Preparation method of PIN type infrared photodetector with super-high external quantum efficiency

Abstract

This invention discloses a method for fabricating a PIN-type infrared photodetector with ultra-high external quantum efficiency. By controlling the ratio of SnI2 and PbI2 in the perovskite precursor solution and introducing a stepped temperature difference, the method achieves a lead-tin distribution with different elemental ratios in the lead-tin alloy perovskite, thereby controlling the bandgap gradient of the perovskite material to realize the multi-exciton effect between band gaps, ultimately enabling the photodetector to achieve ultra-high external quantum efficiency. The method includes the following steps: S1, treating the conductive substrate with ultraviolet ozone, then preparing a PEDOT hole transport layer by spin coating and annealing; S2, spin coating the perovskite precursor solution onto the substrate obtained in step S1 using a stepped temperature difference method and annealing to prepare the perovskite layer; S3, preparing an electron transport layer and a buffer layer on the substrate obtained in step S2 by spin coating; S4, preparing a metal electrode on the buffer layer using a thermal evaporation method to obtain the PIN-type perovskite infrared photodetector with ultra-high external quantum efficiency.

Description

Technical Field

[0001] This invention relates to the fields of photodetector technology, and more specifically, to a method for fabricating a PIN-type infrared photodetector with ultra-high external quantum efficiency. Background Technology

[0002] Photodetectors play a vital role in current scientific development and human life due to their ability to convert light signals into electrical signals. Silicon-based photodetectors are the primary choice in this field. However, due to the inherent properties of silicon, silicon-based photodetectors cannot achieve high absorption coefficients in the near-infrared region. Furthermore, when silicon-based photodetectors are used in a specific wavelength range, a trade-off must be made between detection speed and detection efficiency.

[0003] The core component of perovskite photodetectors is the perovskite material. Compared to silicon, perovskite is a direct bandgap semiconductor with a high absorption coefficient and advantages such as tunable bandgap. Therefore, semiconductor photodetectors based on lead-based perovskite have received widespread attention in recent years. Typically, to extend the near-infrared absorption of lead-based perovskite, it is necessary to dope the perovskite with near-infrared responsive organic polymer materials or quantum dot materials, or form heterojunctions to extend the absorption of perovskite photodetectors in the near-infrared band. However, these methods usually introduce defects, causing carrier recombination losses. Lead-tin alloy perovskite can extend the absorption wavelength of lead-based perovskite to the near-infrared band without introducing additional near-infrared responsive materials. However, existing PIN-type lead-tin alloy perovskites, due to Sn... 2+ The problem of easy oxidation leads to high dark current and low external quantum efficiency in photodetectors. Summary of the Invention

[0004] The purpose of this invention is to design a method for fabricating a PIN-type infrared photodetector with ultra-high external quantum efficiency. By controlling the ratio of SnI2 and PbI2 in the perovskite precursor solution and introducing a step temperature difference, the lead-tin alloy perovskite with different element ratios can be distributed. This controls the bandgap gradient of the perovskite material to achieve the multi-exciton effect between band gaps, ultimately enabling the photodetector to obtain ultra-high external quantum efficiency.

[0005] This invention is achieved through the following technical solution: a method for fabricating an ultra-high external quantum efficiency PIN-type infrared photodetector, comprising the following steps: S1. The conductive substrate is treated with ultraviolet ozone, and then a hole transport layer is prepared by spin coating and annealing. S2. Perovskite precursor solutions containing different excess proportions of SnI2 are spin-coated onto the material obtained in step S1 using a stepped temperature difference method, and then annealed to prepare a perovskite layer; that is, perovskite films are prepared using perovskite precursor solutions with different excess proportions of SnI2, and then annealed to form a perovskite layer; alloy perovskites with different lead-tin ratios are obtained by spin-coating perovskite precursor solutions using a stepped temperature difference method, forming a spontaneous gradual adjustment of the band gradient of lead-tin alloy perovskites, and then annealed to form a perovskite layer; S3. An electron transport layer and a buffer layer are prepared on the substrate obtained in step S2 by spin coating. The thickness of the buffer layer is 10~20 nm (preferably 14 nm). S4. A metal electrode is prepared on the buffer layer by thermal evaporation to obtain the ultra-high external quantum efficiency PIN perovskite infrared photodetector.

[0006] To further improve the fabrication method of the ultra-high external quantum efficiency PIN infrared photodetector described in this invention, the following configuration is adopted: the conductive substrate includes a substrate and a transparent electrode, and the transparent electrode is made of indium tin oxide.

