Quantum dot photodetector and method of making the same

Abstract

The embodiment of the present application relates to the technical field of photoelectric detection, and discloses a quantum dot photoelectric detector and a preparation method thereof.The quantum dot photoelectric detector comprises a PbS quantum dot light-absorbing layer and a SnO2 electron transport layer, and the absorption peak of the PbS quantum dot light-absorbing layer is above 1300 nm.In an example, the structure of the quantum dot photoelectric detector is sequentially arranged from bottom to top as a bottom electrode (made of ITO or gold), a hole transport layer, a PbS quantum dot light-absorbing layer, a buffer layer, a SnO2 electron transport layer and a top electrode (made of ITO).In an example, the SnO2 electron transport layer is prepared by an atomic layer deposition (ALD) method.In the embodiment, for the case that the absorption peak is above 1300 nm, the quantum dot photoelectric detector has a more suitable energy band structure (helpful for the extraction of photo-generated carriers, resulting in better performance), and the SnO2 is used as the electron transport layer, the band gap of which is large enough to realize near-ultraviolet band detection and improve the detection range of the device.In addition, the SnO2 electron transport layer prepared by the ALD method has a denser film and a self-sealing effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photoelectric detection, and in particular to a quantum dot photoelectric detector and a preparation method thereof. BACKGROUND

[0002] A photoelectric detector is a device for converting optical signals into electrical signals, and a quantum dot photoelectric detector, as a photoelectric detector of a new structure, has the advantages of low cost and wide detection range. Generally, a quantum dot photoelectric detector includes a quantum dot light-absorbing layer and an electron transport layer in structure, and in the current prior art, the material of the electron transport layer is almost ZnO (zinc oxide). SUMMARY

[0003] The main purpose of the present application is to provide a quantum dot photoelectric detector and a preparation method thereof, which have the characteristics of being suitable for large-size quantum dots and wide detection range.

[0004] In order to achieve the above-mentioned application purposes, the present application provides a quantum dot photoelectric detector, which includes a PbS quantum dot light-absorbing layer and a SnO2 electron transport layer located thereon, and the absorption peak of the PbS quantum dot light-absorbing layer is above 1300 nm.

[0005] The SnO2 electron transport layer is prepared by an atomic layer deposition method.

[0006] The thickness of the SnO2 electron transport layer is greater than or equal to 20 nm and less than or equal to 50 nm.

[0007] The thickness of the quantum dot light-absorbing layer is greater than or equal to 300 nm and less than or equal to 400 nm.

[0008] The quantum dot photoelectric detector further includes a bottom electrode, a hole transport layer, a buffer layer and a top electrode, and the bottom electrode, the hole transport layer, the PbS quantum dot light-absorbing layer, the buffer layer, the SnO2 electron transport layer and the top electrode are overlapped in sequence.

[0009] The bottom electrode is an ITO bottom electrode or a gold electrode, the hole transport layer includes overlapped NiO hole transport layers and PbS-EDT hole transport layers, the buffer layer is a C60 buffer layer, and the top electrode is an ITO top electrode; the NiO hole transport layer is in contact with the bottom electrode, and the PbS-EDT hole transport layer is in contact with the quantum dot light-absorbing layer.

[0010] The thickness of the NiO hole transport layer is greater than or equal to 33 nm and less than or equal to 45 nm; the thickness of the PbS-EDT hole transport layer is greater than or equal to 25 nm and less than or equal to 40 nm; the thickness of the C60 buffer layer is greater than or equal to 5 nm and less than or equal to 13 nm; and the thickness of the bottom electrode and the top electrode is greater than or equal to 100 nm and less than or equal to 350 nm.

[0011] The application also discloses a preparation method of the quantum dot photodetector.

[0012] forming a hole transport layer on a substrate, wherein the substrate serves as a bottom electrode of the quantum dot photodetector;

[0013] forming a PbS quantum dot light-absorbing layer on the hole transport layer, and the absorption peak of the PbS quantum dot light-absorbing layer is above 1300 nm;

[0014] forming a buffer layer on the PbS quantum dot light-absorbing layer;

[0015] forming a SnO2 electron transport layer on the buffer layer; and

[0016] forming a top electrode of the quantum dot photodetector on the SnO2 electron transport layer.

[0017] The step of forming the SnO2 electron transport layer on the buffer layer comprises depositing the SnO2 electron transport layer on the buffer layer by using an atomic layer deposition method.

