A lead-free halide perovskite luminescent material and its preparation method

Abstract

This invention relates to the field of lead-free halide perovskite luminescent materials, specifically to a lead-free halide perovskite luminescent material and its preparation method, wherein the CsBr x Cl 1‑x Eu 2+ The preparation method of lead-free halide perovskite is as follows: raw materials CsBr, Eucl3, anhydrous ethanol, and tri-n-octylphosphine (TOP) are placed into a polytetrafluoroethylene liner and mixed. The mixture is stirred for one hour to ensure thorough and uniform mixing. Finally, the polytetrafluoroethylene liner is placed in the cylinder sleeve of a reaction vessel and placed in an oven for reaction. After the reaction is completed, the mixture is slowly cooled to room temperature in the oven. After cleaning with anhydrous ethanol and drying, lead-free zero-dimensional perovskite material is obtained. The prepared lead-free halide perovskite material can emit blue light under 365nm excitation and emit blue light with blue afterglow under X-ray irradiation, which can be used for real-time imaging and time-lapse imaging.

Description

Technical Field

[0001] This invention relates to the field of lead-free halide perovskite luminescent materials, specifically to a lead-free halide perovskite luminescent material and its preparation method. Background Technology

[0002] In the past decade of materials science and optoelectronics research, lead-based halide perovskite materials have attracted much attention due to their excellent photoelectric properties. These materials exhibit unique advantages, such as high photoluminescence quantum yield (PLQY), narrow spectral bandwidth, high color purity, excellent carrier mobility, and simple and low-cost solution processing characteristics. As a result, lead-based perovskites have rapidly gained a foothold in fields such as solar cells, light-emitting diodes (LEDs), photodetectors, and lasers.

[0003] However, as the performance of these materials continues to improve in laboratory environments, attention has also been paid to their long-term stability and environmental compatibility in practical applications. A significant drawback of lead-based perovskite materials is their poor chemical stability; they are prone to degradation when exposed to external environments such as air, moisture, or light. This not only affects device performance but also limits their application under unfavorable environmental conditions.

[0004] Furthermore, lead, as a heavy metal, presents another significant challenge due to its toxicity and the resulting environmental problems. Lead intake is harmful to human health, causing damage to the nervous system, with particularly pronounced effects on children. Simultaneously, the environmental risks posed by lead pollution to soil and water sources subject the commercial application of lead-based materials to stringent legal and social constraints. Against the backdrop of increasing global emphasis on sustainable development and environmental protection, the development of lead-free alternatives has become an important and urgent research topic.

[0005] Faced with these challenges, researchers have begun actively exploring lead-free halide perovskite materials, hoping to achieve similar optoelectronic properties with minimal environmental impact. For example, elements such as antimony (Sb) and bismuth (Bi) are considered potential alternatives to lead due to their potentially lower toxicity and abundant crustal reserves. Meanwhile, the introduction of elements such as magnesium (Mg), rubidium (Rb), and cesium (Cs) has also shown varying degrees of potential. However, the efficiency and stability performance of these lead-free materials still fall short of the requirements for practical applications, especially in optoelectronic devices that demand high color purity and high stability.

[0006] In summary, existing technologies present significant shortcomings and challenges in achieving both environmentally friendly and high-performance materials. This necessitates the development of a lead-free perovskite material system that possesses both high photoelectric performance and meets environmental and health requirements. Against this backdrop, halide perovskite materials doped with Eu (europium), especially CsBr, have become increasingly important.x Cl 1-x Eu 2+ Research has emerged in response to this need. This material not only possesses excellent luminescent properties, but also offers promising improvements in environmental friendliness and stability.

[0007] This invention prepares a CsBr x Cl 1-x Eu 2+ Lead-free halide perovskite luminescent materials possess ultra-long photoluminescence lifetime, high transparency, high PLQY, and X-ray induced color-changing properties, and have the potential to be applied in a wide range of fields such as backlight LEDs, scintillators, X-ray detection, and 3D encryption and anti-counterfeiting. Summary of the Invention

[0008] The purpose of this invention is to provide a lead-free halide perovskite luminescent material and its preparation method, which uses the photochromic time generated by X-ray irradiation to achieve dual-mode imaging, either real-time or time-lapse, providing new ideas and directions for the application of perovskite materials in the field of optoelectronics.

