A 2fp vapor post-treatment method for transferring perovskite nanocrystal thin films

Abstract

The application provides a 2FP vapor post-treatment method for a perovskite nanocrystal film, which comprises the following steps: placing a perovskite nanocrystal film formed on a receptor substrate by transfer into a sealed container, introducing 2-fluorothiophenol into the sealed container, making the 2-fluorothiophenol volatilize to form a vapor, and post-treating the transferred perovskite nanocrystal film under the condition that the 2-fluorothiophenol does not directly contact the perovskite nanocrystal film in liquid form. The specific post-treatment additive is used to improve the interface quality of the transferred perovskite nanocrystal film without introducing liquid direct contact, so as to improve the morphology uniformity of the film and the photoelectric performance of the film.

Description

Technical Field

[0001] This invention belongs to the field of post-processing technology for transfer perovskite nanocrystalline thin films, and particularly relates to a 2FP steam post-processing method for transfer perovskite nanocrystalline thin films. Background Technology

[0002] As display technology continues to advance towards higher resolution, miniaturization, and higher color purity, achieving high-precision patterning of luminescent materials has become one of the key technical challenges in the development of next-generation display devices. Perovskite nanocrystals, with their advantages of high luminescent color purity, tunable emission wavelength, and good solution processability, show significant application potential in fields such as light-emitting diodes.

[0003] In the fabrication of perovskite nanocrystal light-emitting devices, traditional spin-coating processes typically rely on solvent systems to construct multi-layer structures. However, due to solvent compatibility issues between different functional layers, it is difficult to achieve layer-by-layer integration of multi-color light-emitting layers, limiting its application in high-resolution displays. Therefore, dry transfer printing technology based on elastomeric media has gradually become an important alternative. This method achieves high-precision integration of different light-emitting layers by avoiding direct solvent interaction.

[0004] The inventors disclosed a method for transferring perovskite quantum dots in Chinese patent application CN118574485A. This method uses polydimethylsiloxane (PDMS) as the transfer medium. First, a perovskite quantum dot film formed on a donor substrate is contacted and peeled off onto the PDMS surface. Then, the quantum dot film is transferred from the PDMS to the acceptor substrate, thereby achieving the transfer of the quantum dot film. This method, by controlling the adhesion work between different interfaces, achieves effective transfer of perovskite quantum dot films at relatively low temperatures while maintaining good optical properties.

[0005] Although the above transfer method can achieve high-precision transfer of perovskite nanocrystalline thin films, it still has the following problems: Since this method is a solid-phase contact transfer process, there are often microscale interface discontinuities or insufficient contact between the transferred perovskite nanocrystalline thin film and the underlying functional layer (such as the hole transport layer), resulting in weak interface coupling, which in turn affects the injection and transport efficiency of charge carriers, and ultimately causes a decrease in the light-emitting performance of the device.

[0006] To address the aforementioned issues, existing technologies have attempted to improve interfacial contact through solvent rinsing (such as ethyl acetate treatment). However, such methods inevitably introduce liquid solvents into direct contact with perovskite nanocrystals, easily damaging their structure and surface ligands, leading to deterioration of luminescent properties. This also weakens the advantage of dry transfer printing in avoiding solvent interference. Therefore, how to effectively post-process the transferred perovskite nanocrystal film without introducing direct liquid solvent contact to improve film morphology and interfacial contact, and enhance its photoelectric properties, has become a pressing technical problem to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a 2FP vapor post-treatment method for transfer perovskite nanocrystalline thin films. By using specific post-treatment additives, the interface quality of the transfer perovskite nanocrystalline thin films can be improved without introducing direct liquid contact, thereby improving the morphological uniformity and photoelectric properties of the films.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is: a 2FP vapor post-treatment method for transfer perovskite nanocrystalline thin films, comprising placing a perovskite nanocrystalline thin film transferred onto a host substrate in a sealed container, introducing 2-fluorothiophenol into the sealed container, causing the 2-fluorothiophenol to volatilize and form vapor, and performing post-treatment on the transfer perovskite nanocrystalline thin film under the condition that the 2-fluorothiophenol does not directly contact the perovskite nanocrystalline thin film in liquid.

