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KR-20260067983-A - PEROVSKITE POLYCRYSTALLINE THIN FILM WITH CONTROLLED CRYSTAL SIZE, MANUFACTURING METHOD THEREOF, AND LASER CONTAINING THE SAME

KR20260067983AKR 20260067983 AKR20260067983 AKR 20260067983AKR-20260067983-A

Abstract

The present invention relates to a perovskite polycrystalline thin film with controlled crystal size, a method for manufacturing the same, and a laser including the same. The perovskite polycrystalline thin film according to the present invention induces continuous growth of perovskite crystals by stabilizing the nucleation and crystal growth processes using polar polymers, and can continuously and precisely control the final crystal size by controlling the final heat treatment temperature of the process, thereby maximizing lasing efficiency. It also forms a uniform surface with almost no surface roughness and possesses excellent luminescence characteristics with a luminescence efficiency reaching 40%. Furthermore, the perovskite polycrystalline thin film of the present invention may enable additional improvement in luminescence efficiency due to the passivation effect generated by the polar polymers. Additionally, the method for manufacturing the perovskite polycrystalline thin film according to the present invention allows for the control of perovskite crystal grain size through a simple process, thereby reducing manufacturing costs and shortening manufacturing time. Furthermore, the laser according to the present invention includes the aforementioned perovskite polycrystalline thin film, thereby maximizing lasing efficiency, allowing for precise control of the wavelength, and possessing excellent luminescence efficiency.

Inventors

  • 이태우
  • 김혜리
  • 장경연

Assignees

  • 서울대학교산학협력단

Dates

Publication Date
20260513
Application Date
20251016
Priority Date
20241106

Claims (17)

  1. A perovskite polycrystalline thin film characterized by comprising a polar polymer in a perovskite precursor and forming it by coating it onto a substrate through a solution process, wherein no intermediate phase is formed from the perovskite precursor during the coating and drying process, and the precursor is formed by directly growing into perovskite crystals through heat treatment.
  2. A thin film according to claim 1, characterized in that the perovskite polycrystalline structure comprises an ABX3 structure. The above A is a monovalent organic cation, a monovalent inorganic cation, or a combination thereof, and The above B is a divalent metal ion, and The above X is F- , Cl- , Br- , I- , SCN- , OCN- , SeCN- , HCO2- , CH3COO- , or a combination thereof.
  3. A thin film according to claim 1, characterized in that the average grain size of the perovskite crystal is 10 nm to 70 nm.
  4. A thin film according to claim 1, characterized in that the peak wavelength of the emission spectrum of the perovskite crystal is 450 nm to 800 nm.
  5. A thin film according to claim 1, characterized in that the peak wavelength of the emission spectrum of the perovskite crystal can be controlled in the visible light to near-infrared (Vis-NIR) region by changing the type of halide of the perovskite crystal.
  6. A thin film according to claim 1, characterized in that the peak wavelength of the emission spectrum of the perovskite crystal can be finely changed within a wavelength shift range of 1 nm to 30 nm by changing the grain size of the perovskite crystal.
  7. A thin film according to claim 1, characterized in that the polar polymer delays the crystallization rate of the perovskite.
  8. A thin film according to claim 1, characterized in that the polar polymer enables stabilization of the crystal growth process and control of crystal size according to the heat treatment temperature.
  9. A thin film according to claim 1, characterized in that delayed crystallization is completed by heat treatment, and the crystal size can be controlled according to the heat treatment temperature.
  10. A thin film according to claim 1, characterized in that the polar polymer is dissolved in the same solvent together with the perovskite precursor.
  11. A thin film according to claim 1, characterized in that the polar polymer is prepared from a mixture containing 1 to 50 parts by weight.
  12. A thin film according to claim 1, characterized in that the polar polymer is polyvinylpyrrolidone (PVP).
  13. A method for manufacturing a perovskite polycrystalline thin film characterized by preparing a mixture containing a perovskite precursor solution and a polar polymer, forming a perovskite liquid film on a substrate using a solution process with said mixture, and then heat-treating said liquid film to delay the crystallization of the perovskite polycrystalline thin film and control the crystal size, and to prevent the formation of an intermediate phase from the perovskite precursor.
  14. In the manufacturing method according to claim 13, A manufacturing method characterized in that the above solution process is spin coating, blade coating, slot die coating, printing coating, or spray coating.
  15. A manufacturing method according to claim 13, characterized in that the heat treatment is performed at a temperature of 50°C to 250°C for 3 seconds to 1 hour.
  16. A method for manufacturing according to claim 13, wherein the solvent of the mixture is any one of dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), γ-butyrolactone (GBL), N-methyl-2-pyrrolidone (NMP), acetonitrile, or a combination thereof.
  17. A laser element characterized by comprising a thin film according to any one of claims 1 to 12, or a thin film manufactured by a manufacturing method according to any one of claims 13 to 16.

