A manganese-doped chloro-lead perovskite hetero luminescent material, a preparation method and application thereof

Abstract

The application discloses a manganese-doped chloro-lead perovskite hetero luminescent material, a preparation method and application thereof, and belongs to the technical field of semiconductor photoelectric functional materials. In the application, oleic acid and oleylamine are used as ligand solutions, PbCl2, a cesium oleate solution and a manganese source are subjected to a solvothermal reaction, and the synergistic regulation and control effect of the Mn source on the nucleation, growth and surface structure evolution of Cs4PbCl6 under the solvothermal condition is utilized, so that a small amount of CsPbCl3 shell layer is in-situ induced to form on the surface layer of the Cs4PbCl6 particle while the main structure of the Cs4PbCl6 is maintained, and finally, the core-shell composite structure of the manganese-doped chloro-lead perovskite hetero luminescent material is constructed. The Cs4PbCl6 inner core, the CsPbCl3 shell layer and the Mn 2+ luminescent center are organically coupled, and the host luminescence, interface luminescence and Mn 2+ characteristic luminescence and other multiple radiation output channels are constructed in the same system.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic functional materials technology, and more specifically to a manganese-doped lead chloride perovskite heteroluminescent material, its preparation method, and its application. Background Technology

[0002] With the continuous development of the new generation of information technology industry, fields such as information display, semiconductor lighting, photoelectric detection, optical information recognition, and wavelength conversion have placed higher demands on high-performance optoelectronic functional materials. In particular, achieving multicolor synergistic luminescence under ultraviolet or short-wavelength excitation conditions, improving energy utilization efficiency, and achieving low-cost solution-based preparation have become important development directions for novel optoelectronic information materials. Perovskite luminescent materials, due to their advantages of tunable bandgap, high luminous efficiency, and relatively simple preparation process, show promising application prospects in optoelectronic displays and optical function conversion.

[0003] In existing perovskite systems, the zero-dimensional halide perovskite Cs4PbCl6 exhibits isolated [PbCl6] structures. 4- The octahedral structure of Cs4PbCl6 allows for the localization of charge carriers, leading to the formation of self-bound excitons and resulting in a large Stokes shift and a wide emission band. Cs4PbCl6-related systems have potential applications in light-emitting devices, photoelectric detection, and information displays. However, their intrinsic luminescence efficiency is limited, and their luminescence behavior is significantly influenced by local lattice relaxation, electron-phonon coupling, and the interface environment. Consequently, the single Cs4PbCl6 system still has limitations in terms of the number of luminescence channels, controllability of energy distribution, and spectral modulation capabilities.

[0004] To improve the luminescence properties of zero-dimensional perovskites and expand their applications in optoelectronic materials, current research typically employs methods that introduce luminescent centers during fabrication. For example, introducing Mn... 2+ Transition metal ions, acting as luminescent centers, emit orange-red light through host sensitization; however, single-phase Mn... 2+ The energy transfer pathways in doped perovskite systems are relatively limited, with host excitons moving towards Mn. 2+ The transfer efficiency is limited by the doping concentration and the local coordination environment, and it is often difficult to simultaneously achieve multicolor output and high-efficiency energy utilization.

[0005] Researchers have proposed a method for "preparation and luminescence mechanism of Mn-doped CsPbCl3 / Cs4PbCl6 composite materials." This existing technology employs an ultrasonic method, using MnCl2, PbCl2, and CsCl as precursor materials. The precursor materials and DMF are ultrasonically treated at room temperature to ensure complete reaction of the precursor materials. The resulting Mn-doped CsPbCl3 / Cs4PbCl6 composite material uses a composite of Cs4PbCl6 and CsPbCl3 as the matrix, with Mn... 2+The doping is mainly present in the CsPbCl3 phase of the matrix. However, in the composite materials prepared by the above-mentioned prior art, under ultrasonic conditions, the reaction tends to preferentially generate CsPbCl3 and gradually transform into Cs4PbCl6. This method makes it difficult to precisely control the ratio and distribution of the two phases, Cs4PbCl6 and CsPbCl3. Moreover, the crystal structures of Cs4PbCl6 and CsPbCl3 are significantly different, and the lattice matching degree at the interface between the two phases is poor, resulting in an increase in interface defect states and non-radiative recombination channels. Consequently, the prepared Mn-doped CsPbCl3 / Cs4PbCl6 composite materials have low energy transfer efficiency, chaotic competition among luminescent channels, unstable spectral output, and limited multi-channel luminescence performance. These problems restrict further improvement of multi-center synergistic luminescence performance, thus limiting the further application of related materials in novel displays, optical conversion, and optoelectronic information functional layers. Summary of the Invention

[0006] To address the above problems, this invention provides a manganese-doped lead chloride perovskite heteroluminescent material, its preparation method, and its applications. This invention uses oleic acid and oleylamine as ligand solutions, and involves a solvothermal reaction of PbCl2, cesium oleate solution, and a manganese source. During the solvothermal reaction, the manganese source not only acts as a source of Mn... 2+ The doped precursor actively promotes the evolution of the local structure from Cs4PbCl6 to CsPbCl3 on the particle surface by adjusting the coordination balance between metal and halogen, the competition between nucleation and growth, and the stability of the local surface structure, thereby forming a core-shell composite structure with Cs4PbCl6 as the core and CsPbCl3 as the shell. Meanwhile, Mn... 2+ It is dispersed in the Cs4PbCl6 core, CsPbCl3 shell, and / or core-shell interface transition region. This invention targets the Cs4PbCl6 core, CsPbCl3 shell, and Mn... 2+ The organic coupling of luminescent centers allows for the construction of host luminescent centers, interface-dependent luminescent centers, and Mn within the material. 2+ A multi-center coupled light-emitting structure with interaction of light-emitting centers.

[0007] The luminescence behavior of the manganese-doped lead chloride perovskite heteroluminescent material prepared in this invention is not dominated by a single center, but rather by the self-bound excitons of the Cs4PbCl6 core, the CsPbCl3 shell, and the Mn... 2+ A multi-level synergistic luminescence network is formed by the luminescent centers. The Cs4PbCl6 core is responsible for high-energy light absorption and initial excited-state energy storage, the CsPbCl3 shell serves as an intermediate energy receiving and redistribution unit, and Mn... 2+This serves as the final low-energy radiation center. Through this cascaded energy transfer mechanism driven by interface coupling, the manganese-doped lead chloride perovskite heteroluminescent material system exhibits multi-center, multi-channel synergistic luminescence characteristics that are significantly different from those of single-phase Mn-doped perovskites.

[0008] This invention provides a method for preparing a manganese-doped lead chloride perovskite heteroluminescent material, comprising the following steps: Using oleic acid and oleylamine as ligand solutions, PbCl2, cesium oleate solution, manganese source, and ligand solution were mixed to obtain a precursor solution. The precursor solution was then subjected to a solvothermal reaction at 160℃–170℃ to form a core with Cs4PbCl6 and Mn... 2 + Partial doping with Cs4PbCl6 was used to induce the formation of a CsPbCl3 shell or island-like interface layer on the core surface, resulting in a manganese-doped lead chloride perovskite heteroluminescent material. The molar amount of cesium ions in the oleic acid cesium solution was four times that of lead ions in PbCl2, and the molar ratio of manganese ions in the manganese source to lead ions in PbCl2 was 0.5–2:1. The volume ratio of PbCl2 to ligand solution was 1 mmol: 55 mL–66 mL, and the volume ratio of oleic acid to oleylamine was 1:10.

[0009] This invention adds the required raw materials according to the stoichiometric relationship of Cs4PbCl6. Taking cesium oleate and PbCl2 as examples, the molar amount of cesium ions in cesium oleate is approximately four times the molar amount of lead ions in PbCl2. Therefore, Cs4PbCl6 nanocrystals are preferentially formed in the initial stage of the reaction. Since MnCl2 is also present in the system, some Mn... 2+ In subsequent processes, it enters the Cs4PbCl6 lattice via isovalent substitution and occupies Pb. 2+ The presence of this PbCl2 site leads to a relative abundance of PbCl2 in the local area. Under cesium-rich conditions, the formation of Cs4PbCl6 is favored, while under lead-rich conditions, the formation of CsPbCl3 is favored. Therefore, this locally abundant PbCl2 will further induce a local phase transition on the already formed Cs4PbCl6 surface, generating a small amount of surface CsPbCl3 phase. Thus, the formation sequence should be: first, Cs4PbCl6 is formed, then Mn... 2+ The partial incorporation of Pb sites into Cs4PbCl6 introduces new luminescent centers to form Mn. 2+ Cs4PbCl6; simultaneously, it induces the in-situ formation of CsPbCl3 on the surface of Cs4PbCl6.

[0010] In this invention, the manganese source is one of the key parameters, as it affects not only Mn 2+ The degree of doping also affects subsequent surface phase transitions and interfacial strain formation. When the amount of manganese source is too small, Mn... 2+Insufficient doping leads to weak orange-red light emission. Furthermore, the limited surface phase transition induction results in insufficient shell strain, hindering the formation of a synergistic luminescence system with three luminescent centers. Excessive manganese source dosage, on the other hand, can easily cause excessive surface phase transitions, resulting in excessive CsPbCl3 phase formation and lattice distortion, increased defects, or concentration quenching, thereby affecting the product's structural stability and luminescence performance.

[0011] Therefore, the amount of manganese source used needs to be limited to ensure that Mn 2+ The luminescence performance is optimal within a reasonable range that allows for the formation of luminescent centers while inducing the construction of appropriate shell / interface structures. More preferably, the molar ratio of manganese ions in the manganese source to lead ions in PbCl2 is 2:1, resulting in the best luminescence performance.

[0012] Preferably, the solvothermal reaction time is 0.5 h to 2.5 h.

[0013] For the all-chlorine system involved in this invention and the formation mechanism of local component rebalancing caused by Mn doping, which further leads to surface phase transitions or surface reconstruction, MnCl2 is the preferred manganese source. This is because, on the one hand, MnCl2 can provide Mn... 2+ Achieve Pb 2+ The substitution of sites introduces Mn-related orange-red luminescent centers; on the other hand, MnCl2 simultaneously provides Cl... - This helps maintain the reaction environment of the chlorine system and participates in surface defect regulation, local chlorine-lead component balance, and surface structure reconstruction. Furthermore, MnCl2 can drive the conversion of Cs4PbCl6 to CsPbCl3 and simultaneously realize the conversion of Mn... 2+ Because of doping, MnCl2 is more advantageous than other manganese sources.