[0009] In the above, the 2-fluorothiophenol has a low boiling point (about 61-62°C) and can form a stable vapor environment under mild conditions. The synergistic effect of the ortho-fluorine substituent and the mercapto group in its molecule can induce the reconstruction of the surface ligands and particle arrangement of perovskite nanocrystals, thereby improving the interface quality of the thin film.

[0010] Furthermore, the 2-fluorothiophenol is dripped into the inner wall, bottom edge, perimeter of the container cavity, or onto a carrier separated from the host substrate in liquid form, so that it acts on the transferred perovskite nanocrystal film only in vapor form. This method avoids direct contact between the 2-fluorothiophenol liquid and the perovskite nanocrystal film, thereby preventing its polar molecules from damaging the perovskite nanocrystal structure and surface ligands, and ensuring that its optical properties are not compromised.

[0011] Furthermore, the post-treatment is performed at room temperature to 80°C for 15–60 minutes. In other embodiments of the invention, the treatment time can be appropriately shortened at higher temperatures to achieve similar post-treatment results.

[0012] Furthermore, the perovskite nanocrystalline thin film transferred onto the acceptor substrate is formed in the following manner: A perovskite nanocrystal layer is pre-formed on a donor substrate, and the perovskite nanocrystal layer is peeled off by contacting the donor substrate with a polydimethylsiloxane elastomer transfer medium. The peeled perovskite nanocrystal layer is then transferred to a acceptor substrate with a hole transport layer.

[0013] Furthermore, the donor substrate is a silicon wafer that has undergone hydrophobic treatment, specifically a silicon wafer treated with octadecyltrichlorosilane. The hydrophobic treatment helps reduce the adhesion between the perovskite nanocrystals and the donor substrate, thereby promoting effective peeling during the transfer process.

[0014] The acceptor substrate is one of ITO conductive glass, glass substrate or quartz substrate.

[0015] Furthermore, a hole transport layer is provided on the acceptor substrate, and the hole transport layer material is selected from one of PTAA, PF8Cz, Poly-TPD, PVK, and TFB.

[0016] Furthermore, the perovskite nanocrystals are cesium lead halide perovskite nanocrystals, and the cesium lead halide perovskite nanocrystals are CsPbX3 nanocrystals, wherein X is selected from one or at least two of Cl, Br, and I.

[0017] Furthermore, the cesium lead halide perovskite nanocrystals are CsPb(Br,I)3 nanocrystals.

[0018] Furthermore, the amount of 2-fluorothiophenol added is adjusted according to the effective volume of the sealed container, the post-treatment temperature, and the post-treatment time, so that 2-fluorothiophenol acts on the transfer perovskite nanocrystalline film in the form of vapor.

[0019] A perovskite light-emitting diode, characterized in that it includes a perovskite nanocrystal light-emitting layer, wherein the perovskite nanocrystal light-emitting layer is a transfer perovskite nanocrystal thin film prepared by the above-mentioned post-processing method.

[0020] The beneficial effects of this invention are mainly reflected in: 1. This invention employs 2-fluorothiophenol vapor to post-treat the transferred perovskite nanocrystalline film. The vapor induces the nanocrystals to rearrange, resulting in a transferred perovskite nanocrystalline film exhibiting excellent surface smoothness and enhanced light-emitting diode (LED) intensity. Ultimately, this significantly improves the luminous performance of LEDs fabricated based on the post-treated perovskite nanocrystalline film. Simultaneously, it avoids direct liquid contact that could damage the perovskite nanocrystals.

[0021] 2. It has clear selectivity, and its technical effects are irreplaceable. When 2-fluorothiophenol comes into direct contact with perovskite nanocrystals in liquid form, it leads to a decrease in luminescence intensity and a deterioration in device performance. However, post-treatment using a vapor method can significantly improve its performance without damaging the perovskite nanocrystal structure.

