A stress relief method for flexible crystalline optoelectronic thin films

Abstract

The application belongs to the technical field of material science and engineering, and discloses a stress elimination method for flexible crystalline optoelectronic thin film. The method comprises the following steps: eliminating the stress of the crystalline optoelectronic thin film by using liquid-phase assisted vibration aging. The method involves complex links such as efficient deposition of the crystalline optoelectronic thin film, selection of a vibration clamp, parameter regulation and matching of a high-frequency vibration source, and needs multi-step precise operation. Meanwhile, the vibration and temperature compensation need to be balanced to avoid adverse effects on the thin film. The application realizes in-situ stress elimination of the crystalline optoelectronic thin film under low-temperature conditions by means of liquid-solid coupling vibration to induce lattice dislocation slip and micro-plastic deformation. The advantage of the application is that the crystalline optoelectronic thin film on any complex substrate can be subjected to global homogenization stress regulation, the thin film quality can be effectively improved, the performance and stability of the crystalline optoelectronic thin film can be enhanced, and the application potential of the crystalline optoelectronic thin film on various substrates and optoelectronic devices is expanded.

Description

Technical Field

[0001] This invention belongs to the field of materials science and engineering technology, and specifically relates to a method for stress relief of flexible crystalline optoelectronic thin films. Background Technology

[0002] Crystalline optoelectronic thin films have wide applications in optoelectronic devices and other fields, but they are prone to stress during fabrication and use, which affects device performance and stability. Stress can lead to film cracking and peeling, increase defect state density, and reduce photoelectric conversion efficiency and carrier mobility. Therefore, eliminating stress in crystalline optoelectronic thin films has become one of the key research issues.

[0003] Currently, common methods for eliminating stress in crystalline optoelectronic thin films include annealing, chemical crosslinking agents, additive engineering, and interface engineering. Annealing adjusts film stress by controlling annealing temperature and time, but precise parameter control is required; otherwise, new stress may be introduced or film performance may be affected. Chemical crosslinking agents utilize the coordination of crosslinking agents with metal ions in the crystalline film, resulting in crosslinking during annealing. This applies compressive stress to the crystalline film to compensate for tensile stress, thereby reducing film stress. However, this method has high requirements for the selection of crosslinking agents and operating conditions, and may introduce side reactions and residues that affect film quality. Additive engineering adds specific substances, such as cyano derivatives and succinates, to the precursor solution to passivate defects and release stress. However, the distribution and reaction characteristics of additives are difficult to control precisely, potentially leading to non-uniform film composition and structure. Interface engineering compensates for residual tensile strain through post-treatment of the interface or modification of the charge transport layer. However, these methods mostly compensate for the release of stress in pre-formed crystalline optoelectronic thin films, with limited effectiveness. Therefore, there is an urgent need to develop an efficient, precise, and non-destructive stress relief technology to overcome these challenges. Summary of the Invention

[0004] Suppressing and eliminating residual stress in crystalline optoelectronic thin films is crucial for improving device efficiency and stability. However, existing methods struggle to precisely control stress, failing to effectively address the severe lattice tensile strain in crystalline optoelectronic thin films. Furthermore, some methods introduce new defects into the film, limiting the performance and stability of optoelectronic devices. To address these limitations, this invention provides a novel method for eliminating stress in crystalline optoelectronic thin films through liquid-phase assisted vibration aging. By achieving precise stress control, this method effectively solves the lattice tensile strain problem in crystalline optoelectronic thin films and eliminates the new stress and performance degradation issues caused by improper parameter control in traditional annealing processes. It also avoids side reactions caused by additive engineering that lead to component inhomogeneity and the introduction of new defects. This technology significantly improves the stability and optoelectronic performance of crystalline optoelectronic thin films, providing a new and effective pathway for enhancing the performance of optoelectronic devices.

[0005] The technical solution adopted in this invention is as follows: A method for stress relief of a flexible crystalline optoelectronic thin film, comprising the following steps: Step 1: The pre-fabricated precursor material is deposited on the pretreated substrate by additive manufacturing, and then a crystalline optoelectronic thin film is formed after post-processing. Step 2: Place the pre-prepared solution in a container. The deposited crystalline optoelectronic thin film is fixed and immersed in the pre-prepared solution using a vibration aging fixture. The fixture is connected to a high-frequency vibration source. At the same time, the container containing the solution and the thin film is connected to a temperature control device. Step 3: Turn on the temperature control device for pretreatment, control the temperature of the solution and the film, start the high-frequency vibration source, control its vibration frequency, power and amplitude, stop after a certain time and remove the film from the fixture; Step 4: Anneal and dry the removed film to obtain a stress-relieved crystalline optoelectronic film.

