A double perovskite material, and a preparation method and application thereof

Abstract

The application discloses a double perovskite material and a preparation method and application thereof, and the chemical formula of the double perovskite material is Cs2AEr Z Bi 1‑Z X6, wherein A is one of Ag, Na and K, X is one or two of halogen anions, and 0 < Z < 1. The double perovskite material provided by the application replaces divalent Pb ions in a conventional double perovskite material with monovalent A (one of Ag, Na and K) ions and trivalent Er and Bi ions, so that the toxicity of the double perovskite material is greatly reduced, the perovskite band gap is controlled, and optical properties in the near-infrared II region are obtained. Due to the regulation of the rare earth element Er on the energy level of the transition metal element Bi, the double perovskite material can realize a luminescent peak with a luminescent center of 1542 nm. The detector prepared from the double perovskite material can realize visible-near-infrared band (447-1550 nm) detection, wherein the visible light region I 光 / I 暗 can reach 10 4 , in particular, the I 光 / I 暗 of 1550 nm and 1310 nm is greater than 10 2 .

Description

TECHNICAL FIELD

[0001] The present application relates to the field of near-infrared photoelectric technology, in particular to a double perovskite material and a preparation method and application thereof. BACKGROUND

[0002] Near-infrared light is an electromagnetic wave with a wavelength in the range of 780-2526 nm, which can be divided into short-wave near-infrared (780-1100 nm) and long-wave near-infrared (1100-2526 nm) according to the 1100 nm wavelength. Due to the high spatiotemporal resolution and deep tissue penetration advantage of near-infrared light, it has been widely used in medical, detection and communication fields. Perovskite materials (APbX3) have a high degree of symmetry of three-dimensional crystals and Pb 2+ unique electronic structure, which is one of the most potential candidate materials for future high-quality light sources and high-definition displays. However, this material contains Pb 2+ , which has certain toxicity. In addition, since the A + cations in this material are usually organic ions or organic-inorganic hybrid ions, they are prone to decomposition when encountering water and oxygen in the air, thus having poor air stability, low device life and other shortcomings.

[0003] To reduce the toxicity of Pb 2+ in perovskite materials, researchers use the method of heterovalent substitution to replace Pb 2+ in APbX3 material with non-toxic or low-toxic trivalent transition metal or rare earth metal ions, forming a double metal type double perovskite (A2B + B 3+ X6, typical A is Cs + , B + is Ag + , Na + , K + , Li + , etc.; B 3+ is Bi 3+ , Sb 3+ , In 3+ , etc.; X is a halogen anion). Among them, A2B + B 3+ X6 is a three-dimensional double metal type double perovskite material formed by replacing two lead ions with one monovalent and one trivalent cation, which has a variable chemical composition, making this type of material exhibit long carrier lifetime, adjustable band gap, simple preparation method and good stability, etc. It has broad application prospects in photovoltaic cells, light-emitting diodes (LEDs), photodetectors and other fields.

[0004] However, the luminescence wavelength of the double-metal type double perovskite material without ion doping is mainly concentrated in the visible light band, and the double peroviskite material with an emission wavelength greater than 1000 nm in the near-infrared band is scarce, and has problems of low luminescence efficiency and difficulty in preparation into a thin film, and is difficult to meet the needs of chip integration technology.

[0005] Therefore, the prior art still needs to be improved and developed. SUMMARY

[0006] In view of the deficiencies of the prior art described above, the purpose of the present application is to provide a double perovskite material and a preparation method and application thereof, aiming to solve the problem of small luminescence wavelength range of the existing double perovskite material.

[0007] The technical scheme of the present application is as follows:

[0008] In a first aspect of the present application, a double perovskite material is provided, and the chemical formula of the double perovskite material is Cs2AEr Z Bi 1-Z X6, wherein A is one of Ag, Na and K, X is one or two of halogen anions, and 0 < Z < 1.