[0007] To further improve the fabrication method of the ultra-high external quantum efficiency PIN infrared photodetector described in this invention, the following configuration is adopted: the material of the hole transport layer is poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS).

[0008] To further improve the fabrication method of the ultra-high external quantum efficiency PIN infrared photodetector described in this invention, the following configuration is specifically adopted: In step S1, when preparing the hole transport layer by spin coating, the poly(3,4-ethylenedioxythiophene)polystyrene sulfonate (PEDOT:PSS) mixed solution is spin-coated at a speed of 3000~4000 (preferably 4000) rpm for 30 seconds; during annealing, the annealing temperature is 150~180 (preferably 150) °C, and the annealing time is 15~20 (preferably 20) minutes.

[0009] To further improve the fabrication method of the ultra-high external quantum efficiency PIN infrared photodetector described in this invention, the following configuration is specifically adopted: the perovskite material in the perovskite precursor solution is ABX3 type perovskite, wherein A is a FAMA mixed cation group; B is a lead and tin metal cation; and X is an iodide anion.

[0010] To further improve the fabrication method of the ultra-high external quantum efficiency PIN infrared photodetector described in this invention, the following configuration is specifically adopted: The specific steps of step S2 are as follows: S2.1 Prepare an excess of SnI2 (5%, 10%, or 15%, etc.) in the PbI2 perovskite precursor solution. At this time, the state of the perovskite precursor solution is a mixture of [FASnI3]:[MAPbI3]. S2.2. The perovskite precursor solution obtained in step S1 is subjected to semiconductor cooling (so that when the perovskite precursor solution is spin-coated onto the substrate, a significant step temperature difference is formed between the surface and the interior, which induces the Sn-based perovskite in the perovskite precursor solution to crystallize too quickly, so that the lead-tin ratio of the entire perovskite film is distributed in a vertical gradient, causing multi-exciton gain between band gaps). The cooling time is controlled so that the substrate surface temperature is low, below 10°C, wherein the substrate is a combination structure of conductive substrate and hole transport layer. S2.3. The cooled substrate is spin-coated with perovskite precursor solution using a two-step spin-coating method. After spin-coating, annealing is performed immediately, and the annealing temperature is 90~100 (preferably 100)℃, and the annealing time is 9~15 (preferably 9) minutes.

[0011] To further improve the fabrication method of the ultra-high external quantum efficiency PIN infrared photodetector described in this invention, the following setup is specifically adopted: The two-step spin coating method is as follows: The first step is to rotate at a speed of 1000~1500 (preferably 1000) revolutions per minute for 10~20 (preferably 10) seconds; The second step is to rotate at a speed of 5000~6000 (preferably 5000) revolutions per minute for 30~40 (preferably 40) seconds.

[0012] To further improve the fabrication method of the ultra-high external quantum efficiency PIN infrared photodetector described in this invention, the following configuration is specifically adopted: the internal structure distribution of the perovskite layer is: MAPbI3 / FAMAPb x Sn 1-x I3 / FASnI3, with a perovskite layer thickness of 1000±200 nm.

[0013] To further improve the fabrication method of the ultra-high external quantum efficiency PIN infrared photodetector described in this invention, the following configuration is adopted: the electron transport layer is made of a fullerene derivative, and the buffer layer is made of polyethyleneimine.

[0014] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention achieves bandgap modulation of perovskite precursor solutions by using SnI2 with excess PbI2, thereby lowering the threshold energy of the multiexciton effect, enhancing the multiexciton effect, and ultimately improving the external quantum efficiency of the device.

[0015] In this invention, SnI2 is used in excess of PbI2, and the temperature difference method facilitates the rapid crystallization of FASnI3 during the preparation of perovskite thin films. This results in an uneven distribution of lead-tin ratio inside the final perovskite thin film, which is beneficial for forming a gradual band gap within the material.

[0016] In this invention, SnI2 is in excess relative to PbI2. This bandgap gradient not only enables the p-type hole transport layer to function, but also expands the range of absorbed light wavelengths by broadening the energy band, thereby increasing the response range of the perovskite infrared photodetector.

[0017] Unlike traditional lead-tin perovskite preparation methods, this invention does not require the use of toxic antisolvents, is low in cost, simple to operate, and is safe and non-toxic.