[0006] Preferably, the pre-prepared precursor raw material in step one is formed from one or more of the following materials, which have the general formulas: ABX3, AX, BX2, copper indium gallium selenide, and cadmium telluride, wherein A is a methylamine cation (CH3NH3). + ), formamidinium cation (CH(NH2)2) + ), ethylamine cation (C2H5NH3) + ), phenylethylamine cation (C6H5CH2NH3) + ), guanidine cation (C(NH2)3) + B is a Group IA cation, B is a Group IVA cation, a copper cation, or a cadmium cation, and X is a Group VIIA anion or a carbonate ion (CO3). 2- ), sulfate ions (SO4) 2- ), nitrate ions (NO3) - ), thiocyanate ions (SCN3) - ), cyanate ion (OCN) - ) or acetate ions (CH3COO - ).

[0007] Preferably, the additive manufacturing method described in step one is one or a combination of physical vapor deposition (PVD), chemical vapor deposition (CVD), solution methods (including spin coating, blade coating, slot coating, and spraying), in-situ crystallization, inkjet printing, screen printing, 3D printing, or atomic layer deposition (ALD).

[0008] Preferably, the substrate for pretreatment in step one is one or a combination of supporting materials, conductive materials, or electron / hole functional materials.

[0009] Furthermore, the supporting material is one or more combinations of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), polycarbonate (PC), polyimide (PI), polyethylene (PE), or polystyrene (PS), and the conductive material is gold nanoparticles, silver nanoparticles, copper nanoparticles, gold nanowires, silver nanowires, copper nanowires, fluorine-doped tin oxide (FTO), indium-doped tin oxide (IT). O), indium zinc oxide (IZO), carbon nanotubes, graphene, MXene, or poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS), wherein the electron / hole functional material is tin oxide (SnO2), titanium oxide (TiO2), zinc oxide (ZnO), vanadium pentoxide (V2O5), nickel oxide (NiO), cadmium selenide (CdSe), cadmium sulfide (CdS), or methyl [6,6]phenyl-C61-butyrate (PC61BM). [6,6]-Phenylacetic-C71-butyrate methyl ester (PC71BM), fullerene (C60), 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone (F4-TCNQ), 3-hexyl polythiophene (P3HT), poly(9-vinylcarbazole) (PVK), [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid (Me-4PACz), [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid (MeO-4P) One or more combinations of ACz, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz), [2-(3,6-diphenyl-9H-carbazole-9-yl)ethyl]phosphonic acid (Me-2PACz), [4-(3,6-diphenyl-9H-carbazole-9-yl)butyl]phosphonic acid (Ph-4PACz), or (E)-(2-(4-(bis(4-methoxyphenyl)amino)phenyl)-1-cyanovinyl)phosphonic acid (MPA-CPA).

[0010] Preferably, the post-processing method in step one includes thermal annealing, solvent vapor treatment, chemical passivation, mechanical imprinting, or photo-assisted processing.

[0011] Preferably, the solvent of the pre-prepared solution in step two is a mixture of one or more solvents selected from acetone, methanol, ethanol, isopropanol, acetonitrile, nitromethane, 1,3-dioxolane, ethyl acetate, chlorobenzene, anisole, mesitylene, tetrahydrofuran, acetyl chloride, benzoyl chloride, dichloromethane, toluene, 1,3-xylene, or benzonitrile. The solute is a mixture of one or more solutes selected from halides, organic amines, organic acids, organic polymers (polyethylene oxide, polyvinyl alcohol, polyacrylic acid, polymethyl methacrylate, and derivatives of the above chemical structures), ionic liquids, or ionic gels. The ratio of solvent volume to substrate area is 5-20 mL / cm². 2 The solute concentration is 0.5-20 mg / mL.

[0012] Preferably, the container in step two is a round or square beaker, a polytetrafluoroethylene mold, or a polypropylene mold.

[0013] Preferably, the vibration aging fixture in step two is an iron fixture, a polytetrafluoroethylene fixture, an aluminum fixture, or a steel fixture.

[0014] Preferably, the temperature range for the pretreatment in step three is -20 to 50 °C.

[0015] Preferably, the high-frequency vibration source in step three has a frequency of 20-100 kHz, a power of 10-1000 W, an amplitude of 0.1-10 mm, and a processing time of 0.5-20 min.

[0016] Preferably, the annealing temperature in step four is 50-120 ℃, and the annealing time is 1-5 min.

