Near infrared spectrum selective detector based on dark current reduction and preparation method

Abstract

The invention provides a near infrared spectrum selective detector based on dark current reduction and a preparation method, and the detector comprises a perovskite / organic cooperation unit which is composed of a built-in filtering perovskite layer and a cooperation response organic layer. Cs0. 05FA0. 8075MA0. 1425Pb (I0. 85Br0. 15) 3 / PTB7-Th: Y6 is utilized to play a perovskite / organic synergistic effect, and the energy level barrier of a perovskite / organic interface and the defect state density of electrons and holes in a device are coordinated by regulating and controlling the ratio of an electron donor and an electron acceptor in an organic heterojunction; the balance of full dissociation and low defect state of excitons is achieved, and light extraction and carrier transmission of a near-infrared band are both considered; the response range of the prepared detector covers the near-infrared first-area wave band without external bias voltage, efficient near-infrared narrow-band detection is achieved, and high external quantum efficiency and responsivity are achieved. Dark current is reduced, the weak light detection capability is improved, and the method has important significance in the field of detection imaging.

Description

Technical Field

[0001] The present invention relates to the technical field of photodetectors and preparation technologies, and particularly relates to a near-infrared spectral selective detector based on reducing dark current and a preparation method thereof. Background Art

[0002] Near-infrared photodetectors have extensive and important applications in fields such as communication, biology, and national defense. For example, in the biological field, near-infrared light detection and imaging have been regarded as a powerful real-time medical diagnosis technology. By adjusting the narrowband detection band and specifically matching the detection target, the background light and noise can be greatly reduced, and high-sensitivity and responsive detection and imaging can be achieved.

[0003] With the complication of detection signals, photodetectors need to develop towards higher efficiency and lower dark current standards. Although certain progress has been made by increasing the thickness of the active layer material or adjusting the optical structure, these methods usually come with an increase in dark current, which limits the performance of the detector in practical applications. In addition, some adjustment methods based on external bias voltage can improve efficiency in some cases, but they also introduce additional noise, non-linear response, and power consumption, affecting the stability of the detector. On the other hand, in the scheme of using an additional blocking layer to achieve narrowband high-efficiency response, the introduction of the interface will inevitably bring more defects, and it is difficult to further suppress the noise current with this process.

[0004] Therefore, how to effectively reduce the dark current while improving the narrow-band photoelectric efficiency has become the core challenge faced by current narrow-band photodetectors. Summary of the Invention

[0005] Aiming at the above problems existing in the prior art, the present invention provides a near-infrared spectral selective detector based on reducing dark current and a preparation method thereof to solve the problems that metal single atoms are prone to aggregation, low dispersion, and unstable loading amount during the reduction process in the existing methods.

[0006] The specific content of the invention is as follows: In the first aspect, the present invention provides a near-infrared spectral selective detector based on reducing dark current, including a perovskite / organic cooperative unit, and the perovskite / organic cooperative unit is composed of a built-in filtering perovskite layer and a cooperative response organic layer; the composition of the built-in filtering perovskite layer is Cs 0.05 FA 0.8075 MA 0.1425 Pb(I 0.85 Br 0.15 )3; the composition of the cooperative response organic layer is an organic heterojunction formed by an electron donor PTB7-Th and an electron acceptor Y6; wherein, The electron donor PTB7-Th is poly([2,6′-4,8-bis(5-ethylhexylthiophenyl)benzo[1,2-b;3,3-b]dithiophene]{3-fluoro-2[(2-ethylhexyl)carbonyl]thiopheno[3,4-b]thiophenediyl}); The electron acceptor Y6 is 12,13-bis(2-ethylhexyl)-3,9-undecylene-12,13-dihydro-[1,2,5]thiadiazolo[3,4-E]thieno[2'',3'',4',5']thieno[2',3',4,5]pyrrolo[3,2-G]thieno[2',3',4,5]thieno[3,2-B]indole-2,10-bis(5,6-difluoro-3-(dicyanomethylene)indene-1-one); The mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 is 1:1.2 - 1:8.

[0007] Optionally, the mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 in the synergistic response organic layer is 1:8.

[0008] Optionally, the thickness of the built-in filtering perovskite layer is 1400 - 1800 nanometers; The thickness of the synergistic response organic layer is 100 - 150 nanometers.