[0018] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing embodiments of this application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The above and other objects, features, and advantages of this application will become clearer through the drawings. The same reference numerals indicate the same parts in all the drawings. The drawings are not intentionally drawn to scale to actual size; the focus is on illustrating the main points of this application.

[0020] Figure 1 This is a schematic diagram of the mechanism of the ultra-high external quantum efficiency of the perovskite infrared photodetector described in this invention.

[0021] Figure 2 This is a flowchart of the preparation method described in this invention. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0024] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "and / or" in this application is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone.

[0025] In the description of this invention, it should be understood that the orientation or positional relationship indicated by terms, etc., is based on the orientation or positional relationship shown in the drawings and is only for the convenience of describing this invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, and "multiple" means two or more, unless otherwise explicitly specified.

[0027] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can also refer to an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0028] It should be noted that in some embodiments, the MOS transistor or MOSFET in the circuit can be replaced by other transistors that perform the same function. For example, the MOS transistor can be replaced by a bipolar transistor, silicon carbide (SiC) transistor, gallium nitride (GaN) transistor, cubic indium phosphide (InP) transistor, gallium arsenide (GaAs) transistor, field-effect transistor (FET), junction field-effect transistor (JFET), heterojunction bipolar transistor (HBT), or insulated-gate bipolar transistor (IGBT). Therefore, the MOS transistor structure in the above examples should not be construed as a limitation of this application.

[0029] Electronic devices can be devices that include circuits or apparatuses containing semiconductor devices, such as mobile phones, computers, televisions, communication devices, etc. The electronic devices provided in this application embodiment have the same implementation principle and technical effects as the high data flow transmission interface structure circuit embodiment described below. For the sake of brevity, any parts not mentioned in the electronic device embodiment can be referred to the corresponding content in the high data flow transmission interface structure circuit embodiment.

[0030] Furthermore, the functional modules in the various embodiments of this application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0031] It can be replaced and can be implemented, wholly or partially, through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented, wholly or partially, in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated.

[0032] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, principle, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, principle, article, or apparatus. Without further limitation, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, principle, article, or apparatus that includes said element.

[0033] Example 1: A method for fabricating a PIN-type infrared photodetector with ultra-high external quantum efficiency involves controlling the ratio of SnI2 and PbI2 in the perovskite precursor solution and introducing a stepped temperature difference to achieve different lead-tin distributions in the lead-tin alloy perovskite. This controls the bandgap gradient of the perovskite material, realizing the multi-exciton effect between band gaps, ultimately enabling the photodetector to achieve ultra-high external quantum efficiency. The method includes the following steps: S1. The conductive substrate is treated with ultraviolet ozone, and then a hole transport layer is prepared by spin coating and annealing. S2. Perovskite precursor solutions containing different excess proportions of SnI2 are spin-coated onto the material obtained in step S1 using a stepped temperature difference method, and then annealed to prepare a perovskite layer; that is, perovskite films are prepared using perovskite precursor solutions with different excess proportions of SnI2, and then annealed to form a perovskite layer; alloy perovskites with different lead-tin ratios are obtained by spin-coating perovskite precursor solutions using a stepped temperature difference method, forming a spontaneous gradual adjustment of the band gradient of lead-tin alloy perovskites, and then annealed to form a perovskite layer; S3. An electron transport layer and a buffer layer are prepared on the substrate obtained in step S2 by spin coating. The thickness of the buffer layer is 10~20 nm (preferably 14 nm). S4. A metal electrode is prepared on the buffer layer by thermal evaporation to obtain the ultra-high external quantum efficiency PIN perovskite infrared photodetector.

[0034] Example 2: This embodiment is a further optimization based on the above embodiment. The similarities with the aforementioned technical solutions will not be repeated here. In order to better realize the preparation method of the ultra-high external quantum efficiency PIN infrared photodetector of the present invention, the following configuration is adopted: the conductive substrate includes a substrate and a transparent electrode, and the transparent electrode is made of indium tin oxide.

[0035] Example 3: This embodiment is a further optimization based on any of the above embodiments. The similarities with the aforementioned technical solutions will not be repeated here. In order to better realize the preparation method of the ultra-high external quantum efficiency PIN infrared photodetector of the present invention, the following setting is adopted: the material of the hole transport layer is poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS).

