A full-laser reversible csPbI3 perovskite film fluorescent patterning method

Abstract

The application discloses a full-laser reversible CsPbI3 perovskite film fluorescent patterning method, wherein CsPbI3 perovskite film is prepared by using CsI, PbX2, OAI and a polymer; laser power density and exposure time are regulated to optimize processing conditions; the film is processed by using a femtosecond laser, ion diffusion and local recrystallization in the CsPbI3 perovskite film can be effectively induced, lattice distortion can be repaired, a regular and ordered lattice structure can be constructed, the defect state density of the CsPbI3 perovskite film can be reduced, and the carrier recombination mechanism can be changed from non-radiative recombination to radiative recombination. Meanwhile, the femtosecond laser can optimize the ultrafast carrier relaxation dynamics of the film, effectively slow down the carrier decay rate, significantly improve the carrier transport performance and radiative recombination ability, and finally realize the improvement of the CsPbI3 perovskite film fluorescence intensity by about 10 4 orders of magnitude.

Description

Technical Field

[0001] This invention relates to the field of perovskite materials technology, and in particular to a fully laser-reversible method for fluorescent patterning of CsPbI3 perovskite thin films. Background Technology

[0002] Metal halide perovskite materials have attracted widespread attention in recent years due to their high fluorescence quantum yield, tunable bandgap, long carrier diffusion length, high defect tolerance, and excellent photoelectric conversion performance, in fields such as light-emitting devices, photodetectors, solar cells, anti-counterfeiting labels, and optical information storage. In particular, all-inorganic CsPbI3 perovskite materials, with their narrow bandgap, excellent photostability, and strong red light emission capability, show significant application prospects in high-density optical information storage and fluorescent anti-counterfeiting.

[0003] Currently, perovskite-based fluorescent patterning technologies mainly include inkjet printing, photolithography, thermal embossing, chemical etching, and laser direct writing. While inkjet printing and photolithography can achieve large-area pattern fabrication, they typically require complex masks or multi-step processing steps, resulting in cumbersome fabrication processes, limited spatial resolution, and difficulty in achieving dynamic rewrite functionality. Chemical etching methods usually require the introduction of additional chemical reagents, which can easily cause irreversible damage to perovskite materials, leading to poor stability.

[0004] In recent years, laser direct writing technology has been gradually applied to the field of perovskite patterning due to its advantages such as non-contact, high resolution and local processing capability.

[0005] In existing research, femtosecond lasers are commonly used to induce ablation, thermal vaporization, or localized structure removal in perovskite thin films to achieve patterning. However, these methods are mostly destructive processing mechanisms, which can easily lead to localized material damage, fluorescence quenching, and decreased device stability. Furthermore, most existing technologies can only achieve single-write operations, making it difficult to achieve high-quality erasure and rewriting in the same area, thus failing to meet the application requirements for reusable information storage and dynamic anti-counterfeiting.

[0006] Furthermore, existing perovskite laser processing techniques typically offer low fluorescence enhancement factors, mostly concentrated in the 10–100x range, resulting in limited pattern contrast and difficulty in achieving high-brightness, high-stability fluorescence information storage. No research has been reported on using femtosecond lasers to induce localized ion migration and recrystallization in CsPbI3 perovskite films to achieve defect repair, ultra-high fluorescence enhancement, and fully laser-reversible erasure / writing.

[0007] CN119141001A discloses a high-precision patterning method for perovskite thin films and its application. However, the patterns formed by this method are usually irreversible structures. Once the processing is completed, it is difficult to achieve high-quality erasure and rewriting in the original area, which cannot meet the requirements of repeatable information storage and dynamic anti-counterfeiting applications. It usually requires the use of different processing equipment, additional chemical treatment steps, or multiple processing technologies to achieve pattern writing and erasure, which results in high system complexity and is not conducive to device integration and practical application promotion. Moreover, it mainly uses the high-energy action of femtosecond lasers to achieve film ablation, thermal vaporization, or material removal. Its processing mechanism is a destructive processing method. The local temperature rises rapidly exceeds the material ablation threshold. Its essence is a laser ablation mechanism, which can easily lead to thermal vaporization, material peeling, or irreversible structural damage to the film, making it difficult to maintain material integrity and stable optical performance.