[0022] Furthermore, when other vapor treatment agents (such as 4-fluorothiophenol or non-polar organic solvents) are used to treat the transferred perovskite nanocrystalline films, similar effects cannot be obtained, and may even lead to a decline in device performance, indicating that the 2-fluorothiophenol vapor has obvious selectivity and is irreplaceable. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the experimental process of the technical solution of the present invention; Figure 2 The UV absorption-photoluminescence spectrum of the post-treated CsPb(Br,I)3 perovskite nanocrystal thin film obtained in Example 1 of this invention (including the untreated control group). Figure 3 The TrPL pattern and PLQY of the post-processed CsPb(Br,I)3 perovskite nanocrystalline thin film obtained in Example 1 of this invention; Figure 4 AFM morphology characterization of the post-processed CsPb(Br,I)3 perovskite nanocrystalline thin film obtained in Example 1 of the present invention. Figure 5 Characterization of the dipole moment arrangement of the post-processed CsPb(Br,I)3 perovskite nanocrystalline thin film obtained in Example 1 of the present invention. Figure 6 The current-voltage-brightness curves of the light-emitting diodes prepared based on the post-processed CsPb(Br,I)3 perovskite nanocrystalline thin films obtained in Example 1 of this invention are shown. Figure 7 Efficiency-brightness curves of light-emitting diodes prepared based on the post-processed CsPb(Br,I)3 perovskite nanocrystalline thin films obtained in Example 1 of the present invention. Figure 8 The emission spectrum of a light-emitting diode prepared based on the post-processed CsPb(Br,I)3 perovskite nanocrystalline thin film obtained in Example 1 of the present invention is shown. Figure 9 Photographs of CsPb(Br,I)3 nanocrystal solutions with different volume fractions added in Comparative Example 1; Figure 10The performance of the light-emitting diodes prepared in Comparative Example 1 based on the addition of different volume fractions of CsPb(Br,I)3 nanocrystals is shown in (a is the current-voltage curve, b is the brightness-voltage curve, and c is the efficiency-brightness curve). Figure 11 The performance of the light-emitting diodes prepared by the CsPb(Br,I)3 nanocrystalline thin films obtained by the above method in Comparative Example 2 is shown in a diagram (a is the current-voltage curve, b is the brightness-voltage curve, and c is the efficiency-brightness curve). Figure 12 The performance of the light-emitting diodes prepared by the CsPb(Br,I)3 nanocrystalline thin films obtained by the above method in Comparative Example 3 is shown in (a is the current-voltage curve, b is the brightness-voltage curve, and c is the efficiency-brightness curve). Detailed Implementation

[0024] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0025] The present invention will be further described in detail below through embodiments: Example 1: Post-treatment of perovskite nanocrystalline films using 2FP vapor deposition: First, prepare the following: octadecyltrichlorosilane-treated silicon wafers, ITO substrates, PTAA, CsPb(Br,I)3 nanocrystals, 2-fluorothiophenol (2FP), polydimethylsiloxane (PDMS), a heating stage, a glass container with a cap, and a glove box. Spin-coat the CsPb(Br,I)3 nanocrystals onto the octadecyltrichlorosilane-treated silicon wafer, while simultaneously performing plasma cleaning on the PDMS and ITO substrate for 30 seconds, followed by transfer to the glove box. Next, spin-coat the PTAA onto the ITO and anneal at 150°C for 30 minutes.

[0026] Picking up perovskite nanocrystals: A silicon wafer spin-coated with perovskite nanocrystals is placed on a 60°C hot stage. PDMS is used to contact the silicon wafer. After peeling, CsPb(Br,I)3 nanocrystals are stripped onto PDMS. Release process of perovskite nanocrystals: PDMS is brought into contact with an ITO substrate spin-coated with PTAA. The PDMS and the ITO substrate spin-coated with PTAA are placed together on a 60°C hot stage and heated for 30 seconds. The PDMS is then slowly peeled off, and the CsPb(Br,I)3 nanocrystals are successfully transferred onto the ITO substrate spin-coated with PTAA.

[0027] 2-Fluorophenoxyphenol (2FP) vapor post-treatment process for perovskite nanocrystals: An ITO substrate with transferred perovskite nanocrystals was placed in a glass container. 100 μL of 2FP solution was evenly added around the perimeter of the container. The container was capped and allowed to stand at room temperature for 30 minutes. The ITO substrate was then removed, completing the vapor post-treatment process for the transferred CsPb(Br,I)3 nanocrystalline film. 2-Fluorophenoxyphenol (2FP) is volatile at room temperature; its molecules can spontaneously transfer from the liquid phase to the gas phase, thus forming 2FP vapor in the environment.