[0036] Example 4: This embodiment is a further optimization based on any of the above embodiments. The similarities with the aforementioned technical solutions will not be repeated here. To further better realize the preparation method of the ultra-high external quantum efficiency PIN infrared photodetector described in this invention, the following settings are specifically adopted: In step S1: when preparing the hole transport layer by spin coating, the poly(3,4-ethylenedioxythiophene)polystyrene sulfonate (PEDOT:PSS) mixed solution is spin coated at a speed of 3000~4000 (preferably 4000) rpm for 30 seconds; when performing annealing treatment, the annealing temperature is 150~180 (preferably 150)℃, and the annealing time is 15~20 (preferably 20) minutes.

[0037] Example 5: This embodiment is a further optimization based on any of the above embodiments. The similarities with the aforementioned technical solutions will not be repeated here. In order to better realize the preparation method of the ultra-high external quantum efficiency PIN infrared photodetector of the present invention, the following setting is adopted: the perovskite material in the perovskite precursor solution is ABX3 type perovskite, wherein A is FAMA mixed cationic group; B is lead and tin metal cation; and X is iodide anion.

[0038] Example 6: This embodiment is a further optimization based on any of the above embodiments. The similarities with the aforementioned technical solutions will not be repeated here. Furthermore, to better realize the fabrication method of an ultra-high external quantum efficiency PIN infrared photodetector described in this invention, the following configuration is specifically adopted: The specific steps of step S2 are as follows: S2.1 Prepare an excess of SnI2 (5%, 10%, or 15%, etc.) in the PbI2 perovskite precursor solution. At this time, the state of the perovskite precursor solution is a mixture of [FASnI3]:[MAPbI3]. S2.2. The perovskite precursor solution obtained in step S1 is subjected to semiconductor cooling (so that when the perovskite precursor solution is spin-coated onto the substrate, a significant step temperature difference is formed between the surface and the interior, which induces the Sn-based perovskite in the perovskite precursor solution to crystallize too quickly, so that the lead-tin ratio of the entire perovskite film is distributed in a vertical gradient, causing multi-exciton gain between band gaps). The cooling time is controlled so that the substrate surface temperature is low, below 10°C, wherein the substrate is a combination structure of conductive substrate and hole transport layer. S2.3. The cooled substrate is spin-coated with perovskite precursor solution using a two-step spin-coating method. After spin-coating, annealing is performed immediately, and the annealing temperature is 90~100 (preferably 100)℃, and the annealing time is 9~15 (preferably 9) minutes.

[0039] Example 7: This embodiment is a further optimization based on any of the above embodiments. The similarities with the aforementioned technical solutions will not be repeated here. Furthermore, to better realize the fabrication method of an ultra-high external quantum efficiency PIN-type infrared photodetector described in this invention, the following setup is specifically adopted: The two-step spin-coating method is as follows: The first step is to rotate at a speed of 1000~1500 (preferably 1000) revolutions per minute for 10~20 (preferably 10) seconds; The second step is to rotate at a speed of 5000~6000 (preferably 5000) revolutions per minute for 30~40 (preferably 40) seconds.

[0040] Example 8: This embodiment is a further optimization based on any of the above embodiments. The similarities with the aforementioned technical solutions will not be repeated here. Furthermore, to better realize the fabrication method of an ultra-high external quantum efficiency PIN infrared photodetector described in this invention, the following configuration is specifically adopted: the internal structure distribution of the perovskite layer is: MAPbI3 / FAMAPb x Sn 1-x I3 / FASnI3, the perovskite layer thickness is approximately 1000 nm.

[0041] Example 9: This embodiment is a further optimization based on any of the above embodiments. The similarities with the aforementioned technical solutions will not be repeated here. In order to better realize the preparation method of the ultra-high external quantum efficiency PIN infrared photodetector of the present invention, the following setting is adopted: the material of the electron transport layer is a fullerene derivative, and the material of the buffer layer is polyethyleneimine.

[0042] Example 10: A method for fabricating an ultra-high external quantum efficiency PIN-type infrared photodetector, combined with Figure 1, Figure 2 As shown, it includes the following steps: (1) Substrate cleaning and ultraviolet ozone treatment: The ITO substrate was cleaned in sequence with acetone, anhydrous alcohol and deionized water.

[0043] (2) Spin-coating PEDOT:PSS solution and annealing: Spin-coating PEDOT:PSS solution onto ITO substrate at 4000 rpm for 30 seconds. Then annealing was performed at 150°C for 15 minutes to form a hole transport layer. The sample was then transferred to a glove box.

