A far-infrared perovskite luminescent material, device and preparation method

Abstract

The present invention belongs to the field of electroluminescent devices, and mainly relates to a far-infrared perovskite luminescent material, a device and a preparation method. The far-infrared perovskite luminescent material has the molecular formula: (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 . The far-infrared perovskite luminescent material is used as the luminescent layer. The preparation method of the far-red perovskite luminescent device comprises the following steps: (1) spin coating the electron transport layer ZnO / PEIE on the glass substrate ITO and annealing; (2) preparing the far-infrared perovskite luminescent material precursor and spin coating it on the electron transport layer ZnO / PEIE; (3) spin coating the hole transport layer; (4) evaporating MoOx / Au electrode. The material is a 735nm far-red perovskite luminescent material with an excess of A position and a very small amount of Br, which improves the stability of the spectrum; the device can stably emit 735nm far-red light; the method of the present invention optimizes the luminescent material and device prepared by experiments, so that the device exhibits very excellent spectral stability and has a very stable spectral output under different voltage drives.

Description

Technical Field

[0001] The invention belongs to the field of electroluminescent devices, and mainly relates to a far-infrared perovskite luminescent material, a device and a preparation method. Background Art

[0002] In recent years, with the in-depth study of perovskite materials by researchers, related research in the fields of solar cells, light-emitting diodes, photodetectors, lasers, etc. has achieved rapid development. Perovskite materials have many excellent optoelectronic properties, such as adjustable band gap, high color purity, solution preparation, high mobility, high quantum yield, etc., which makes perovskite shine in the field of light-emitting diodes and is expected to become the next generation of new display technology. Since the first perovskite light-emitting diode (PeLED) synthesized at room temperature was reported in 2014, PeLEDs have made breakthrough progress in multiple emission bands. Among them, the external quantum efficiency (EQE) of blue light has reached 12.8%; the external quantum efficiency of green light has reached 28.1%; the external quantum efficiency of near-infrared light has reached 22.2%.

[0003] The chemical formula of perovskite is mostly ABX3, where the A position represents an organic cation and the B position is usually Pb 2+ Sn 2 + , X is a halogen element, usually Cl - Br - ,I - . Among the many different types of perovskites, organic-inorganic hybrid halide perovskites can adjust the band gap by adjusting the cation stoichiometry at the A site or the halogen anion stoichiometry at the X site. This unique advantage makes it stand out in the manufacture of wavelength-tunable light-emitting diodes. At present, the perovskite components used to realize green light perovskite light-emitting diodes are mainly pure bromine-based perovskites (ABBr3). Blue light perovskite light-emitting diodes are mainly achieved by doping a certain amount of chloride ions into pure bromine-based perovskites (ABBr3) to increase the wavelength of perovskites (ABBr x Cl 3-x ) band gap, making its spectrum blue-shifted, thus achieving blue light emission. For the orange and red light bands, a certain amount of iodine ions is doped into the pure bromine-based perovskite (ABBr3) to reduce the perovskite (ABBr x I 3-x )’s band gap causes the spectrum to redshift, thus achieving orange and red light emission.

[0004] As early as 2015, Kumawat (Kumawat N, Dey A, Kumar A, et al. Band Gap Tuning of CH3NH3Pb (Br 1-x Cl x ) (3) Hybrid Perovskite for Blue Electroluminescence[J].ACSApplied Materials&Interfaces,2015,7(24):13119-13124.) et al. studied the three-dimensional perovskite MAPb(Br 1-x Cl x )3, the PL spectrum was continuously tunable over a wide range from 539nm to 413nm. 1.08 Cl 1.92 Perovskite sky blue LED device, EQE < 0.1%, brightness 1.7 cd·m -2 Until now, one of the important ways to achieve sky blue LED is still the mixing of halogen bromine and chlorine.

[0005] Since the band gap of pure bromine-based perovskite (ABBr3) just meets the emission in the green light band, for the green light region of perovskite light-emitting diodes, researchers have focused more on regulating the n-value distribution of quasi-two-dimensional perovskites. By introducing different organic large cations at the A position to regulate the distribution of n values, efficient green light devices can be prepared.

