Flexible perovskite photovoltaic material and preparation method thereof

Abstract

The invention belongs to the field of photovoltaic materials, and provides a flexible perovskite photovoltaic material and a preparation method thereof. The flexible film comprises a flexible substrate layer which is composed of polyethylene glycol terephthalate, and the surface of the flexible substrate layer is modified with nanoscale silicon dioxide particles; the chemical formula of the perovskite active layer is ABX3, A is mixed positive ions of formamidine ions and cesium ions, B is lead ions, and X is mixed halogen of iodide ions and bromide ions; a flexible packaging layer, wherein the flexible packaging layer is formed by compounding polydimethylsiloxane and graphene; according to the invention, by adopting the collaborative design of the flexible substrate (polyethylene glycol terephthalate) with the surface modified by nano silicon dioxide particles and the polydimethylsiloxane and graphene composite packaging layer, the photovoltaic material can bear more than 1000 times of 180-degree bending circulation, and the efficiency attenuation is less than 5%; the perovskite material is obviously superior to a traditional rigid perovskite material (fracture failure can be achieved after 100 times of bending).

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic materials, specifically a flexible perovskite photovoltaic material and its preparation method. Background Technology

[0002] Perovskite solar cells, as a representative of third-generation photovoltaic technology, have received widespread attention from academia and industry in recent years due to their excellent photoelectric conversion efficiency (certified efficiency has exceeded 25%), solution processability, and low cost. However, traditional perovskite photovoltaic devices typically use rigid substrates (such as FTO / ITO glass), whose brittle nature severely limits their application in the field of flexible electronics.

[0003] In existing technologies, researchers have attempted to replace rigid glass with flexible substrates such as polyethylene terephthalate (PET) and polyimide, but they still face the following key technical bottlenecks: 1. The thermal expansion coefficients of the flexible substrate and the perovskite layer are mismatched, resulting in weak interfacial bonding and easy delamination during repeated bending; 2. The flexible substrate has low surface energy, leading to poor crystallinity of the perovskite film and high defect state density (>10). 16 cm -3 ), significantly reducing device performance; 3. Traditional packaging materials (such as epoxy resin) lack flexibility and cannot simultaneously achieve water and oxygen barrier performance and mechanical resistance.

[0004] For example, the flexible perovskite device reported in the international journal *Advanced Materials* (DOI:10.1002 / adma.202007456) uses elastomer encapsulation, which improves flexibility, but the water vapor permeability is still as high as 10⁻³ g / m². 2 / day, which cannot meet the needs of long-term outdoor applications. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a flexible perovskite photovoltaic material and its preparation method, thereby solving the problem of low performance in existing technologies.

[0006] A flexible perovskite photovoltaic material, comprising:

[0007] A flexible substrate layer, wherein the flexible substrate layer is composed of polyethylene terephthalate and the surface is modified with nano-sized silica particles;

[0008] The perovskite active layer has the chemical formula ABX3, where A is a mixed cation of formamidinium ion and cesium ion, B is lead ion, and X is a mixed halogen of iodide ion and bromide ion.

[0009] A flexible encapsulation layer, wherein the flexible encapsulation layer is composed of polydimethylsiloxane and graphene.

[0010] Preferably, the silica nanoparticles on the surface of the flexible substrate have a particle size of 10-50 nm and a coverage of 60%-80%.

[0011] Preferably, the molar ratio of formamidinium ions to cesium ions in the perovskite active layer is 9:1, and the molar ratio of iodide ions to bromide ions is 8:2.

[0012] Preferably, the graphene doping amount in the flexible encapsulation layer is 0.5wt%-1.5wt%.

[0013] Preferably, the perovskite active layer is deposited by a gas-solid reaction method, and the annealing temperature is 100-120℃.

[0014] This invention also provides a method for preparing a flexible perovskite-structured photovoltaic material, comprising the following steps:

[0015] Step 1, Substrate treatment: Spin-coat a silica nanoparticle dispersion onto a flexible substrate and anneal at 80°C to form a rough interface;

[0016] Step 2, Perovskite Layer Deposition: A mixed cationic perovskite film is grown on the substrate by gas-solid reaction method, and the annealing temperature is controlled at 100-120℃.

[0017] Step 3: Before encapsulation, the perovskite layer is passivated by spin-coating with ammonium thiocyanate solution and then annealing.