[0017] This invention proposes a method to eliminate stress in crystalline optoelectronic thin films using liquid-phase assisted high-frequency vibration. The solution forms a solvation layer at the grain boundaries and within the lattice of the crystalline thin film, and then high-frequency vibration induces vibration in the solution, effectively solving the problem of lattice tensile strain in crystalline optoelectronic thin films. The temperature control device eliminates the adverse effects of heat generated by high-frequency vibration on the crystalline optoelectronic thin film. A schematic diagram of the overall device structure is shown below. Figure 1 As shown.

[0018] The present invention has the following beneficial effects: (1) Precise control of stress release. This method, through vibration of specific frequency and amplitude in combination with liquid phase assisted environment, can penetrate deep into the interior of crystalline optoelectronic thin film, realize uniform stress elimination from the surface to the deep layer, solve the problem of only surface stress release or excessive local stress concentration caused by traditional annealing process, and ensure that the overall stress level of the thin film is significantly reduced and uniformly distributed.

[0019] (2) Effective compensation for lattice mismatch. During vibration aging, the liquid environment forms a solvation layer at the lattice and grain boundaries of the crystalline thin film, providing a suitable space for lattice adjustment and promoting the rearrangement of the lattice under vibration, thereby improving the internal stress caused by lattice mismatch. This is more advantageous than the traditional chemical crosslinking agent or additive method, as it will not damage the integrity of the lattice due to the introduction of additional substances, and at the same time enhances the stability of the lattice.

[0020] (3) Improve the photoelectric performance of thin films. Liquid-phase assisted vibration aging can not only eliminate stress, but also optimize the crystal quality of crystalline photoelectric thin films, reduce the defect state density, and thus improve carrier mobility and photoelectric conversion efficiency. Traditional methods often fail to balance photoelectric performance when eliminating stress, and may even lead to performance degradation due to process defects. This method achieves the dual goals of stress elimination and performance improvement, providing better protection for the application of crystalline photoelectric thin films in optoelectronic devices. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the crystalline optoelectronic thin film stress relief device of the present invention; Figure 2 This is a comparison image of the crystalline optoelectronic thin film before and after stress relief according to the present invention.

[0022] In this diagram, A is the vibration source, B is the container, C is the solution, D is the clamping device and crystalline optoelectronic thin film, and E is the temperature control device. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The following embodiments are based on the technology of the present invention and provide detailed implementation methods and operating steps, but the scope of protection of the present invention is not limited to the following embodiments.

[0024] Example 1 This embodiment relates to a stress relief method for flexible crystalline optoelectronic thin films. The pre-prepared precursor solution is a 1.6 M FAPbI3 solution. The additive manufacturing method is a solution method. The pre-treated substrate is a glass / ITO / SnO2 substrate. The pre-prepared solution is a 2 mg / mL polymethyl methacrylate / anisole solution. The vibration fixture is a polytetrafluoroethylene fixture. The vibration source has a vibration frequency of 25 kHz, a power of 400 W, an amplitude of 3 mm, and a processing time of 8 min. The specific steps are as follows: (1) A 1.6 M FAPbI3 precursor solution was deposited on a glass / ITO / SnO2 substrate by spin coating, and annealed at 100 °C for 40 min and 150 °C for 5 min to obtain a crystalline optoelectronic thin film. (2) Dissolve polymethyl methacrylate in anisole solution with a concentration of 2 mg / mL. Place 50 mL of the above pre-prepared solution in a 200 mL beaker. Fix the deposited crystalline optoelectronic thin film with a clamp device and immerse it in the pre-prepared solution. The clamp is connected to a high-frequency vibration source. At the same time, connect the container containing the solution and the thin film to a temperature control device. (3) Turn on the temperature control device, set the temperature to 0 ℃ for 5 min of pretreatment, then start the vibration source, the vibration frequency is 25 kHz, the power is 400 W, the amplitude is 3 mm, the treatment time is 8 min, and the film is removed after the treatment is completed. (4) The film was treated at 70 °C for 5 min on a hot table, and then cooled and dried to finally obtain a stress-relieved crystalline optoelectronic film.