[0009] Preferably, the chemical formula of the double perovskite material is Cs2NaEr Z Bi 1-Z I 6-y Cl y , Cs3Er Z Bi 1-Z I 6-y Cl y , Cs2NaEr Z Bi 1-Z I6 or Cs2NaEr Z Bi 1-Z Cl6, wherein 0 < y < 6. For example, the chemical formula of the double perovskite material can be Cs2NaEr 0.05 Bi 0.95 Cl6, Cs2NaEr 0.05 Bi 0.95 I 5.5 Cl 0.5 , Cs2NaEr 0.05 Bi 0.95 I6, etc., but is not limited thereto.

[0010] In a second aspect of the present application, a preparation method of the above-mentioned double perovskite material is provided, and the preparation method comprises the following steps:

[0011] dissolving CsX, AX, ErX3 and BiX3 in a hydrohalic acid solution to form a double perovskite precursor solution;

[0012] subjecting the double perovskite precursor solution to a hydrothermal reaction to obtain a double perovskite material with a chemical formula of Cs2AEr Z Bi 1-Z X6.

[0013] Preferably, the molar ratio of CsX, AX, ErX3 and BiX3 is 2:1:Z:(1-Z).

[0014] Preferably, the temperature of the hydrothermal reaction is 150-180℃, and the time is 4-12h.

[0015] Preferably, after the double perovskite precursor solution is subjected to the hydrothermal reaction, a double perovskite solution is obtained, and the double perovskite solution is sequentially subjected to a cooling treatment, a washing treatment and a drying treatment.

[0016] Preferably, the cooling treatment specifically comprises cooling the double perovskite solution to room temperature.

[0017] Preferably, the washing treatment specifically comprises filtering double perovskite powder from the double perovskite solution, and washing the double perovskite powder with one of anhydrous ethanol, methanol and isopropanol.

[0018] Preferably, the drying treatment specifically comprises drying the double perovskite powder after the washing treatment at a temperature of 60-100℃ for 4-12h.

[0019] In a fourth aspect, the application provides application of the double perovskite material in a photoelectric detector, a photovoltaic cell and a light-emitting diode.

[0020] Beneficial effects: The application provides a double perovskite material, a preparation method and application thereof. The double perovskite material provided by the application replaces divalent Pb ions in a conventional double perovskite with monovalent A (one of Ag, Na and K) ions and trivalent Er and Bi ions, so that the toxicity is greatly reduced. Moreover, due to the regulation of the rare earth element Er on the energy level of the transition metal element Bi, the double perovskite material can realize a luminescent center with a luminescent peak of 1542nm.

[0021] The detector prepared by using the double perovskite material can realize visible-near infrared band (447-1550nm) detection, wherein the visible light region I 光 / I 暗 can reach 10 4 , in particular, the I 光 / I 暗 of 1550nm and 1310nm is greater than 10 2 . BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1Cs2NaEr 0.05 Bi 0.95 X-ray diffraction pattern (a) and SEM pattern (b) of the Cl6 double perovskite material. 0.05 Bi 0.95 I 5.5 Cl 0.5 X-ray diffraction pattern (c) and SEM pattern (d) of the double perovskite material.

[0023] Figure 2 Cs2NaEr 0.05 Bi 0.95 UV-visible-near infrared absorption graph (a) and Tauc graph (b) of the Cl6 double perovskite material.

[0024] Figure 3 Cs2NaEr 0.05 Bi 0.95 Emission spectrum graph of the Cl6 double perovskite material under 980nm laser excitation: (a) is 400-900nm, (b) is 900-1700nm.

[0025] Figure 4 Cs2NaEr 0.05 Bi 0.95 I 5.5 Cl 0.5 (a) absorption spectrum and photoluminescence spectrum of the double perovskite material, (b) Tauc graph.