[0009] Optionally, the detector structure from bottom to top is a transparent ITO substrate, an anode modification layer, a built-in filtering perovskite layer, a synergistic response organic layer, an electron transport layer, a cathode modification layer, and a cathode; where The composition of the anode modification layer is a mixture of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate; The composition of the electron transport layer is C 60 ; The composition of the cathode modification layer is 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; The composition of the cathode is Ag.

[0010] Optionally, the external quantum efficiency of the detector at a working wavelength of 700 - 930 nm is not less than 65%; The dark current of the detector at -0.1V is not greater than 2.13E-9 A / cm 2 ;

[0011] In a second aspect, the present invention provides a method for preparing the near-infrared spectral selectivity detector based on reducing dark current according to the first aspect above, including: sequentially preparing an anode modification layer, a perovskite / organic synergistic unit, an electron transport layer, a cathode modification layer, and a cathode on the surface of a substrate; where the perovskite / organic synergistic unit is composed of a built-in filtering perovskite layer and a synergistic response organic layer; The preparation steps of the built-in filtering perovskite layer include: spin-coating the precursor solution on the surface of the anode modification layer at a low speed of 300-500 revolutions per minute, dropping an appropriate amount of chlorobenzene, continuing to spin-coat at 900-1200 revolutions per minute for 50-60 s, and after annealing treatment, forming the built-in filtering perovskite layer on the surface of the anode modification layer; The preparation steps of the synergistic response organic layer include: mixing an electron donor PTB7-Th and an electron acceptor Y6 with a mass ratio of 1:1.2-1:8 in chloroform, and spin-coating on the surface of the built-in filtering perovskite layer at 1500-2000 revolutions per minute, and after annealing treatment, forming a synergistic response organic layer on the surface of the built-in filtering perovskite layer; The precursor solution is prepared according to the elemental stoichiometric ratio of Cs 0.05 FA 0.8075 MA 0.1425 Pb(I 0.85 Br 0.15 )3. Using CsI, FAI, MABr, PbI2 and PbBr2 as solutes, dissolve them in a mixed solution composed of N,N-dimethylformamide and dimethyl sulfoxide.

[0012] Optionally, the preparation steps of the anode modification layer include: spin-coating a dispersion containing poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate on the surface of the substrate at 5000 revolutions per minute, and after annealing treatment, forming the anode modification layer on the surface of the substrate.

[0013] Optionally, the preparation steps of the electron transport layer include: evaporating C 60 onto the surface of the synergistic response organic layer at an evaporation rate of 0.02-0.08 nm / s to form the electron transport layer.

[0014] Optionally, the preparation steps of the cathode modification layer include: evaporating BCP onto the surface of the electron transport layer at an evaporation rate of 0.02-0.08 nm / s to form the cathode modification layer.

[0015] Optionally, the preparation steps of the cathode include: evaporating BCP onto the surface of the cathode modification layer at an evaporation rate of 0.05-0.15 nm / s to form the cathode.

[0016] Compared with the prior art, the present invention has the following advantages: The present invention provides a near-infrared spectral selective detector based on reducing dark current, including a perovskite / organic synergistic unit, and the perovskite / organic synergistic unit is composed of a built-in filtering perovskite layer and a synergistic response organic layer; the composition of the built-in filtering perovskite layer is Cs 0.05 FA 0.8075 MA0.1425 Pb(I 0.85 Br 0.15 )3; The composition of the synergistic response organic layer is an organic heterojunction formed by the electron donor PTB7-Th and the electron acceptor Y6; the mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 is 1:1.2 - 1:8; the present invention utilizes Cs 0.05 FA 0.8075 MA 0.1425 Pb(I 0.85 Br 0.15 )3 / PTB7-Th:Y6 to exert the perovskite / organic synergistic effect. By regulating the ratio of the electron donor and the electron acceptor inside the organic heterojunction, coordinating the energy level barrier at the perovskite / organic interface and the density of defect states of electrons and holes inside the device, an equilibrium of sufficient exciton dissociation and low defect states is achieved, taking into account light extraction and carrier transport in the near-infrared band; the prepared detector has a response range covering the first near-infrared band without an external bias voltage, realizing efficient narrow-band detection in the near-infrared, with a high external quantum efficiency and responsivity; the reduction of dark current is achieved, improving the weak light detection ability, which is of great significance in the field of detection imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 Shows the structural schematic diagram of the near-infrared spectral selective detector provided by the embodiment of the present invention; Figure 2 Shows the external quantum efficiency diagram of the near-infrared spectral selective detector provided by the embodiment of the present invention; Figure 3 Shows the dark current curve diagram of the near-infrared spectral selective detector provided by the embodiment of the present invention; Figure 4 Shows the defect state density diagram of the near-infrared spectral selective detector provided by the embodiment of the present invention; Figure 5 Shows the responsivity curve diagram of the near-infrared spectral selective detector provided by the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually illustrative only and in no way limits the present invention and its application or use. Based on the embodiments of the present invention, any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with the features of other existing technologies falls within the protection scope of the present invention. In addition, all other embodiments obtained by those of ordinary skill in the art without creative efforts also belong to the protection scope of the present invention.