[0028] Figure 1 This is a schematic diagram of the experimental process in Embodiment 1 of the present invention. Figure 2 The UV absorption-photoluminescence spectrum of the post-treated CsPb(Br,I)3 perovskite nanocrystal thin film obtained in Example 1 of this invention (including the untreated control group). Figure 3 The TrPL spectrum and PLQY of the post-processed CsPb(Br,I)3 perovskite nanocrystalline thin film obtained in Example 1 of this invention are shown. Figure 4 AFM morphology characterization of the post-processed CsPb(Br,I)3 perovskite nanocrystalline thin film obtained in Example 1 of this invention. Figure 5 Characterization of the dipole moment arrangement of the post-processed CsPb(Br,I)3 perovskite nanocrystalline thin film obtained in Example 1 of this invention. Figure 6 The current-voltage-brightness curves are shown for the light-emitting diodes prepared based on the post-processed CsPb(Br,I)3 perovskite nanocrystalline thin films obtained in Example 1 of this invention. Figure 7 Efficiency-brightness curves of light-emitting diodes prepared based on the post-processed CsPb(Br,I)3 perovskite nanocrystalline thin film obtained in Example 1 of this invention. Figure 8 The emission spectrum of the light-emitting diode prepared based on the post-processed transferred CsPb(Br,I)3 perovskite nanocrystal thin film obtained in Example 1 of this invention is shown. It can be seen that the transferred perovskite nanocrystals are of good quality and still maintain good optical performance.

[0029] Example 2: The difference from Example 1 is that CsPb(Br,I)3 nanocrystals are replaced with CsPbI3 nanocrystals, while the rest of the post-processing methods are the same.

[0030] Post-treatment of perovskite nanocrystalline films using 2FP vapor deposition: First, prepare the following: octadecyltrichlorosilane-treated silicon wafers, ITO substrates, PTAA, CsPbI3 nanocrystals, 2-fluorothiophenol (2FP), polydimethylsiloxane (PDMS), a heating stage, a glass container with a cap, and a glove box. Spin-coat the CsPbI3 nanocrystals onto the octadecyltrichlorosilane-treated silicon wafer, while simultaneously performing plasma cleaning on the PDMS and ITO substrate for 30 seconds, followed by transfer to the glove box. Next, spin-coat the PTAA onto the ITO and anneal at 150°C for 30 minutes.

[0031] Picking up perovskite nanocrystals: A silicon wafer with perovskite nanocrystals spin-coated is placed on a 60°C hot stage. PDMS is used to contact the silicon wafer. After peeling, CsPbI3 nanocrystals are stripped onto the PDMS. Release process of perovskite nanocrystals: PDMS is brought into contact with an ITO substrate spin-coated with PTAA. The PDMS and the ITO substrate spin-coated with PTAA are placed together on a 60°C hot stage and heated for 30 seconds. The PDMS is then slowly peeled off, and the CsPbI3 nanocrystals are successfully transferred onto the ITO substrate spin-coated with PTAA.

[0032] The 2FP vapor post-treatment process for perovskite nanocrystals: An ITO substrate with transferred perovskite nanocrystals was placed in a glass container. 100 μL of 2FP solution was evenly dropped around the container. The container was then capped and left to stand at room temperature for 30 minutes. The ITO substrate was then removed, thus completing the vapor post-treatment process for the transferred CsPbI3 nanocrystalline film. Similar performance improvements were observed in the same tests.

[0033] Example 3: The difference from Example 1 is that CsPb(Br,I)3 nanocrystals are replaced with CsPbBr3 nanocrystals, while the rest of the post-processing methods are the same.

[0034] Post-treatment of perovskite nanocrystalline films using 2FP vapor deposition: First, prepare the following: octadecyltrichlorosilane-treated silicon wafers, ITO substrates, PTAA, CsPbBr3 nanocrystals, 2-fluorothiophenol (2FP), polydimethylsiloxane (PDMS), a heating stage, a glass container with a cap, and a glove box. Spin-coat the CsPbBr3 nanocrystals onto the octadecyltrichlorosilane-treated silicon wafer, while simultaneously performing plasma cleaning on the PDMS and ITO substrate for 30 seconds, followed by transfer to the glove box. Next, spin-coat the PTAA onto the ITO and anneal at 150°C for 30 minutes.