[0014] Preferably, the precursor solution is prepared by: using oleic acid and oleylamine as ligand solutions, mixing PbCl2, manganese source and ligand solutions evenly, and then adding cesium oleate solution to obtain the precursor solution.

[0015] It should be noted that in the preparation process of this invention, PbCl2, MnCl2, oleic acid and oleylamine are first mixed in the same system and then sonicated to fully disperse them to form a relatively homogeneous mixed solution; then cesium oleate solution is added and sonicated for about 5 minutes before proceeding to the subsequent reaction.

[0016] It is important to emphasize that the thorough dispersion and uniform mixing of PbCl2 and MnCl2 in the organic ligand system are beneficial for improving the homogeneity of the reaction system. Adding the cesium oleate solution after thorough mixing of the reaction system facilitates the initiation of Cs-Pb-Cl related nucleation and subsequent structural evolution in a relatively uniform reaction environment. Further sonication after adding the cesium oleate solution further enhances the system homogeneity, preventing localized concentration inhomogeneities from adversely affecting the phase composition and structural reproducibility of the product. Adding the cesium oleate solution too early, or reacting directly before the precursors are sufficiently dispersed, can easily lead to uneven local component distribution and unstable nucleation processes, thereby affecting the phase composition, heterostructure formation, and luminescence properties of the final product.

[0017] Preferably, the method for preparing cesium oleate solution is as follows: cesium carbonate, oleic acid and solvent are mixed and a neutralization reaction is carried out to obtain cesium oleate solution.

[0018] Preferably, the ratio of cesium carbonate, oleic acid, and solvent is 1 mmol: 2-3 mL: 16-20 mL, with octadecene as the solvent. In this invention, octadecene is primarily used as a high-boiling-point nonpolar solvent, and the resulting perovskite nanocrystals are also better suited to a nonpolar environment. Therefore, octadecene is beneficial for maintaining uniform dispersion, stable nucleation and growth, and the ligand state on the product surface. If other solvents are used, the conditions of nonpolarity, high boiling point, and chemical inertness cannot be simultaneously met, which may affect product preparation and luminescence properties.

[0019] Preferably, the neutralization reaction temperature is 150℃~160℃, and the neutralization reaction time is 1h~2h.

[0020] Preferably, the ratio of manganese source to ligand solution is 0.1 mmol: 2.5 mL to 11 mL; and the volume ratio of oleic acid to oleylamine is 1:10.

[0021] This invention provides a manganese-doped lead chloride perovskite heteroluminescent material prepared by the above-described method. The manganese-doped lead chloride perovskite heteroluminescent material has a Cs₄PbCl₆ core, with CsPbCl₃ forming a shell or island-like interface layer on the Cs₄PbCl₆ surface, and Mn... 2+ It is mainly distributed in the core, and also partially distributed in the shell and / or core-shell interface region, thus forming a multi-center coupled light-emitting structure.

[0022] The composite material contains a core Cs4PbCl6 self-bound exciton channel, a shell CsPbCl3 correlated luminescence channel, and Mn. 2+ The light-emitting channel allows for parallel transmission of core excitation energy via paths from the core to the shell, from the core to Mn, and from the shell to Mn.

[0023] The manganese-doped lead chloride perovskite heteroluminescent material has a Cs4PbCl6 core as the main body, with a relatively small amount of CsPbCl3 distributed on the outer surface of Cs4PbCl6, forming a continuous shell, local shell, and / or island-like interface layer structure; the Mn 2+ The CsPbCl6 core, CsPbCl3 shell, and / or core-shell interface transition region are dispersed. The material as a whole exhibits a core-shell / hetero-interface composite structure with CsPbCl6 as the main phase and CsPbCl3 heterophase locally constructed on the surface. The core retains the main structural features of zero-dimensional CsPbCl6, while the surface CsPbCl3 acts as an outer coating phase or local interface phase in close contact with the core, thereby constructing host luminescent centers, interface-associated luminescent centers, and Mn luminescent sites within the material. 2+ A multi-center coupled light-emitting structure with interaction of light-emitting centers.

[0024] This invention provides the application of the aforementioned manganese-doped lead chloride perovskite heteroluminescent material in the preparation of ultraviolet-excited luminescent materials, wavelength conversion materials, or optoelectronic display functional materials. Specifically, in use, the manganese-doped lead chloride perovskite heteroluminescent material can be composited with resins, polymers, silicone, epoxy encapsulants, or other transparent substrates as a luminescent functional component to form luminescent thin films, fluorescence conversion layers, luminescent coatings, or display functional layers, and then coated, encapsulated, or integrated into ultraviolet LED chips, backlight devices, display devices, or other optoelectronic devices. Under ultraviolet or near-ultraviolet light excitation, the material absorbs short-wavelength light and emits visible light, thereby realizing ultraviolet-excited luminescence, wavelength conversion, and display function output.

[0025] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes the synergistic regulatory effect of the oleic acid and oleylamine ligand system and the Mn source on the nucleation, growth, and surface structure evolution of Cs4PbCl6 under solvothermal conditions, enabling Mn... 2+ Doping and in-situ surface phase transition are coupled and completed in the same reaction system. Specifically, this invention controls the molar amount of cesium ions in the cesium oleate solution to be four times the molar amount of lead ions in PbCl2, and under the ligand environment of oleic acid and oleylamine and solvothermal conditions, Pb... 2+ Cs + Mn 2+ and Cl - First, a dynamic coordination equilibrium is established, preferentially nucleating and forming Cs4PbCl6 in the initial stage of the reaction, which constitutes the main crystalline phase of the final product. Simultaneously, in a high oleylamine ligand environment with an oleic acid to oleylamine volume ratio of 1:10, the strong coordination of oleylamine molecules on the nanocrystal surface moderately weakens the surface lattice stability, providing a favorable local chemical environment for subsequent surface structure evolution. As the solvothermal reaction proceeds, the manganese source not only serves as Mn... 2+The doping source simultaneously alters the local metal-halogen coordination environment on the surface of Cs4PbCl6 particles. A closed solvothermal environment of 160℃–170℃ provides high-temperature and high-pressure conditions, significantly promoting surface ion migration, local dissolution-recrystallization, and lattice rearrangement, causing preferential local phase reconstruction on the highly active Cs4PbCl6 surface layer. This results in the in-situ formation of a CsPbCl3 shell or island-like interface layer on the surface of the Cs4PbCl6 particles, ultimately constructing a core-shell composite structure of manganese-doped lead chloride perovskite heteroluminescent material. In this invention, the Cs4PbCl6 core and CsPbCl3 shell form effective interfacial coupling at the contact interface through in-situ phase transition, resulting in low interface defect state density and high energy transfer efficiency. Simultaneously, Mn... 2+ The distribution of Cs4PbCl6 in the core, shell, and interface regions is synchronous with the formation of heterogeneous structures. The CsPbCl3 core provides the host-related luminescence basis, while the CsPbCl3 shell or interface layer introduces additional luminescence and energy transition pathways. Mn 2+ It provides orange-red light emission; different luminescent centers achieve synergistic effects through energy transfer, interface coupling and local structure regulation, so that the excitation energy can be effectively distributed and output among multiple luminescent centers. The energy transfer path is clear and the spectral output is stable, thus solving the defects of existing manganese-doped perovskite luminescent material systems such as weak interface coupling, low energy transfer efficiency and limited multi-channel luminescence performance.

[0026] This invention combines a Cs4PbCl6 core, a CsPbCl3 shell, and Mn 2+ The luminescent centers are organically coupled, constructing host luminescence, interfacial luminescence, and Mn luminescence within the same system. 2+ It features multiple radiation output channels, including characteristic luminescence. In the core-shell heterostructure constructed in this invention, the Cs4PbCl6 core serves as the high-energy excitation absorption and self-bound exciton forming unit, the CsPbCl3 shell serves as the intermediate energy receiving and redistribution unit, and Mn... 2+ It can serve as a low-energy radiation output center, and the excitation energy can be orderly cascaded and utilized through multiple paths such as nucleus-shell, nucleus-Mn, and shell-Mn, which is beneficial to improving the spectral control capability and luminescence function integration of the system.

[0027] This invention utilizes the synergistic regulatory effect of MnCl2 on nucleation, growth and surface structure evolution under solvothermal conditions to induce the formation of a small amount of CsPbCl3 shell or island-like interface layer in situ on the particle surface while maintaining the main structure of Cs4PbCl6. The preparation route is simple, easy to implement and has good process operability.

[0028] The manganese-doped lead chloride perovskite heteroluminescent material obtained by this invention can simultaneously exhibit near-ultraviolet, blue, and orange-red luminescence characteristics under ultraviolet excitation, making it suitable for use as an ultraviolet-excited luminescent material, wavelength conversion material, and optoelectronic display functional material. It can provide a new technical approach for the design of optoelectronic information materials in the field of next-generation information technology.

[0029] This invention achieves synergistic optimization of the luminescence behavior of composite perovskites from two levels: structural construction and energy flow regulation. It not only has a clear material structure basis, but also a clear functional orientation, which is of great significance for the development of multicolor luminescence, tunable luminescence and interface-coupled optoelectronic functional materials. Attached Figure Description

[0030] Figure 1 This document presents a flowchart and mechanism diagram for the preparation of manganese-doped lead chloride perovskite heteroluminescent materials according to the present invention. (a) is a flowchart of the solvothermal synthesis of manganese-doped lead chloride perovskite heteroluminescent materials; (b) is a flowchart of the Mn... 2+ Schematic diagram of B-site substitution in Cs4PbCl6 lattice and Mn 2+ (c) Schematic diagram of B-site substitution in CsPbCl3 lattice and structural model of Cs4PbCl6 core-CsPbCl3 shell; (d) Schematic diagram of the formation process of manganese-doped lead chloride perovskite heteroluminescent material.