[0026] Figure 5 I-V curve graph of the visible-near infrared double perovskite detector prepared in the application example under 19.8mW light power condition under 447nm, 520nm, 669nm, 808nm, 1060nm, 1310nm, 1550nm wavelength light. DETAILED DESCRIPTION

[0027] The present application provides a double perovskite material and a preparation method and application thereof, in order to make the purpose, technical scheme and effect of the present application more clear and definite, the present application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0028] The embodiment of the present application provides a double perovite material, the chemical formula of the double perovskite material is Cs2AEr Z Bi 1- Z X6, wherein A is one of Ag, Na and K, X is one or two of halogen anions, and 0

[0029] In some embodiments, the double perovskite material has a chemical formula of Cs2NaEr Z Bi 1-Z I 6-y Cl y , Cs3Er Z Bi 1-Z I 6-y Cl y , Cs2NaEr Z Bi 1-Z I6or Cs2NaEr Z Bi 1-Z Cl6, where 0 < y < 6.

[0030] This embodiment takes Cs2NaEr x Bi 1-x I 6-y Cl y as an example to illustrate the technical principles, and other chemical formulas are the same. Cs2NaEr x Bi 1-x I 6-y Cl y is a co-doped compound based on transition metal element Bi with special electronic structure and rare earth element Er with relatively complex atomic structure, wherein the Bi ion has 0, +1, +2, +3 and +5 valence states, and has a strong spin-orbit coupling effect; the 4 I 13 / 2 → 4 I 15 / 2 about 1550 nm fluorescence can be obtained. Due to the alloying effect of Bi 3+ , the spacing between Er 3+ is increased, and the resulting lattice distortion promotes the energy transfer from Bi 3+ to Er 3+ , ultimately realizing the enhancement of up-conversion 2 H 11 / 2 , 4 S 3 / 2 and 4 F 9 / 2 and down-conversion near-infrared 4 I 13 / 2 → 4 I 15 / 2 . In addition, the cross-relaxation effect between Bi 3+ and Er 3+ energy levels can make the Cs2NaEr x Bi 1-x I 6-y Cl yThe luminescence and detection performance is realized in the visible-near infrared II region (447-1550 nm).

[0031] The embodiment of the present application provides the preparation method of the double perovskite material, and the preparation method comprises the following steps:

[0032] CsX, AX, ErX3 and BiX3 are dissolved in a hydrohalic acid solution to form a double perovskite precursor solution;

[0033] The double perovskite precursor solution is subjected to a hydrothermal reaction to obtain a double perovskite material with a chemical formula of Cs2AEr Z Bi 1-Z X6.

[0034] The preparation method provided by the embodiment combines the solvothermal method with vacuum evaporation, and is used for preparing the double perovskite material with the chemical formula of Cs2AEr Z Bi 1-Z X6 under the condition that the temperature is not more than 160 DEG C, and the double perovskite material overcomes the defect of high energy consumption in the preparation of the near-infrared fluorescent material by traditional high-temperature calcination.

[0035] In some embodiments, the molar ratio of the CsX, AX, ErX3 and BiX3 is 2:1:Z:(1-Z).

[0036] In some embodiments, the hydrohalic acid solution is at least one of hydrochloric acid, hydroiodic acid and hydrobromic acid.

[0037] In some embodiments, the temperature of the hydrothermal reaction is 150-180 DEG C, and the time is 4-12 h.

[0038] If the temperature of the hydrothermal reaction is low, the double perovskite material cannot be completely dissolved, and too many impurities are precipitated; if the temperature is too high, a dangerous accident is prone to occur, and the composition of the coprecipitation is prone to be non-uniform.

[0039] In some preferred embodiments, the temperature of the hydrothermal reaction is 160 DEG C, and the time is 8 h.

[0040] In some embodiments, after the double perovskite precursor solution is subjected to the hydrothermal reaction, a double perovskite solution is obtained, and the double perovskite solution is sequentially subjected to cooling treatment, washing treatment and drying treatment.

[0041] In some embodiments, the cooling treatment specifically comprises cooling the double perovskite solution to room temperature.

