Optical anisotropic luminous solar concentrator and preparation method thereof

Abstract

The invention discloses an optical anisotropic luminous solar concentrator and a preparation method thereof, and the optical anisotropic luminous solar concentrator is of a layered structure and is prepared by blade coating a halide perovskite CsPbBr3 nanowire layer on a glass substrate. The layered structure is composed of a glass substrate, an ultraviolet curing adhesive layer and at least two functional layers, and each functional layer is composed of a CsPbBr3 perovskite nanowire-polymethyl methacrylate composite light-emitting film. Under the action of the halide perovskite CsPbBr3 nanowire, the probability that fluorescence emitted by the light-emitting solar concentrator is conducted to the side edge parallel to the substrate can be greatly increased, so that the loss of an escape cone in the direction perpendicular to the substrate is reduced; meanwhile, due to the introduced optical spacing layer, the reabsorption loss of the device can be reduced, the conversion efficiency of the device is improved, the transmittance is relatively good, and the preparation cost is relatively low.

Description

Technical Field

[0001] This invention relates to an optically anisotropic solar energy concentrator and its fabrication method, belonging to the field of optoelectronic devices. Background Technology

[0002] A light-emitting solar concentrator is a device that uses a transparent matrix doped with fluorophores to concentrate sunlight. It absorbs sunlight incident on the front of the device and conducts it to the sides via downconversion by the fluorophore and waveguides. Finally, the solar energy is converted into electrical energy through side-coupled photovoltaic devices. This device can achieve photoelectric conversion without affecting indoor lighting and holds promise for integration with glass windows, curtain walls, and greenhouses to create building-integrated photovoltaics (BIPV). Over the past four decades, fluorophore materials for light-emitting solar concentrators have undergone iterations from organic dyes, lanthanide hybrids, and quantum dots, but all face significant limitations: organic dyes suffer from severe self-absorption and are prone to photodegradation; lanthanide materials have low absorption spectrum matching with sunlight and are expensive; and the complex structural design of quantum dots restricts their practicality. Perovskite nanocrystals, however, exhibit excellent optical and electronic properties due to their tunable size, dimensions, composition, and morphology. Their broad absorption spectrum, narrow emission linewidth, and excellent defect tolerance give them unique advantages as fluorophore materials for light-emitting solar concentrators. Furthermore, solution-based fabrication simplifies their thin-film integration process. Currently, luminescent solar concentrators still face some challenges in practical applications: their photoelectric conversion efficiency is relatively low, and optical losses such as escape cone loss, reabsorption loss, and non-radiative recombination loss need further suppression. Therefore, a new strategy is needed to both match the solar spectrum and reduce optical losses while simultaneously improving the conversion efficiency of the solar concentrator, thus enabling building-integrated photovoltaic devices. Summary of the Invention

[0003] The purpose of this invention is to provide an optically anisotropic solar concentrator and its fabrication method, so as to achieve the directional propagation of self-emitted fluorescence to the side of the device, effectively reduce optical losses such as escape cone loss and reabsorption loss, and improve the device conversion efficiency.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: an optically anisotropic solar energy concentrator, which is a layered structure, wherein the layered structure consists of a glass substrate, an ultraviolet light curable adhesive layer, and at least two functional layers, wherein the functional layers are composed of a CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film.

[0005] The method for preparing the optically anisotropic solar concentrator includes the following steps:

[0006] (1) Preparation of CsPbBr3 perovskite nanowires by hot injection method: Cesium carbonate (Cs2CO3) was mixed with oleic acid (OA) and 1-octadecene (ODE) under a nitrogen atmosphere and heated and stirred to form a cesium oleate precursor solution; Lead bromide (PbBr2) was mixed with 1-octadecene (ODE) by hot injection method and heated and stirred under a nitrogen atmosphere, and n-octylamine (OCT) and oleylamine (OAM) were injected in sequence. After heating, a lead bromide precursor solution was obtained, and then the cesium oleate precursor solution was injected. After the reaction was completed, the mixture was immediately cooled; then toluene was added, and the CsPbBr3 nanowires were obtained by separation and purification.

[0007] (2) Preparation of CsPbBr3 perovskite nanowire-polymethyl methacrylate (PMMA) composite luminescent film: Toluene and polymethyl methacrylate were mixed, stirred and heated. Then, the toluene solution of CsPbBr3 perovskite nanowires was added to the polymethyl methacrylate-toluene solution and stirred evenly. Subsequently, the CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film was coated onto a glass substrate by a blade coating method. Finally, the coated glass slide was placed on a heating stage and heated.

[0008] (3) Preparation of optically anisotropic solar concentrator: Two optically anisotropic CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent films obtained in step (2) are bonded face to face using an ultraviolet light curing adhesive, and the samples are irradiated with ultraviolet light using a 320-400nm ultraviolet lamp to cure them, thus obtaining an optically anisotropic solar concentrator; or two optically anisotropic CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent films obtained in step (2) are bonded face to face on both sides of an optical spacer layer (glass substrate) using an ultraviolet light curing adhesive, and the samples are irradiated with ultraviolet light using a 320-400nm ultraviolet lamp to cure them, thus obtaining an optically anisotropic solar concentrator based on an optical spacer layer.