[0031] Figure 2 The surface morphology and elemental distribution of Cs4PbCl6 prepared in Comparative Example 1 and the manganese-doped lead chloride perovskite heteroluminescent material prepared in Example 3 were characterized. (a) is a TEM image of Cs4PbCl6 prepared in Comparative Example 1; (b) is a high-resolution TEM image of Cs4PbCl6 prepared in Comparative Example 1; (c) is a TEM image of the manganese-doped lead chloride perovskite heteroluminescent material prepared in Example 3; (d) is a high-resolution TEM image of the manganese-doped lead chloride perovskite heteroluminescent material prepared in Example 3; (e) is a high-resolution TEM image of the manganese-doped lead chloride perovskite heteroluminescent material of Example 3; (f) is a statistical analysis of the particle size distribution of Cs4PbCl6 prepared in Comparative Example 1; (g) is a statistical analysis of the particle size distribution of the manganese-doped lead chloride perovskite heteroluminescent material prepared in Example 1; and (h) is an EDS elemental distribution diagram of the manganese-doped lead chloride perovskite heteroluminescent material prepared in Example 1, with Cs, Pb, Cl, and Mn elements from left to right.

[0032] Figure 3The structure, composition, and phase identification of the manganese-doped lead chloride perovskite heteroluminescent material prepared in Example 3 are shown below. (a) SAED diffraction hexagonal phase diagram; (b) High-resolution TEM and interface moiré fringes and Cs4PbCl6 lattice fringes; (c) EDS energy spectrum and elemental molar ratio; (d) XPS spectrum and peak fitting diagram of Cs 3d; (e) XPS spectrum and peak fitting diagram of Pb 4f; (f) XPS spectrum and peak fitting diagram of Cl 2p; (g) XPS spectrum and peak fitting diagram of Mn 2p; (h) Integrated area ratio of Cs, Pb, and Cl in the relevant components of Cs4PbCl6 / CsPbCl3 based on XPS peaks; (i) Comparison of XRD patterns and standard cards between pure Cs4PbCl6 and the manganese-doped lead chloride perovskite heteroluminescent material.

[0033] Figure 4 The images show the surface morphology of the manganese-doped lead chloride perovskite heteroluminescent materials prepared in Examples 2 to 5. (a) Example 3; (b) Example 2; (c) Example 5; (d) Example 4.

[0034] Figure 5 The images show the emission, excitation, absorption spectra, and physical images of different materials. (a) shows the emission spectrum of pure-phase Cs4PbCl6 nanocrystals; (b) shows the excitation spectrum of pure-phase Cs4PbCl6 nanocrystals; (c) shows the absorption spectrum of pure-phase Cs4PbCl6 nanocrystals, with an inset in (c) showing a physical image of the pure-phase Cs4PbCl6 nanocrystals; (d) shows the emission spectrum of the manganese-doped lead chloride perovskite heteroluminescent material prepared in Example 1; (e) shows the excitation spectrum of the manganese-doped lead chloride perovskite heteroluminescent material prepared in Example 1; and (f) shows the absorption spectrum of the manganese-doped lead chloride perovskite heteroluminescent material prepared in Example 1, with an inset in (f) showing a physical image of the manganese-doped lead chloride perovskite heteroluminescent material.

[0035] Figure 6 The concentration-dependent spectral characteristics of the manganese-doped lead chloride perovskite heteroluminescent material prepared in Example 1 are shown. (a) represents the emission spectrum at different relative concentrations; (b) represents the emission spectrum of Mn... 2+ (c) Enlarged view of the luminescent region; (d) Excitation spectrum of 418 nm emission and emission spectrum of 290 nm excitation and their spectral overlap; (e) Peak position decomposition and comparison of emission spectra at CO and 1 / 10 CO concentrations; (f) Emission peak position of Cs4PbCl6 and CsPbCl3 with relative concentration; (f) Emission intensity at 350 nm, 410 nm and 610 nm with relative concentration, with the inset in (f) showing Mn. 2+ The enhancement of luminescence compared to Cs4PbCl6 and CsPbCl3.

[0036] Figure 7 The following are time-resolved photoluminescence decay curves and double-exponential fitting results for different materials at different monitoring wavelengths. Specifically, (a) shows the time-resolved photoluminescence decay curve and double-exponential fitting results for pure-phase Cs4PbCl6 at a monitoring wavelength of 350 nm; (b) shows the time-resolved photoluminescence decay curve and double-exponential fitting results for the manganese-doped lead chloride perovskite heteroluminescent material prepared in Example 1 at a monitoring wavelength of 350 nm; (c) shows the time-resolved photoluminescence decay curve and double-exponential fitting results for the manganese-doped lead chloride perovskite heteroluminescent material prepared in Example 1 at a monitoring wavelength of 410 nm; and (d) shows the time-resolved photoluminescence decay curve and double-exponential fitting results for the manganese-doped lead chloride perovskite heteroluminescent material prepared in Example 1 at a monitoring wavelength of 600 nm.

[0037] Figure 8 A schematic diagram of the energy level structure and luminescence mechanism of a manganese-doped lead chloride perovskite heteroluminescent material. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] The present invention aims to provide a composite perovskite material with controllable structure, clear interface coupling, and multi-channel synergistic luminescence characteristics, in order to solve the problems of single luminescence center, low excitation energy distribution efficiency, limited spectral tunability, and difficulty in meeting the application requirements of ultraviolet excitation luminescence, wavelength conversion and optoelectronic display functional materials in the prior art.

[0040] Mn prepared by this invention 2+ The Cs4PbCl6@CsPbCl3 system is characterized by a Cs4PbCl6 core, with CsPbCl3 thin shells or island-like interface layers locally formed on the surface, and Mn... 2+ A composite luminescent network distributed around the core, shell, and interface. This system can simultaneously exhibit near-ultraviolet emission from core-bound excitons, shell-correlated blue light emission, and Mn emission. 2+ The material emits orange-red light and exhibits multiple parallel energy transfer paths, including core-to-shell, core-to-Mn, and shell-to-Mn, indicating that constructing multi-center, multi-channel luminescent materials through interface coupling design is a feasible technical approach.

[0041] Example 1 A method for preparing a manganese-doped lead chloride perovskite heteroluminescent material includes the following steps: Step 1, Preparation of cesium oleate: Add 0.814 g Cs₂CO₃, 40 mL octadecene, and 5 mL oleic acid to a three-necked flask and degas at 120 °C for 1 hour under nitrogen protection. Then raise the temperature to 150 °C and heat for 90 min until Cs₂CO₃ and oleic acid react completely to form a homogeneous and transparent cesium oleate solution.

[0042] Step 2, Mn 2+ Synthesis of the Cs4PbCl6@CsPbCl3 composite structure: 0.1 mmol of PbCl2, 0.2 mmol of MnCl2, 0.5 mL of dry oleic acid, and 5 mL of oleylamine were mixed and ultrasonically dispersed until a homogeneous solution was formed. Then, 0.8 mL of cesium oleate solution was added, and ultrasonication continued for 5 min to obtain the precursor solution. The precursor solution was transferred to a hydrothermal reactor and reacted at 160 °C for 1 h. After the reaction, 3 mL of ethyl acetate was added to the reaction system to wash the product, and then the mixture was centrifuged at 10,000 rpm for 5 min. The supernatant was discarded, and the resulting precipitate was the manganese-doped lead chloride perovskite heteroluminescent material. This precipitate was dissolved in 5 mL of n-hexane and ultrasonically dispersed for 3 min. The resulting dispersion was stored for later use.

[0043] In the specific experimental process, in order to preserve the manganese-doped lead chloride perovskite heteroluminescent material, the precipitate obtained in the above steps was dissolved in 5 mL of n-hexane and ultrasonically dispersed for 3 minutes. The resulting dispersion was then stored for later use. The reason for this operation is that, on the one hand, the particles are less likely to agglomerate in the solution, and on the other hand, it can isolate oxygen and moisture, which is beneficial for long-term storage.

[0044] Example 2 A method for preparing a manganese-doped lead chloride perovskite heteroluminescent material includes the following steps: Step 1, Preparation of cesium oleate: Add 0.814 g Cs₂CO₃, 40 mL octadecene, and 5 mL oleic acid to a three-necked flask and degas at 120 °C for 1 hour under nitrogen protection. Then raise the temperature to 150 °C and heat for 90 min until Cs₂CO₃ and oleic acid react completely to form a homogeneous and transparent cesium oleate solution.

[0045] Step 2, Mn 2+Synthesis of the Cs4PbCl6@CsPbCl3 composite structure: 0.1 mmol of PbCl2, 0.1 mmol of MnCl2, 0.5 mL of dry oleic acid, and 5 mL of oleylamine were mixed and ultrasonically dispersed until a homogeneous solution was formed. Then, 0.8 mL of cesium oleate solution was added, and ultrasonication continued for 5 min to obtain the precursor solution. The precursor solution was transferred to a hydrothermal reactor and reacted at 160 °C for 2 h. After the reaction, 3 mL of ethyl acetate was added to the reaction system to wash the product, and then the mixture was centrifuged at 10,000 rpm for 5 min, discarding the supernatant. The resulting precipitate was the manganese-doped lead chloride perovskite heteroluminescent material; it was dissolved in 5 mL of n-hexane and ultrasonically dispersed for 3 min. The resulting dispersion was stored for later use.

[0046] Example 3 A method for preparing a manganese-doped lead chloride perovskite heteroluminescent material includes the following steps: Step 1, Preparation of cesium oleate: Add 0.814 g Cs₂CO₃, 40 mL octadecene, and 5 mL oleic acid to a three-necked flask and degas at 120 °C for 1 hour under nitrogen protection. Then raise the temperature to 150 °C and heat for 90 min until Cs₂CO₃ and oleic acid react completely to form a homogeneous and transparent cesium oleate solution.

[0047] Cesium oleate is abbreviated as Cs-Oleate. It should be noted that Cs-Oleate solutions will solidify at temperatures below 100°C. Therefore, they need to be reheated until completely dissolved before injection to ensure that the solution remains clear and transparent.