[0018] The step of depositing the SnO2 electron transport layer on the buffer layer by using the atomic layer deposition method comprises, when the atomic layer deposition method is used, using a source to adopt TDMASn and water or TDMASn and ozone, controlling the chamber temperature to be between 80 and 100 degrees, controlling the reaction source purging time to be 10 seconds, controlling the water source bottle pulse to be 0.1 seconds, controlling the tin source pulse to be 1 second, and controlling the growth cycle to be 250 cycles.

[0019] The step of depositing the SnO2 electron transport layer on the buffer layer by using the atomic layer deposition method comprises, when the atomic layer deposition method is used, using a source to adopt TDMASn and water or TDMASn and ozone, controlling the chamber temperature to be 70 degrees, controlling the reaction source purging time to be 10 seconds, controlling the water source bottle pulse to be 0.1 seconds, controlling the tin source pulse to be 1 second, and controlling the growth cycle to be 250 cycles.

[0020] The step of using the atomic layer deposition method to deposit the SnO2 electron transport layer on the buffer layer comprises: using TDMASn and water, or TDMASn and ozone as the source, controlling the chamber temperature to be 80 degrees, controlling the reaction source purge time to be 5 seconds, controlling the water source bottle pulse to be 0.1 seconds, controlling the tin source pulse to be 1 second, and controlling the growth cycle to be 250 cycles when the atomic layer deposition method is used.

[0021] The step of using the atomic layer deposition method to deposit the SnO2 electron transport layer on the buffer layer comprises: using TDMASn and water, or TDMASn and ozone as the source, controlling the chamber temperature to be 80 degrees, controlling the reaction source purge time to be 20 seconds, controlling the water source bottle pulse to be 0.1 seconds, controlling the tin source pulse to be 1 second, and controlling the growth cycle to be 250 cycles when the atomic layer deposition method is used.

[0022] The thickness of the SnO2 electron transport layer is greater than or equal to 20 nm and less than or equal to 50 nm, and the thickness of the quantum dot light absorption layer is greater than or equal to 300 nm and less than or equal to 400 nm.

[0023] The beneficial effects of the embodiments of the present application are as follows:

[0024] The quantum dot photoelectric detector of the embodiments of the present application adopts the SnO2 electron transport layer instead of the ZnO electron transport layer when the absorption peak of the PbS quantum dot light absorption layer is above 1300 nm. Since the conduction band position of SnO2 is lower than that of ZnO, when the absorption peak of the PbS quantum dot light absorption layer is above 1300 nm, the energy band position of the SnO2 electron transport layer is more matched with the energy band position of the PbS quantum dot light absorption layer, thereby helping to extract photoelectric charges and ensuring the performance of the quantum dot photoelectric detector, so the quantum dot photoelectric detector of the embodiments of the present application is very suitable for application in the scene of large-size quantum dots (absorption peak above 1300 nm). At the same time, since the band gap of SnO2 is also larger than that of ZnO, the transmittance of SnO2 in the near-ultraviolet band is higher, so the absorbance of the quantum dot light absorption layer in the near-ultraviolet band can be increased, thereby expanding the detection range of the quantum dot photoelectric detector.

[0025] In addition, in further embodiments, SnO2 can be prepared by the atomic layer deposition (ALD) method, so that the film is more dense, so that the quantum dot photoelectric detector can achieve self-packaging. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 and Figure 2 are energy band diagrams of quantum dot photoelectric detectors, in which Figure 1 and Figure 2In the embodiment, the absorption peak of the PbS quantum dot is 1300 nm, and the material of the electron transport layer is ZnO and SnO2 respectively.

[0027] Figure 3 is a structural schematic diagram of a quantum dot photoelectric detector according to an embodiment of the present application;

[0028] Figure 4 is a flow schematic diagram of a preparation method of a quantum dot photoelectric detector according to an embodiment of the present application;

[0029] Figure 5 is a schematic diagram of a dark current of a quantum dot photoelectric detector;

[0030] Figure 6 is a schematic diagram of a change of a photocurrent with a bias voltage;

[0031] Figure 7 is a schematic diagram of a full-spectrum EQE; and

[0032] Figure 8 and Figure 9 are schematic diagrams of changes of photocurrents-light intensities of the embodiments and the comparative examples, i.e., linear dynamic range performance diagrams of the detectors. DETAILED DESCRIPTION

[0033] In order to make the technical problems to be solved by the present application, technical solutions and beneficial effects more clear, explicit and apparent, the present application will be further described in detail below in combination with the drawings and embodiments. 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.