[0006] Like blue LEDs, one of the ways to realize red LEDs is through organic-inorganic mixed halide perovskites, but red LEDs are bromine-iodine mixed systems. In 2018, Wang Jianpu (You, Ke, Nana, et al. Defect Passivation for Red Perovskite Light-Emitting Diodes with Improved Brightness and Stability. [J]. Journal of Physical Chemistry Letters, 2018.) et al. changed 5AVA 0.3 -FA 0.47 Cs 0.53 Pb(I 1-y Br y)3, the ratio of Br to I was adjusted to obtain a wide range of red light continuous spectrum adjustable from 605nm to 675nm. In 2020, Xiao Zhengguo (Fang Z, Chen W, Shi Y, et al. Dual Passivation of Perovskite Defects for Light-Emitting Diodes with External Quantum Efficiency Exceeding 20% ​​[J]. Advanced Functional Materials, 2020, 30 (12): 1909754.1-1909754.9.) et al. 0.33 Cs 0.67 Pb(I 0.7 Br 0.3 )3 The additive FPMATFA with dual passivation effect was introduced into the organic-inorganic mixed halide perovskite to obtain a red light LED with a luminescence peak at 694nm and an EQE of 20.9%.

[0007] At present, perovskite has made great progress in the mainstream luminous color domains such as green light, red light, and near-infrared. However, its development in the far-red light region is slightly lagging behind. Few researchers have paid attention to the far-red light in the range of 700nm to 750nm. However, far-red light is indispensable in the field of LED plant lighting. Far-red light (around 735nm) can control the entire process of plants from germination to nutritional growth to flowering. And the appropriate combination of far-red light with blue light and red light can provide better chromatographic coverage. Therefore, the development of far-red light is of great significance to fill the full spectrum of perovskite luminescence and broaden the application scenarios of perovskite LEDs. Perovskite light-emitting diodes in the far-red region are also mainly realized through organic-inorganic mixed halide perovskites.

[0008] However, in order to obtain 735nm far-red perovskite light-emitting devices, it is necessary to adjust its band gap by doping at the X or A position. When more halogen is doped at the X position, it will lead to electric field-induced phase separation, making the spectrum of the perovskite light-emitting diode unstable and prone to redshift or blueshift with increasing voltage. Summary of the invention

[0009] Based on this, the object of the present invention is to provide a far-red perovskite luminescent material, which is a 735nm far-red perovskite luminescent material with an excess amount of A position and a very small amount of Br to improve the stability of the spectrum; another object of the present invention is to provide a far-red perovskite light-emitting device, which can stably emit 735nm far-red light; another object of the present invention is to provide a method for preparing a far-red perovskite light-emitting device, which optimizes the prepared luminescent materials and devices through experiments, so that the device exhibits very excellent spectral stability and has a very stable spectral output under different voltage drives.

[0010] A far-infrared perovskite luminescent material, the molecular formula of which is: (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 .

[0011] A far-infrared perovskite light-emitting device uses the far-infrared perovskite light-emitting material as a light-emitting layer.

[0012] The device provided by the present invention emits light at a wavelength of 735nm far-infrared light, which has important reference significance for applications in the fields of display and lighting.

[0013] Preferably, the far-infrared perovskite light-emitting device has a positive structure.

[0014] ITO / ZnO / PEIE / (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 / TFB / MoOx / Au.

[0015] More preferably, the thickness of the ZnO / PEIE is 30 nm. 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 The thickness of is 50nm, the thickness of TFB is 40nm, the thickness of MoOx is 7nm, and the thickness of Au is 50nm.

[0016] The preparation method of the far-infrared perovskite light-emitting device comprises the following steps: (1) spin coating an electron transport layer ZnO / PEIE on an ITO glass substrate, and annealing; (2) preparing a far-infrared perovskite light-emitting material (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5The precursor solution is spin-coated on the electron transport layer ZnO / PEIE, and annealed to obtain a light-emitting layer; (3) a hole transport layer [(9,9-dioctylfluorene-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)] layer is spin-coated on the light-emitting layer; and (4) a MoOx / Au electrode is evaporated on the hole transport layer.