[0020] If specific experimental steps or conditions are not specified in the embodiments, the operations or conditions of the conventional experimental steps described in the existing technologies in this field can be followed. Reagents and other instruments not indicating the manufacturer can be obtained as conventional reagent products through commercial purchase. In addition, the accompanying drawings are only schematic diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings represent the same or similar parts, and thus the repeated description thereof will be omitted. Some of the block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0021] Technologies, methods, and devices known to those of ordinary skill in the relevant fields may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the specification of the present invention.

[0022] In the description of the present invention, it should be understood that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Without further statement, the above terms have no special meaning and thus should not be construed as limiting the protection scope of the present invention.

[0023] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] Before the detailed description of a near-infrared spectral selective detector and a preparation method thereof based on reducing dark current provided by the present invention, it is necessary to make the following description of the related technologies: In the prior art, introducing an organic heterojunction structure or a material composite strategy can improve the optoelectronic performance of infrared detectors to a certain extent, but the problems of high dark current and maintaining high spectral selectivity have not been solved simultaneously. Especially in weak infrared light detection, traditional material structure designs often struggle to maintain efficient optoelectronic conversion while reducing dark current, resulting in the performance of the detector falling short of the ideal level. Additionally, narrowband designs based on single organic materials are often restricted by factors such as the material bandgap and carrier transport characteristics, making it difficult to achieve high spectral selectivity, low dark current, and efficient carrier transport simultaneously. Therefore, although existing structure optimization methods have improved device performance to some extent, they still cannot effectively suppress dark current while meeting the requirements of efficient near-infrared weak light narrowband detection, and there is an urgent need for new solutions.

[0025] Therefore, the present invention explores a perovskite / organic-based structure. By introducing a perovskite / organic synergistic unit into the device and regulating the mass ratio of the donor and acceptor of the organic heterojunction in it, the perovskite / organic synergistic effect is exerted, achieving both an increase in efficiency and a reduction in dark current simultaneously. The specific implementation details are as follows: In a first aspect, the present invention provides a near-infrared spectral selectivity detector based on reducing dark current, comprising a perovskite / organic synergistic unit, and the perovskite / organic synergistic unit is composed of an internal filtering perovskite layer and a synergistic response organic layer; the composition of the internal filtering perovskite layer is Cs 0.05 FA 0.8075 MA 0.1425 Pb(I 0.85 Br 0.15 )3; the composition of the synergistic response organic layer is the PTB7-Th:Y6 organic heterojunction formed by the electron donor PTB7-Th and the electron acceptor Y6.

[0026] In specific implementation, based on the perovskite / organic structure, the present invention constructs a perovskite / organic synergistic unit in the detector, which is specifically composed of an internal filtering perovskite layer and a synergistic response organic layer. The perovskite / organic synergistic unit adopts a Cs 0.05 FA 0.8075 MA 0.1425 Pb(I 0.85 Br 0.15 )3 / PTB7-Th:Y6 structure. By regulating the mass ratio of the donor and acceptor of the PTB7-Th:Y6 organic heterojunction in the synergistic response organic layer, the phase distribution uniformity of the organic heterojunction, the energy level barrier at the synergistic interface, and the defect state density of electrons and holes inside the device are affected, enabling the full dissociation of excitons and the balance of low defect states; the mass ratio of the electron donor PTB7-Th and the electron acceptor Y6 that is conducive to reducing the defect state density and dark current inside the organic heterojunction is obtained as 1:1.2 - 1:8.