[0034] In the subsequent description, the suffixes such as "module", "component" or "unit" used to represent elements are only for the convenience of the description of the present application, and have no specific meaning. Therefore, "module", "component" or "unit" can be used mixedly.

[0035] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence.

[0036] The present application will be described below in combination with the drawings through embodiments.

[0037] In the existing quantum dot photodetector, the mainstream structure includes: PbS quantum dot light absorption layer and ZnO electron transport layer. The inventors of the present application found that in the current application, quantum dots with an absorption peak less than 1200 nm are still mainstream, and for quantum dots with an absorption peak less than 1200 nm, the above structure can obtain good photoelectric detection performance. However, it can be expected that in the future, large-size quantum dots will be possible to be applied, and the inventors of the present application invented that for large-size quantum dots, the performance of the above structure will quickly decay, so a new structure needs to be developed to make it still have good performance in the scenario of large-size quantum dots. It should be noted that the absorption peak of the quantum dot is in a positive relationship with the size of the quantum dot, that is, the larger the size of the quantum dot, the longer the absorption peak wavelength, so the above-mentioned large-size quantum dot can refer to a quantum dot with an absorption peak above 1300 nm.

[0038] As shown in Figure 1 , it is a band diagram of a quantum dot photodetector. In Figure 1 , the material of the quantum dot light absorption layer is PbS quantum dot, and the material of the electron transport layer is ZnO, wherein the absorption peak of the PbS quantum dot light absorption layer is 1300 nm. As shown in the figure, for the PbS quantum dot light absorption layer, when its absorption peak is 1300 nm, the conduction band position of the PbS quantum dot is about -4.1 eV, and the conduction band position of the ZnO is about -3.86 eV. It should be noted that the absorption peak is inversely proportional to the conduction band position, that is, the longer the absorption peak, the lower the conduction band position. Since the electron moves in the direction of lower energy, and in the scenario of Figure 1 , there is a potential barrier between the PbS quantum dot and the ZnO, which causes the photo-generated charge to be unable to conduct from the PbS quantum dot light absorption layer to the ZnO electron transport layer, thereby causing the performance of the photodetector to be poor. If you want to overcome this potential barrier, a feasible way is to apply a certain bias voltage, but this needs to make great improvements in the structure of the quantum dot photodetector.

[0039] As shown in Figure 2 , it is another band diagram of a quantum dot photodetector. In Figure 2 , the material of the quantum dot light absorption layer is PbS quantum dot, and the material of the electron transport layer is SnO2, wherein the absorption peak of the PbS quantum dot light absorption layer is 1300 nm. As shown in the figure, the conduction band position of the SnO2 is about -4.28 eV, which is lower than the conduction band position of the PbS quantum dot (-4.1 eV), so the photo-generated charge can naturally conduct from the PbS quantum dot light absorption layer to the SnO2 electron transport layer, thereby ensuring the performance of the quantum dot photodetector.

[0040] In addition, using SnO2 as the electron transport layer material can broaden the detection range of quantum dot photodetectors. This is because SnO2 has a larger bandgap (about 4.13 eV) than ZnO (about 3.3 eV), so SnO2 has higher transmittance in the near-ultraviolet band, which can increase the absorbance of the quantum dot layer in the near-ultraviolet band and achieve the purpose of expanding the detection range of quantum dot photodetectors.

[0041] Furthermore, the inventors of this invention also realized that when using new materials as electron transport layers, the fabrication process is also a key factor that needs to be considered. For example, for some materials, although they can ensure that the conduction band position of the electron transport layer matches the band position of the PbS quantum dot light-absorbing layer (absorption peak above 1300 nm), the fabrication process will damage the PbS quantum dot light-absorbing layer, causing interface defects. Therefore, such materials are also unqualified. When SnO2 is selected, the SnO2 electron transport layer can be formed by atomic layer deposition (ALD). This process is very gentle and will not damage the quantum dot light-absorbing layer. At the same time, the SnO2 film prepared by this process is more dense, which not only reduces leakage current, but also has a self-encapsulating effect that isolates water and oxygen.

[0042] Therefore, using SnO2 as the electron transport layer makes quantum dot photodetectors suitable for large-sized quantum dots, while also broadening the detection range of quantum dot photodetectors. For example, the detection range can include near-ultraviolet light, visible light, and short-wave infrared light, and its fabrication process is also very suitable for the requirements.