[0048] Step 2, Mn 2+ Synthesis of the Cs4PbCl6@CsPbCl3 composite structure: 0.1 mmol of PbCl2, 0.05 mmol of MnCl2, 0.5 mL of dry oleic acid, and 5 mL of oleylamine were mixed and ultrasonically dispersed until a homogeneous solution was formed. Then, 0.8 mL of cesium oleate solution was added, and ultrasonication continued for 5 min to obtain the precursor solution. The precursor solution was transferred to a hydrothermal reactor and reacted at 160 °C for 2 h. After the reaction, 3 mL of ethyl acetate was added to the reaction system to wash the product, and then the mixture was centrifuged at 10,000 rpm for 5 min. The supernatant was discarded, and the resulting precipitate was the manganese-doped lead chloride perovskite heteroluminescent material.

[0049] Example 4 A method for preparing a manganese-doped lead chloride perovskite heteroluminescent material includes the following steps: Step 1, Preparation of Cesium Oleate: Add 0.814 g Cs₂CO₃, 50 mL octadecene, and 7.5 mL oleic acid to a three-necked flask and degas at 120 °C for 1 hour under nitrogen protection. Then raise the temperature to 160 °C and heat for 60 min until Cs₂CO₃ and oleic acid react completely to form a homogeneous and transparent cesium oleate solution.

[0050] Step 2, Mn 2+ Synthesis of the Cs4PbCl6@CsPbCl3 composite structure: 0.1 mmol of PbCl2, 0.2 mmol of MnCl2, 0.6 mL of dry oleic acid, and 6 mL of oleylamine were mixed and ultrasonically dispersed until a homogeneous solution was formed. Then, 0.8 mL of cesium oleate solution was added, and ultrasonication continued for 5 min to obtain the precursor solution. The precursor solution was transferred to a hydrothermal reactor and reacted at 170 °C for 2.5 h. After the reaction, 3 mL of ethyl acetate was added to the reaction system to wash the product, and then the mixture was centrifuged at 10,000 rpm for 5 min, discarding the supernatant. The resulting precipitate was the manganese-doped lead chloride perovskite heteroluminescent material; it was dissolved in 5 mL of n-hexane and ultrasonically dispersed for 3 min. The resulting dispersion was stored for later use.

[0051] Example 5 A method for preparing a manganese-doped lead chloride perovskite heteroluminescent material includes the following steps: Step 1, Preparation of Cesium Oleate: Add 0.814 g Cs₂CO₃, 45 mL octadecene, and 6 mL oleic acid to a three-necked flask and degas at 120 °C for 1 hour under nitrogen protection. Then raise the temperature to 155 °C and heat for 120 min until Cs₂CO₃ and oleic acid react completely to form a homogeneous and transparent cesium oleate solution.

[0052] Step 2, Mn 2+ Synthesis of the Cs4PbCl6@CsPbCl3 composite structure: 0.1 mmol of PbCl2, 0.2 mmol of MnCl2, 0.55 mL of dry oleic acid, and 5.5 mL of oleylamine were mixed and ultrasonically dispersed until a homogeneous solution was formed. Then, 0.8 mL of cesium oleate solution was added, and ultrasonication continued for 5 min to obtain the precursor solution. The precursor solution was transferred to a hydrothermal reactor and reacted at 165 °C for 0.5 h. After the reaction, 3 mL of ethyl acetate was added to the reaction system to wash the product, and then the mixture was centrifuged at 10,000 rpm for 5 min, discarding the supernatant. The resulting precipitate, which is the manganese-doped lead chloride perovskite heteroluminescent material, was dissolved in 5 mL of n-hexane and ultrasonically dispersed for 3 min. The resulting dispersion was stored for later use.

[0053] Comparative Example 1 A method for preparing a lead chloride perovskite material includes the following steps: The difference from Example 1 is that MnCl2 was not added to the precursor solution.

[0054] Step 1, Preparation of Cesium Oleate: Add 0.814 g Cs₂CO₃, 40 mL octadecene, and 5 mL oleic acid to a three-necked flask and degas at 120 °C for 1 hour under nitrogen protection. Then raise the temperature to 150 °C until Cs₂CO₃ and oleic acid react completely to form a homogeneous and transparent cesium oleate solution.

[0055] Step 2, Cs4PbCl6 Synthesis: 0.1 mmol of PbCl2 was dissolved in 0.5 mL of dry oleic acid and 5 mL of oleylamine, and ultrasonically dispersed until a homogeneous mixture was formed. Then, 0.8 mL of cesium oleate solution was added to the mixture and ultrasonication continued for 5 min to obtain the precursor solution. The precursor solution was transferred to a hydrothermal reactor and reacted at 160 °C for 1 hour. After the reaction was complete, 3 mL of ethyl acetate was added to the reaction system to wash the product, and then the mixture was centrifuged at 10,000 rpm for 5 min, discarding the supernatant. The resulting precipitate was the lead chloride perovskite material; it was dissolved in 5 mL of n-hexane and ultrasonically dispersed for 3 min, and the resulting dispersion was stored for later use.

[0056] The products prepared in the examples and the products prepared in Comparative Example 1 are characterized and analyzed below.

[0057] like Figure 1 As shown in (a), Mn 2+ Doped composite nanocrystals were prepared using a solvothermal method: PbCl2, cesium oleate, and MnCl2 were added to a ligand system of oleic acid and oleylamine. The precursors were then ultrasonically dispersed to promote uniform dispersion. The reaction system was then transferred to a sealed reactor and reacted at 160°C for 1 hour to obtain the final product. The high temperature and high pressure environment under solvothermal conditions is beneficial for increasing ion migration rates and enhancing local chemical potential gradients. This makes the system more prone to surface reconstruction and local phase evolution during the dynamic processes of dissolution, migration, and recrystallization, thus providing favorable kinetic conditions for the formation of the composite structure. Figure 1 The TEM image corresponding to (a) shows that the obtained product mainly consists of well-dispersed nanoparticles with particle sizes on the order of tens of nanometers. The overall morphology is relatively uniform, and no large number of independently precipitated second-phase nanocrystals were observed. This result indicates that if a second phase exists in the system, it is more likely to be distributed on the outer layer of the main particles in the form of surface enrichment or local coating, rather than precipitating as a large number of independent particles. Combined with subsequent structural and surface composition characterization results, Figure 1 The product shown in (a) is a composite structure model with Cs4PbCl6 as the main particles and CsPbCl3 locally generated on the outer layer; wherein, CsPbCl3 is in the form of thin layers or islands.

[0058] Figure 1 (b) further gives Mn 2+ Occupancy patterns in Cs₄PbCl₆ and CsPbCl₃ lattices and schematic diagrams of the present invention. The basic structural unit of both Cs₄PbCl₆ and CsPbCl₃ is [PbCl₆]. 4- Octahedral structures exist, but those in Cs₄PbCl₆ are spatially isolated, exhibiting typical zero-dimensional structural characteristics, while those in CsPbCl₃ form a continuous framework through corner-sharing connections. Based on valence state matching and compatibility with local coordination environments, Mn... 2+ Prefer to replace Pb by substituting B. 2+ This results in the formation of Mn-Cl localized coordination structures in both Cs4PbCl6 and CsPbCl3 phases, introducing different crystal field environments. Based on this, Figure 1 (b) of the paper proposes a structural model for the present invention: a Cs4PbCl6 core with a locally formed CsPbCl3 thin shell on the outside, exhibiting a discontinuous island-like covering. This structural feature not only differs from... Figure 1 The morphological results shown in (a) are consistent with those in the previous paper, providing the necessary structural basis for subsequent optical property analysis. On the one hand, the close contact between the core and shell phases at the nanoscale makes the interface region a potential channel for excited-state coupling and energy exchange; on the other hand, Mn... 2+ Distributed in the core phase, shell phase, and near the interface, this provides conditions for establishing a multi-channel energy transfer network in space. Therefore, this core-shell composite structure provides a basis for subsequent understanding of Cs4PbCl6 core luminescence, CsPbCl3 shell luminescence, and Mn... 2+ The synergistic relationship between sensitized luminescence lays the structural foundation.

[0059] In the ligand environment of oleic acid and oleylamine, Pb 2+ Mn 2+ Cs + With Cl - First, a dynamic coordination equilibrium is established; under solvothermal conditions, the system preferentially nucleates to form thermodynamically more readily formed Cs4PbCl6 bulk particles. Compared to the undoped system, the introduction of a high dose of MnCl2 not only provides Mn... 2+ The doping source significantly alters the local metal-halogen coordination equilibrium in the precursor solution and the subsequent crystallization pathway. For example... Figure 1 As shown in (c), on the one hand, Mn 2+ The addition of Mn increases the probability of effective nucleation center formation in the system, making it easier to generate a higher nucleation density in the early stages of the reaction, thereby distributing the limited precursor to more nuclei, resulting in a smaller final particle size than pure Cs4PbCl6; on the other hand, Mn 2+ For Pb 2+Local coordination perturbations at the sites and the resulting surface strain accumulation weaken the stability maintenance of the single Cs4PbCl6 phase by the particle surface, making the surface region more susceptible to structural instability and surface reconstruction compared to the core. Under conditions of high temperature and high pressure promoting ion migration, the local surface region thus evolves from zero-dimensional Cs4PbCl6 to a more interconnected CsPbCl3 local phase, preferentially attaching to the surface of the already formed Cs4PbCl6 core via heterogeneous nucleation. Since this process is mainly limited to the outer layer of the particle and constrained by finite reaction time, ligand passivation, and ion diffusion rate, the new surface phase cannot continue to grow sufficiently into independent particles or a complete dense shell. Instead, it is kinetically frozen to the core surface in a thin layer or island-like manner, ultimately forming a composite structure with Cs4PbCl6 as the core and a local shell of CsPbCl3 covering it. Therefore, MnCl2 in this system does not merely act as a doping precursor, but also as a structural evolution inducing factor. As the reaction proceeds, the nucleation process in the system is enhanced, while subsequent crystal growth is somewhat limited. Subsequently, local reconstruction occurs on the particle surface, forming a local environment conducive to the formation of heterogeneous phases in the surface region, ultimately promoting the formation of local heterostructures. This continuous kinetic process jointly determines the reduction in particle size and the formation of core-shell composite structures.