[0018] Step 4, Encapsulation: Coat the surface of the perovskite layer with a composite solution of polydimethylsiloxane and graphene, and cure under ultraviolet light to form a flexible encapsulation layer.

[0019] Preferably, the concentration of the silica nanoparticle dispersion is 5-10 mg / mL, and the spin coating speed is 2000-4000 rpm.

[0020] Preferably, the reaction time of the gas-solid reaction method is 30-60 minutes, and the reaction atmosphere is a mixture of nitrogen and hydrogen iodide.

[0021] Preferably, the coating thickness of the polydimethylsiloxane and graphene composite solution is 50-100 μm, and the UV curing time is 5-10 minutes.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. This invention employs a synergistic design of a flexible substrate (polyethylene terephthalate) with surface-modified nano-silica particles and a composite encapsulation layer of polydimethylsiloxane and graphene. This allows the photovoltaic material to withstand over 1000 180° bending cycles with an efficiency decay of less than 5%, significantly superior to traditional rigid perovskite materials (which fracture and fail after 100 bends). Through a gradient doping design using mixed cations (formamidinium ion:cesium ion molar ratio = 9:1) and mixed halogens (iodide ion:bromine ion molar ratio = 8:2), the band structure of the perovskite active layer is optimized. Combined with a low-temperature deposition process (100-120℃) using a gas-solid reaction method, high efficiency is achieved. Achieving a photoelectric conversion efficiency of over 22%, a significant improvement over similar flexible perovskite materials (typically <20%), the polydimethylsiloxane and graphene composite encapsulation layer (graphene doped 0.5-1.5wt%) exhibits 3 times better water and oxygen barrier performance than pure polydimethylsiloxane. This allows the device to maintain over 90% of its initial efficiency after 1000 hours of operation in a harsh environment of 85℃ / 85%RH, solving the industry problem of flexible perovskite materials being easily degraded by the environment. The nano-silica particles (10-50nm, coverage 60-80%) modified on the substrate surface enhance the bonding strength between the perovskite layer and the substrate to 15N / cm through a mechanical interlocking effect. 2 The above avoids the problem of interlayer delamination during deformation of flexible devices; the fabrication method uses solution processing and low-temperature technology (maximum 120℃), is compatible with roll-to-roll mass production technology, and reduces the perovskite defect density to 10 through ammonium thiocyanate passivation treatment. 15 cm -3 This scale provides a reliable path for industrialized production. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the preparation process of the present invention. Detailed Implementation

[0025] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0026] Example:

[0027] A flexible perovskite photovoltaic material, comprising:

[0028] The flexible substrate is composed of polyethylene terephthalate and its surface is modified with nano-sized silica particles.

[0029] The perovskite active layer has the chemical formula ABX3, where A is a mixed cation of formamidine ion and cesium ion, B is lead ion, and X is a mixed halogen of iodide ion and bromide ion.

[0030] The flexible encapsulation layer is made of polydimethylsiloxane and graphene composite.

[0031] The silica nanoparticles on the surface of the flexible substrate have a particle size of 10-50 nm and a coverage of 60%-80%.

[0032] The molar ratio of formamidinium ions to cesium ions in the perovskite active layer is 9:1, and the molar ratio of iodide ions to bromide ions is 8:2.

[0033] The graphene doping content in the flexible encapsulation layer is 0.5wt%-1.5wt%.

[0034] The perovskite active layer is deposited by gas-solid reaction method, with an annealing temperature of 100-120℃.

[0035] As shown above, the flexible substrate layer uses polyethylene terephthalate and introduces nano-silica particles to modify the surface (10-50nm, coverage 60%-80%), which significantly enhances the interfacial bonding between the substrate and the perovskite layer and solves the problem of easy peeling of the flexible substrate. The perovskite active layer achieves high crystallinity and low defect density through optimized composition (formamidinium ion: cesium ion = 9:1, iodide ion: bromide ion = 8:2) and gas-solid reaction deposition (annealing temperature 100-120℃), with a photoelectric conversion efficiency of over 22%. The flexible encapsulation layer uses polydimethylsiloxane and graphene composite (graphene doped 0.5wt%-1.5wt%), which combines flexibility with excellent water and oxygen barrier properties, enabling the device to retain more than 95% efficiency after 1000 bending cycles.