[0009] In step (1), the molar ratio of cesium carbonate (Cs2CO3), lead bromide (PbBr2), and oleic acid (OA) is 2:1:6. When preparing the cesium oleate precursor solution, cesium carbonate, oleic acid, and 1-octadecyl ODE are added in a molar ratio of 1:3:40. Under nitrogen protection, the mixture is heated and stirred until all the cesium carbonate reacts with the oleic acid and the solution becomes completely clear, thus obtaining the cesium oleate precursor solution.

[0010] In step (1), lead bromide (PbBr2) and 1-octadecene ODE are mixed evenly, nitrogen gas is introduced for exhaust treatment, and then heated and stirred. In a nitrogen environment, n-octylamine (OCT) and oleylamine (OAM) are injected sequentially, and the reaction is heated until the solution becomes opaque white to obtain a lead bromide precursor solution. The molar ratio of lead bromide (PbBr2), 1-octadecene ODE, n-octylamine (OCT) and oleylamine (OAM) is 1:80:24:12.

[0011] In step (1), CsPbBr3 perovskite nanowires are prepared by hot injection method. The cesium oleate precursor solution prepared in step (1) is heated to form a clear and transparent cesium oleate precursor solution. The cesium oleate precursor solution is rapidly injected into the lead bromide precursor solution. After injection, the reaction is allowed to proceed fully, and then the solution is rapidly placed in an ice bath to cool, thus obtaining the original solution of CsPbBr3 nanowires.

[0012] In step (1), the separation and purification of CsPbBr3 perovskite nanowires is carried out by adding toluene to the original solution of CsPbBr3 perovskite nanowires, centrifuging, discarding the supernatant after centrifugation, and retaining the precipitate, which is the CsPbBr3 perovskite nanowire.

[0013] In step (2), toluene and polymethyl methacrylate are mixed, and then heated and stirred to fully dissolve the polymethyl methacrylate to obtain a polymethyl methacrylate-toluene solution; the toluene solution of CsPbBr3 perovskite nanowires is added to the polymethyl methacrylate-toluene solution and stirred to mix them evenly.

[0014] In step (2), a composite light-emitting film with a smooth surface and a thickness of 100 μm is scraped onto a glass slide using a scraping method. The scraped glass slide is then placed on a heating table for heating and curing.

[0015] In step (3), the CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film covering the glass substrate is cut into 2×2cm pieces. 2 After determining the dimensions, two optically anisotropic CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent films were bonded face-to-face using a UV-curable adhesive. The samples were then irradiated with 320–400 nm UV light until the UV-curable adhesive was completely cured.

[0016] In step (3), the CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film covering the glass substrate is cut into 2×2cm pieces. 2After determining the dimensions, an optical spacer layer (a 2mm thick glass plate) was attached to the CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film using a UV-curable adhesive. The CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film was then attached to the other side of the optical spacer layer. Finally, the sample was irradiated with 320–400 nm UV light until the UV-curable adhesive was completely cured.

[0017] Beneficial effects:

[0018] (1) Simple operation, high material utilization, low dependence on equipment, and short preparation cycle;

[0019] (2) The layered structure of this light-emitting film sandwiched between two glass substrates can protect the light-emitting film from being easily damaged;

[0020] (3) It has high optical transmittance, which can ensure indoor lighting while coupling with side photovoltaic devices to convert light energy into electrical energy;

[0021] (4) It has excellent environmental stability and can be applied to high humidity environments and rainy days;

[0022] (5) The present invention realizes the anisotropy of the fluorescence emitted by the light-emitting solar energy emitter, reduces the escape cone loss of the device and improves the edge emission efficiency; the optical anisotropy is reflected in the composite light-emitting film composed of CsPbBr3 perovskite nanowires and polymethyl methacrylate, which can achieve an improvement of 1.75 times compared with the optical anisotropy of CsPbBr3 perovskite nanocrystals of the same concentration.

[0023] (6) In this invention, the escape cone loss is greatly reduced by introducing an optical spacer layer, which also reduces the reabsorption loss and improves the absorption efficiency, PLQY and edge emission efficiency of the device, thus achieving a significant improvement in external optical efficiency. After adding the optical spacer layer, the escape cone loss of this optical anisotropic solar concentrator can be as low as 19.6%, which is far below the limit of 25% for isotropic material devices. Attached Figure Description

[0024] Figure 1 The results are shown in Example 1: TEM (a, b, c), high-resolution TEM (d), energy-dispersive X-ray spectroscopy (EDS) (e), and elemental mapping (fi).

[0025] Figure 2 The transmission spectrum (a), PL and PLE spectra (b) of the CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film in Example 1 are shown.

[0026] Figure 3Anisotropy test images of the CsPbBr3 perovskite nanocrystal-polymethyl methacrylate composite luminescent film (a) and the CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film (b) in Example 1 are shown.

