Infrared detector based on 2.0 micron PbS colloidal quantum dots and preparation method thereof

Abstract

The invention relates to an infrared detector based on 2.0 micron PbS colloidal quantum dots and a preparation method thereof, the infrared detector is composed of an anode conducting layer, a hole transport layer, a colloidal quantum dot film, an electron transport layer, an electron blocking layer and a cathode conducting layer, the colloidal quantum dot film adopts PbS-PbX, the preparation method adopts 9.7 nm PbS colloidal quantum dots to carry out liquid phase exchange, and the hole transport layer and the electron blocking layer are combined to form the infrared detector based on 2.0 micron PbS colloidal quantum dots. The PbS-PbX ink containing the halogen short-chain ligand is spin-coated on the hole transport layer. And the prepared infrared detector has a good rectification characteristic and relatively high infrared sensitivity at a 2350 nm infrared light source.

Description

Technical Field

[0001] The present invention relates to an infrared detector based on 2.0 micron PbS colloidal quantum dots and a preparation method thereof. Background Art

[0002] Photovoltaic heterojunction infrared detectors are high-performance infrared detection devices based on heterojunction structures. They exploit the band offset and interface properties between different semiconductor materials to achieve efficient detection of infrared light. Their core principle is to separate photogenerated carriers through the built-in electric field of the heterojunction, thereby improving the detector's responsivity and sensitivity. Currently, reports on photovoltaic heterojunction infrared detectors based on PbS colloidal quantum dots (CQDs) have mostly focused on the shortwave infrared band of 1.7 microns and shorter, while reports on wavelengths longer than 1.7 microns are rare.

[0003] PbS colloidal quantum dots (CQDs) are a popular direct-narrow bandgap semiconductor material in the field of infrared detectors. Thin films made from them are often the most critical component of detectors. However, when the infrared exciton absorption peak of PbS CQDs reaches 2.0 microns (PbS CQD particle size is approximately 10 nm), the quantum confinement effect weakens. This is determined by the material itself. However, high-quality PbS CQD films can still be prepared through liquid-phase ligand exchange to improve carrier mobility. Combined with other functional layers, they can be fabricated into photovoltaic heterojunction infrared detectors. Summary of the Invention

[0004] The present invention relates to an infrared detector based on 2.0 micron PbS colloidal quantum dots and a preparation method thereof.

[0005] An infrared detector based on 2.0 micron PbS colloidal quantum dots, characterized in that the infrared detector is a multi-layer composite structure, consisting of an anode conductive layer, a hole transport layer, a colloidal quantum dot film, an electron transport layer, an electron blocking layer and a cathode conductive layer in sequence; The anode conductive layer is made of Au; The hole transport layer is made of Bi2O x Se 3-x； The colloidal quantum dot film adopts PbS-PbX; The electron transport layer is made of ZnO; The electron blocking layer is made of ZnO NCs; The cathode conductive layer is made of ITO.

[0006] Specifically, the thickness of Au is 41 nm.

[0007] Specifically, the thickness of the PbS-PbX is 77 nm.

[0008] Specifically, the Bi2O x Se 3-x The thickness is 28nm.

[0009] Specifically, the thickness of the ZnO is 155 nm.

[0010] Specifically, the thickness of the ITO is 247 nm.

[0011] The preparation method of the infrared detector based on 2.0 micron PbS colloidal quantum dots is characterized by being achieved by the following steps: S1, clean the quartz substrate and dry it thoroughly using a high-purity nitrogen gun; S2, preparing an Au electrode pattern through a mask, and using vacuum physical plating to form an Au electrode pattern on a substrate as an anode conductive layer; S3, prepare a layer of Bi2Se3 on the Au anode conductive layer, then place it in a vacuum annealing furnace for annealing, while introducing oxygen to dope oxygen atoms into Bi2Se3, and finally obtain Bi2O x Se 3-x Prepared hole transport layer; In S4, 9.7 nm PbS colloidal quantum dots were prepared by liquid phase exchange to form PbS-PbX ink containing halogen short chain ligands, which was then spin-coated on Bi2O x Se 3-x Then, the film was placed on a heating platform at 70°C and dried for 15 minutes to form a colloidal quantum dot film. S5, depositing ZnO on the colloidal quantum dot film by vacuum physical coating method for 20 min as an electron transport layer; S6, spin-coating ZnO NCs solution on the electron transport layer and drying it on a heating platform at 70 °C for 15 min to serve as an electron blocking layer; S7, depositing ITO as a cathode conductive layer on the electron blocking layer by vacuum physical coating method for 20 minutes.