[0008] In conclusion, there is an urgent need to develop a new technical solution to address the problems existing in the current technology and meet the needs of the current market. Summary of the Invention

[0009] To address the limitations of existing technologies, such as limited control methods, reliance on chemical modification, and low spatial resolution, this invention provides a fully laser-reversible solution: utilizing femtosecond lasers to induce local recrystallization of CsPbI3 perovskite films, thereby increasing fluorescence intensity by approximately 10%. 4 This method, based on femtosecond laser writing—low-power laser annealing erasure—rewriting, enables fully laser-rewritable anti-counterfeiting tags and optical information storage devices. A single write operation can achieve up to 10... 4 The fluorescence is enhanced by orders of magnitude, and the performance remains unchanged after 60 days of long-term storage.

[0010] Therefore, it is necessary to provide a fully laser-reversible method for fluorescent patterning of CsPbI3 perovskite thin films, comprising the following steps: S1. Mix CsI, PbX2, OAI (oleoamine iodide) and the polymer to obtain a precursor solution; S2. The precursor solution is dropped onto the substrate surface, spin-coated, and annealed to obtain a CsPbI3 film; S3. The CsPbI3 thin film was processed by femtosecond laser to obtain a fully laser-reversible CsPbI3 perovskite thin film. in, X is selected from one or more of I, Br, and Cl; In step S3, the power density of the femtosecond laser is 2.62-4.60 GW / cm². 2 .

[0011] Further, in step S1, the polymer is PMMA.

[0012] Furthermore, in step S2, the annealing temperature is 45-55℃ and the time is 5-10 minutes.

[0013] Furthermore, in step S3, the wavelength of the femtosecond laser is 800-900nm.

[0014] Furthermore, in step S3, the pulse width of the femtosecond laser is 260-280 fs.

[0015] Furthermore, in step S3, the exposure time of the femtosecond laser is 2-5 seconds.

[0016] Furthermore, in step S3, femtosecond laser processing is performed using a 60× objective lens.

[0017] Furthermore, in step S3, the frequency of the femtosecond laser is 75-85MHz.

[0018] Furthermore, in the CsPbI3 perovskite film, the CsPbI3 perovskite is a locally recrystallized perovskite.

[0019] The present invention also provides the application of CsPbI3 perovskite thin films prepared by the fully laser-reversible CsPbI3 perovskite thin film fluorescence patterning method in the fields of anti-counterfeiting and information storage.

[0020] Unlike existing technologies that can only achieve single-processing or irreversible patterning, this invention can utilize the same laser system to achieve a fully reversible laser cycle of "writing-erasing-rewriting" simply by adjusting the laser parameters. It does not require the introduction of additional chemical reagents, photomasks, or multiple sets of equipment, making the operation simpler and the system more integrated. This invention does not achieve patterning through laser ablation or thermal vaporization, but rather through femtosecond laser-induced local ion diffusion and recrystallization of CsPbI3 perovskite thin films to achieve defect repair and lattice ordering. Therefore, it does not cause significant material removal or irreversible structural damage and belongs to a non-destructive light modulation mechanism.

[0021] This invention, by precisely controlling the femtosecond laser power density and exposure time, keeps the laser action within the non-ablation threshold range, significantly reducing the defect state density of the thin film and promoting the transition of carrier recombination mechanism from non-radiative recombination to radiative recombination, thereby achieving approximately 10-1 4 The fluorescence enhancement effect is orders of magnitude higher; while the comparison document mainly shows structural changes after laser ablation, which cannot achieve such a high degree of fluorescence enhancement.

[0022] This invention enables in-situ erasure and rewriting of local information. After 10 cycles, the fluorescence intensity remains at more than 95% of the initial write value, demonstrating excellent cycle stability and reusability. It is more suitable for high-security anti-counterfeiting and high-density optical information storage fields.