[0043] Based on the above, the structure of an embodiment of the quantum dot photodetector of the present invention will be described below with reference to the accompanying drawings.

[0044] like Figure 3 The diagram shown is a schematic representation of an embodiment of the quantum dot photodetector 3 of the present invention. From bottom to top, it comprises: a bottom electrode 30, a hole transport layer 31, a quantum dot light-absorbing layer 32, a buffer layer 33, a SnO2 electron transport layer 34, and a top electrode 35. The bottom electrode 30, hole transport layer 31, quantum dot light-absorbing layer 32, buffer layer 33, SnO2 electron transport layer 34, and top electrode 35 are sequentially stacked to form a layered structure.

[0045] It should be noted that the above structure is only illustrative and not a limitation of the present invention. For example, in some cases, the buffer layer 33 may be omitted, and in other cases, the hole transport layer 31 may be a single-layer or multi-layer structure, etc.

[0046] In one embodiment, the bottom electrode 30 can be an ITO (indium tin oxide) bottom electrode or a gold (Au) electrode.

[0047] In an embodiment, the thickness of the bottom electrode 30 is greater than or equal to 100 nm and less than or equal to 350 nm, for example, 150 nm, 200 nm, 350 nm, 300 nm or 330 nm.

[0048] In an embodiment, the hole transport layer 31 comprises a NiO hole transport layer 311 and a PbS-EDT hole transport layer 312.

[0049] In an embodiment, the thickness of the NiO hole transport layer 311 is greater than or equal to 33 nm and less than or equal to 45 nm, for example, 35 nm, 40 nm.

[0050] In an embodiment, the thickness of the PbS-EDT hole transport layer 312 is greater than or equal to 25 nm and less than or equal to 40 nm, for example, 30 nm, 35 nm.

[0051] In an embodiment, the absorption peak of the quantum dot light absorption layer 32 is above 1300 nm, for example, 1400 nm, 1500 nm.

[0052] In an embodiment, the thickness of the quantum dot light absorption layer 32 is greater than or equal to 300 nm and less than or equal to 400 nm, for example, 330 nm, 350 nm, 380 nm.

[0053] In an embodiment, the buffer layer 33 can be a C60 buffer layer.

[0054] In an embodiment, the thickness of the buffer layer 33 is greater than or equal to 5 nm and less than or equal to 13 nm, for example, 8 nm, 10 nm.

[0055] In an embodiment, the SnO2 electron transport layer is prepared by atomic layer deposition (ALD). The detailed process of preparing the SnO2 electron transport layer by atomic layer deposition can refer to the method embodiment, which is not described here.

[0056] In an embodiment, the top electrode 35 can be an ITO top electrode.

[0057] In an embodiment, the thickness of the top electrode 35 is greater than or equal to 100 nm and less than or equal to 350 nm, for example, 150 nm, 180 nm, 220 nm, 280 nm, 330 nm.

[0058] The structure of the quantum dot photodetector of the embodiment of the application is described in detail above, and the preparation method of the quantum dot photodetector is described below.

[0059] As Figure 4Fig. 1 is a flow diagram of an embodiment of a method for manufacturing a quantum dot photodetector according to the present application. The method comprises the following steps:

[0060] Step S40: Forming a hole transport layer on the substrate. The substrate serves as a bottom electrode of the quantum dot photodetector.

[0061] The substrate can be made of ITO or gold. In step S40, before forming the hole transport layer, the substrate is cleaned. The cleaning method can include sequentially using deionized water, acetone, isopropyl alcohol, and anhydrous ethanol to ultrasonically clean the substrate for about 10-40 minutes.

[0062] After cleaning the substrate, a NiO hole transport layer can be formed using a magnetron sputtering method, and then a PbS-EDT hole transport layer can be formed using a spin coating method. Specifically, the chamber is first evacuated to 3e -3 Pa, and then argon gas is introduced into the chamber to a pressure of 3 Pa. The gas flow rate is set to 100 sccm, the radio frequency sputtering power supply is powered on at 200 W, and sputtering is performed for 7 min to obtain the NiO hole transport layer. After forming the NiO hole transport layer, PbS quantum dot solution, diluted EDT (ethanedithiol) solution, and acetonitrile are sequentially spin-coated thereon to obtain the PbS-EDT hole transport layer. The PbS quantum dot solution can have a concentration of 40 mg / ml, and the solvent can be n-octane. The EDT solution can have a concentration by volume ratio of 0.01%, and the solvent can be acetonitrile.