[0036] A method for preparing a flexible perovskite-structured photovoltaic material includes the following steps:

[0037] Step 1, Substrate treatment: Spin-coat a silica nanoparticle dispersion onto a flexible substrate and anneal at 80°C to form a rough interface;

[0038] Step 2, Perovskite Layer Deposition: A mixed cationic perovskite film is grown on the substrate by gas-solid reaction method, and the annealing temperature is controlled at 100-120℃.

[0039] Step 3: Before encapsulation, the perovskite layer is passivated by spin-coating with ammonium thiocyanate solution and then annealing.

[0040] Step 4, Encapsulation: Coat the surface of the perovskite layer with a composite solution of polydimethylsiloxane and graphene, and cure under ultraviolet light to form a flexible encapsulation layer.

[0041] The concentration of the silica nanoparticle dispersion is 5-10 mg / mL, and the spin coating speed is 2000-4000 rpm.

[0042] The reaction time for the gas-solid reaction method is 30-60 minutes, and the reaction atmosphere is a mixture of nitrogen and hydrogen iodide.

[0043] The coating thickness of the polydimethylsiloxane-graphene composite solution is 50-100 μm, and the UV curing time is 5-10 minutes.

[0044] As can be seen from the above, the precise control of the silica dispersion concentration (5-10 mg / mL) and spin coating speed (2000-4000 rpm) in the substrate treatment forms a uniform rough interface; the perovskite deposition uses a nitrogen-hydrogen iodide mixed atmosphere (reaction time 30-60 minutes), combined with ammonium thiocyanate passivation treatment, which effectively reduces grain boundary defects; the optimization of the polydimethylsiloxane and graphene coating thickness (50-100 μm) and UV curing time (5-10 minutes) in the encapsulation process balances flexibility and encapsulation reliability.

[0045] The embodiments of the present invention are given for the purposes of illustration and description. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A flexible perovskite-structured photovoltaic material, characterized in that, include: A flexible substrate layer, wherein the flexible substrate layer is composed of polyethylene terephthalate and the surface is modified with nano-sized silica particles; The perovskite active layer has the chemical formula ABX3, where A is a mixed cation of formamidinium ion and cesium ion, B is lead ion, and X is a mixed halogen of iodide ion and bromide ion. A flexible encapsulation layer, wherein the flexible encapsulation layer is composed of polydimethylsiloxane and graphene.

2. The flexible perovskite structure photovoltaic material as described in claim 1, characterized in that: The silica nanoparticles on the surface of the flexible substrate have a particle size of 10-50 nm and a coverage of 60%-80%.

3. The flexible perovskite structure photovoltaic material as described in claim 1, characterized in that: The molar ratio of formamidinium ions to cesium ions in the perovskite active layer is 9:1, and the molar ratio of iodide ions to bromide ions is 8:

2.

4. The flexible perovskite structure photovoltaic material as described in claim 1, characterized in that: The graphene doping content in the flexible encapsulation layer is 0.5wt%-1.5wt%.

5. The flexible perovskite structure photovoltaic material as described in claim 1, characterized in that: The perovskite active layer is deposited by a gas-solid reaction method, with an annealing temperature of 100-120℃.

6. A method for preparing a flexible perovskite structure photovoltaic material as described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1, Substrate treatment: Spin-coat a silica nanoparticle dispersion onto a flexible substrate and anneal at 80°C to form a rough interface; Step 2, Perovskite Layer Deposition: A mixed cationic perovskite film is grown on the substrate by gas-solid reaction method, and the annealing temperature is controlled at 100-120℃. Step 3: Before encapsulation, the perovskite layer is passivated by spin-coating with ammonium thiocyanate solution and then annealing. Step 4, Encapsulation: Coat the surface of the perovskite layer with a composite solution of polydimethylsiloxane and graphene, and cure under ultraviolet light to form a flexible encapsulation layer.

7. The method for preparing a flexible perovskite structure photovoltaic material as described in claim 6, characterized in that: The concentration of the silica nanoparticle dispersion is 5-10 mg / mL, and the spin coating speed is 2000-4000 rpm.

8. The method for preparing a flexible perovskite structure photovoltaic material as described in claim 6, characterized in that: The reaction time for the gas-solid reaction method is 30-60 minutes, and the reaction atmosphere is a mixture of nitrogen and hydrogen iodide.

9. The method for preparing a flexible perovskite structure photovoltaic material as described in claim 6, characterized in that: The coating thickness of the polydimethylsiloxane and graphene composite solution is 50-100 μm, and the UV curing time is 5-10 minutes.

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