[0023] The present invention has the following beneficial effects: This invention prepares CsPbI3 perovskite films using CsI, PbX2, OAI, and polymers. By optimizing the processing conditions through control of laser power density and exposure time, and then treating the films with femtosecond lasers, ion diffusion and local recrystallization within the CsPbI3 perovskite films are effectively induced. This repairs lattice distortion, constructs a regular and ordered lattice structure, reduces the defect state density of the CsPbI3 perovskite films, and promotes the shift from non-radiative recrystallization to radiative recrystallization dominance in the carrier recrystallization mechanism. Simultaneously, femtosecond lasers optimize the ultrafast carrier relaxation dynamics of the films, effectively slowing down the carrier decay rate and significantly improving carrier transport performance and radiative recrystallization capability, ultimately achieving an approximately 10% increase in fluorescence intensity of the CsPbI3 perovskite films. 4 Magnitude; Compared with existing technologies, this invention, by strictly controlling the femtosecond laser power density, exposure time and focusing conditions, keeps the laser energy within the "non-ablation threshold" range of the perovskite thin film. Attached Figure Description

[0024] Figure 1 A schematic diagram of a femtosecond laser-induced fluorescence patterning system for CsPbI3 perovskite thin films and its underlying principle. Figure 1 (a) is a schematic diagram of the optical path system for femtosecond laser processing; Figure 1 (b) is a schematic diagram of fluorescent writing of different structures on CsPbI3 perovskite thin films using femtosecond lasers.

[0025] Figure 2 A schematic diagram of a CsPbI3 perovskite thin film; Figure 2 (a) is a schematic diagram of the synthesis of CsPbI3 thin films; Figure 2 (b) is the XRD pattern of the CsPbI3 thin film.

[0026] Figure 3 Fluorescence images, spectra, and schematic diagrams for different laser power densities and exposure times; Figure 3 (a) Fluorescence images with different laser power densities and exposure times; Figure 3 (b) Spectra of different laser power densities and exposure times; Figure 3 (c) Fluorescence spectra of CsPbI3 perovskite films under different femtosecond laser power densities; Figure 3 (d) shows the fluorescence intensity distribution of CsPbI3 perovskite films under different femtosecond laser power densities.

[0027] Figure 4 This is a schematic diagram of the fluorescence enhancement mechanism.

[0028] Figure 5 Pump detection images of the laser-processed and unetched areas; Figure 5 (a) is a pump detection map of the untreated area; Figure 5 (b) is a fitting plot of carrier dynamics decay in the untreated region; Figure 5 (c) is the transient absorption two-dimensional spectrum of the laser-processed region; Figure 5 (d) is a fitting diagram of carrier dynamics attenuation in the laser-processed region.

[0029] Figure 6 A schematic diagram illustrating a reversible erase / write cycle (information storage); Figure 6 (a) is a schematic diagram before writing; Figure 6 (b) is a schematic diagram of writing "8888"; Figure 6 (c) is a schematic diagram of writing "2026"; Figure 6 (d) is a schematic diagram of writing "2028". Detailed Implementation

[0030] To more clearly illustrate the technical solution of the present invention, the following embodiments are provided. Unless otherwise stated, the raw materials, reactions, and post-processing methods appearing in the embodiments are all commercially available raw materials and technical methods well known to those skilled in the art.

[0031] The terms "preferred," "more preferably," and "more suitable" used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0032] It should be understood that, except in any operational instance or otherwise indicated, all figures representing the amounts of ingredients used, for example, in the specification and claims, should be understood to be modified in all cases by the term "about". Therefore, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are approximations varying with the desired performance to be obtained according to the invention.

[0033] PMMA, polymethyl methacrylate, molecular weight 12000, purchased from Benoway.

[0034] Preparation Example Preparation of CsPbI3 thin films.

[0035] S1-1. Clean the glass substrate sequentially with deionized water, ethanol and acetone; dry the cleaned substrate with nitrogen gas and place it in a plasma ozone cleaner for 10 minutes for later use. S1-2. Weigh out 0.2 mmol of CsI, 0.2 mmol of PbI2, 0.1 mmol of OAI, 1 g of PMMA and 5 mL of DMF solvent respectively; put the weighed drugs into sample vials and add magnetic stirring to obtain the precursor solution; S2. The cleaned glass substrate is adsorbed onto the spin coater, the acceleration is set to 1000 rpm / s, the rotation speed is set to 2500 rpm, and the spin coater is set to 30s; 80ul of precursor solution is dropped onto the glass substrate, and then the spin coater is started to obtain a transparent precursor wet film; the precursor wet film is placed on a hot stage and annealed at 50℃ for 10min to obtain a CsPbI3 thin film. Figure 2 (a) is a schematic diagram of the synthesis of CsPbI3 thin films; Figure 2 (b) shows the XRD pattern of the CsPbI3 thin film, which shows that its diffraction peaks are consistent with the CsPbI3 standard card, proving that the CsPbI3 thin film was successfully prepared.