[0063] Step S42: Forming a PbS quantum dot light-absorbing layer on the hole transport layer.

[0064] Specifically, step S42 can include the following steps. First, PbS quantum dots are synthesized. Then, the PbS quantum dots are prepared into a quantum dot slurry. Finally, the prepared quantum dot slurry is diluted and spin-coated on the hole transport layer.

[0065] The step of preparing the quantum dots into a slurry can include the following steps. The mass of the quantum dots is weighed, and a pipette is used to prepare a quantum dot solution with a concentration of 10 mg / mL in n-octane, i.e., solution A. In a glove box, lead iodide (PbI2) and lead bromide (PbBr2) are weighed, added to a centrifuge tube, and 10 mL of DMF (N,N-dimethylformamide) is added to prepare a ligand solution and fully dissolved, i.e., solution B. Solutions A and B are filtered separately, and then mixed to obtain solution C. After shaking for 30-60 s, the supernatant is removed after the solution is stratified. 10 mL of n-octane is added to the above solution C. After shaking for 20-40 s, the supernatant is removed after the solution is stratified. The above steps are repeated twice. The above solution is transferred to a centrifuge tube, centrifuged at 9000 r for 5 min, and the supernatant is discarded. The residual liquid on the tube opening and tube wall is wiped clean with a cotton swab, and the centrifuge tube is placed in the transition bin of the glove box to dry the solvent (for 50-80 minutes).

[0066] In the step, the quantum dot paste is diluted to 250-400 mg / ml, and the solvent is a mixture of BTA (n-butylamine) and DMF, with a ratio of 4:1. Then, the quantum dot paste is spin-coated on the hole transport layer, with a spin speed of 2500 r / min and a spin time of 40 s. Then, the sample is placed on a hot stage at 85°C for annealing for 10 min, and a quantum dot light-absorbing layer with a thickness of 300-400 nm is obtained.

[0067] Step S44: forming a buffer layer on the quantum dot light-absorbing layer.

[0068] In this step, a C60 buffer layer is prepared by using a thermal evaporation deposition process. During the deposition, the chamber is vacuumed to 5e -4 Pa, and the deposition current is controlled to be 70-80 A.

[0069] Step S46: forming a SnO2 electron transport layer on the buffer layer. In this step, the conduction band position of the SnO2 electron transport layer is controlled to be lower than the conduction band position of the quantum dot light-absorbing layer.

[0070] In this step, a SnO2 electron transport layer is prepared by using an atomic layer deposition process.

[0071] Step S48: forming a top electrode of the quantum dot photodetector on the SnO2 electron transport layer.

[0072] In this step, an ITO top electrode is prepared by using a magnetron sputtering deposition method. During the preparation, the chamber is vacuumed to 2e -3 -4e -3 Pa, argon gas is introduced into the chamber to a pressure of 0.3-1.0 Pa, the gas flow rate is set to 20-40 sccm, the direct current sputtering power is turned on to 80-120 W, and the sputtering time is 15-25 min, so as to obtain an ITO electrode layer with a thickness of 220-360 nm.

[0073] In the above step S46, the atomic layer deposition process has a great influence on the final performance of the device. The following examples are provided for illustration.

[0074] In the embodiment numbered 1, when the atomic layer deposition method is used in step S46, the source uses TDMASn and water, or TDMASn and ozone, the chamber temperature is controlled to be between 80-100 degrees, the reaction source purge time is controlled to be 10 seconds, the water source bottle pulse is controlled to be 0.1 s, the tin source pulse is controlled to be 1 s, and the growth cycle is controlled to be 250 cycles.

[0075] In the embodiment numbered 2, step S46 uses TDMASn and water, or TDMASn and ozone as the source when using the atomic layer deposition method, controls the chamber temperature to be 70 degrees, controls the reaction source purging time to be 10 seconds, controls the water source bottle pulse to be 0.1 s, controls the tin source pulse to be 1 s, and controls the growth cycle to be 250 cycles.

[0076] In the embodiment numbered 3, step S46 uses TDMASn and water, or TDMASn and ozone as the source when using the atomic layer deposition method, controls the chamber temperature to be 80 degrees, controls the reaction source purging time to be 5 seconds, controls the water source bottle pulse to be 0.1 s, controls the tin source pulse to be 1 s, and controls the growth cycle to be 250 cycles.