[0042] In some embodiments, the washing treatment specifically comprises filtering double perovskite powder from the double perovskite solution, and washing the double perovskite powder by using one of anhydrous ethanol, methanol and isopropanol.

[0043] In some embodiments, the drying treatment is specifically drying the double perovskite powder after washing treatment at a temperature of 60-100℃ for 4-12h.

[0044] If the temperature is too low, it is not easy to dry; if the temperature is too high, it is easy to cause explosive boiling and powder splashing.

[0045] In some preferred embodiments, the drying treatment is specifically drying the double perovskite powder after washing treatment at a temperature of 80℃ for 8h.

[0046] In some embodiments, a preparation method of the above-mentioned double perovskite material is provided, and the preparation method comprises the following steps:

[0047] In a hydrothermal kettle at 160℃, CsX, AX, ErX3 and BiX3 are dissolved in a hydrochloric acid solution in a molar ratio of 2:1:Z:(1-Z) to form a double perovskite precursor solution;

[0048] After the double perovskite precursor solution is reacted at a temperature of 160℃ for 8h, a double perovskite solution is obtained;

[0049] The double perovskite solution is cooled to room temperature, and then a double perovskite powder is filtered out from the cooled double perovskite solution, and the double perovskite powder is washed with anhydrous ethanol for three times, and then the washed double perovskite powder is dried at 80℃ for 8h to obtain a double perovskite material of the chemical formula Cs2AEr Z Bi 1-Z X6.

[0050] The application further provides applications of the above-mentioned double perovskite material in photoelectric detectors, photovoltaic cells and light-emitting diodes.

[0051] The technical solutions in the embodiments of the application will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the application, but not all the embodiments of the application, which are only used to illustrate but not limit the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0052] Embodiment 1

[0053] Cs2NaEr 0.05 Bi 0.95 Cl6 double perovskite material, comprising the following steps:

[0054] a) 0.6734g of cesium chloride, 0.1169g of sodium chloride, 0.3648g of erbium chloride and 0.2102g of bismuth chloride are sequentially added into a hydrothermal kettle, and then 25mL of hydrochloric acid is added into the hydrothermal kettle, and after the hydrothermal kettle is sealed, it is heated in a 160℃ air drying oven for 8h;

[0055] b) The closed hydrothermal kettle heated in step a) is cooled to room temperature with an ice water bath, and the perovskite powder is filtered out and washed with anhydrous ethanol three times. The perovskite powder is filtered out and dried in a drying oven at 80°C for 8h, and then taken out and placed in a nitrogen glove box for storage.

[0056] Example 2

[0057] Cs2NaEr 0.05 Bi 0.95 I 5.5 Cl 0.5 The preparation of a double perovskite material includes the following steps:

[0058] a) 1.0392g of cesium iodide, 0.1169g of sodium chloride, 0.3648g of erbium chloride, and 0.2102g of bismuth chloride are sequentially added to a hydrothermal kettle, and then 25mL of hydrochloric acid is added to the hydrothermal kettle. After sealing the hydrothermal kettle, it is heated in a forced air drying oven at 160°C for 8h;

[0059] b) The closed hydrothermal kettle heated in step a) is cooled to room temperature with an ice water bath, and the perovskite powder is filtered out and washed with anhydrous ethanol three times. The perovskite powder is filtered out and dried in a drying oven at 80°C for 8h, and then taken out and placed in a nitrogen glove box for storage.

[0060] Example 3

[0061] Cs2NaEr 0.05 Bi 0.95 I6The preparation of a double perovskite material includes the following steps:

[0062] a) 1.0392g of cesium iodide, 0.2998g of sodium iodide, 0.7306g of erbium iodide, and 0.3931g of bismuth iodide are sequentially added to a hydrothermal kettle, and then 25mL of hydrochloric acid is added to the hydrothermal kettle. After sealing the hydrothermal kettle, it is heated in a forced air drying oven at 160°C for 8h;

[0063] b) The closed hydrothermal kettle heated in step a) is cooled to room temperature with an ice water bath, and the perovskite powder is filtered out and washed with anhydrous ethanol three times. The perovskite powder is filtered out and dried in a drying oven at 80°C for 8h, and then taken out and placed in a nitrogen glove box for storage.

