: A Holistic Perspective

Exploring the Effects of Structural and Surface Modifications of Lead Halide Perovskite Nanocrystals on Photocatalytic CO₂ Reduction: A Holistic Perspective

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.