[0077] In the embodiment numbered 4, step S46 uses TDMASn and water, or TDMASn and ozone as the source when using the atomic layer deposition method, controls the chamber temperature to be 80 degrees, controls the reaction source purging time to be 20 seconds, controls the water source bottle pulse to be 0.1 s, controls the tin source pulse to be 1 s, and controls the growth cycle to be 250 cycles.

[0078] As shown in FIG. 1, it is a schematic diagram of the dark current of the embodiments numbered 1-4. The quantum dot photodetector pursues a small dark current under a reverse voltage. As shown in the figure, the dark current of the embodiment numbered 1 is significantly smaller than that of the embodiments numbered 2-4, and thus the performance of the embodiment numbered 1 is better than that of the embodiments numbered 2-4. Figure 5

[0079] As shown in FIG. 2, it is a performance comparison diagram of the embodiment numbered 1 and the comparative example. The comparative example is a comparative example using a ZnO electron transport layer, and the process for preparing the ZnO electron transport layer is to evaporate ZnO by magnetron sputtering. The sputtering ZnO process is as follows: the chamber is vacuumed to 3e -3 Pa, the argon flow is 99 sccm, the oxygen flow is 1 sccm, the chamber pressure is kept at about 3 Pa, the radio frequency sputtering power is turned on at 200 w, and sputtering is performed for 30 min to obtain a 120-200 nm thick ZnO electron transport layer. It should be noted that the comparative example is the same as the embodiment numbered 1 except that the step of preparing the ZnO electron transport layer is different. Figures 6 to 9 As shown in FIG. 3, it is a schematic diagram of the change of the photocurrent with the bias voltage. The quantum dot photodetector pursues a photocurrent saturation point voltage as close to 0 V or greater than 0 V as possible. As shown in the figure, it can be seen that the embodiment numbered 1 meets the requirement, while the photocurrent saturation point voltage of the comparative example is close to -0.5 V.

[0080] Figure 6 As shown in FIG. 4, it is a schematic diagram of the change of the photocurrent with the bias voltage. The quantum dot photodetector pursues a photocurrent saturation point voltage as close to 0 V or greater than 0 V as possible. As shown in the figure, it can be seen that the embodiment numbered 1 meets the requirement, while the photocurrent saturation point voltage of the comparative example is close to -0.5 V.

[0081] As shown in FIG. 5, it is a schematic diagram of the change of the photocurrent with the bias voltage. The quantum dot photodetector pursues a photocurrent saturation point voltage as close to 0 V or greater than 0 V as possible. As shown in the figure, it can be seen that the embodiment numbered 1 meets the requirement, while the photocurrent saturation point voltage of the comparative example is close to -0.5 V. Figure 7 ​​As shown, it is a schematic diagram of full spectrum EQE (spectrum effect). As shown, the EQE of the embodiment numbered 1 is generally greater than the comparative example in each waveband, and in the near ultraviolet direction, the corresponding wavelength of the embodiment numbered 1 can be widened to 300 nm, while the comparative example is only close to 400 nm.

[0082] As shown in Figure 8 and 9 , it is a schematic diagram of the change of light intensity-photocurrent of the embodiment numbered 1 and the comparative example respectively, i.e. the schematic diagram of the change of photocurrent with light intensity. As shown in Figure 8 and 9 , under the condition of the laboratory test range, the embodiment numbered 1 is linear in the test range and LDR (linear dynamic range) > 80 dB. While the comparative example is not linear in the test range and LDR < 70 dB due to the limited ability to extract charges under strong light.

[0083] It should be noted that in this paper, the term "including", "containing" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or system including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such process, method, article or system. Without more limitations, the element defined by the statement "including a" does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0084] The above-mentioned embodiment number of the application is only for description, not representing the advantages and disadvantages of the embodiments.

[0085] The above is only the preferred embodiment of the application, and does not limit the patent scope of the application. Any equivalent structure or equivalent process transformation using the content of the application specification and drawings, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the application.