[0036] Example Preparation of fully laser-reversible CsPbI3 perovskite thin films.

[0037] S3. The CsPbI3 thin film was placed on a three-dimensional displacement stage and treated with a femtosecond laser with a wavelength of 800 nm, a pulse width of 274 fs, a frequency of 80 MHz, and a 60× objective lens, achieving a power density of 3.64 GW / cm². 2 The exposure time is 3 seconds. The specific principle of etching is as follows: Figure 1 As shown. Figure 1 (a) is a schematic diagram of the optical path system for femtosecond laser processing; Figure 1 (b) is a schematic diagram of fluorescent writing of different structures on CsPbI3 perovskite thin films using femtosecond lasers.

[0038] Test Example 1 By changing the power density of the femtosecond laser in the embodiments (2.62-4.60 GW / cm²), 2 The fluorescence enhancement properties of CsPbI3 perovskite films were adjusted by adjusting the exposure time (1-5s), and fluorescence spectroscopy and transient absorption were tested.

[0039] Figure 3 (a) Fluorescence images with different laser power densities and exposure times; Figure 3 (b) Spectra of different laser power densities and exposure times; from Figure 3 The results from (a) to (b) show that the power density is 3.64 GW / cm². 2 When the exposure time is 3 seconds, the fluorescence enhancement reaches its maximum value of 10. 4 Order of magnitude.

[0040] Figure 3 (c) Fluorescence spectra of CsPbI3 perovskite films under different femtosecond laser power densities; Figure 3 (d) shows the fluorescence intensity distribution of CsPbI3 perovskite films under different femtosecond laser power densities. It can be seen that at a power density of 3.64 GW / cm², the fluorescence intensity distribution is significantly higher. 2 The fluorescence enhancement factor is greatest when the exposure time is 3 seconds.

[0041] Furthermore, experimental results show that the present invention possesses a "non-ablation recrystallization parameter window." Within this window, the femtosecond laser primarily induces local ion migration and recrystallization, thereby achieving defect repair and ultra-high fluorescence enhancement; however, beyond this window, the mechanism gradually shifts to ablation dominance.

[0042] Specifically, at a power density of 3.64 GW / cm² 2 When the fluorescence enhancement reaches its maximum value, the fluorescence enhancement reaches its maximum value when the femtosecond laser power density exceeds 3.64 GW / cm². 2 Subsequently, the fluorescence intensity of the CsPbI3 perovskite film began to decrease significantly, indicating that as the laser power further increased, the material gradually approached and entered the ablation power region. At this point, phenomena such as enhanced local heat accumulation, lattice structure destruction, and material ablation occurred in the laser-treated area, leading to fluorescence quenching. Simultaneously, the film structure suffered irreversible damage, making it difficult to restore the original fluorescence performance through subsequent laser treatment. Therefore, this invention achieves local recrystallization and defect repair by strictly controlling the femtosecond laser parameters within the non-ablation threshold range, thereby obtaining a significant fluorescence enhancement effect.

[0043] Figure 4 The mechanism diagram reveals the physical mechanism of ultra-high fluorescence enhancement: the original CsPbI3 film has a distorted lattice and high-density defects ( Figure 4(Left side) Photogenerated carriers mainly undergo non-radiative recombination; after femtosecond laser treatment, Cs is induced. + Pb 2+ I - Ion diffusion and local recrystallization occur to form an ordered lattice; after recrystallization, the defect state density decreases significantly, and radiative recrystallization becomes dominant. Figure 4 right).

[0044] Figure 5 (a) is a pump detection map of the untreated area; Figure 5 (b) is a fitting plot of carrier dynamics decay in the untreated region; Figure 5 (c) is the transient absorption two-dimensional spectrum of the laser-processed region; Figure 5 (d) is a fitting diagram of carrier dynamics attenuation in the laser-processed region.

[0045] Figure 5 The results (a)-(d) further show that the ultrafast carrier relaxation dynamics of the sample changed significantly after femtosecond laser treatment, and the carrier decay process slowed down, indicating that the local defect state density decreased and the carrier transport and radiative recombination ability was enhanced, thus achieving ultra-high fluorescence enhancement effect.