[0060] like Figure 2 As shown in (a), pure Cs4PbCl6 nanocrystals exhibit a polyhedral particle morphology, good dispersibility, and no obvious agglomeration. Figure 2 The high-resolution TEM image corresponding to (b) shows clear and continuous lattice fringes, indicating that the particles have high crystallinity. The interplanar spacing was measured. d =0.282nm, which can be attributed to the (223) crystal plane of hexagonal Cs4PbCl6, further confirming that the prepared sample has a clear crystal structure. Figure 2 (f) Based on statistical results, the average particle size of pure Cs4PbCl6 is about 40 nm, and the particle size distribution is relatively concentrated.

[0061] from Figure 2 As shown in (c), after the introduction of MnCl2, the overall morphology of the sample still maintains the regular nanocrystalline characteristics, but the particle size is significantly reduced. Figure 2 The particle size statistics of (g) in the sample show that the average particle size decreases to approximately 32.5 nm, and the overall distribution shifts towards smaller sizes. The introduction of MnCl2 mainly reduces the particle size by regulating the nucleation and growth competition in the solvothermal process: on the one hand, the additional Cl... - The salt effect alters the metal halide-ligand complexation and dissolution equilibrium, making the system more likely to rapidly reach a higher supersaturation during the heating phase, thereby increasing the instantaneous nucleation density; on the other hand, Mn 2+MnCl2 and its halogen coordination compounds may participate in coordination on the nanocrystal surface and partially passivate active growth sites, raising the barriers to ion attachment and epitaxial growth, and inhibiting further crystal growth. Simultaneously, the dynamic equilibrium of dissolution-redeposition under solvothermal conditions is further shifted towards renucleation by MnCl2. These effects collectively lead to the distribution of more nuclei to the precursor and limited single-particle growth, ultimately resulting in an average particle size reduction from approximately 40 nm to approximately 32.5 nm. However, the lattice fringes remain clear, indicating that the size reduction stems from a change in kinetic pathways rather than crystallinity degradation. Figure 2 (d) and Figure 2 In (e), particles of different sizes all exhibit clear lattice fringes, with interplanar spacings of [missing information]. d =0.277nm and d =0.381nm, corresponding to the (006) and (300) crystal planes of hexagonal Cs4PbCl6. This indicates that the introduction of MnCl2 did not destroy the main crystal framework structure of Cs4PbCl6, and the particles still maintained good crystal integrity and order under small size conditions.

[0062] To verify the spatial distribution of doped / introduced elements, Figure 2 Figure (h) shows the EDS mapping of the MnCl2-doped sample. The Cs, Pb, and Cl signals are uniformly distributed in the particle region, indicating that the main halide framework composition is consistent. The Mn element signal is also detectable in the particle region and is dispersed, indicating that the Mn species has been successfully introduced into the sample system and has not shown severe phase separation or local large particle enrichment at the macroscale.

[0063] It is further important to emphasize that, in both the pure Cs4PbCl6 sample without MnCl2 and the sample treated with MnCl2, no isolated CsPbCl3 nanocrystals were observed in the low-magnification TEM field. This phenomenon indicates that if CsPbCl3-related components are present in the system, they are more likely to appear as interfacial phases or thin surface layers tightly coupled with Cs4PbCl6, such as island-like shells or local epitaxial layers, rather than as a large number of independent second-phase particles that can be directly resolved in TEM. This morphological evidence echoes the results of subsequent compositional and surface-sensitive characterization indicating surface-rich CsPbCl3 features, providing important support for constructing a Cs4PbCl6@CsPbCl3 composite structure model.

[0064] like Figure 3 As shown in (a), the SAED diffraction rings can be mainly attributed to the hexagonal phase Cs4PbCl6, while two weaker diffraction rings can be matched with the diffraction of CsPbCl3. Based on the comparison of the ring radius of the weak rings with the standard card, this invention assigns them to the (200) and (100) crystal planes of CsPbCl3, with corresponding interplanar spacings of 0.280 nm and 0.56 nm, respectively. Figure 3 In (b), the Cs4PbCl6 lattice fringes can be clearly measured from the HRTEM image of the same region. d 1 =0.275nm is marked as the (006) crystal plane, and the period is also present. D The moiré fringes are 0.939 nm. This invention hypothesizes that there may be a superposition and coupling of two near-period lattices at the interface, such as the (006) crystal plane of Cs4PbCl6 and the (200) crystal plane of CsPbCl3. To provide a semi-quantitative assessment of the interface geometry, this invention employs a two-dimensional moiré relation: ; in, θ Let be the in-plane angle between the two sets of lattice fringes. Substitute... D =0.939nm d 1 =0.275nm and SAED locked d 2 =0.280nm, therefore we can obtain θ The result of approximately 16.96º has a clear physical meaning: it indicates that the moiré fringes mainly originate from the finite in-plane orientation difference at the interface, rather than the simple difference in interplanar spacing.

[0065] Furthermore, the geometric mismatch of the interplanar spacing is: ; This mismatch is relatively small, typically <5%, indicating that Cs4PbCl6 and CsPbCl3 possess the geometric conditions for heterogeneous interface coupling at the interface. Combined with the weak CsPbCl3 signal in SAED, suggesting its low content and its possible island-like thin-layer distribution, it is understandable that the CsPbCl3 lattice fringes are not easily resolved stably in a single HRTEM.

[0066] Based on the quantitative results of the EDS energy spectrum of the doped sample, see Figure 3In the interpolation table (c), the atomic percentages of each element are as follows: Cs 35.35%, Pb 10.53%, Cl 53.29%, and Mn 0.83%. To facilitate comparison of stoichiometric relationships, Pb is normalized to 1, yielding the overall atomic ratios: Cs / Pb ≈ 35.35 / 10.53 = 3.36, Cl / Pb ≈ 53.29 / 10.53 = 5.06, and Mn / Pb ≈ 0.83 / 10.53 = 0.079. These ratios provide important quantitative support for the sample's structural composition and phase synergy. First, the measured atomic ratios of Cs, Pb, and Cl are approximately 3.36:1:5.06, significantly deviating from the stoichiometry of Cs, Pb, and Cl in the ideal single-phase Cs₄PbCl₆, but also far from approaching the stoichiometric characteristics of Cs, Pb, and Cl in CsPbCl₃. Its value lies between the two and leans more towards Cs4PbCl6, indicating that the sample is still dominated by Cs4PbCl6, while a certain proportion of CsPbCl3-related components participate in the overall average composition statistics. This conclusion is consistent with the phenomenon in SAED where Cs4PbCl6 diffraction rings are dominant and CsPbCl3 only shows weak diffraction rings; in other words, the composition reflected by EDS, which is closer to the bulk average composition, still shows that Cs4PbCl6 is dominant. Secondly, the average stoichiometry of the two phases can be used to semi-quantitatively explain the above proportions. Using Pb as the stoichiometric standard, the overall atomic ratio of EDS is regarded as a weighted average of the contributions of Cs4PbCl6 and CsPbCl3. Let x be the proportion of Pb in the Cs4PbCl6 structural environment, then: Cs / Pb = 4x + 1(1-x) = 1 + 3x, Cl / Pb = 6x + 3(1-x) = 3 + 3x. According to the EDS measurement results, Cs / Pb≈3.36. Substituting this into the above formula, we get: 1+3x=3.36, which gives x≈0.79. Similarly, from Cl / Pb≈5.06, we get: 3+3x=5.06, which gives x≈0.69. This indicates that approximately 70%–80% of Pb is still in the Cs4PbCl6 structural environment, while CsPbCl3 accounts for only a small proportion. Considering the quantitative error of EDS for the light element Cl, the differences in local sampling, and the influence of non-ideal stoichiometry in the interface region, the above results are reasonable. This result is consistent with the characterization conclusions of SAED and XPS. In SAED, the diffraction ring of Cs4PbCl6 is dominant, while CsPbCl3 only shows weak diffraction characteristics, indicating that Cs4PbCl6 is the main phase and the content of CsPbCl3 is low.

[0067] like Figure 3As shown in (d) to (g), the high-resolution XPS spectra of Cs 3d, Pb 4f, and Cl 2p in the Mn-doped Cs4PbCl6 sample can all be fitted with two groups of components, indicating that the corresponding elements are in two different local chemical environments. Combining the peak position differences and the aforementioned structural analysis, the high-binding-energy component can be attributed to the Cs4PbCl6-related chemical state, while the lower-binding-energy component corresponds to the CsPbCl3-related chemical state, indicating the presence of Cs4PbCl6 and CsPbCl3 composite or interfacial coexistence characteristics in the sample. It should be noted that... Figure 3 The peak area statistics shown in (h) indicate that the relative proportion of CsPbCl3-related components in XPS is higher than that of Cs4PbCl6-related components. This result is not contradictory to the results of EDS and SAED, which show that Cs4PbCl6 is the main component and CsPbCl3 content is relatively low. This is mainly due to the difference in detection scale between different characterization methods. XPS mainly reflects the chemical state information of the nanoparticle surface, while EDS and SAED focus more on the overall or bulk average structure. Therefore, the stronger CsPbCl3-related XPS signal indicates that CsPbCl3 is more likely to be enriched on the particle surface or interface region, while the main structure inside the sample is still dominated by Cs4PbCl6. It can be inferred that the sample is more likely to form a composite structure of Cs4PbCl6 core / CsPbCl3 surface island thin layer or interface phase, rather than a large amount of independent CsPbCl3 nanocrystal precipitation. In addition, a small amount of Pb was also detected in the Pb 4f spectrum. 0 The relevant components indicate the presence of locally reduced lead species on the sample surface. Their origin is related to surface halogen vacancies, coordination unsaturation, interfacial charge reconstruction, or slight dissociation of surface Pb-Cl bonds during XPS testing. Overall, the XPS results strongly support the existence of a clear surface and bulk chemical stratification characteristic in the sample, providing important evidence for understanding its interfacial structure and related optical behavior.