[0035] Pick-up process of perovskite nanocrystals: Place the silicon wafer with perovskite nanocrystals spin-coated on a 60°C hot stage, contact the silicon wafer with PDMS, and after peeling, the CsPbBr3 nanocrystals are peeled off onto the PDMS. Release process of perovskite nanocrystals: PDMS is brought into contact with an ITO substrate spin-coated with PTAA. The PDMS and the ITO substrate spin-coated with PTAA are placed together on a 60°C hot stage and heated for 30 seconds. The PDMS is then slowly peeled off, and the CsPbBr3 nanocrystals are successfully transferred onto the ITO substrate spin-coated with PTAA.

[0036] The 2FP vapor post-treatment process for perovskite nanocrystals: An ITO substrate with transferred perovskite nanocrystals was placed in a glass container. 100 μL of 2FP solution was evenly dropped around the container. The container was then capped and left to stand at room temperature for 30 minutes. The ITO substrate was then removed, thus completing the vapor post-treatment process for the transferred CsPbBr3 nanocrystalline film. Similar performance improvements were observed in the same tests.

[0037] Application example: A light-emitting diode includes an ITO conductive glass, a hole injection layer, a hole transport layer, a perovskite nanocrystal light-emitting layer, an electron transport layer, and an electrode layer, wherein the perovskite nanocrystal light-emitting layer is a transfer perovskite nanocrystal thin film prepared by the method of Example 1.

[0038] The target substrate (recipient substrate) includes not only ITO substrates, but also glass substrates, quartz substrates, etc.

[0039] Furthermore, the hole transport layer may include one or more of the following: poly(9-vinylcarbazole) (PVK), poly[(4,4′-(N-(4-sec-butylphenyl)diphenylamine)] (PolyTPD), poly[9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)]-diphenylamine] (TFB), and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA).

[0040] The electron transport layer may include one or more of the following: 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi), 2,4,6-tris[3-(diphenylphosphino)phenyl]-1,3,5-triazole (PO-T2T), di[2-((oxo)diphenylphosphino)phenyl] ether (DPEPO), and 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1''-terphenyl]-3,3''-diyl]dipyridine (TmPyPB).

[0041] Comparative Example 1: The difference from Example 1 is that the 2FP liquid directly contacts the CsPb(Br,I)3 perovskite nanocrystals.

[0042] First, 2FP liquid was directly added to a CsPb(Br,I)3 nanocrystalline solution at volume fractions of 0%, 5%, 10%, and 30%, respectively. Then, the resulting nanocrystalline solution was used to fabricate a light-emitting diode.

[0043] Figure 9 Photos of CsPb(Br,I)3 nanocrystal solutions with different volume fractions added. Figure 10 The performance of light-emitting diodes (LEDs) fabricated based on the addition of different volume fractions of CsPb(Br,I)3 nanocrystals is shown in Figure 1 (a is the current-voltage curve, b is the luminance-voltage curve, and c is the efficiency-luminance curve). It can be seen that direct contact between the 2FP solution and the perovskite nanocrystals leads to a decrease in luminescence, a deterioration in PLQY, and a degradation in device performance.

[0044] Comparative Example 2: The difference from Example 1 is that the CsPb(Br,I)3 nanocrystalline film was post-treated with 4-fluorothiophenol (4FP) vapor.

[0045] First, the preparation of the CsPb(Br,I)3 nanocrystalline thin film was the same as in Example 1. Then, the ITO substrate was placed in a glass container, and 100 μL of 4FP solution was evenly dropped around the container. The container was then capped and left to stand at room temperature for 15, 30, and 45 minutes, respectively. The ITO substrate was then removed, thus completing the 4FP vapor post-treatment process for the transferred CsPb(Br,I)3 nanocrystalline thin film. Figure 11 The performance of the light-emitting diodes (LEDs) fabricated from the CsPb(Br,I)3 nanocrystalline thin films obtained by the above method is shown in Figure a (current-voltage curve, b (brightness-voltage curve), c (efficiency-brightness curve)). It can be seen that vapor treatment of the 4FP transferred perovskite nanocrystalline thin film degrades its device performance. The above verifies that the 2FP of Example 1 of this invention has adjacent F... - and SH - Groups can induce the rearrangement of perovskite nanocrystals.

[0046] Comparative Example 3: The difference from Example 1 is that common hexane vapor was used for the post-treatment of the transferred CsPb(Br,I)3 nanocrystalline film.