Claims

1. A quantum dot photodetector, characterized in that, The PbS quantum dot light-absorbing layer and the SnO2 electron transport layer, the absorption peak of the PbS quantum dot light-absorbing layer being 1300 nm; Further comprising: a bottom electrode, a hole transport layer, a buffer layer and a top electrode, wherein the bottom electrode, the hole transport layer, the PbS quantum dot light-absorbing layer, the buffer layer, the SnO2 electron transport layer and the top electrode are overlapped in sequence; The bottom electrode is an ITO bottom electrode or a gold electrode, the hole transport layer comprises: an overlapped NiO hole transport layer and a PbS-EDT hole transport layer, the buffer layer is a C60 buffer layer, and the top electrode is an ITO top electrode; wherein the NiO hole transport layer is in contact with the bottom electrode, and the PbS-EDT hole transport layer is in contact with the PbS quantum dot light-absorbing layer. The SnO2 electron transport layer is prepared by an atomic layer deposition method.

2. The quantum dot photodetector of claim 1, wherein, The thickness of the SnO2 electron transport layer is greater than or equal to 20 nm and less than or equal to 50 nm.

3. The quantum dot photodetector of claim 1, wherein, The thickness of the PbS quantum dot light-absorbing layer is greater than or equal to 300 nm and less than or equal to 400 nm.

4. The quantum dot photodetector of claim 1, wherein, The thickness of the NiO hole transport layer is greater than or equal to 33 nm and less than or equal to 45 nm, the thickness of the PbS-EDT hole transport layer is greater than or equal to 25 nm and less than or equal to 40 nm, the thickness of the C60 buffer layer is greater than or equal to 5 nm and less than or equal to 13 nm, and the thickness of the bottom electrode and the top electrode is greater than or equal to 100 nm and less than or equal to 350 nm.

5. The quantum dot photodetector of claim 1, wherein, The method comprises the following steps:

6. A method for preparing a quantum dot photodetector, comprising: forming a hole transport layer on a substrate, wherein the substrate serves as a bottom electrode of the quantum dot photodetector; forming a PbS quantum dot light-absorbing layer with an absorption peak of 1300 nm on the hole transport layer; forming a buffer layer on the PbS quantum dot light-absorbing layer; forming a SnO2 electron transport layer on the buffer layer; and forming a top electrode of the quantum dot photodetector on the SnO2 electron transport layer; The bottom electrode is an ITO bottom electrode or a gold electrode, the hole transport layer comprises: an overlapped NiO hole transport layer and a PbS-EDT hole transport layer, the buffer layer is a C60 buffer layer, and the top electrode is an ITO top electrode; wherein the NiO hole transport layer is in contact with the bottom electrode, and the PbS-EDT hole transport layer is in contact with the PbS quantum dot light-absorbing layer. The step of forming the SnO2 electron transport layer on the buffer layer comprises: depositing the SnO2 electron transport layer on the buffer layer by using an atomic layer deposition method; 7. The production method according to claim 6, wherein The step of depositing the SnO2 electron transport layer on the buffer layer by using the atomic layer deposition method comprises: In the atomic layer deposition method, a source is used to adopt TDMASn and water, or TDMASn and ozone, the chamber temperature is controlled to be between 80 and 100 degrees, the reaction source purging time is controlled to be 10 seconds, the water source bottle pulse is controlled to be 0.1 s, the tin source pulse is controlled to be 1 s, and the growth cycle is controlled to be 250 cycles. ​ Or, when using the atomic layer deposition method, using source using TDMASn and water, or TDMASn and ozone, controlling the chamber temperature to be 70 degrees, controlling the reaction source purge time to be 10 seconds, controlling the water source bottle pulse to be 0.1s, controlling the tin source pulse to be 1s, and controlling the growth cycle to be 250 cycles; Or, when using the atomic layer deposition method, using source using TDMASn and water, or TDMASn and ozone, controlling the chamber temperature to be 80 degrees, controlling the reaction source purge time to be 5 seconds, controlling the water source bottle pulse to be 0.1s, controlling the tin source pulse to be 1s, and controlling the growth cycle to be 250 cycles; Or, when using the atomic layer deposition method, using source using TDMASn and water, or TDMASn and ozone, controlling the chamber temperature to be 80 degrees, controlling the reaction source purge time to be 20 seconds, controlling the water source bottle pulse to be 0.1s, controlling the tin source pulse to be 1s, and controlling the growth cycle to be 250 cycles.

8. The production method according to claim 6, wherein The thickness of the SnO2 electron transport layer is greater than or equal to 20nm and less than or equal to 50nm; and the thickness of the PbS quantum dot light absorption layer is greater than or equal to 300nm and less than or equal to 400nm.

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