[0017] A far-infrared perovskite light-emitting device, the structure of which is a positive structure

[0018] ITO / ZnO / PEIE / (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 / TPBi / TFB / MoOx / Au.

[0019] The present invention introduces a high electron mobility organic small molecule TPBi antisolvent to adjust the recombination position of electron-hole pairs from the electron injection layer / perovskite interface to the perovskite body, thereby improving the recombination efficiency, greatly improving the problem of electron imbalance, and improving the electron transport capacity in the perovskite body, thereby greatly improving the device luminescence efficiency.

[0020] The preparation method of the far-infrared perovskite light-emitting device comprises the following steps: (s1) spin coating an electron transport layer ZnO / PEIE on a glass substrate ITO, and annealing; (s2) preparing a far-infrared perovskite light-emitting material (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 The precursor liquid is spin-coated on the electron transport layer ZnO / PEIE. When the precursor liquid is spin-coated to 7 / 10, (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 A chlorobenzene antisolvent containing TPBi is uniformly added to the surface layer and annealed to obtain a light-emitting layer, wherein the concentration of TPBi in the chlorobenzene antisolvent is 0.1 mg / ml; (s3) a hole transport layer [(9,9-dioctylfluorene-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)] is spin-coated on the top of the light-emitting layer; (s4) a MoOx / Au electrode is evaporated on the top of the hole transport layer.

[0021] Preferably, in the preparation method of the far-infrared perovskite light-emitting device, the steps of spin coating the electron transport layer ZnO / PEIE are as follows: (11) in an environment where the air humidity is less than 40% and the temperature is about 20°C, the speed of the coating machine is 4000 rpm, and the zinc oxide layer is spin coated, and then the PEIE layer is spin coated on the surface of the zinc oxide layer; (12) annealing on a 90°C hot plate.

[0022] Preferably, in step (s2), the speed of the glue spreader is set to 1000 rpm, and the perovskite precursor solution is uniformly dripped on the electron transport layer. When 1 / 10 of the total amount of the perovskite precursor solution is dripped, the speed of the glue spreader is set to 4000 rpm, and the perovskite precursor solution is continued to be uniformly dripped. When the perovskite precursor solution is dripped to 7 / 10 of the total amount, the TPBi anti-solvent is quickly dripped onto the perovskite surface, and then annealed on a hot stage at 100°C.

[0023] More preferably, the (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 The preparation of the precursor solution comprises the following steps: (a) according to (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 The reagents were weighed in a stoichiometric ratio and dissolved in a DMF / DMSO (N,N-dimethylformamide / dimethyl sulfoxide) mixed solvent to obtain a solution A with a concentration of 0.28 M / ml, wherein the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide was 4:1;

[0024] (b) dissolving a certain amount of NH2(CH2)4CO2H in a DMF / DMSO (N,N-dimethylformamide / dimethyl sulfoxide) mixed solvent to obtain a 10 mg / ml solution B, wherein the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is 4:1;

[0025] (c) mixing solution A and solution B in equal volume ratio, wherein the concentration of Pb is 0.14 M;

[0026] (d) The mixed solution was placed on a shaker at 60° C. for 12 h to obtain a precursor solution of the perovskite light-emitting material.

[0027] Compared with the prior art, the far-infrared perovskite luminescent material (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5By increasing the adjustment range of the band gap by the A position and reducing the adjustment range of the band gap by the X position, that is, by introducing excessive A positions to roughly adjust the band gap and reduce the spectral shift caused by the X position, a spectrally stable 735nm far-red perovskite luminescent material is obtained.

[0028] by (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 The device as the light-emitting layer emits far-red light at a wavelength of 735nm, which has important reference significance for applications in the fields of display and lighting.