[0025] Example 2 This embodiment relates to a stress relief method for flexible crystalline optoelectronic thin films, which differs from Embodiment 1 in that: the pre-prepared solution is a 0.5 mg / mL polymethyl methacrylate / anisole solution, the vibration source frequency is 20 kHz, the power is 10 W, the amplitude is 0.1 mm, and the processing time is 20 min. The specific steps are as follows: (1) A 1.6 M FAPbI3 precursor solution was deposited on a glass / ITO / SnO2 substrate by spin coating, and annealed at 100 °C for 40 min and 150 °C for 5 min to obtain a crystalline optoelectronic thin film. (2) Dissolve polymethyl methacrylate in anisole solution with a concentration of 0.5 mg / mL. Place 50 mL of the above-prepared solution in a 200 mL beaker. Fix the deposited crystalline optoelectronic thin film with a clamp device and immerse it in the prepared solution. The clamp is connected to a high-frequency vibration source. At the same time, connect the container containing the solution and the thin film to a temperature control device. (3) Turn on the temperature control device, set the temperature to -20 ℃ for 5 min of pretreatment, then start the vibration source, the vibration frequency is 20 kHz, the power is 10 W, the amplitude is 0.1 mm, the treatment time is 20 min, and the film is removed after the treatment is completed. (4) The film was treated at 50 °C for 5 min on a hot plate, and then cooled and dried to finally obtain a stress-relieved crystalline optoelectronic film.

[0026] Example 3 This embodiment relates to a stress relief method for flexible crystalline optoelectronic thin films, which differs from Embodiment 1 in that: in step (1), the precursor solution is 1.6 M Cs. 0.05 FA 0.95The PbI3 solution was used as the pretreated substrate, which was a PET / ITO / Me-4PACz substrate. The pre-prepared solution in step (2) was a 3 mg / mL polyvinyl alcohol / toluene solution. In step (3), the temperature was set to 20 °C, the vibration frequency of the vibration source was 20 kHz, the power was 600 W, the amplitude was 1 mm, and the treatment time was 10 min.

[0027] The specific steps are as follows: (1) 1.6 M Cs 0.05 FA 0.95 PbI3 precursor solution was deposited on PET / ITO / Me-4PACz substrate by spin coating, and crystalline optoelectronic thin film was obtained after annealing at 100 °C for 15 min. (2) Dissolve polyvinyl alcohol in toluene solution to a concentration of 3 mg / mL. Place 50 mL of the above pre-prepared solution in a 200 mL beaker. Fix the deposited crystalline photoelectric thin film with a clamp device and immerse it in the pre-prepared solution. The clamp is connected to a high-frequency vibration source. At the same time, connect the container containing the solution and the thin film to a temperature control device. (3) Turn on the temperature control device, set the temperature to 20 ℃ for 5 min of pretreatment, then start the vibration source, the vibration frequency is 20 kHz, the power is 600 W, the amplitude is 1 mm, the treatment time is 10 min, and the film is removed after the treatment is completed. (4) The film was treated at 70 °C for 5 min on a hot table, and then cooled and dried to finally obtain a stress-relieved crystalline optoelectronic film.

[0028] Example 4 This embodiment relates to a stress relief method for flexible crystalline optoelectronic thin films, which differs from Embodiment 3 in that: the pre-prepared solution is a 20 mg / mL polyvinyl alcohol / toluene solution, the vibration source has a vibration frequency of 100 kHz, a power of 1000 W, an amplitude of 10 mm, and a processing time of 0.5 min.

[0029] The specific steps are as follows: (1) 1.6 M Cs 0.05 FA 0.95 PbI3 precursor solution was deposited on PET / ITO / Me-4PACz substrate by spin coating, and crystalline optoelectronic thin film was obtained after annealing at 100 °C for 15 min. (2) Dissolve polyvinyl alcohol in toluene solution to a concentration of 20 mg / mL. Place 50 mL of the above pre-prepared solution in a 200 mL beaker. Fix the deposited crystalline photoelectric thin film with a clamp device and immerse it in the pre-prepared solution. The clamp is connected to a high-frequency vibration source. At the same time, connect the container containing the solution and the thin film to a temperature control device. (3) Turn on the temperature control device, set the temperature to 50 ℃ for 5 min of pretreatment, then start the vibration source, the vibration frequency is 100 kHz, the power is 1000 W, the amplitude is 10 mm, the treatment time is 0.5 min, and remove the film after the treatment is completed. (4) The film was treated at 120 °C for 1 min on a hot table, and then cooled and dried to finally obtain a stress-relieved crystalline optoelectronic film.

Claims

1. A method for stress relief of a flexible crystalline optoelectronic thin film, characterized in that, The steps of the method are as follows: Step 1: The pre-fabricated precursor material is deposited on the pretreated substrate by additive manufacturing, and then post-processed to form a crystalline optoelectronic thin film; Step 2: Place the pre-prepared solution in a container. The deposited crystalline optoelectronic thin film is fixed and immersed in the pre-prepared solution using a vibration aging fixture. The fixture is connected to a high-frequency vibration source. At the same time, the container containing the solution and the thin film is connected to a temperature control device. Step 3: Turn on the temperature control device for pretreatment, control the temperature of the solution and the film, start the high-frequency vibration source, control its vibration frequency, power and amplitude, stop after a certain time and remove the film from the fixture; Step 4: Anneal and dry the removed film to obtain a stress-relieved crystalline optoelectronic film.