[0068] like Figure 3As shown in (i), the XRD patterns of undoped Cs4PbCl6 and Mn-doped samples were compared and analyzed. The diffraction peaks of both groups of samples generally matched well with the hexagonal Cs4PbCl6 standard card PDF#73-2477, indicating that the main crystal structure of the samples remained Cs4PbCl6 regardless of the introduction of Mn, demonstrating that Mn doping did not change the main crystal phase framework of the material. This suggests that the introduction of Mn occurred in a local coordination environment or at the surface / interface level, rather than inducing a fundamental phase transition in the main structure. It is noteworthy that, in addition to the Cs4PbCl6 main phase diffraction peaks, several additional diffraction peaks were observed in the undoped sample. These peaks can be attributed to byproduct phases such as PbCl2 and CsCl, indicating that under undoped conditions, there was a certain degree of component segregation or incomplete reaction during the precursor reaction, leading to the coexistence of impurity phases. In contrast, these impurity phase peaks in the Mn-doped sample were significantly weakened or even almost disappeared, indicating that the introduction of Mn optimized the crystal growth process to some extent and improved the phase purity of the product. In other words, Mn doping not only did not destroy the main phase structure of Cs4PbCl6, but also made the formation of the target phase more selective by adjusting the growth kinetics, improving the local coordination balance, or suppressing the precipitation of secondary phases.

[0069] like Figure 4 As shown in (a) and (b) of the figures, compared with Example 1, when the reaction time was extended to 2 hours, the samples still maintained an approximately granular or polyhedral morphology, without obvious structural collapse or severe agglomeration, indicating that extending the reaction time in this reaction system does not significantly change the basic morphological characteristics of the product. However, with the extension of the reaction time, the crystal growth process became more complete, and some particles grew further, resulting in an increase in the average size of the samples. Simultaneously, due to the difference in growth rates between different crystal nuclei, a longer reaction time easily leads to the phenomenon of small particles continuing to dissolve and large particles continuing to grow, thus increasing the non-uniformity of particle size distribution. Figure 4 As shown in (c), under conditions of high MnCl2 addition and short reaction time, the system exhibits high supersaturation, which favors rapid nucleation, resulting in a large number of small nanoparticles. Simultaneously, the short reaction time restricts subsequent particle growth, leading to relatively small and uniformly distributed sample sizes. In contrast, Figure 4 In (d), when the reaction time was extended to 2.5 h, some particles underwent continuous growth and maturation, forming larger particles; at the same time, a certain number of small particles remained in the system, ultimately resulting in a sample morphology where large and small particles coexisted. This indicates that under conditions of higher MnCl2 addition, the reaction time has a more significant effect on the control of sample size. Shorter reaction times are beneficial for obtaining smaller and more uniform particles, while excessively long reaction times can easily lead to further particle growth and exacerbate differences in size distribution.

[0070] Therefore, the basic morphology of the sample did not change significantly after the reaction time was extended, but the particle size increased and the size distribution became more uneven. When the amount of MnCl2 added was high and the reaction time was short, the system rapidly nucleated and formed a large number of small and evenly distributed particles. Further extending the reaction time promoted particle growth and maturation, resulting in a morphology in which large and small particles coexist.

[0071] On the other hand, in the Mn-doped sample, in addition to the main Cs4PbCl6 peak, a weak additional diffraction signal can be distinguished near the characteristic diffraction position of CsPbCl3 (100). Considering the low intensity of this peak and the insignificance of the other CsPbCl3 characteristic peaks, it can be inferred that the content of CsPbCl3 in the sample is small, and the crystal volume fraction is limited, insufficient to exhibit complete and strong independent phase diffraction characteristics in XRD. Therefore, this CsPbCl3 is more likely not as a large amount of independent precipitation. Combined with SAED, ED, and high-resolution lattice fringe analysis, it is shown that the Mn-doped sample forms a composite structure with Cs4PbCl6 as the main core and a small amount of CsPbCl3 island-like thin layers or interface phases on the outer layer, rather than a simple mechanical mixture of two independent crystal phases. Overall, the results of multiple structural characterizations jointly prove that Mn doping causes the sample to introduce a small amount of CsPbCl3-related interface phases on the particle surface while maintaining the main Cs4PbCl6 structure, thus forming a composite structure with obvious surface-bulk phase layering characteristics. This structure implies that the system may simultaneously exhibit host phase luminescence, interface state modulation, and transphase energy / carrier coupling processes. Therefore, its spectral response is no longer solely determined by the single Cs4PbCl6 phase, but is more likely influenced by the surface CsPbCl3 phase and its interface interactions. Based on this, the following analysis will combine absorption, excitation, and emission spectra to further investigate the luminescence origin and related energy transfer mechanisms of the sample.

[0072] like Figure 5 As shown in (a) to (c), the pure Cs4PbCl6 sample exhibits stable near-ultraviolet broadband emission around 350 nm under excitation at 280 nm to 295 nm. Its effective excitation is mainly concentrated in the 275 nm to 300 nm range, which roughly corresponds to the characteristic absorption range of 260 nm to 300 nm in the absorption spectrum. The sample exhibits a large Stokes shift, indicating that its luminescence originates from typical self-bound exciton radiative recombination. This result is consistent with isolated [PbCl6] in zero-dimensional Cs4PbCl6. 4- The strongly localized excited states and significant lattice relaxation characteristics induced by the octahedron are consistent.

[0073] Compared to the pure phase, Mn 2+ The Cs4PbCl6@CsPbCl3 composite sample exhibits a more complex spectral response. For example... Figure 5 As shown in (d) to (f), in addition to retaining near-ultraviolet emission, doping also resulted in two new emission bands located at 418 nm and 610 nm, which can be attributed to the free exciton emission of the CsPbCl3 shell and the Mn emission, respectively. 2+ The characteristic orange-red light emission was observed. Simultaneously, the emission of self-bound excitons located at 350 nm in the original pure Cs4PbCl6 shifted to approximately 368 nm in the recombination system, with a significantly weakened intensity. Considering that the particle size did not increase after doping, and that Cs4PbCl6 does not possess significant quantum confinement redshift conditions within its current size range, this spectral change originates from a redistribution of emission output caused by multi-channel excitation energy competition, interface coupling, and reabsorption processes after the formation of the recombination structure, rather than a simple size effect. Furthermore, the Stokes shift of the self-bound excitons increased from 0.885 eV to 0.9643 eV after interface coupling, indicating a further increase in the configurational mismatch between its excited and ground states. The self-bound excitons underwent more significant local lattice relaxation before radiative recombination. This suggests that the formation of the CsPbCl3 shell not only altered the energy flow path between the core and shell but also modulated the local structural environment and vibrational characteristics of the Cs4PbCl6 near-interface region, thereby enhancing the self-binding and relaxation characteristics of the self-bound excitons. It should be noted that a larger Stokes shift does not necessarily mean enhanced self-bound exciton luminescence; in this composite system, due to the interfacial energy shifting towards the CsPbCl3 shell and Mn... 2+ The luminescence center is shunted, and superimposed with reabsorption and multi-channel competitive relaxation, resulting in self-bound exciton luminescence that ultimately exhibits the characteristics of both intensity reduction and apparent redshift.

[0074] The PLE spectrum further reveals the intrinsic correlation between different luminescent centers. For 418 nm emission, its excitation spectrum exhibits a significant main excitation peak at approximately 285 nm and a broad excitation band in the range of 330 nm to 380 nm. The former is highly consistent with the intrinsic excitation range of Cs4PbCl6, indicating that the luminescence of the CsPbCl3 shell is not entirely dominated by its own direct absorption, but is closely related to the absorption and excitation process of the Cs4PbCl6 core. The latter, however, significantly overlaps with the self-bound exciton emission band of Cs4PbCl6, indicating that the near-ultraviolet emission of the core can be further reabsorbed by the shell and used to excite 418 nm emission. Therefore, the luminescence of the CsPbCl3 shell includes at least two types of contributions: first, high-energy light is first absorbed by the Cs4PbCl6 core and then transferred to the surface CsPbCl3 shell through core / shell interface coupling; second, the self-bound exciton emission of Cs4PbCl6 acts as a secondary light source, which is reabsorbed by the shell and participates in luminescence. Based on the current steady-state PL, PLE, and absorption results, a more reasonable physical picture is that there is effective interfacial energy coupling between Cs4PbCl6 and a small amount of CsPbCl3 on the surface, which may be accompanied by local carrier transfer, thereby jointly promoting shell luminescence.

[0075] Mn 2+ The excitation behavior of luminescence also exhibits multi-source sensitization characteristics. Figure 5 As shown in (e), the PLE spectrum emitted at 610 nm exhibits a significant excitation response in the 270 nm–300 nm range, indicating that Mn 2+ Part of the luminescence originates from the host sensitization process of Cs4PbCl6, that is, the excitation energy can be transferred from the excited state of Cs4PbCl6 to Mn. 2+ The luminescent center. Furthermore, another significant excitation band is observed in the vicinity of approximately 396 nm to 410 nm, a region corresponding to the free exciton absorption characteristics of the CsPbCl3 shell, indicating that the CsPbCl3 shell can also act as a source of Mn. 2+ An effective sensitization channel. Meanwhile, the broad excitation band of 330 nm–380 nm further indicates that there is spectral overlap between the self-bound exciton emission of Cs4PbCl6 and the Mn-related absorption, suggesting that the reabsorption process may also be involved in Mn absorption. 2+ The formation of luminescence. This shows that in Mn... 2+ In the Cs4PbCl6@CsPbCl3 composite system, Mn 2+ The luminescence is not determined by a single excitation pathway, but is sensitized by the Cs4PbCl6 core, the CsPbCl3 shell, and the self-bound exciton reabsorption process.

[0076] Based on the above analysis, the excited-state relaxation process in this composite structure can be summarized as a multi-center, multi-channel cascaded energy flow network: high-energy light is first absorbed by the Cs4PbCl6 nucleus and forms a self-bound exciton; subsequently, part of the excitation energy is transferred to the CsPbCl3 shell through interfacial coupling, producing 418nm emission; the other part can be directly or indirectly transferred to Mn. 2+ The luminescent center produces 610 nm emission; simultaneously, the self-bound exciton luminescence of Cs4PbCl6 can also serve as a secondary excitation source, reacting with CsPbCl3 and Mn. 2+ The relevant absorption bands are further utilized. Therefore, this system simultaneously contains Cs4PbCl6 to CsPbCl3 and Cs4PbCl6 to Mn. 2+ and CsPbCl3 to Mn 2+ Multiple energy transfer pathways, accompanied by a parallel process of self-bound exciton reabsorption-assisted excitation, are involved. This multi-level energy convergence mechanism can well explain the weakening of self-bound exciton luminescence after doping, the appearance of luminescence in the 418nm shell, and the 610nm Mn luminescence. 2+ Experimental phenomena such as significantly enhanced luminescence.