[0046] Test Example 2 The fully laser-reversible CsPbI3 perovskite thin film obtained in the preparation example was subjected to reversible erase-write cycle tests.

[0047] The writing parameters were as follows: A femtosecond laser with a wavelength of 800 nm, a pulse width of 274 fs, a frequency of 80 MHz, and a 60× objective lens was used to process the CsPbI3 thin film; the power density was 2.62 GW / cm². 2 ; Parameters for local erasure: Local erasure is performed using a defocused scanning method under the same laser power conditions as the writing step. By increasing the laser spot size, the actual power density is reduced, thereby achieving local elimination of the fluorescent pattern.

[0048] Writing: The pattern "8888" was written during scanning and is clearly visible under a fluorescence microscope. Figure 6 (a) is a schematic diagram before writing; Figure 6 (b) is a schematic diagram of writing "8888".

[0049] Partial erasure and pattern update: Switching the same laser to low-power continuous mode, only the left half of the "8888" area is defocused for scanning. After erasure, the fluorescence in the scanned area disappears, while the unscanned area retains its original fluorescence, thus transforming the original pattern "8888" into "2026". Figure 6 (c) is a schematic diagram of writing "2026", which proves that the present invention can realize local information erasure and in-situ pattern update.

[0050] Rewriting: Using the same operating parameters, rewrite the erased area to make it fluoresce brightly again. The pattern then changes from "2026" to "2028," and the bright pattern is visible under a fluorescence microscope. Figure 6 (d) is a schematic diagram of writing "2028", and it can be seen that the writing strength is comparable to that of the first writing.

[0051] The above write-partial erase-write cycle was repeated 10 times. The fluorescence intensity after each write remained above 95% of the value of the first write, indicating that the present invention has excellent reversible write stability.

[0052] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0053] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for fully laser-reversible fluorescent patterning of CsPbI3 perovskite thin films, characterized in that, Includes the following steps: S1. Mix CsI, PbX2, OAI and the polymer to obtain a precursor solution; S2. The precursor solution is dropped onto the substrate surface, spin-coated, and annealed to obtain a CsPbI3 film; S3. The CsPbI3 thin film was processed by femtosecond laser to obtain a fully laser-reversible CsPbI3 perovskite thin film. in, X is selected from one or more of I, Br, and Cl; In step S3, the power density of the femtosecond laser is 2.62-4.60 GW / cm². 2 .

2. The fully laser-reversible fluorescent patterning method for CsPbI3 perovskite thin films according to claim 1, characterized in that, In step S1, the polymer is PMMA.

3. The fully laser-reversible fluorescent patterning method for CsPbI3 perovskite thin films according to claim 1, characterized in that, In step S2, the annealing temperature is 45-55℃ and the time is 5-10 minutes.

4. The fully laser-reversible fluorescent patterning method for CsPbI3 perovskite thin films according to claim 1, characterized in that, In step S3, the wavelength of the femtosecond laser is 800-900nm.

5. The fully laser-reversible fluorescent patterning method for CsPbI3 perovskite thin films according to claim 1, characterized in that, In step S3, the pulse width of the femtosecond laser is 260-280 fs.

6. The fully laser-reversible fluorescent patterning method for CsPbI3 perovskite thin films according to claim 1, characterized in that, In step S3, the exposure time of the femtosecond laser is 2-5 seconds.

7. The fully laser-reversible fluorescent patterning method for CsPbI3 perovskite thin films according to claim 1, characterized in that, In step S3, femtosecond laser processing is performed using a 60× objective lens.

8. The fully laser-reversible fluorescent patterning method for CsPbI3 perovskite thin films according to claim 1, characterized in that, In step S3, the frequency of the femtosecond laser is 75-85MHz.

9. The fully laser-reversible fluorescent patterning method for CsPbI3 perovskite thin films according to claim 1, characterized in that, In the CsPbI3 perovskite film, the CsPbI3 perovskite is a locally recrystallized perovskite.

10. The application of CsPbI3 perovskite thin films prepared by the fully laser-reversible CsPbI3 perovskite thin film fluorescence patterning method according to any one of claims 1-9 in the fields of anti-counterfeiting and information storage.

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