[0027] Figure 4 The absorption efficiency (a), escape cone loss, and edge emission efficiency (b) of the anisotropic solar concentrator in Example 2; the absorption efficiency (d), escape cone loss, and edge emission efficiency (e) of the optical anisotropic solar concentrator based on the optical spacer layer; and the PLQY (c) and external optical efficiency (f) of the anisotropic solar concentrator and the optical anisotropic solar concentrator based on the optical spacer layer.

[0028] Figure 5 This is a stability test diagram of the optically anisotropic solar concentrator in Example 2.

[0029] Figure 6 This is a stability test diagram of the optical anisotropic solar concentrator based on the optical spacer layer in Example 2.

[0030] Figure 7 The JV curve test diagrams are for the optically anisotropic solar concentrator and the optically anisotropic solar concentrator based on the optical spacer layer in Example 2.

[0031] Figure 8 The escape cone loss and edge emission efficiency of the optical anisotropic solar concentrator based on the optical spacer layer in Example 3 are shown.

[0032] Figure 9 These are schematic diagrams of two layered structures of the present invention. Detailed Implementation

[0033] The present invention will be further explained below with reference to the embodiments and accompanying drawings.

[0034] An optically anisotropic solar concentrator with a layered structure is disclosed, which is fabricated by coating a CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film onto a glass substrate. The CsPbBr3 perovskite nanowire significantly increases the probability of fluorescence emitted by the solar concentrator being conducted to the side parallel to the substrate, thereby reducing the escape cone loss in the direction perpendicular to the substrate. The introduced optical spacer layer can reduce the reabsorption loss of the device while improving the conversion efficiency of the device.

[0035] The layered structure is one of the following:

[0036] (1) The layered structure consists of a glass substrate, a CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film, an ultraviolet light curing adhesive, a CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film and a glass substrate from top to bottom.

[0037] (2) The layered structure consists of, from top to bottom, a glass substrate, a CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film, an ultraviolet light curing adhesive, an optical spacer layer (glass substrate), an ultraviolet light curing adhesive, a CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film, and a glass substrate.

[0038] The optical anisotropy is manifested in the composite luminescent film composed of CsPbBr3 perovskite nanowires and polymethyl methacrylate, which can achieve an improvement of 1.75 times in optical anisotropy compared with CsPbBr3 perovskite nanocrystals of the same concentration.

[0039] The escape cone loss is far below the 25% limit for isotropic material devices, meaning that with the addition of an optical spacer layer, the escape cone loss of the optical anisotropic solar concentrator can be as low as 19.6%.

[0040] The method for fabricating the optically anisotropic solar energy concentrator includes the following steps:

[0041] (1) Preparation of CsPbBr3 perovskite nanowires by hot injection method: Cesium carbonate (Cs2CO3) was mixed with oleic acid (OA) and 1-octadecene (ODE) under a nitrogen atmosphere and heated and stirred to form a cesium oleate precursor solution; Lead bromide (PbBr2) was mixed with 1-octadecene (ODE) by hot injection method and heated and stirred under a nitrogen atmosphere, and n-octylamine (OCT) and oleylamine (OAM) were injected in sequence. After heating, a lead bromide precursor solution was obtained, and then the cesium oleate precursor solution was injected. After the reaction was completed, the mixture was immediately cooled; then toluene was added, and the CsPbBr3 nanowires were obtained by separation and purification.

[0042] (2) Preparation of CsPbBr3 perovskite nanowire-polymethyl methacrylate (PMMA) composite luminescent film: Toluene and polymethyl methacrylate were mixed, stirred and heated. Then, the toluene solution of CsPbBr3 perovskite nanowires was added to the polymethyl methacrylate-toluene solution and stirred evenly. Subsequently, the CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film was coated onto a glass substrate by a blade coating method. Finally, the coated glass slide was placed on a heating stage and heated.

[0043] (3) Preparation of optically anisotropic solar concentrator: Two optically anisotropic CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent films obtained in step (2) are bonded face to face using an ultraviolet light curing adhesive, and the samples are irradiated with ultraviolet light using a 320-400nm ultraviolet lamp to cure them, thus obtaining an optically anisotropic solar concentrator; or two optically anisotropic CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent films obtained in step (2) are bonded face to face on both sides of an optical spacer layer (glass substrate) using an ultraviolet light curing adhesive, and the samples are irradiated with ultraviolet light using a 320-400nm ultraviolet lamp to cure them, thus obtaining an optically anisotropic solar concentrator based on an optical spacer layer.

[0044] In step (1), the molar ratio of cesium carbonate (Cs2CO3), lead bromide (PbBr2), and oleic acid (OA) is 2:1:6. When preparing the cesium oleate precursor solution, cesium carbonate, oleic acid, and 1-octadecyl ODE are added in a molar ratio of 1:3:40. Under nitrogen protection, the mixture is heated and stirred until all the cesium carbonate reacts with the oleic acid and the solution becomes completely clear, thus obtaining the cesium oleate precursor solution.