[0077] at last, Figure 5 The absorption spectrum of (f) further supports the above-mentioned mechanism analysis. The Mn-doped sample exhibits two distinct absorption features at approximately 286 nm and 412 nm, respectively. The former corresponds to the intrinsic absorption of Cs₄PbCl₆, while the latter can be attributed to the free exciton absorption associated with the CsPbCl₃ shell. Furthermore, Figure 5 The inset (f) shows a photograph of the actual sample, demonstrating that it emits a distinct red-orange fluorescence under 365nm ultraviolet light excitation, directly confirming the presence of Mn in the composite system. 2+ The effective establishment of the luminescence channel was confirmed. This result corroborates the PL and PLE spectral analyses, further supporting the formation of a Cs4PbCl6-based matrix with a small amount of CsPbCl3 coating and Mn-containing Mn in the sample. 2+ A composite structure model involving luminescent centers. Although the low content of CsPbCl3 makes it difficult to exhibit a clear independent diffraction signal in XRD, its high radiation efficiency still allows it to produce a clearly discernible optical response in both absorption and emission spectra.

[0078] like Figure 6 As shown in (a) to (d) in the figure, Mn 2+The Cs4PbCl6@CsPbCl3 sample exhibited significant concentration-dependent luminescence behavior. As the solution concentration decreased, the self-bound exciton luminescence, which was initially suppressed at high concentrations, gradually increased and became clearly visible, while the relative proportion of CsPbCl3-related luminescence decreased. Simultaneously, the emission peaks of self-bound excitons and CsPbCl3 shifted from approximately 368 nm and 418 nm to approximately 350 nm and 405 nm, respectively. Furthermore, at high concentrations, CsPbCl3 luminescence was significantly asymmetrical with a pronounced tail on the long-wavelength side, while at low concentrations, the peak shape gradually became more symmetrical. These results indicate that at high concentrations, the interparticle spacing decreased, and reabsorption, self-absorption, and energy transfer processes were enhanced, leading to preferential loss of short-wavelength emission and causing an apparent redshift and spectral distortion. As the concentration decreased, these concentration-induced optical coupling processes weakened, allowing the intrinsic luminescence of self-bound excitons and CsPbCl3 to be released, resulting in enhanced luminescence, symmetrical peak shape, and an overall blueshift.

[0079] Figure 6 As shown in (c), the self-bound exciton emission of Cs4PbCl6 significantly overlaps with the wide excitation window of 320nm–400nm in the PLE under 418nm monitoring, indicating that the near-ultraviolet emission of the Cs4PbCl6 core can be effectively coupled to the emission channel of the CsPbCl3 shell. This process may involve both radiative reabsorption and localized short-range Förster-type energy transfer, but considering the more pronounced redshift and tailing characteristics at high concentrations, the reabsorption / internal filtering effect should be dominant. In contrast, Mn 2+ The luminescence showed only a limited increase with decreasing concentration, and the increase was significantly smaller than that of self-bound excitons and CsPbCl3 luminescence, indicating that Mn 2+ The channel is more controlled by local interface sensitization and Mn center capture processes than by simply enhanced interparticle reabsorption. Figure 6 The inset (f) shows that the Mn / self-bound exciton and Mn / CsPbCl3 intensity ratios increase with increasing concentration, further indicating that Mn under high concentration conditions... 2+ Emission exhibits a higher relative advantage in multi-channel competition; however, this result should be interpreted as a suppression of self-bound excitons and CsPbCl3 channels by stronger reabsorption and energy redistribution, rather than a direct increase in the efficiency of intrinsic transfer from the host to Mn. Overall, the concentration-dependent luminescence of this complex system essentially reflects the interaction between self-bound excitons, CsPbCl3 exciton states, and Mn. 2+ The results reveal a complex interplay of competition and cooperation among the luminescent centers. The findings indicate that solution concentration not only alters the relative output ratios of each luminescent center but also significantly modulates the energy distribution and competitive relaxation mechanisms within the system. Further verification using time-resolved spectroscopy and kinetic analysis is needed to further differentiate the specific roles of local energy transfer and radiative reabsorption in this system.

[0080] To further reveal Mn 2+ The kinetic relationship between different luminescent centers in the Cs4PbCl6@CsPbCl3 composite system was investigated. Time-resolved photoluminescence tests were performed on pure Cs4PbCl6 and the composite sample at different monitoring wavelengths. The decay curves were well fitted by a double exponential function, such as... Figure 7 As shown in (a) to (d), the lifetime parameters obtained from fitting τ1 and τ2 are 24.8 ns, accounting for 85.45%; while the fast component of 1.37 ns has a lower proportion and is close to the instrument response time. Therefore, this near-ultraviolet luminescence is mainly attributed to the self-bound exciton radiative recombination of Cs4PbCl6. In contrast, Mn 2+ The main lifetime of the Cs4PbCl6@CsPbCl3 composite sample at the same monitoring wavelength was significantly shortened to 11.3 ns, accounting for 81.87%, while the fast component at 1.38 ns was still close to the time-resolved limit. This indicates that after the formation of the composite structure, the emission near 350 nm is still dominated by self-bound exciton channels, but their decay dynamics have been significantly modulated by newly added competitive deactivation processes. Combining the aforementioned steady-state PL, PLE, and absorption results, it can be seen that these newly added channels mainly originate from the interfacial energy transfer from the core excited state to the surface CsPbCl3 shell and from the host to Mn. 2+ Sensitization of the luminescent center and the reabsorption / secondary excitation process under spectral overlap conditions. Based on the donor lifetime model, the principal lifetime of self-bound excitons in pure Cs4PbCl6 is taken as the donor lifetime τ without energy transfer. D The master lifetime at 350 nm in the composite sample was used as the donor lifetime τ after transfer. DA The energy transfer efficiency η can be obtained. ET =1-τ DA / τ D ≈54.4%, corresponding to the transfer rate constant k ET =1 / τ DA -1 / τ D ≈4.82×107s -1 This result quantitatively demonstrates that more than half of the excitation energy that could have been released through the self-bound exciton channel in the composite system was diverted to other luminescence paths, directly confirming from a kinetic perspective the experimental phenomenon that the steady-state luminescence of the self-bound exciton was significantly weakened after doping.

[0081] At a monitoring wavelength of 410 nm, the decay curve of the composite sample can be decomposed into two kinetic components at 13.5 ns and 1.23 ns, accounting for 70.84% ​​and 29.16%, respectively. It is worth emphasizing that the papers "Unlocking Brightness in CsPbCl3 Perovskite Nanocrystals: Screening Ligands and Metal Halides for Effective Deep Trap Passivation" published by Fyuza-Maneiro et al. in *ACS Energy Letters*, Vol. 10, No. 4, 2025, and "Growth of highly stable and luminescent CsPbX3 (X = Cl, Br, and I) nanoplates via ligand-mediated anion exchange of CsPbCl3 nanocubes" published by Uddin, M. A et al. in *Chemistry of Materials*, Vol. 32, No. 12, 2020, are relevant. In AlX3, it was recorded that the near-band edge / exciton luminescence lifetime of independent CsPbCl3 nanocrystals in the 400nm–410nm range is typically only in the order of several nanoseconds, with common reports focusing on around 1ns–3ns. Therefore, the 13.5ns observed in this invention differs significantly from the typical intrinsic lifetime of pure CsPbCl3. This significantly longer lifetime indicates that the 410nm channel cannot be simply regarded as intrinsic band edge luminescence of isolated pure-phase CsPbCl3, but should be understood as near-band edge luminescence in Mn 2+The effective lifetime of the shell / interface in the Cs4PbCl6@CsPbCl3 core / shell composite structure, modulated by interface coating and multi-channel coupling, is shown. The differences are mainly due to three factors: First, CsPbCl3 does not exist as independent nanocrystals, but rather as a small amount of shell distributed on the surface of the Cs4PbCl6 core. The interface formation has a certain passivating effect on shell-related defects, thereby reducing the nonradiative recombination rate and extending the shell exciton lifetime. Second, the 285nm excitation primarily acts on the Cs4PbCl6 core, so the 410nm channel may continue to receive energy injection from the excited state of the core during decay. Third, the steady-state spectrum shows that self-bound exciton emission near 350nm extends to near 410nm on the long-wavelength side; therefore, a certain degree of self-bound exciton tail overlap is unavoidable at this monitoring wavelength. Therefore, the decay recorded at 410 nm is not a pure decay of single-shell luminescence, but a complex dynamic response resulting from the convolution of CsPbCl3 shell / interface correlated luminescence, long-wavelength tailing of core self-bound excitons, and core-shell continuous sensitization energy supply. Meanwhile, although the fast component at 1.23 ns is close to the instrument response time, its relative proportion increases from approximately 18% at 350 nm to approximately 29% at 410 nm, indicating that this component cannot be entirely attributed to the instrument response and is more likely to include a genuine contribution from the rapid dynamics of the shell / interface. Considering that the near-band edge luminescence of independent CsPbCl3 is typically on the 1 ns–3 ns timescale, this fast component can be reasonably interpreted as a shell / interface correlated rapid radiative recombination or rapid deactivation process, superimposed with a small amount of IRF convolution contribution. Therefore, the 410 nm channel does not reflect the single lifetime of pure CsPbCl3, but rather a complex dynamic process involving core self-bound excitons, shell exciton states, and core / shell interface coupling.