[0064] Comparative Example 1

[0065] Cs2NaBiI 5.5 Cl 0.5 The preparation of a double perovskite material includes the following steps:

[0066] a) 1.0392 g of cesium iodide, 0.1169 g of sodium chloride, 0.6307 g of bismuth chloride were sequentially added into an autoclave, then 25 mL of hydrochloric acid was added into the autoclave, the autoclave was sealed and heated in a blast drying oven at 160°C for 8 h;

[0067] b) The sealed autoclave heated in step a) was cooled to room temperature with an ice water bath, then the perovskite powder was filtered out and washed with anhydrous ethanol for three times, the perovskite powder was filtered out and dried in a drying oven at 80°C for 8 h, then it was taken out and stored in a nitrogen glove box.

[0068] Comparative Example 2

[0069] Cs3Er 0.05 Bi 0.95 I 5.5 Cl 0.5 Preparation of a double perovskite material, comprising the following steps:

[0070] a) 1.0392 g of cesium iodide, 0.2245 g of cesium chloride, 0.3648 g of erbium chloride, 0.2102 g of bismuth chloride were sequentially added into an autoclave, then 25 mL of hydrochloric acid was added into the autoclave, the autoclave was sealed and heated in a blast drying oven at 160°C for 8 h;

[0071] b) The sealed autoclave heated in step a) was cooled to room temperature with an ice water bath, then the perovskite powder was filtered out and washed with anhydrous ethanol for three times, the perovskite powder was filtered out and dried in a drying oven at 80°C for 8 h, then it was taken out and stored in a nitrogen glove box.

[0072] Application Example

[0073] Preparation of a visible-near infrared double perovskite detector, comprising the following steps:

[0074] (i) Substrate cleaning: ITO glass substrate was sequentially cleaned in deionized water, isopropyl alcohol, acetone and ethanol for 20 min under ultrasonic cleaning, to remove the surface stains, then the surface organic solvent was removed using a nitrogen gun, and then treated under ozone for 20 min to remove residual organic reagents and improve the hydrophilic and hydrophobic properties of the substrate surface.

[0075] (ii) Preparation of electron transport layer: 50 mg / mL of 15% MgO ZnO nanoalcohol solution was configured to 20 mg / mL with anhydrous ethanol and shaken for 5 min using an ultrasonic cleaning instrument. 100 uL of the configured nano-ZnO ethanol solution was extracted with a pipette and spin-coated at a speed of 2000 rpm for 30 s, and then annealed at 100°C for 15 min.

[0076] (iii) Preparation of double perovskite thin film: the Cs2NaEr 0.05Bi 0.95 Cl6 double perovskite material was placed in a tungsten boat for thermal evaporation in a vacuum coating machine at a vacuum degree of 5 × 10⁻⁶. -4 Under the conditions of Pa and 35 W power, Cs2NaEr was deposited at a deposition rate of 0.2 Å (0.1 nm) / s. 0.05 Bi 0.95 Cl6 double perovskite material was vapor-deposited onto an ITO glass substrate with spin-coated ZnO to form a polycrystalline thin film. The vapor-deposited sample was removed from the vacuum coating machine and placed on a 160°C heating stage for annealing at 160°C for 15 minutes to promote densification of the polycrystalline thin film and reduce film defects.