[0029] The preparation method of the invention is simple and easy to operate, has low requirements on conditions when preparing the device, and has low preparation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a structural diagram of a far-infrared perovskite light-emitting device 10;

[0031] In the figure: 1-IT0 substrate layer; 2-electron transport layer; 3-gradient heterojunction perovskite light-emitting layer; 4-TPBi; 5-hole transport layer; 6-electrode layer;

[0032] Figure 2 Schematic diagram of forming a gradient heterojunction of TPBi in a perovskite layer by an antisolvent method;

[0033] Figure 3 is a curve diagram of current density and voltage of the devices prepared in Example 1 and Comparative Example 1;

[0034] Figure 4 is a curve diagram of brightness and voltage of the devices prepared in Example 1 and Comparative Example 1;

[0035] Figure 5 is a curve diagram of efficiency and voltage of the devices prepared in Example 1 and Comparative Example 1;

[0036] Figure 6 is an electroluminescence curve diagram of the device prepared in Example 1 at different voltages;

[0037] Figure 7 It is the electroluminescence curve of the device prepared in comparative example 1 at different voltages. DETAILED DESCRIPTION

[0038] The specific implementation scheme of a gradient heterojunction far-red perovskite light-emitting device and a preparation method thereof according to the present invention is described in detail below in conjunction with the accompanying drawings.

[0039] Example 1

[0040] like Figure 1 As shown, this embodiment provides a method for preparing a far-infrared perovskite light-emitting device, comprising the following steps:

[0041] Step (1) Cleaning the Indium Tin Oxide (ITO) Substrate

[0042] An ITO substrate of size 1.5 cm×1.5 cm was ultrasonically cleaned using glass cleaning agent, deionized water, acetone, isopropanol, and anhydrous ethanol in sequence; each solution was ultrasonically cleaned for 15 minutes, then dried with nitrogen, and ozone was applied for 15 minutes to obtain a clean ITO substrate.

[0043] Step (2) Preparation of electron transport layer

[0044] Control the indoor ambient air humidity below 40% and the temperature at about 20°C; take 40ul of the prepared ZnO precursor solution and drop it on the surface of the clean ITO substrate, set the speed of the glue machine to 4000r.mp, and the spin coating time to 45s; then, take 50ul of the prepared 1.5mg / ml PEIE solution and drop it on the ZnO surface, set the speed of the glue machine to 5000r.mp, and the spin coating time to 45s; transfer the substrate with the ZnO layer and PEIE layer spin-coated to the glove box and anneal on a 90°C hot stage for 10min.

[0045] Step (3) Preparation of perovskite light-emitting layer

[0046] Step 3-1: Follow (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 Chemical formula: Weigh 0.28M of the reagent and dissolve it in 1ml of DMF / DMSO mixed solvent (DMF:DMSO=4:1) to obtain an orange-yellow solution X; then dissolve 5AVA in the DMF / DMSO mixed solvent to obtain a 10mg / ml solution Y; mix equal volumes of X and Y to obtain a mixed solution Z. Place the mixed solution Z on a shaker at 60°C for 12h to obtain a perovskite precursor solution.

[0047] Step 3-2: Dissolve 0.1 mg TPBi in 1 ml chlorobenzene solution to obtain 0.1 mg / ml TPBi anti-solvent, and stir at room temperature for 2 h to obtain TPBi anti-solvent.

[0048] Step 3-3: Take 35ul of perovskite precursor solution and drop it on the electron transport layer, set the spin coater speed to 4000r.mp, and the spin coating time to 50s. After 35s of spin coating, take 150ul of TPBi anti-solvent and drop it on the rotating perovskite surface at a uniform speed; after the spin coating is completed, anneal it on a 105℃ hot plate for 10min.

[0049] Step (4) Preparation of hole transport layer

[0050] Weigh 10 mg of TFB solid, dissolve it in 1 ml of chlorobenzene solution, and stir at room temperature for 2 h to obtain a 10 mg / ml TFB solution; set the spin coater speed to 3000 rpm, the spin coating time to 30 s, and do not perform annealing.