[0045] In step (1), lead bromide (PbBr2) and 1-octadecene ODE are mixed evenly, nitrogen gas is introduced for exhaust treatment, and then heated and stirred. In a nitrogen environment, n-octylamine (OCT) and oleylamine (OAM) are injected sequentially, and the reaction is heated until the solution becomes opaque white to obtain a lead bromide precursor solution. The molar ratio of lead bromide (PbBr2), 1-octadecene ODE, n-octylamine (OCT) and oleylamine (OAM) is 1:80:24:12.

[0046] In step (1), CsPbBr3 perovskite nanowires are prepared by hot injection method. The cesium oleate precursor solution prepared in step (1) is heated to form a clear and transparent cesium oleate precursor solution. The cesium oleate precursor solution is rapidly injected into the lead bromide precursor solution. After injection, the reaction is allowed to proceed fully, and then the solution is rapidly placed in an ice bath to cool, thus obtaining the original solution of CsPbBr3 nanowires.

[0047] In step (1), the separation and purification of CsPbBr3 perovskite nanowires is carried out by adding toluene to the original solution of CsPbBr3 perovskite nanowires, centrifuging, discarding the supernatant after centrifugation, and retaining the precipitate, which is the CsPbBr3 perovskite nanowire.

[0048] In step (2), toluene and polymethyl methacrylate are mixed, and then heated and stirred to fully dissolve the polymethyl methacrylate to obtain a polymethyl methacrylate-toluene solution; the toluene solution of CsPbBr3 perovskite nanowires is added to the polymethyl methacrylate-toluene solution and stirred to mix them evenly.

[0049] In step (2), a composite light-emitting film with a smooth surface and a thickness of 100 μm is scraped onto a glass slide using a scraping method. The scraped glass slide is then placed on a heating table for heating and curing.

[0050] In step (3), the CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film covering the glass substrate is cut into 2×2cm pieces. 2 After determining the dimensions, two optically anisotropic CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent films were bonded face-to-face using a UV-curable adhesive. The samples were then irradiated with 320–400 nm UV light until the UV-curable adhesive was completely cured.

[0051] In step (3), the CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film covering the glass substrate is cut into 2×2cm pieces. 2 After determining the dimensions, an optical spacer layer (a 2mm thick glass plate) was attached to the CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film using a UV-curable adhesive. The CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film was then attached to the other side of the optical spacer layer. Finally, the sample was irradiated with 320–400 nm UV light until the UV-curable adhesive was completely cured.

[0052] Example 1

[0053] (1) Preparation of CsPbBr3 perovskite nanowires: 0.4 g of cesium carbonate (Cs2CO3), 1.2 mL of oleic acid (OA), and 15 mL of 1-octadecene (ODE) were placed in a three-necked flask. Under nitrogen protection, the mixture was heated and stirred at 120 °C for 60 min. The temperature was then increased to 150 °C and reacted for 30 min until all the cesium carbonate and oleic acid reacted, and the solution became completely clear, yielding the cesium oleate precursor. 0.2202 g of lead bromide (PbBr2) and 15 mL of 1-octadecene (ODE) were added to the three-necked flask, and nitrogen was introduced for venting for 30 min. The mixture was then heated at 120 °C for 60 min with magnetic stirring. Then, under nitrogen atmosphere, 2.4 mL of n-octylamine (OCT) and 2.4 mL of oleylamine (OAM) were injected sequentially. The heating temperature was then set to 135 °C for 60 min, after which the solution turned opaque white. The pre-prepared cesium oleate precursor was heated to 120°C to form a clear and transparent precursor solution. 2.1 mL of this solution was rapidly injected into a three-necked flask. After injection, the reaction was allowed to proceed for 50 min. The flask was then rapidly placed in an ice bath to cool to 40°C-50°C, yielding the stock solution of CsPbBr3 perovskite nanowires. 20 mL of toluene was added to the stock solution, and the mixture was centrifuged at 6000 rpm for 5 min. After centrifugation, the supernatant was discarded, and the precipitate was retained. The precipitate was the CsPbBr3 perovskite nanowire. TEM, high-resolution TEM, energy-dispersive X-ray spectroscopy (EDS), and elemental mapping results were subsequently measured.

[0054] (2) Preparation of CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film: 8 mL of toluene and 1.0 g of polymethyl methacrylate were mixed in a glass bottle; then heated and stirred at 60 °C for 24 h in an oil bath at 250 rpm / min. Afterwards, 0.05 mmol of CsPbBr3 nanowires grown for 50 min were dissolved in 2 mL of toluene solution and added to the polymethyl methacrylate-toluene solution, and stirred at 600 rpm / min for 15 min to ensure uniform mixing. Subsequently, a composite luminescent film with a smooth surface and a thickness of 100 μm was coated onto a glass slide using a blade coating method. Finally, the coated glass slide was placed on a heating stage and heated at 60 °C for 5 min, then cooled and set aside for later use. Transmission spectroscopy, PL, and PLE spectroscopy were then performed.

