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CN-121992500-A - All-inorganic lead-free two-dimensional perovskite single crystal and preparation method and application thereof

CN121992500ACN 121992500 ACN121992500 ACN 121992500ACN-121992500-A

Abstract

The invention relates to the technical field of photoelectric detectors and semiconductor materials, and particularly provides an all-inorganic lead-free two-dimensional perovskite monocrystal, and a preparation method and application thereof. The invention fundamentally changes the crystallization kinetics and the surface state of the lead-free two-dimensional perovskite by introducing the N-ethyl-N-methylpiperidine iodized salt and then combining the improved cooling crystallization means of firstly quick and secondly slow and introducing the seed crystal, and solves the problems of low crystal quality, poor X-ray detection and poor visible light detection device performance of the lead-free two-dimensional perovskite caused by poor growth controllability and more surface defects. The obtained monocrystal has large size, low defect density and smooth surface, and is favorable for electrode contact and carrier extraction. The performance of the detector based on the monocrystal is greatly improved (the sensitivity of the X-ray detector reaches about 60000 mu C-Gy ‑1 ·cm ‑2 , the responsivity of the visible light dual-mode detector exceeds 4000mA/W, and the response speed is within 1 ms).

Inventors

  • LAI ZHENGXUN
  • PENG XIN
  • MENG YOU

Assignees

  • 长沙半导体技术与应用创新研究院

Dates

Publication Date
20260508
Application Date
20260212

Claims (10)

  1. 1. The full-inorganic lead-free two-dimensional perovskite single crystal is characterized by having a chemical general formula of A 3 B 2 X 9 , wherein A is Rb or Cs, B is Sb or Bi, C is I or Br, the defect density of the full-inorganic lead-free two-dimensional perovskite single crystal is less than 10 9 cm -3 , ra is less than 1nm, the area is 3mm multiplied by 6mm-5mm multiplied by 12mm, and the thickness is 1-3mm.
  2. 2. A method for preparing an all-inorganic lead-free two-dimensional perovskite single crystal according to claim 1, comprising the steps of: S1, mixing weighed A 2 CO 3 、B 2 O 3 and N-ethyl-N-methylpiperidine iodized salt, adding halogen acid, stirring at 120-150 ℃ for reaction for 1-4 hours, and adding hypophosphorous acid to control the crystallization process to obtain saturated precursor solution; and S2, filtering the saturated precursor solution, placing the solution in a sealed environment, controlling the temperature to a supersaturated state through a program, introducing seed crystals, slowly cooling and crystallizing, removing residual mother liquor on the surface, and drying to obtain the all-inorganic lead-free two-dimensional perovskite single crystal.
  3. 3. The method for preparing an all-inorganic lead-free two-dimensional perovskite single crystal according to claim 2, wherein in the step S1, the amount of A 2 CO 3 is 3-4mmol, the amount of B 2 O 3 is 1.5-3mmol, the amount of halogen acid is 10-15mL, the amount of N-ethyl-N-methylpiperidine iodide salt is 0.1-0.3mmol, and the amount of hypophosphorous acid is 0.2-0.6mL.
  4. 4. The method for preparing an all-inorganic lead-free two-dimensional perovskite single crystal according to claim 2, wherein in the step S2, the temperature is reduced to a solution supersaturation state at a temperature of 1-2 ℃ per hour, the slow temperature reduction rate is 0.2-0.5 ℃ per hour, and the total temperature reduction time is 7-14 days.
  5. 5. The method for preparing an all-inorganic lead-free two-dimensional perovskite single crystal according to claim 2, wherein in the step S2, the drying temperature is 50-70 ℃ and the time is 2-4h.
  6. 6. An X-ray detector based on the all-inorganic lead-free two-dimensional perovskite single crystal according to claim 1.
  7. 7. The X-ray detector of an all-inorganic lead-free two-dimensional perovskite single-crystal according to claim 6, wherein the X-ray detector has a vertical structure and is composed of an electrode, the all-inorganic lead-free two-dimensional perovskite single-crystal and an electrode in this order from top to bottom.
  8. 8. An all-inorganic lead-free two-dimensional perovskite single-crystal X-ray detector according to claim 6, wherein the sensitivity of the X-ray detector is up to 60000 μc-Gy -1 ·cm -2 .
  9. 9. A dual-mode detector of visible light based on the all-inorganic lead-free two-dimensional perovskite single crystal of claim 1.
  10. 10. The visible light dual-mode detector of the all-inorganic lead-free two-dimensional perovskite single crystal according to claim 9, wherein the visible light dual-mode detector is of a horizontal structure, the responsivity exceeds 4000mA/W, and the response speed is within 1 ms.