[0051] Step (5) Electrode deposition

[0052] The samples of the spin-coated electron transport layer, gradient heterojunction perovskite light-emitting layer, and hole transport layer were transferred to the evaporation mask and placed in a high vacuum evaporation device for evaporation of the metal electrode MoOx / Au, where the thickness of MoOx is 7nm and the thickness of Au is 50nm.

[0053] like Figure 1 and Figure 2 As shown, a far-red perovskite light-emitting device prepared by the above method includes: an ITO substrate layer 1; an electron transport layer 2 located on the ITO substrate layer; a gradient heterojunction perovskite light-emitting layer 3 located on the electron transport layer; a hole transport layer 5 located on the gradient heterojunction perovskite light-emitting layer; and an electrode layer 6 located on the hole transport layer; TPBi4 is embedded in the gradient heterojunction perovskite light-emitting layer 3, and the gradient heterojunction far-red perovskite light-emitting device structure is an upright structure ITO / ZnO / PEIE / (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 / TPBi / TFB / MoOx / Au; emission wavelength is 735nm.

[0054] Comparative Example 1

[0055] In this comparative example 1, only the preparation of the perovskite light-emitting layer in step (3) is different from that in Example 1, in that TPBi is not added and only pure chlorobenzene solution is used as the anti-solvent, specifically:

[0056] According to (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 Chemical formula: Weigh 0.28M of the reagent and dissolve it in 1ml of DMF / DMSO mixed solvent (DMF:DMSO=4:1) to obtain an orange-yellow solution X; then dissolve 5AVA in the DMF / DMSO mixed solvent to obtain a 10mg / ml solution Y; mix equal volumes of X and Y to obtain a mixed solution Z. Place the mixed solution Z on a shaker at 60°C for 12h to obtain a perovskite precursor solution.

[0057] Take 35ul of perovskite precursor solution and drop it on the electron transport layer, set the spin coater speed to 4000r.mp, and the spin coating time to 50s. After 35s of spin coating, take 150ul of pure chlorobenzene solvent and drop it on the rotating perovskite surface at a uniform speed; after the spin coating is completed, anneal it on a 105℃ hot plate for 10min.

[0058] The remaining steps are the same as those in the first embodiment and will not be described again here.

[0059] Performance Testing

[0060] like Figure 3 As shown, the light-emitting device with a gradient heterojunction formed by introducing TPBi antisolvent in Example 1 has a smaller current at a low voltage of 0.5-2.5V, indicating that the addition of TPBi antisolvent adjusts the recombination position of electron-hole pairs from the electron injection layer / perovskite interface to the perovskite body, and the electron mobility is high, thereby improving the recombination efficiency, so that the leakage is smaller and the charge loss is smaller.

[0061] like Figure 4 and Figure 5 As shown, Figure 4 After the devices of Example 1 and Comparative Example 1 are turned on, at the same voltage, the brightness of Example 1 is higher than that of Comparative Example 1, and as the voltage increases, the brightness difference between the two increases; Figure 5 The external quantum efficiency of the device prepared in Example 1 is 11.6%, while the external quantum efficiency of the device prepared in Example 1 is only 9.6%, and the external quantum efficiency increases by 21%. In addition, the device of Example 1 can achieve a relatively high efficiency at a lower voltage, indicating that the charge injection in Example 1 is more balanced, which promotes the effective occurrence of radiative recombination, thereby improving the luminous efficiency of the device.

[0062] like Figure 6 and Figure 7 As shown, the devices prepared in Example 1 and Comparative Example 1 both have an emission wavelength of 735 nm, and their electroluminescence spectra do not shift significantly when the voltage is increased from 1.5 V to 4 V, and the spectra are relatively stable, indicating that this perovskite (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 Has a stable spectrum.

[0063] The above only expresses several embodiments of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and the present invention is also intended to include these modifications and modifications.

Claims

1. A far-infrared perovskite luminescent material, characterized in that: Its molecular formula is: (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 .