[0077] (iv) Preparation of hole transport layer and silver electrode: 12 mg of poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4-(N-(4-sec-butylphenyl)diphenylamine)] (TFB) was added to a glass bottle containing 1 mL of chloroform and shaken to dissolve. 90 μL of the TFB solution was spin-coated at 3000 rpm for 30 s. The spin-coated device was then transferred to a vacuum coating machine and coated under a vacuum of 5 × 10⁻⁶. -4 A 10 nm MoO3 hole transport layer was deposited at a deposition rate of 0.1 Å (0.1 nm) / s under Pa and 42 W power conditions; and a vacuum degree of 5 × 10⁻⁶ was maintained. -4 Under the conditions of Pa and 82W power, 20nm of Ag was deposited at a deposition rate of 0.5 Å (0.1nm) / s, and then the Ag electrode thickness was increased to 100nm by deposition at a deposition rate of 1.0 Å (0.1nm) / s.

[0078] Performance testing

[0079] 1. Regarding the Cs2NaEr prepared in Example 1 0.05 Bi 0.95 Cl6 double perovskite material and Cs2NaEr prepared in Example 2 0.05 Bi 0.95 I 5.5 Cl 0.5 X-ray diffraction and SEM characterization of double perovskite materials, such as Figure 1 .

[0080] Figure 1 (a) is Cs2NaEr prepared in Example 1 of this invention. 0.05 Bi 0.95 X-ray diffraction patterns of Cl6 double perovskite material and Cs2NaBiCl6 (ICSD No. 77-1831) and Cs2NaErCl6 (ICSD No. 890053) standards. The figures show that the strong diffraction peaks at 14.18°, 28.52°, and 59.00° are characteristic of Cs2NaErCl6. 0.05 Bi0.95 The diffraction peaks of (111), (222) and (444) planes of the Csl6 double perovskite material correspond to the Fm3m space group. The central peak positions of the diffraction peaks of the Csl6 double perovskite material are obviously shifted from the diffraction peaks of (111), (222) and (444) planes of the Csl6 and Csl6 standard samples, because the alloying of transition metal element Bi and rare earth element Er leads to the change of the crystal lattice, which makes the lattice constant of the Csl6 double perovskite material larger than that of the Csl6 and Csl6 standard samples. 0.05 Bi 0.95 The diffraction peak position of (111) plane of the Csl6 double perovskite material is shifted from the low angle of Csl6 to the high angle of Csl6. Figure 1 Fig. (b) is the XRD pattern of the Csl6 double perovskite material prepared in Example 1 of the present application. 0.05 Bi 0.95 Fig. (a) is the scanning electron microscope (SEM) image of the Csl6 double perovskite material annealed at 160°C for 5 min. It is obvious from the figure that the Csl6 double perovskite material is polycrystalline, and the average size of the single crystal grain is 200-500 nm. 0.05 Bi 0.95 Fig. (c) and (d) are the XRD pattern and SEM image of the Csl6 double perovskite material prepared in Example 2 of the present application. 0.05 Bi 0.95 I 5.5 Cl 0.5 The XRD pattern and SEM image of the double perovskite material.

[0081] 2, The UV-visible-near infrared absorption and band gap of the Csl6 double perovskite material prepared in Example 1 of the present application were detected. 0.05 Bi 0.95 The UV-visible-near infrared absorption and band gap of the Csl6 double perovskite material were detected. Figure 2 .

[0082] Figure 2 Fig. (a) is the UV-visible-near infrared absorption curve of the Csl6 double perovskite material prepared in Example 1 of the present application. It can be seen from the figure that the Csl6 double perovskite material has a strong absorption peak at about 375 nm, and has weak absorption states at 530 nm, 750 nm and 1200 nm. 0.05 Bi 0.95 Fig. (b) is the UV-visible-near infrared absorption curve of the Csl6 double perovskite material prepared in Example 2 of the present application. 0.05 Bi 0.95 The Csl6 double perovskite material has a strong absorption peak at about 375 nm, and has weak absorption states at 530 nm, 750 nm and 1200 nm. 0.05 Bi 0.95 The band gap of the Csl6 double perovskite material was determined (see Fig. (b)). Figure 2 The linear fitting of the absorption edge gives the photon energy of 3.10 eV, i.e. the band gap of the Csl6 double perovskite material is 3.10 eV. 0.05 Bi 0.95 The band gap of the Csl6 double perovskite material is 3.10 eV.