[0009] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0010] A lead-free halide perovskite luminescent material, wherein the luminescent material is a lead-free zero-dimensional perovskite material with the chemical formula CsBr x Cl 1-x Eu 2+ , where 0≤x≤1.

[0011] Furthermore, x = 0.9.

[0012] Furthermore, the CsBr x Cl 1-x Eu 2+ Lead-free halide perovskite luminescent materials can emit blue light when excited at 365 nm and when irradiated with X-rays, accompanied by a blue afterglow.

[0013] On the other hand, the present invention proposes a method for preparing the above-mentioned luminescent material, comprising the following steps:

[0014] S1: Add CsBr and EuCl3 to the tetrafluoroethylene liner and mix to obtain product A;

[0015] S2: Next, anhydrous ethanol and TOP are added to the mixture obtained in step S1 and stirred thoroughly until they are mixed evenly to obtain mixture B;

[0016] S3: Place the mixture B obtained in step S2 into an oven for reaction. After cooling to room temperature, remove the liquid from the polytetrafluoroethylene liner, wash the bottom powder lumps with anhydrous ethanol, and dry to obtain CsBr. x Cl 1-x Eu 2+ Lead-free halide perovskite luminescent materials.

[0017] Furthermore, in step S1, the mass ratio of CsBr to EuCl3 is CsBr:EuCl3=3:1.

[0018] Furthermore, in step S2, the volume amounts of TOP and anhydrous ethanol added are 3 ml of TOP and 7 ml of anhydrous ethanol, respectively.

[0019] Furthermore, in step S3, the reaction conditions in the oven are 180°C for 12 hours.

[0020] On the other hand, this invention proposes the application of the above-mentioned luminescent materials and their preparation methods in real-time imaging and time-lapse imaging.

[0021] The beneficial effects of this invention are:

[0022] The material proposed in this invention is significantly superior to traditional lead-based perovskite materials in terms of environmental friendliness and safety. Lead, as a heavy metal, poses a significant threat to human health and the environment with long-term exposure; its toxicity can cause damage to the nervous system, especially severe in children. This invention utilizes CsBr... x Cl 1-x Eu 2+ The material completely avoids the use of lead, instead using europium (Eu) as a dopant. Eu has low toxicity and is abundant in the Earth's crust, ensuring the material's environmental friendliness and sustainability. Therefore, the material's environmental impact during production, use, and disposal is significantly reduced, making it more valuable in today's increasingly stringent environmental regulations.

[0023] Secondly, this material exhibits excellent optoelectronic properties, especially its potential applications in amplifiers and light-emitting devices. CsBr x Cl 1-x Eu 2+ The material emits highly efficient blue light when excited by 365nm ultraviolet light and exhibits blue light and blue afterglow under X-ray irradiation. Its high PLQY (photoluminescence quantum yield) means that the material can effectively convert a large amount of incident light energy into visible light under photoexcitation, becoming a highly efficient light source. Thanks to its unique chemical structure and doping elements, the material's band structure is optimized and carrier mobility is improved, making the photoelectric conversion process more efficient and meeting the stringent requirements of modern optoelectronic devices for improved light output and efficiency.

[0024] The CsBr proposed in this invention x Cl 1-x Eu 2+ The material's ultralong photoluminescence lifetime provides a technological foundation for applications such as time-lapse imaging and night-light displays. This phenomenon originates from crystal defects and the formation of their recombination states within the material, effectively suppressing non-radiative recombination and thus extending the luminescence time. Optimized synthesis conditions (such as reaction temperature and time) promote a more stable crystal structure, reducing energy loss at the luminescent centers and enabling the luminescent state to be maintained for an extended period after excitation. This characteristic allows the material to significantly improve user experience and functionality in night-light applications and other devices requiring continuous light emission.

[0025] Meanwhile, the photochromic properties exhibited by this material provide an innovative solution for real-time and time-lapse imaging technologies. Under X-ray irradiation, CsBr x Cl 1-x Eu 2+ The material can achieve photochromism through specific physicochemical changes, creating unique imaging effects. This characteristic is mainly due to the electron transfer process and energy transfer mechanism within the material, enabling it to exhibit different optical properties under different excitation conditions. Combining real-time and time-lapse imaging in dual-mode applications can open up new application scenarios in fields such as medical imaging, security monitoring, and high-tech display devices. Based on the material's inherent tunability and flexible application, its practical application in cutting-edge technologies is further promoted.