[0044] (3) Control the temperature gradient of the substrate and adjust the excess SnI2 in different proportions to form a perovskite photosensitive layer with a gradual internal band gap. Annealing is performed. Specifically, a perovskite layer is prepared on the hole transport layer by spin coating. The perovskite material is FAMAPbSnI3. After cooling the PEDOT:PSS substrate, a two-step spin coating method is used. In the first stage, the rotation speed is 1000 rpm, the acceleration is 1000 rpm / s, and the spin coating time is 10 seconds. In the second stage, the rotation speed is 5000 rpm, the acceleration is 4000 rpm / s, and the spin coating time is 40 seconds. Then, annealing is performed. The PCBM and PEI buffer layer are spin-coated sequentially, including the following steps: (4) Spin-coating PCBM solution onto the surface of the perovskite layer at a spin rate of 2000 rpm for 20 seconds without annealing to complete the preparation of the electron transport layer. (5) Spin-coat PEI solution onto the electron transport layer at a spin rate of 4000 rpm and an acceleration of 4000 rpm / s for 30 seconds to complete the preparation of the cathode modification layer.

[0045] (6) Thermal evaporation of Ag: A silver electrode is thermally evaporated on the above substrate at a thermal evaporation rate of 0.3 nm / s and a evaporation thickness of 100 nm.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention are within the protection scope of the present invention.

Claims

1. A method for fabricating a PIN-type infrared photodetector with ultra-high external quantum efficiency, characterized in that: Includes the following steps: S1. The conductive substrate is treated with ultraviolet ozone, and then a hole transport layer is prepared by spin coating and annealing. S2. Perovskite precursor solutions containing different excess proportions of SnI2 are spin-coated onto the substrate obtained in step S1 using a stepped temperature difference method, and then annealed to prepare a perovskite layer. The specific steps are as follows: S2.1 Prepare a perovskite precursor solution in which SnI2 is in excess of PbI2. At this time, the state of the perovskite precursor solution is a mixture of [FASnI3]:[MAPbI3]. S2.

2. Perform semiconductor cooling on the substrate obtained in step S1, and control the cooling time to keep the substrate surface temperature low, below 10°C. The substrate is a combination structure of a conductive substrate and a hole transport layer. S2.

3. The cooled substrate is spin-coated with perovskite precursor solution using a two-step spin-coating method. After spin-coating, annealing is performed immediately at a temperature of 90~100℃ for 9~15 minutes. S3. An electron transport layer and a buffer layer are prepared on the substrate obtained in step S2 by spin coating. S4. A metal electrode is prepared on the buffer layer by thermal evaporation to obtain the ultra-high external quantum efficiency PIN perovskite infrared photodetector.

2. The method for fabricating an ultra-high external quantum efficiency PIN-type infrared photodetector according to claim 1, characterized in that: The conductive substrate includes a substrate and a transparent electrode, and the transparent electrode is made of indium tin oxide.

3. The method for fabricating an ultra-high external quantum efficiency PIN infrared photodetector according to claim 1, characterized in that: The hole transport layer is made of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS).

4. The method for fabricating an ultra-high external quantum efficiency PIN-type infrared photodetector according to claim 3, characterized in that: In step S1: when preparing the hole transport layer by spin coating, the poly(3,4-ethylenedioxythiophene)polystyrene sulfonate (PEDOT:PSS) mixed solution is spin coated at a speed of 3000~4000 rpm for 30 seconds; when performing annealing treatment, the annealing temperature is 150~180℃ and the annealing time is 15~20 minutes.

5. The method for fabricating an ultra-high external quantum efficiency PIN-type infrared photodetector according to claim 1, characterized in that: The perovskite precursor solution contains ABX3 type perovskite, where A is FAMA; B is lead or tin; and X is iodine.

6. The method for fabricating an ultra-high external quantum efficiency PIN-type infrared photodetector according to claim 1, characterized in that: The two-step spin coating method is specifically as follows: First, rotate at a speed of 1000-1500 revolutions per minute for 10-20 seconds; The second step is to rotate the cylinder at a speed of 5000-6000 revolutions per minute for 30-40 seconds.

7. The method for fabricating an ultra-high external quantum efficiency PIN-type infrared photodetector according to claim 1, characterized in that: The internal structure of the perovskite layer is distributed as follows: MAPbI3 / FAMAPb x Sn 1-x I3 / FASnI3, with a perovskite layer thickness of 1000±200 nm.

8. The method for fabricating an ultra-high external quantum efficiency PIN-type infrared photodetector according to claim 1, characterized in that: The electron transport layer is made of fullerene derivatives, and the buffer layer is made of polyethyleneimine.

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