Description

All-inorganic lead-free two-dimensional perovskite single crystal and preparation method and application thereof Technical Field The invention relates to the technical field of photoelectric detectors and semiconductor materials, in particular to an all-inorganic lead-free two-dimensional perovskite monocrystal, and a preparation method and application thereof. Background In recent years, perovskite materials have received a great deal of attention in the field of X-ray and visible light detection. However, the prior art still has the outstanding problems that the lead-based perovskite has excellent performance, but the biotoxicity of lead limits the application of the lead-based perovskite in human body contact scenes such as medical images, and the like, the organic components in the organic-inorganic hybrid perovskite are easy to be influenced by heat, light and moisture, so that the device has poor stability and short service life, and the lead-free two-dimensional perovskite (such as A 3B2X9) has the environment-friendly performance, but the device performance is far inferior to that of the lead-based perovskite, and the bottleneck is that the crystal quality is poor, and the method is characterized in that (1) the growth controllability is poor, large-size single crystals, usually only millimeter-sized fragments, are difficult to obtain by a traditional method, the surface roughness is larger than 10nm, the electrode contact is influenced, and the carrier extraction efficiency is reduced, and (3) the defect density is high, the defect density is higher than 10 11cm-3, so that serious non-radiative recombination is caused. In the prior art, general quaternary ammonium salt is mostly adopted for passivation, but the molecular structure and the crystal surface of the quaternary ammonium salt are poor in adaptability, the passivation effect is limited, and insulating impurities can be possibly introduced. These structural defects directly result in low detector responsivity (below 500 mA/W), slow response speed (greater than 100 ms), and poor stability. Therefore, the development of a special additive capable of synchronously regulating and controlling the crystallization process and the surface state from the growth source is a key for breaking through the performance bottleneck of the lead-free perovskite. Based on the above, the invention designs an all-inorganic lead-free two-dimensional perovskite single crystal, and a preparation method and application thereof. Disclosure of Invention The invention provides an all-inorganic lead-free two-dimensional perovskite single crystal and a preparation method and application thereof, and aims to solve the problems existing in the background art. In order to achieve the above purpose, the embodiment of the invention provides an all-inorganic lead-free two-dimensional perovskite single crystal, and a preparation method and application thereof. The invention uses N-ethyl-N-methyl piperidine iodized salt as surface passivating agent, and combines the improved cooling crystallization means of quick-speed-after-slow-speed-and seed crystal introduction, thus fundamentally changing the crystallization kinetics and surface state of lead-free two-dimensional perovskite and successfully preparing high-quality all-inorganic lead-free 329 type perovskite single crystal. Successfully solves the problems of low crystal quality, and poor performance of X-ray detection and visible light detection devices caused by poor growth controllability and a large number of surface defects of the lead-free two-dimensional perovskite. Compared with the traditional linear alkyl ammonium salt or aromatic ammonium salt, the cyclic piperidine cation of the N-ethyl-N-methyl piperidine iodized salt has rigid space configuration and moderate volume, can be more effectively and selectively adsorbed on a specific crystal face, obviously changes the surface energy, promotes the preferential growth of crystals along a two-dimensional plane, and has better interaction with halogen vacancies and metal dangling bonds on the surfaces of the crystals, thereby realizing efficient intrinsic passivation and reducing the surface defect state density. An aspect of the embodiment of the invention provides an all-inorganic lead-free two-dimensional perovskite single crystal, which has a chemical general formula of A 3B2X9, wherein A is Rb or Cs, B is Sb or Bi, C is I or Br; The all-inorganic lead-free two-dimensional perovskite monocrystal has large size, low defect density and smooth surface, wherein the area is 3mm multiplied by 6mm-5mm multiplied by 12mm, the thickness is 1-3mm, the defect density is less than 10 9cm-3, and the Ra is less than 1nm. More preferably, the area is 5mm by 12mm and the thickness is 3mm. In one aspect of the embodiment of the invention, there is also provided a method for preparing the above all-inorganic leadless two-dimensional perovskite single crystal, comprising the following