[0082] Unlike nanosecond-level self-bound exciton and shell / interface correlated luminescence, Mn at 600 nm... 2+ The luminescence exhibits typical millisecond-scale long lifetime decay behavior, which can be decomposed into two kinetic components with similar proportions: 1.48 ms and 28.75 ms. Previous studies have shown that Mn... 2+ In CsPbCl3, it typically exhibits a luminescence lifetime of approximately 1 ns to 2 ms, while in 0D Mn... 2+ In Cs4PbCl6, a longer lifetime of tens of milliseconds is observed. Therefore, these two decay components are highly consistent with the typical timescales of CsPbCl3-related sensitization and ODCs4PbCl6-related sensitization, respectively. Based on existing technology and combined with the aforementioned steady-state spectroscopy and PLE evidence, the 1.48 ms and 28.75 ms components can be reasonably attributed to CsPbCl3→Mn. 2+ and Cs4PbCl6→Mn 2+ Two types of sensitization processes. This indicates that Mn2+ In this composite system, the system is not excited by a single host, but rather receives power from both the shell and the zero-dimensional kernel. In other words, Mn 2+ More closely resembles the Cs4PbCl6 core, CsPbCl3 shell, and Mn 2+ The terminal low-energy radiation sink in a multi-level energy flow network. By combining lifetime results at three monitoring wavelengths (350 nm, 410 nm, and 600 nm), a relatively complete chain of kinetic evidence can be established: On the one hand, the significantly shortened exciton lifetime of the core-bound cells corresponds to approximately 54.4% of the excitation energy diversion, indicating the existence of effective nucleus-to-shell and nucleus-to-Mn energy dissipation pathways after the formation of the composite structure; on the other hand, the 410 nm channel significantly deviates from the typical lifetime range of independent CsPbCl3, indicating that the shell luminescence has been profoundly reshaped by interface coating, spectroscopic overlap, and continuous energy supply; furthermore, the two millisecond-level components at 600 nm further confirm the presence of Mn. 2+ The luminescence is simultaneously sensitized from both the shell and the zero-dimensional kernel. Therefore, Mn... 2+ Cs4PbCl6@CsPbCl3 is not a simple single-phase doped luminescent system, but a composite luminescent network with distinct interface coupling characteristics, dual-source energy supply behavior, and a multi-channel synergistic luminescence mechanism. Based on lifetime dynamics, the core self-bound exciton, shell exciton state, and Mn... 2+ The luminescent centers and cascaded sensitization evidence chain provide more direct experimental evidence for understanding the multi-center coupled luminescence and energy distribution mechanism in low-dimensional perovskite composite structures, which is also one of the important innovations of this invention.

[0083] Based on steady-state spectroscopy, concentration-dependent luminescence behavior, and time-resolved kinetic analysis, it is possible to establish, for example... Figure 8 The Mn shown 2+ A luminescence mechanism model of the Cs4PbCl6@CsPbCl3 composite system. The system consists of a Cs4PbCl6 core coated with a small amount of CsPbCl3 shell, with Mn introduced at the core / shell interface. 2+ The luminescent center. Since Cs4PbCl6 is a typical zero-dimensional perovskite, the electron-hole pairs generated after photoexcitation readily form self-bound excitons under strong localized lattice relaxation. Therefore, under high-energy excitation, the Cs4PbCl6 core first absorbs a photon, and the electron transitions from the valence band to the conduction band. Subsequently, it enters the self-bound exciton energy level through non-radiative relaxation and undergoes radiative recombination to produce near-ultraviolet emission hv1, around 350 nm. This process corresponds to the intrinsic luminescent channel of the core in the recombination system.

[0084] Meanwhile, the Cs4PbCl6 core and the surface CsPbCl3 shell do not simply coexist as two phases, but rather form an effective interfacial coupling at the contact interface. This interfacial coupling allows the core excitation energy to be partially transferred to the shell, rather than being limited to its own self-bound exciton radiation, thus achieving free exciton blue light emission hv2 (around 410 nm) in CsPbCl3. In other words, the luminescence of the CsPbCl3 shell not only includes its own exciton recombination contribution but is also sensitized by the interface from the Cs4PbCl6 core. Therefore, the shell-related luminescence kinetically deviates significantly from the typical intrinsic lifetime of independent CsPbCl3 nanocrystals, exhibiting effective decay behavior influenced by continuous energy supply and interfacial modulation. This result demonstrates that core-to-shell energy transfer is a key step in establishing a multi-channel luminescence network in this composite system.

[0085] Based on this, Mn 2+ The luminescent centers further act as a low-energy radiation sink in the entire system. (See figure for Mn). 2+ of 4 The T1 excited state can simultaneously accept two types of upstream energy input: one is direct sensitization from the self-bound excitons of the Cs4PbCl6 core, and the other is indirect sensitization from the CsPbCl3 shell. The former forms a nucleus-to-Mn channel, and the latter forms a shell-to-Mn channel. After these two types of energy transfer, Mn... 2+ The excited state eventually passes through 4 T1 direction 6 The A1 transition emits the characteristic orange-red emission hv3. Lifetime analysis further indicates that Mn 2+ The luminescence exhibits dual kinetic characteristics, correlated with both CsPbCl3 and zero-dimensional Cs4PbCl6, thus confirming the Mn luminescence at a kinetic level. 2+ The dual-source sensitization nature.

[0086] Therefore, the luminescence behavior in this composite system is not dominated by a single center, but rather by the self-bound excitons of the Cs4PbCl6 core, the CsPbCl3 shell, and Mn. 2+ A multi-level synergistic luminescence network composed of luminescent centers. Its energy flow path can be summarized as: core absorption and self-bound exciton formation, core-shell interface sensitization, and parallel energy supply from the core to Mn and from the shell to Mn. 2+ The terminal emits light. The Cs4PbCl6 core is responsible for high-energy light absorption and initial excited-state energy storage, the CsPbCl3 shell serves as an intermediate energy receiving and redistribution unit, and Mn... 2+ It then serves as the final low-energy radiation center. It is precisely this cascaded energy transfer mechanism driven by interface coupling that enables Mn... 2+ The Cs4PbCl6@CsPbCl3 system exhibits a multi-center, multi-channel synergistic luminescence characteristic that is significantly different from that of single-phase Mn-doped perovskites.

[0087] Existing core-shell perovskites typically employ CsPbX3 as the luminescent core and Cs4PbX6 as a wide-bandgap shell. The shell primarily serves to reduce surface defects, suppress nonradiative recombination, and improve the photoluminescence quantum efficiency and stability of the material; essentially, it represents a technology centered on shell passivation. However, the manganese-doped lead chloride perovskite heteroluminescent material prepared in this invention uses Cs4PbCl6 as the core, with a CsPbCl3 shell or island-like interface layer formed in situ on its surface, and Mn... 2+ A composite heterostructure distributed across the core, shell, and / or core-shell interface region. In this structure, the surface CsPbCl3 does not merely function as a passive protective layer, but rather interacts with the core and Mn. 2+ The luminescent centers collectively constitute the functional interface layer for luminescence and energy transfer, thus forming a multi-center coupled luminescent structure, where the surface CsPbCl3 plays both the role of interface coupling and luminescence participation. Therefore, the core-shell structure of the manganese-doped lead chloride perovskite heteroluminescent material in this invention is fundamentally different from the conventional core-shell structure of luminescent core / passivation shell formed in the prior art.

[0088] In terms of preparation mechanism, existing technologies mostly obtain the core-shell structure of materials through conventional epitaxial growth or coating methods. However, this invention emphasizes that, under the condition that the overall reaction system is designed according to the tendency of Cs4PbCl6 formation, MnCl2 participates in the system evolution from the initial stage of the reaction, and on the one hand, it serves as a source of Mn to provide Mn. 2+ Doping, introducing Mn 2+ Related orange-red light emission centers; on the other hand, by influencing the subsequent local component distribution and surface structure evolution, they induce local phase transitions or surface reconstructions on the surface of already formed or forming Cs4PbCl6 nanocrystals, thereby forming a small amount of CsPbCl3 shells or island-like interface layers on their surface.

[0089] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0090] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing a manganese-doped lead chloride perovskite heteroluminescent material, characterized in that, Includes the following steps: Using oleic acid and oleylamine as ligand solutions, PbCl2, cesium oleate solution, manganese source and ligand solution were mixed to obtain precursor solution; The precursor solution was subjected to a solvothermal reaction at 160℃~170℃ to form a core of Cs4PbCl6, while Mn 2+ Partial doping with Cs4PbCl6 was used to induce the formation of a CsPbCl3 shell or island-like interface layer on the core surface, resulting in a manganese-doped lead chloride perovskite heteroluminescent material. The molar amount of cesium ions in cesium oleate solution is 4 times the molar amount of lead ions in PbCl2. The molar ratio of manganese ions in the manganese source to lead ions in PbCl2 is 0.5–2:1; The volume ratio of PbCl2 to ligand solution is 1 mmol: 55 mL to 66 mL, and the volume ratio of oleic acid to oleylamine is 1:

10.

2. The method for preparing the manganese-doped lead chloride perovskite heteroluminescent material according to claim 1, characterized in that, The precursor solution is prepared by mixing PbCl2, manganese source and oleylamine as ligand solutions, and then adding cesium oleate solution to obtain the precursor solution.

3. The method for preparing the manganese-doped lead chloride perovskite heteroluminescent material according to claim 1, characterized in that, The solvothermal reaction time is 0.5 h to 2.5 h.

4. The method for preparing the manganese-doped lead chloride perovskite heteroluminescent material according to claim 1, characterized in that, The manganese source is MnCl2.

5. The method for preparing the manganese-doped lead chloride perovskite heteroluminescent material according to claim 1, characterized in that, The method for preparing cesium oleate solution is as follows: cesium carbonate, oleic acid and solvent are mixed and a neutralization reaction is carried out to obtain cesium oleate solution.

6. The method for preparing the manganese-doped lead chloride perovskite heteroluminescent material according to claim 5, characterized in that, The ratio of cesium carbonate, oleic acid, and solvent is 1 mmol: 2 mL to 3 mL: 16 mL to 20 mL, and the solvent is octadecene.

7. The method for preparing the manganese-doped lead chloride perovskite heteroluminescent material according to claim 1, characterized in that, The neutralization reaction temperature is 150℃~160℃, and the neutralization reaction time is 1h~2h.

8. A manganese-doped lead chloride perovskite heteroluminescent material, characterized in that, The manganese-doped lead chloride perovskite heteroluminescent material was prepared using the preparation method described in any one of claims 1 to 7.

9. The application of the manganese-doped lead chloride perovskite heteroluminescent material of claim 8 in the preparation of ultraviolet-excited luminescent materials, wavelength conversion materials or optoelectronic display functional materials.

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