[0055] (3) Preparation of CsPbBr3 perovskite nanocrystals: 0.276 g of lead bromide (PbBr2) and 20 mL of 1-octadecene (ODE) were placed together in a three-necked flask and heated and stirred at 120 °C for 60 min under nitrogen protection. Subsequently, 2 mL of n-octylamine (OCT) and 2 mL of oleic acid (OA) were rapidly injected into the reaction solution, and the reaction was allowed to proceed for 30 min. Finally, the temperature was raised to 150 °C, and then 0.74 mL of cesium oleate precursor solution (preheated to 120 °C) was rapidly injected. After injection, the reaction was allowed to proceed for 5 s, and then the three-necked flask was rapidly placed in an ice bath to cool to 40 °C-50 °C to obtain the stock solution of CsPbBr3 nanocrystals. The stock solution of CsPbBr3 nanocrystals was divided into two equal portions, and methyl acetate was added to the stock solution at a volume ratio of 1:1. The mixture was then centrifuged at 7800 rpm for 10 min. After centrifugation, discard the supernatant containing excess ligands and unreacted byproducts, retain the precipitate, and disperse the precipitate in a mixture of 5 mL n-hexane and 5 mL methyl acetate. Then, centrifuge the mixture again at 7500 rpm for 10 min. After centrifugation, discard the supernatant and retain the precipitate, which is CsPbBr3 perovskite nanocrystals.

[0056] (4) Preparation of CsPbBr3 perovskite nanocrystal-polymethyl methacrylate composite luminescent film: 8 mL of toluene and 1.0 g of polymethyl methacrylate were mixed in a glass bottle and then heated and stirred at 60 °C for 24 h in an oil bath at 250 rpm / min. Afterwards, 0.05 mmol of CsPbBr3 perovskite nanocrystals were dispersed in 2 mL of toluene and then added to the polymethyl methacrylate-toluene solution. The mixture was stirred at 600 rpm / min for 15 min until homogeneous. Subsequently, a composite luminescent film with a smooth surface and a thickness of 100 μm was coated onto a glass slide using a blade coating method. Finally, the coated glass slide was placed on a heating stage and heated at 60 °C for 5 min, then cooled and set aside for later use. Anisotropy tests were then performed on the preparation of the CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film and the CsPbBr3 perovskite nanocrystal-polymethyl methacrylate composite luminescent film, respectively.

[0057] Figure 1The images show the TEM (a, b, c), high-resolution TEM (d), energy-dispersive X-ray spectroscopy (EDS) (e), and elemental mapping results (fi) of the CsPbBr3 perovskite nanowires in Example 1. At low magnification, the CsPbBr3 nanowires exhibit a high-density, well-dispersed distribution, with a smooth and straight surface. The high-resolution TEM image clearly shows highly ordered lattice fringes with a lattice spacing of 0.51 nm, corresponding to the

[100] crystal plane of the cubic phase CsPbBr3, indicating that the nanowires preferentially grow along the

[100] direction, forming a typical one-dimensional structure. In addition to the nanowires, some coexisting quasi-spherical nanocrystals were also observed, indicating that the prepared CsPbBr3 is actually a mixture of nanowires and nanocrystals. The three elements Cs, Pb, and Br are continuously and uniformly distributed on both the nanowires and nanocrystals. Quantitative analysis shows that the atomic ratio of the elements is Cs:Pb:Br = 0.91:1.13:4.63, close to the theoretical stoichiometric ratio.

[0058] Figure 2 The transmission spectrum (a), PL, and PLE spectra (b) of the CsPbBr3 perovskite nanowire-polymethyl methacrylate (PMMA) composite luminescent film in Example 1 are shown. The composite luminescent film has a high average transmittance of 83% in the 300nm-800nm ​​wavelength range, which can meet the light-gathering requirements of building photovoltaic glass; the optimal excitation peak is located near 470nm, and the emission peak is located near 520nm.

[0059] Figure 3 Anisotropy test images were obtained for the CsPbBr3 perovskite nanocrystal-polymethyl methacrylate (PMMA) composite luminescent film (a) and the CsPbBr3 perovskite nanowire-polymethyl methacrylate (PMMA) composite luminescent film (b) in Example 1. The anisotropy value r of the composite luminescent film was calculated using the following formula:

[0060]

[0061] In the formula, I VV This represents the intensity of the vertically polarized emitted light detected under vertically polarized light excitation. I VH This represents the intensity of the horizontally polarized emitted light detected under vertically polarized light excitation. G is the grating correction factor, G = I. HV / I HH This is used to correct the difference in the response of an instrument system to light with different polarization directions. Among them, I... HV This represents the intensity of vertically polarized emitted light detected under horizontally polarized light excitation. HHThis represents the intensity of the horizontally polarized emitted light detected under horizontally polarized light excitation. The calculated value of r for isotropic perovskite nanocrystals is 0.28, while the anisotropy value of r for the CsPbBr3 perovskite nanowire-polymethyl methacrylate (PMMA) composite luminescent film is 0.49. Clearly, the composite luminescent film prepared using anisotropic CsPbBr3 perovskite nanowires as the fluorophore exhibits strong orientation and a large anisotropy value.