[0026] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 CsBr:Eu 2+ Crystal structure diagram of lead-free halide perovskite materials.

[0029] Figure 2 CsBr:Eu 2+ X-ray diffraction (XRD) data of lead-free halide perovskite materials.

[0030] Figure 3 CsBr:Eu 2+Scanning electron microscopy (SEM), elemental distribution mapping, and atomic ratio of lead-free halide perovskite materials.

[0031] Figure 4 CsBr:Eu 2+ Excitation and emission spectra of lead-free halide perovskite materials. The optimal emission peak is deep blue emission at 442 nm.

[0032] Figure 5 CsBr:Eu 2+ Lead-free halide perovskite materials exhibit a PLQY of up to 92.3% under 365 nm excitation.

[0033] Figure 6 CsBr:Eu 2+ Light yield of lead-free halide perovskite materials. From the graph, we can clearly see that the light yield of CECB is higher than that of commercial powders.

[0034] Figure 7 CsBr:Eu 2+ The stability of lead-free halide perovskite materials remained essentially unchanged after one hour of X-ray irradiation.

[0035] Figure 8 CsBr:Eu 2+ A photograph of lead-free halide perovskite material after being ground into powder and pressed into tablets by a machine, under X-ray irradiation.

[0036] Figure 9 CsBr:Eu 2+ A photograph of the attenuation of lead-free halide perovskite material after 5 minutes of X-ray irradiation. Detailed Implementation

[0037] 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. Example 1

[0038] This embodiment describes a CsBr x Cl 1-x Eu 2+ A lead-free halide perovskite luminescent material was prepared with CsBr and EuCl3 in a molar ratio of CsBr:EuCl3 = 3:1. 7 ml of anhydrous ethanol and 3 ml of TOP were added. The specific preparation steps are as follows:

[0039] S1: CsBr and EuCl3 were added to the tetrafluoroethylene liner according to the proportion and mixed to obtain product A.

[0040] S2: Add anhydrous ethanol and TOP to mixture A from step S1, and stir thoroughly to obtain mixture B.

[0041] S3: Place the mixture B obtained in step S2 into an oven and keep it at 180℃ for 12 hours. After cooling to room temperature, wash and dry it with anhydrous ethanol to obtain CsBr. x Cl 1-x Eu 2+ Lead-free halide perovskite luminescent materials.

[0042] As shown in Table 1, CsBr x Cl 1-x Eu 2+ Distribution map of lead-free halide perovskite materials (total number spectrum)

[0043] element signal type Wire Wt% Wt%Sigma At% P EDS K-line system 0.34 0.04 0 Cl EDS K-line system 8.49 0.05 13.20 Br EDS L-line system 21.19 0.11 35.70 Cs EDS L-line system 59.34 0.16 44.32 Eu EDS L-line system 10.64 0.17 6.78 Total 100.00 100.00

[0044] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a lead-free halide perovskite luminescent material, characterized in that, The luminescent material is a lead-free zero-dimensional perovskite material with the chemical formula CsBr. x Cl 1-x Eu 2+ The method for preparing the luminescent material includes the following steps: S1: Add CsBr and EuCl3 to the tetrafluoroethylene liner and mix to obtain product A; S2: Next, anhydrous ethanol and TOP are added to the mixture obtained in step S1 and stirred thoroughly until they are mixed evenly to obtain mixture B; S3: Place the mixture B obtained in step S2 into an oven for reaction. After cooling to room temperature, remove the liquid from the polytetrafluoroethylene liner, wash the bottom powder lumps with anhydrous ethanol, and dry to obtain CsBr. x Cl 1-x Eu 2+ Lead-free halide perovskite luminescent materials; In step S1, the mass ratio of CsBr to EuCl3 is CsBr:EuCl3 = 3:1; In step S2, the volumetric amounts of TOP and anhydrous ethanol added are 3 ml of TOP and 7 ml of anhydrous ethanol, respectively. In step S3, the reaction conditions in the oven are 180°C for 12 hours.

2. The lead-free halide perovskite luminescent material prepared by the preparation method described in claim 1.

3. The lead-free halide perovskite luminescent material as described in claim 2, characterized in that: The lead-free halide perovskite luminescent material emits blue light under 365nm excitation and under X-ray irradiation, accompanied by a blue afterglow.

4. The application of the luminescent material as described in claim 2 or 3 in real-time imaging and time-lapse imaging.

Images