2. The stress relief method for a flexible crystalline optoelectronic thin film according to claim 1, characterized in that, The pre-prepared precursor raw material mentioned in step one is formed by combining one or more of the following materials, the general formulas of which are: ABX3, AX, BX2, copper indium gallium selenide, cadmium telluride, where A is a methylamine cation, formamidinium cation, ethylamine cation, phenylethylamine cation, guanidine cation or group IA cation, B is a group IVA cation, copper cation or cadmium cation, and X is a group VIIA anion, carbonate ion, sulfate ion, nitrate ion, thiocyanate ion, cyanate ion or acetate ion.

3. The stress relief method for a flexible crystalline optoelectronic thin film according to claim 1, characterized in that, The additive manufacturing method described in step one is one or a combination of physical vapor deposition, chemical vapor deposition, solution method, in-situ crystallization, inkjet printing, screen printing, 3D printing, or atomic layer deposition.

4. The stress relief method for a flexible crystalline optoelectronic thin film according to claim 1, characterized in that, The pre-treated substrate structure in step one is one or a combination of supporting materials, conductive materials, or electron / hole functional materials.

5. The stress relief method for a flexible crystalline optoelectronic thin film according to claim 1, characterized in that, The post-processing methods mentioned in step one include thermal annealing, solvent vapor treatment, chemical passivation, mechanical imprinting, or photo-assisted processing.

6. The stress relief method for a flexible crystalline optoelectronic thin film according to claim 1, characterized in that, The solvent for the pre-prepared solution in step two is a mixture of one or more solvents selected from acetone, methanol, ethanol, isopropanol, acetonitrile, nitromethane, 1,3-dioxolane, ethyl acetate, chlorobenzene, anisole, mesitylene, tetrahydrofuran, acetyl chloride, benzoyl chloride, dichloromethane, toluene, 1,3-xylene, or benzonitrile. The solute is a mixture of one or more solutes selected from halides, organic amines, organic acids, organic polymers, ionic liquids, or ionic gels. The ratio of solvent volume to substrate area is 5-20 mL / cm². 2 The solute concentration is 0.5-20 mg / mL.

7. The stress relief method for a flexible crystalline optoelectronic thin film according to claim 1, characterized in that, The container mentioned in step two is a round or square beaker, a polytetrafluoroethylene mold, or a polypropylene mold; the vibration aging fixture is an iron fixture, a polytetrafluoroethylene fixture, an aluminum fixture, or a steel fixture.

8. The stress relief method for a flexible crystalline optoelectronic thin film according to claim 1, characterized in that, The temperature range for the pretreatment in step three is -20 to 50 ℃, the frequency of the high-frequency vibration source is 20 to 100 kHz, the power is 10 to 1000 W, the amplitude is 0.1 to 10 mm, and the processing time is 0.5 to 20 min.

9. The stress relief method for a flexible crystalline optoelectronic thin film according to claim 1, characterized in that, The annealing temperature in step four is 50-120 ℃, and the annealing time is 1-5 min.

10. The stress relief method for a flexible crystalline optoelectronic thin film according to claim 4, characterized in that, The supporting material is one or more of the following: glass, polyethylene terephthalate, polyethylene naphthalate, polymethyl methacrylate, polyvinyl alcohol, polycarbonate, polyimide, polyethylene, and polystyrene. The conductive material is one or more of the following: gold nanoparticles, silver nanoparticles, copper nanoparticles, gold nanowires, silver nanowires, copper nanowires, fluorine-doped tin oxide, indium-doped tin oxide, indium zinc oxide, carbon nanotubes, graphene, MXene, or poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid. The electron / hole functional material is tin oxide, titanium oxide, zinc oxide, vanadium pentoxide, nickel oxide, cadmium selenide, cadmium sulfide, methyl [6,6]-phenyl-C61-butyrate, and [6,6]-phenyl-C61-butyrate. 71-Methyl butyrate, fullerene, 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone, 3-hexyl polythiophene, poly(9-vinylcarbazole), [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid, [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, [2-(3,6-diphenyl-9H-carbazole-9-yl)ethyl]phosphonic acid, [4-(3,6-diphenyl-9H-carbazole-9-yl)butyl]phosphonic acid, or (E)-(2-(4-(bis(4-methoxyphenyl)amino)phenyl)-1-cyanovinyl)phosphonic acid)

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