[0062] Example 2

[0063] (1) Preparation of CsPbBr3 perovskite nanowires: 0.4 g of cesium carbonate (Cs2CO3), 1.2 mL of oleic acid (OA), and 15 mL of 1-octadecene (ODE) were placed in a three-necked flask. Under nitrogen protection, the mixture was heated and stirred at 120 °C for 60 min. The temperature was then increased to 150 °C and reacted for 30 min until all the cesium carbonate (Cs2CO3) and oleic acid (OA) reacted, and the solution became completely clear, yielding the cesium oleate precursor. 0.2202 g of lead bromide (PbBr2) and 15 mL of 1-octadecene (ODE) were added to the three-necked flask, and nitrogen was introduced for venting for 30 min. The mixture was then heated at 120 °C for 60 min with magnetic stirring. Then, under nitrogen atmosphere, 2.4 mL of n-octylamine (OCT) and 2.4 mL of oleylamine (OAM) were injected sequentially. The heating temperature was then set to 135 °C for 60 min, after which the solution turned opaque white. The pre-prepared cesium oleate precursor was heated to 120°C to form a clear and transparent precursor solution. 2.1 mL of the cesium oleate precursor solution was rapidly injected into a three-necked flask. After injection, the reaction was allowed to proceed for 50 min. Subsequently, the three-necked flask was rapidly placed in an ice bath to cool to 40°C-50°C, yielding the stock solution of CsPbBr3 perovskite nanowires. 20 mL of toluene was added to the stock solution of CsPbBr3 perovskite nanowires, and the mixture was centrifuged at 6000 rpm / min for 5 min. After centrifugation, the supernatant was discarded, and the precipitate was retained.

[0064] (2) Preparation of CsPbBr3 perovskite nanowire-polymethyl methacrylate (PMMA) composite luminescent film: 8 mL of toluene and 1.0 g of PMMA were mixed in a glass bottle; then heated and stirred at 60 °C for 24 h in an oil bath at 250 rpm / min. Afterwards, 0.1 mmol of CsPbBr3 nanowires grown for 50 min were dissolved in 2 mL of toluene solution and added to the PMMA-toluene solution, and stirred at 600 rpm / min for 15 min to ensure uniform mixing. Subsequently, a smooth composite luminescent film with a thickness of 100 μm was coated onto a glass slide using a blade coating method.

[0065] (3) Fabrication of anisotropic light-emitting solar concentrator (LSC): A CsPbBr3 perovskite nanowire-polymethyl methacrylate composite film coated on a glass substrate was cut into 2×2cm pieces. 2 The dimensions were determined, and then two optically anisotropic CsPbBr3 perovskite nanowire-polymethyl methacrylate composite films were bonded face-to-face using a UV-curable adhesive. The samples were irradiated with 320–400 nm UV light until the UV-curable adhesive was completely cured, resulting in a device with a nanowire concentration of 0.1 mmol / g. Subsequently, absorption efficiency, escape cone loss, edge emission efficiency, PLQY, external optical efficiency, stability, and JV curve were tested.

[0066] (4) Fabrication of an optically anisotropic solar concentrator (OSL-LSC) based on an optical spacer layer: The CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film covering the glass substrate was cut into 2×2cm pieces. 2 The dimensions were determined, and then two CsPbBr3 perovskite nanowire-polymethyl methacrylate (PMMA) composite luminescent films were bonded to both sides of the optical spacer layer (a 2 mm thick glass plate) using a UV-curable adhesive. The samples were irradiated with 320–400 nm UV light until the UV-curable adhesive was completely cured, resulting in a device with a nanowire concentration of 0.1 mmol / g. Subsequently, its absorption efficiency, escape cone loss, edge emission efficiency, PLQY, external optical efficiency, stability, and JV curve were tested.

[0067] Figure 4 The figures show the absorption efficiency (a), escape cone loss, and edge emission efficiency (b) of the anisotropic solar concentrator in Example 2; the absorption efficiency (d), escape cone loss, and edge emission efficiency (e) of the optical anisotropic solar concentrator based on the optical spacer layer; and the PLQY (c) and external optical efficiency (f) of both the anisotropic solar concentrator and the optical anisotropic solar concentrator based on the optical spacer layer. The OSL-LSC has an absorption efficiency of 26.0%, higher than the anisotropic LSC's 23.7%; the edge emission efficiencies of the OSL-LSC and the anisotropic LSC are 74.5% and 70.5%, respectively; the PLQY of the OSL-LSC and the anisotropic LSC are 3.31% and 3.14%, respectively; and the external optical efficiencies of the OSL-LSC and the anisotropic LSC are 0.64% and 0.52%, respectively. This indicates that the addition of the optical spacer layer significantly improves all parameters.

[0068] Figure 5The stability test diagram of the optically anisotropic solar concentrator in Example 2 shows that the device has good stability and can maintain 88% of the initial value after 30 days; the peak position is relatively stable and always stays at around 523nm.