[0012] Specifically, in step S1, the cleaning process uses a mixed solution of deionized water, ammonia water and hydrogen peroxide to boil at 80° C. and then rinses with deionized water.

[0013] Specifically, in step S3, the Au-plated substrate is placed in a cavity containing a Bi2Se3 target, and the pre-deposition time is 2 min and the time is 20 s.

[0014] The technical effect of the present invention is that the prepared infrared detection device has good rectification characteristics and high infrared sensitivity under 2350nm infrared light source, and shows great application potential in the field of short-wave infrared detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the photovoltaic heterojunction infrared detector of Example 1.

[0016] Figure 2 The detector of Example 1 IV Characteristic curve, where the horizontal axis is voltage and the vertical axis is current.

[0017] Figure 3 The detector log of Example 1 IV Characteristic curve, where the horizontal axis is voltage and the vertical axis is current.

[0018] Figure 4 1 is a curve showing the relationship between the response rate and the detection rate and the applied bias voltage of Example 1, wherein the horizontal and vertical axes represent voltage and the vertical axis represents detection rate.

[0019] Among them, there are an anode conductive layer 1, a hole transport layer 2, a colloidal quantum dot film 3, an electron transport layer 4, an electron blocking layer 5, and a cathode conductive layer 6. DETAILED DESCRIPTION

[0020] Example: An infrared detector based on 2.0 micron PbS colloidal quantum dots, the infrared detector is a multi-layer composite structure, which consists of an anode conductive layer, a hole transport layer, a colloidal quantum dot film, an electron transport layer, an electron blocking layer and a cathode conductive layer in sequence; the anode conductive layer is made of Au with a thickness of 41nm; the hole transport layer is made of Bi2O x Se 3-x , with a thickness of 28nm; the colloidal quantum dot film adopts PbS-PbX, with a thickness of 77nm; the electron transport layer adopts ZnO, with a thickness of 155nm; the electron blocking layer adopts ZnO NCs; the cathode conductive layer adopts ITO, with a thickness of 247nm.

[0021] The preparation method of the infrared detector based on 2.0 micron PbS colloidal quantum dots is achieved by the following steps: S1, cleaning the quartz substrate by boiling it in a mixed solution of deionized water, ammonia and hydrogen peroxide at 80°C, rinsing it with deionized water, and drying it thoroughly with a high-purity nitrogen gun; S2, preparing an Au electrode pattern through a mask, and using vacuum physical plating to form an Au electrode pattern on a substrate as an anode conductive layer; S3, the Au-plated substrate is placed in a chamber containing a Bi2Se3 target material, the pre-deposition time is 2 minutes, and then placed in a vacuum annealing furnace for annealing, while oxygen is introduced to allow oxygen atoms to be doped into Bi2Se3, and finally Bi2O x Se 3-xPrepared hole transport layer; In S4, 9.7 nm PbS colloidal quantum dots were prepared by liquid phase exchange to form PbS-PbX ink containing halogen short chain ligands, which was then spin-coated on Bi2O x Se 3-x Then, the film was placed on a heating platform at 70°C and dried for 15 minutes to form a colloidal quantum dot film. S5, depositing ZnO on the colloidal quantum dot film by vacuum physical coating method for 20 min as an electron transport layer; S6, spin-coating ZnO NCs solution on the electron transport layer and drying it on a heating platform at 70 °C for 15 min to serve as an electron blocking layer; S7, depositing ITO as a cathode conductive layer on the electron blocking layer by vacuum physical coating method for 20 minutes.

[0022] like Figure 2 As shown, from IV From the characteristic curve, as the forward bias voltage gradually decreases, the induced current decreases to 0 under all lighting conditions, and as the negative bias voltage increases, the induced current does not increase, indicating that the application of the reverse electric field has a significant obstacle to the migration of carriers. It also proves that the photovoltaic heterojunction detector under this structure has good rectification characteristics. Under the irradiation of 2350nm infrared light source, the rectification ratio at ±1V is 1.3×10 2 .