[0083] 3. Regarding the Cs₂NaEr prepared in Example 1 0.05 Bi 0.95 Cl6 double perovskite materials excited by a 980nm laser, such as Figure 3 .

[0084] from Figure 3 As can be seen from this, Cs2NaEr 0.05 Bi 0.95 Cl6 double perovskite materials exhibit upconversion ( ) under 980 nm laser excitation. Figure 3 (a) and downconversion (a) Figure 3 The phenomenon described in (b) is due to Er. 3+ The doping of Bi makes 3+ The increased spacing between them, resulting in lattice distortion, promotes the growth of Bi 3+ To Er 3+ The energy transfer ultimately leads to upconversion at 535nm ( 2 H 11 / 2 ), 558nm 4 S 3 / 2 ) and 663nm ( 4 F 9 / 2 )arrive 4 I 15 / 2 The transition and downconversion at 1542nm ( 4 I 13 / 2 → 4 I 15 / 2 The enhancement of ).

[0085] 4. Regarding the Cs2NaEr prepared in Example 2 0.05 Bi 0.95 I 5.5 Cl 0.5 The double perovskite material was subjected to UV-Vis absorption and photoluminescence tests, such as... Figure 4 .

[0086] Figure 4 (a) is Cs2NaEr prepared in Example 2 of this invention. 0.05 Bi 0.95 I 5.5 Cl 0.5 UV-Vis absorption curves and PL curves of the double perovskite material. As shown in the figure, Cs₂NaEr 0.05 Bi 0.95 I 5.5 Cl 0.5 The double perovskite material exhibits a strong absorption peak around 650 nm and an absorption tail state in the 700-800 nm range. Tauc plots were used to analyze Cs₂NaEr. 0.05 Bi 0.95 I5.5 Cl 0.5 The band gap of the double perovskite material was determined (see Figure 4 The linear fit of the absorption edge gives the photon energy of 1.59 eV and 1.89 eV, respectively. The average of the two values gives the band gap of Cs2NaEr 0.05 Bi 0.95 I 5.5 Cl 0.5 The band gap of the double perovskite material is 1.74 eV.

[0087] 5、 Figure 5 The I-V curves of the visible-near infrared double perovskite detector prepared for the application example under 19.8 mW optical power at 447 nm, 520 nm, 669 nm, 808 nm, 1060 nm, 1310 nm, 1550 nm wavelength illumination. The detector exhibits a visible-near infrared ultra-wide spectral response, in which under 19.8 mW optical power, the I 光 / I 暗 is greater than 10 4 , and the I 光 / I 暗 is greater than 10 2 .

[0088] It should be understood that the application of the present application is not limited to the above examples, and those of ordinary skill in the art can make improvements or changes according to the above description, and all such improvements and changes shall belong to the protection scope of the appended claims of the present application.

Claims

1. Use of a double perovskite material of formula Cs2NaEr 0.05 Bi 0.95 I 5.5 Cl 0.5 in a photodetector.

2. Use of a double perovskite material according to claim 1, characterized in that The preparation method of the double perovskite material comprises the following steps: a) 1.0392 g of cesium iodide, 0.1169 g of sodium chloride, 0.3648 g of erbium chloride, and 0.2102 g of bismuth chloride are sequentially added into a hydrothermal kettle, then 25 mL of hydrochloric acid is added into the hydrothermal kettle, the hydrothermal kettle is sealed, and the sealed hydrothermal kettle is heated in a blast drying oven at 160 DEG C for 8 h; b) the sealed hydrothermal kettle heated in step a) is cooled to room temperature by using an ice water bath, then the perovskite powder is filtered out, the perovskite powder is washed three times by using anhydrous ethanol, the perovskite powder is filtered out, and the perovskite powder is dried in a drying oven at 80 DEG C for 8 h, and then the perovskite powder is taken out and stored in a nitrogen glove box.

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