[0069] Figure 6 The stability test diagram of the optical anisotropic solar concentrator based on the optical spacer layer in Example 2 shows that the addition of the optical spacer layer improves the stability of the device, which can maintain 93% of the initial value after 30 days; the peak position is relatively stable, always remaining at around 523nm.

[0070] Figure 7 The JV curve test graphs for the optically anisotropic solar concentrator and the optically anisotropic solar concentrator based on the optical spacer layer in Example 2, and Table 1 show the performance test parameters for the optically anisotropic solar concentrator and the optically anisotropic solar concentrator based on the optical spacer layer in Example 2. The results show that the addition of the optical spacer layer helps to improve the PCE of the device, and the short-circuit current, short-circuit current density, open-circuit voltage and fill factor are all increased.

[0071] Table 1. Performance test parameters of optical anisotropy and optical anisotropy solar concentrators based on optical spacers.

[0072]

[0073] Example 3

[0074] (1) Preparation of CsPbBr3 perovskite nanowires: 0.4 g of cesium carbonate (Cs2CO3), 1.2 mL of oleic acid (OA), and 15 mL of 1-octadecene (ODE) were placed in a three-necked flask. Under nitrogen protection, the mixture was heated and stirred at 120 °C for 60 min. The temperature was then increased to 150 °C and reacted for 30 min until all the cesium carbonate (Cs2CO3) and oleic acid (OA) reacted, and the solution became completely clear, yielding the cesium oleate precursor. 0.2202 g of lead bromide (PbBr2) and 15 mL of 1-octadecene (ODE) were added to the three-necked flask, and nitrogen was introduced for venting for 30 min. The mixture was then heated at 120 °C for 60 min with magnetic stirring. Then, under nitrogen atmosphere, 2.4 mL of n-octylamine (OCT) and 2.4 mL of oleylamine (OAM) were injected sequentially. The heating temperature was then set to 135 °C for 60 min, after which the solution turned opaque white. The pre-prepared cesium oleate precursor was heated to 120°C to form a clear and transparent precursor solution. 2.1 mL of the cesium oleate precursor solution was rapidly injected into a three-necked flask. After injection, the reaction was allowed to proceed for 50 min. Subsequently, the three-necked flask was rapidly placed in an ice bath to cool to 40°C-50°C, yielding the stock solution of CsPbBr3 perovskite nanowires. 20 mL of toluene was added to the stock solution of CsPbBr3 perovskite nanowires, and the mixture was centrifuged at 6000 rpm / min for 5 min. After centrifugation, the supernatant was discarded, and the precipitate was retained.

[0075] (2) Preparation of CsPbBr3 perovskite nanowire-polymethyl methacrylate (PMMA) composite luminescent film: 8 mL of toluene and 1.0 g of PMMA were mixed in a glass bottle; then heated and stirred at 60 °C for 24 h in an oil bath at 250 rpm / min. Afterwards, 0.025 mmol of CsPbBr3 nanowires grown for 50 min were dissolved in 2 mL of toluene solution and added to the PMMA-toluene solution, and stirred at 600 rpm / min for 15 min to ensure uniform mixing. Subsequently, a smooth composite luminescent film with a thickness of 100 μm was coated onto a glass slide using a blade coating method.

[0076] (3) Fabrication of an optically anisotropic solar concentrator (OSL-LSC) based on an optical spacer layer: The CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film covering the glass substrate was cut into 2×2cm pieces. 2The dimensions were determined, and then two CsPbBr3 perovskite nanowire-polymethyl methacrylate (PMMA) composite luminescent films were bonded to both sides of the optical spacer layer (a 2 mm thick glass plate) using a UV-curable adhesive. The samples were irradiated with 320–400 nm UV light until the UV-curable adhesive was completely cured, resulting in a device with a nanowire concentration of 0.025 mmol / g. Escape cone loss and edge emission efficiency were then measured.

[0077] Figure 8 The figures show the escape cone loss and edge emission efficiency of the optical anisotropic solar concentrator based on the optical spacer layer in Example 3. When the nanowire concentration is set to 0.025 mmol / g, the escape cone loss is as low as 19.6%, which is far below the 25% limit for isotropic material devices. This indicates that using anisotropic fluorescent nanowires can indeed increase the fluorescence emission probability parallel to the substrate direction, thereby reducing the escape cone loss perpendicular to the substrate direction.

[0078] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An optically anisotropic solar energy concentrator, characterized in that: The optically anisotropic solar concentrator has a layered structure, which consists of a glass substrate, an ultraviolet-curable adhesive layer, and at least two functional layers. The functional layers are composed of CsPbBr3 perovskite nanowires-polymethyl methacrylate composite luminescent films.