[0047] First, the preparation of the CsPb(Br,I)3 nanocrystalline thin film was the same as in Example 1. Then, the ITO substrate was placed in a glass container, and 100 μL of hexane solution was evenly dropped around the container. The container was then capped and left to stand at room temperature for 30 minutes. The ITO substrate was then removed, thus completing the hexane vapor post-treatment process for the transferred CsPb(Br,I)3 nanocrystalline thin film. Figure 12The performance of the light-emitting diodes (LEDs) fabricated from the CsPb(Br,I)3 nanocrystalline thin films obtained by the above method is shown in Figures a (current-voltage curve), b (brightness-voltage curve), and c (efficiency-brightness curve). It can be seen that treating the transferred perovskite nanocrystalline thin film with hexane vapor degrades its device performance.

[0048] The present invention has been illustrated with the above embodiments to explain the detailed preparation method of the present invention. However, the present invention is not limited to the above detailed preparation method, that is, it does not mean that the present invention must rely on the above product and detailed preparation method to be implemented. Those skilled in the art should understand that any improvement to the present invention, or the combination or equivalent substitution of the raw materials of the present invention, falls within the protection scope and disclosure scope of the present invention.

Claims

1. A 2FP steam post-treatment method for transferring perovskite nanocrystalline thin films, characterized in that, The method includes placing a perovskite nanocrystalline film transferred onto a host substrate in a sealed container, introducing 2-fluorothiophenol into the sealed container, causing the 2-fluorothiophenol to volatilize and form vapor, and performing post-processing on the transferred perovskite nanocrystalline film under the condition that the 2-fluorothiophenol does not come into direct liquid contact with the perovskite nanocrystalline film.

2. The 2FP steam post-treatment method for transferring perovskite nanocrystalline thin films according to claim 1, characterized in that, The 2-fluorothiophenol is added in liquid form to the inner wall, bottom edge, perimeter of the container cavity, or a carrier separated from the host substrate, so that it acts on the transfer perovskite nanocrystal film only in vapor form.

3. The 2FP steam post-treatment method for transferring perovskite nanocrystalline thin films according to claim 1, characterized in that, The post-treatment is carried out at room temperature to 80°C for 15 to 60 minutes.

4. The 2FP steam post-treatment method for transferring perovskite nanocrystalline thin films according to claim 1, characterized in that, The perovskite nanocrystalline thin film transferred onto the acceptor substrate is formed in the following manner: A perovskite nanocrystal layer is pre-formed on a donor substrate, and the perovskite nanocrystal layer is peeled off by contacting the donor substrate with a polydimethylsiloxane elastomer transfer medium. The peeled perovskite nanocrystal layer is then transferred to a acceptor substrate with a hole transport layer.

5. The 2FP steam post-treatment method for transferring perovskite nanocrystalline thin films according to claim 4, characterized in that, The donor substrate is a silicon wafer that has undergone hydrophobic treatment, and the silicon wafer is a silicon wafer treated with octadecyltrichlorosilane; The acceptor substrate is one of ITO conductive glass, glass substrate or quartz substrate.

6. The 2FP steam post-treatment method for transferring perovskite nanocrystalline thin films according to claim 4, characterized in that, The acceptor substrate has a hole transport layer, and the hole transport layer material is selected from PTAA, PF8Cz, Poly-TPD, PVK, and TFB.

7. The 2FP steam post-treatment method for transferring perovskite nanocrystalline thin films according to claim 6, characterized in that, The perovskite nanocrystals are cesium lead halide perovskite nanocrystals, and the cesium lead halide perovskite nanocrystals are CsPbX3 nanocrystals, wherein X is selected from one or at least two of Cl, Br, and I.

8. The 2FP steam post-treatment method for transferring perovskite nanocrystalline thin films according to claim 7, characterized in that, The cesium lead halide perovskite nanocrystals are CsPb(Br,I)3 nanocrystals.

9. The 2FP steam post-treatment method for transferring perovskite nanocrystalline thin films according to claim 1, characterized in that, The amount of 2-fluorothiophenol added is adjusted according to the effective volume of the sealed container, the post-treatment temperature, and the post-treatment time, so that 2-fluorothiophenol acts on the transfer perovskite nanocrystalline film in the form of vapor.

10. A perovskite light-emitting diode, characterized in that, It includes a perovskite nanocrystal light-emitting layer, wherein the perovskite nanocrystal light-emitting layer is a transfer perovskite nanocrystal thin film prepared by the post-processing method according to any one of claims 1 to 9.

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