[0023] like Figure 3 As shown in the figure, under the irradiation of 350nm infrared light source, the ratio of light to dark current at ±1V is 9, among which the induced current is the largest under the irradiation of 660nm light source, and the response is close to one order of magnitude with the dark current under the bias of -0.5V. This is because the light source with a wavelength of 660nm has higher energy, and more photons excite the photosensitive layer to produce more photogenerated carriers, and the rectification characteristics of the device are better.

[0024] like Figure 4 As shown in the figure, the response rate R of the device under the illumination of two different LED wavelengths of 1700 / 2350 nm is calculated, and the R / V curve is drawn. It is obvious that the response rate of the device under the illumination of the four light sources is larger in the positive bias region, and with the increase of the wavelength of the light source, the value of the response rate R also increases. When a voltage of 1.1 V is applied to the 2350 nm light source (the light power density is 0.132 mW / cm -2), the highest response rate was obtained at 1.0 V, which was 7.48 mA / W, which basically corresponds to the exciton absorption peak of PbS CQDs at 2050 nm. Secondly, the detectivity D* under illumination with two different LED wavelengths of 1700 nm and 2350 nm was calculated, and the D* / V curve was drawn. It can be seen that the overall change trend of D* is consistent with the response rate. In the positive bias region, it still increases with the increase of the wavelength of the irradiated light source. Under the 2350 nm light source, when a bias of 1.0 V is applied, the detectivity D* reaches a maximum value of 2.9×10 11 Jones, has the highest detectivity value among the PbS CQDs photovoltaic heterojunction infrared detectors with detection wavelengths exceeding 2000nm reported so far, proving the high infrared sensitivity during this period.

[0025] Comparative example: ZnO / PbS-TBAI / BDT / NiO x The heterostructured PbS short-wave infrared detector is used as a comparison. Its detection performance reaches its maximum at 2100nm, with a response rate R of 0.385 A / W and a detectivity D* of 1.47×10 11 Jones, compared with the detection performance of the present invention, they are all inferior to the technical solutions of the embodiment; the detection performance of the PbS infrared laser imaging detector with PbS / 3D-Graphene structure reaches its maximum at 2200nm, with a response rate R of 52 A / W and a detection rate D* of 6.8×10 10 Jones, compared with the detection performance embodied by the present invention, the detection rate D* is one order of magnitude lower than that of the present invention.

Claims

1. Infrared detector based on 2.0 micron PbS colloidal quantum dots, characterized by The infrared detector is a multi-layer composite structure, which is composed of an anode conductive layer, a hole transport layer, a colloidal quantum dot film, an electron transport layer, an electron blocking layer and a cathode conductive layer in sequence; The anode conductive layer is made of Au; The hole transport layer is made of Bi2O x Se 3-x； The colloidal quantum dot film adopts PbS-PbX; The electron transport layer is made of ZnO; The electron blocking layer is made of ZnO NCs; The cathode conductive layer is made of ITO.

2. The infrared detector based on 2.0 micron PbS colloidal quantum dots according to claim 1, characterized in that The thickness of Au is 41nm; the thickness of PbS-PbX is 77nm; the thickness of Bi2O x Se 3-x The thickness of is 28nm; the thickness of ZnO is 155nm; the thickness of ITO is 247nm.

3. Preparation method of infrared detector based on 2.0 micron PbS colloidal quantum dots, characterized in that This is achieved by following these steps: S1, clean the quartz substrate and dry it thoroughly using a high-purity nitrogen gun; S2, preparing an Au electrode pattern through a mask, and using vacuum physical plating to form an Au electrode pattern on a substrate as an anode conductive layer; S3, prepare a layer of Bi2Se3 on the Au anode conductive layer, then place it in a vacuum annealing furnace for annealing, while introducing oxygen to dope oxygen atoms into Bi2Se3, and finally obtain Bi2O x Se 3-x Prepared hole transport layer; In S4, 9.7 nm PbS colloidal quantum dots were prepared by liquid phase exchange to form PbS-PbX ink containing halogen short chain ligands, which was then spin-coated on Bi2O x Se 3-x Then, the film was placed on a heating platform at 70°C and dried for 15 minutes to form a colloidal quantum dot film. S5, depositing ZnO on the colloidal quantum dot film by vacuum physical coating method for 20 min as an electron transport layer; S6, spin-coating ZnO NCs solution on the electron transport layer and drying it on a heating platform at 70 °C for 15 min to serve as an electron blocking layer; S7, depositing ITO as a cathode conductive layer on the electron blocking layer by vacuum physical coating method for 20 minutes.

Images