Description

Perovskite polycrystalline thin film with controlled crystal size, manufacturing method thereof, and laser containing the same The present invention relates to a perovskite polycrystalline thin film with controlled crystal size, a method for manufacturing the same, and a laser including the same. More specifically, the invention relates to a perovskite polycrystalline thin film in which the crystal size can be continuously controlled to adjust the wavelength and maximize lasing efficiency, a method for manufacturing a perovskite polycrystalline thin film in which the size of bromine-based perovskite crystal grains can be controlled through a simple spin coating process by adding a polar polymer, and a laser including the same. In the present invention, the term "laser" refers to a case in which the FWHM of the emission spectrum is sufficiently narrow (less than 10 nm) compared to a general emission spectrum, and a critical point phenomenon is observed in which, at the moment the pump intensity is increased and a specific threshold is exceeded, the increase in emission intensity according to the pump intensity increases compared to when the threshold is not exceeded. This includes all cases where amplification phenomena occur due to stimulated luminescence in the material from the perspective of operating principles. It may additionally include, but is not necessarily the case, enhancement of coherence through feedback of the optical structure. In the present invention, the laser exists in the form of a thin film on a substrate with high transmittance, and after being excited by energy injected by an external light source, it generates a lasing phenomenon. Lasers in the visible light band provide high color purity through the narrow linewidth characteristic of laser light sources and can emit high-brightness light; furthermore, when integrated with optical structures, they can deliver light with high directivity, making them ideal light sources for future display technologies such as AR/VR displays. Perovskite lasers possess high gain values in the visible light wavelength range, allow for low-cost fabrication and wavelength tuning, can be grown regardless of the substrate, and are suitable for the fabrication of chip-based devices; as such, they are important materials that can be developed as light sources for future displays. Perovskites exhibit excellent properties not only in lasers but also in solar cells and light-emitting diodes (LEDs). In this context, the crystal size of the perovskite significantly influences its luminescence characteristics. Perovskites in the form of small nanoparticles display high luminescence efficiency due to strong quantum confinement effects, whereas in large polycrystalline or single-crystal perovskites, quantum confinement effects are reduced, allowing excitons to easily separate into free electrons and holes at room temperature. This provides advantageous characteristics for operating solar cells that require the extraction of electrons and holes. The influence of perovskite crystal size on perovskite emissive layers for lasers has not yet been clearly elucidated. However, to maximize the lasing effect, charge loss due to Auger recombination at high charge densities must be minimized; in this regard, a larger crystal size than a small one (10–20 nm) may be preferable. Conversely, to maximize the lasing effect, non-radiative coupling must be minimized; in this regard, a smaller crystal size than a large one (>50 nm), which has a relatively low luminescence efficiency due to a low electron-hole recombination probability, may be preferable. Perovskite nanoparticles synthesized by a general nanoparticle synthesis process have a size of about 10 nm or less, whereas, conversely, general polycrystalline perovskite films have a size of about 100 nm or more unless subjected to a special process. On the other hand, by continuously producing perovskites with a size between 10 nm and 70 nm through this process, the disadvantages of the two perovskites are appropriately offset and the advantages are maximized, thereby achieving the most efficient perovskite raising with the most efficient size. Perovskites possess the characteristic of being able to freely control wavelengths across a wide range, extending from blue, green, red, to near-infrared regions, by adjusting the halide ratio. Additionally, this manufacturing method allows for precise wavelength adjustment in increments of several nanometers by continuously controlling the size of the perovskite crystals. After determining the approximate wavelength range through halide ratio adjustment, this manufacturing method can be utilized to precisely match the emission wavelength to the desired wavelength. By using this method, precise wavelength adjustment can be easily achieved during the fabrication process without the need for detailed halide ratio control during the mixing stage. Conventional nanoparticle synthesis processes sta