2. A far-infrared perovskite light-emitting device, characterized in that: Its structure is the positive structure ITO / ZnO / PEIE / (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 / TFB / MoOx / Au.

3. The far-infrared perovskite light-emitting device according to claim 2, characterized in that: The thickness of the ZnO / PEIE is 30 nm. 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 The thickness of is 50nm, the thickness of TFB is 40nm, the thickness of MoOx is 7nm, and the thickness of Au is 50nm.

4. The method for preparing the far-infrared perovskite light-emitting device according to claim 3, characterized in that: The method comprises the following steps: (1) spin coating an electron transport layer ZnO / PEIE on an ITO glass substrate and annealing; (2) preparing a far-infrared perovskite luminescent material (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 The precursor solution is spin-coated on the electron transport layer ZnO / PEIE, and annealed to obtain a light-emitting layer; (3) a hole transport layer [(9,9-dioctylfluorene-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)] layer is spin-coated on the light-emitting layer; and (4) a MoOx / Au electrode is evaporated on the hole transport layer.

5. A far-infrared perovskite light-emitting device, characterized in that: Its structure is upright structure ITO / ZnO / SO / (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Bro 0.5 / TPBi / TFB / MoOx / Au。 6. The method for preparing the far-infrared perovskite light-emitting device according to claim 5, characterized in that: The method comprises the following steps: (s1) spin coating an electron transport layer ZnO / PEIE on an ITO glass substrate and annealing; (s2) preparing a far-infrared perovskite luminescent material (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 The precursor liquid is spin-coated on the electron transport layer ZnO / PEIE. When the precursor liquid is spin-coated to 7 / 10, (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 A chlorobenzene antisolvent containing TPBi is uniformly added to the surface layer and annealed to obtain a light-emitting layer, wherein the concentration of TPBi in the chlorobenzene antisolvent is 0.1 mg / ml; (s3) a hole transport layer [(9,9-dioctylfluorene-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)] is spin-coated on the top of the light-emitting layer; (s4) a MoOx / Au electrode is evaporated on the top of the hole transport layer.

7. The method for preparing a far-infrared perovskite light-emitting device according to any one of claims 4 or 6, characterized in that: The steps of spin coating the electron transport layer ZnO / PEIE are as follows: (11) in an environment with air humidity less than 40% and temperature of 20°C, the spin coating speed of the coating machine is 4000 rpm, and the zinc oxide layer is spin coated, and then the PEIE layer is spin coated on the surface of the zinc oxide layer; (12) annealing on a 90°C hot plate.

8. The method for preparing the far-infrared perovskite light-emitting device according to claim 6, characterized in that: In step (s2), the speed of the glue spreader is set to 1000 rpm, and the perovskite precursor solution is uniformly dripped on the electron transport layer. When 1 / 10 of the total amount of the perovskite precursor solution is dripped, the speed of the glue spreader is set to 4000 rpm, and the perovskite precursor solution is continued to be uniformly dripped. When the perovskite precursor solution is dripped to 7 / 10 of the total amount, the TPBi anti-solvent is quickly dripped onto the perovskite surface, and then annealed on a hot stage at 100°C.

9. The method for preparing a far-infrared perovskite light-emitting device according to any one of claims 4 or 6, characterized in that: Said (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 The preparation of the precursor solution comprises the following steps: (a) according to (FA 0.33 Cs 0.67 ) 2.85 PbI 4.35 Br 0.5 The reagents were weighed in a stoichiometric ratio and dissolved in a DMF / DMSO mixed solvent to obtain a solution A with a concentration of 0.28 M / ml, wherein the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide was 4:1; (b) dissolving a certain amount of NH2(CH2)4CO2H in a DMF / DMSO mixed solvent to obtain a 10 mg / ml solution B, wherein the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is 4:1; (c) mixing solution A and solution B in equal volume ratio, wherein the concentration of Pb is 0.14 M; (d) The mixed solution was placed on a shaker at 60° C. for 12 h to obtain a precursor solution of the perovskite light-emitting material.

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