2. A method for preparing the optically anisotropic solar energy concentrator according to claim 1, characterized in that: Includes the following steps: (1) Preparation of CsPbBr3 perovskite nanowires by hot injection method: Cesium carbonate (Cs2CO3) was mixed with oleic acid (OA) and 1-octadecene (ODE) under nitrogen atmosphere and heated and stirred to form cesium oleate precursor solution; Lead bromide (PbBr2) was mixed with 1-octadecene (ODE) by hot injection method and heated and stirred under nitrogen atmosphere, and n-octylamine (OCT) and oleylamine (OAM) were injected in sequence. After heating, lead bromide precursor solution was obtained, and then cesium oleate precursor solution was injected. After the reaction was completed, the mixture was immediately cooled. Subsequently, toluene was added, and CsPbBr3 nanowires were obtained by separation and purification. (2) Preparation of CsPbBr3 perovskite nanowire-polymethyl methacrylate (PMMA) composite luminescent film: Toluene and polymethyl methacrylate were mixed, stirred and heated. Then, the toluene solution of CsPbBr3 perovskite nanowires was added to the polymethyl methacrylate-toluene solution and stirred evenly. Subsequently, the CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film was coated onto a glass substrate by a blade coating method. Finally, the coated glass slide was placed on a heating stage and heated. (3) Preparation of optically anisotropic solar concentrator: Two optically anisotropic CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent films obtained in step (2) are bonded face to face using an ultraviolet light curing adhesive, and the samples are irradiated with ultraviolet light using a 320-400nm ultraviolet lamp to cure them, thus obtaining an optically anisotropic solar concentrator; or two optically anisotropic CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent films obtained in step (2) are bonded face to face on both sides of an optical spacer layer (glass substrate) using an ultraviolet light curing adhesive, and the samples are irradiated with ultraviolet light using a 320-400nm ultraviolet lamp to cure them, thus obtaining an optically anisotropic solar concentrator based on an optical spacer layer.

3. The method according to claim 2, characterized in that: In step (1), the molar ratio of cesium carbonate (Cs2CO3), lead bromide (PbBr2), and oleic acid (OA) is 2:1:

6. When preparing the cesium oleate precursor solution, cesium carbonate, oleic acid, and 1-octadecyl ODE are added in a molar ratio of 1:3:

40. Under nitrogen protection, the mixture is heated and stirred until all the cesium carbonate reacts with the oleic acid and the solution becomes completely clear, thus obtaining the cesium oleate precursor solution.

4. The method according to claim 2, characterized in that: In step (1), lead bromide (PbBr2) and 1-octadecene ODE are mixed evenly, nitrogen gas is introduced for exhaust treatment, and then the mixture is heated and stirred. In a nitrogen atmosphere, n-octylamine (OCT) and oleylamine (OAM) are injected sequentially, and the mixture is heated until the solution becomes opaque white to obtain a lead bromide precursor solution. The molar ratio of lead bromide (PbBr2), 1-octadecene ODE, n-octylamine (OCT), and oleylamine (OAM) is 1:80:24:

12.

5. The method according to claim 2, characterized in that: In step (1), CsPbBr3 perovskite nanowires are prepared by hot injection method. The cesium oleate precursor solution prepared in step (1) is heated to form a clear and transparent cesium oleate precursor solution. The cesium oleate precursor solution is rapidly injected into the lead bromide precursor solution. After injection, the reaction is allowed to proceed fully, and then the solution is rapidly placed in an ice bath to cool, thus obtaining the original solution of CsPbBr3 nanowires.

6. The method according to claim 2, characterized in that: In step (1), the separation and purification of CsPbBr3 perovskite nanowires is carried out by adding toluene to the original solution of CsPbBr3 perovskite nanowires, centrifuging, discarding the supernatant after centrifugation, and retaining the precipitate, which is the CsPbBr3 perovskite nanowire.

7. The method according to claim 2, characterized in that: In step (2), toluene and polymethyl methacrylate are mixed, and then heated and stirred to fully dissolve the polymethyl methacrylate to obtain a polymethyl methacrylate-toluene solution; the toluene solution of CsPbBr3 perovskite nanowires is added to the polymethyl methacrylate-toluene solution and stirred to mix them evenly.

8. The method according to claim 2, characterized in that: In step (2), a composite light-emitting film with a smooth surface and a thickness of 100 μm is scraped onto a glass slide using a scraping method. The scraped glass slide is then placed on a heating table for heating and curing.

9. The method according to claim 2, characterized in that: In step (3), the CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film covering the glass substrate is cut into 2×2cm pieces. 2 After determining the dimensions, two optically anisotropic CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent films were bonded face-to-face using a UV-curable adhesive. The samples were then irradiated with 320–400 nm UV light until the UV-curable adhesive was completely cured.

10. The method according to claim 2, characterized in that: In step (3), the CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film covering the glass substrate is cut into 2×2cm pieces. 2 After determining the dimensions, an optical spacer layer was attached to the CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film using a UV-curable adhesive. The CsPbBr3 perovskite nanowire-polymethyl methacrylate composite luminescent film was then attached to the other side of the optical spacer layer. Finally, the sample was irradiated with 320–400 nm UV light until the UV-curable adhesive was completely cured.

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