[0027] In specific implementation, the electron donor PTB7-Th in the synergistic response organic layer is poly([2,6′-4,8-bis(5-ethylhexylthiophenyl)benzo[1,2-b;3,3-b]dithiophene]{3-fluoro-2[(2-ethylhexyl)carbonyl]thiopheno[3,4-b]thiophenediyl}); the electron acceptor Y6 is 12,13-bis(2-ethylhexyl)-3,9-undecylene-12,13-dihydro-[1,2,5]thiadiazolo[3,4-E]thiopheno[2'',3'',4',5']thiopheno[2',3',4,5]pyrrolo[3,2-G]thiopheno[2',3',4,5]thiopheno[3,2-B]indole-2,10-bis(5,6-difluoro-3-(dicyanomethylene)indene-1-one); preferably, the mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 is 1:8.

[0028] In some embodiments, the thickness of the built-in filtering perovskite layer is 1400-1800 nanometers to ensure filtering out high-energy visible light, reducing hot carrier injection, ensuring a visible light absorption rate > 99%, and a near-infrared transmittance > 90%; the thickness of the synergistic response organic layer is 100-150 nanometers to balance high responsivity and low noise.

[0029] See Figure 1 , the detector structure provided by the embodiment of the present invention is, from bottom to top in sequence, a transparent ITO substrate 1, an anode modification layer 2, a built-in filtering perovskite layer 3, a synergistic response organic layer 4, an electron transport layer 5, a cathode modification layer 6, and a cathode 7; wherein, the composition of the anode modification layer 2 is a mixture of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate (PEDOT:PSS); the composition of the electron transport layer 5 is C 60 ; the composition of the cathode modification layer 6 is 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP); the composition of the cathode 7 is Ag.

[0030] The detector obtained by the present invention has an external quantum efficiency of not less than 65% at a working wavelength of 700-930 nm, and the dark current of the detector at -0.1V is not greater than 2.13E-9 A / cm 2 .

[0031] In a second aspect, the present invention provides a preparation method of the above-mentioned near-infrared spectral selective detector based on reducing dark current in the first aspect. The preparation method includes: sequentially preparing an anode modification layer, a perovskite / organic synergistic unit, an electron transport layer, a cathode modification layer, and a cathode on the surface of a substrate; wherein, the perovskite / organic synergistic unit is composed of a built-in filtering perovskite layer and a synergistic response organic layer; wherein, The preparation of the built-in filtering perovskite layer adopts a two-stage spin-coating method, and the steps include: first, spin-coat the precursor solution on the surface of the anode modification layer at a low speed of 300-500 revolutions per minute, then drop an appropriate amount of chlorobenzene, continue to spin-coat at 900-1200 revolutions per minute for 50-60 s, and after annealing treatment, form a built-in filtering perovskite layer on the surface of the anode modification layer; the total spin-coating time is 110-130 s, and chlorobenzene is used as an antisolvent, which induces uniform nucleation and inhibits phase separation by instantaneously reducing the solubility of the precursor.

[0032] The preparation steps of the synergistic response organic layer include: mixing the electron donor PTB7-Th and the electron acceptor Y6 with a mass ratio of 1:1.2-1:8 in chloroform, and spin-coating on the surface of the built-in filtering perovskite layer at 1500-2000 revolutions per minute, and after annealing treatment, form a synergistic response organic layer on the surface of the built-in filtering perovskite layer; The precursor solution is prepared according to the elemental stoichiometric ratio of Cs 0.05 FA 0.8075 MA 0.1425 Pb(I 0.85 Br 0.15 )3, using CsI, FAI, MABr, PbI2 and PbBr2 as solutes, and dissolving them in a mixed solution composed of N,N-dimethylformamide and dimethyl sulfoxide.

[0033] In some embodiments, before preparing each functional layer, the substrate needs to be pretreated, cleaned to remove surface impurities. Specifically, the ITO substrate is ultrasonically cleaned in ethanol for 30 minutes, dried with nitrogen, and placed in an ultraviolet ozone machine for 90 seconds; further, an anode modification layer, a built-in filtering perovskite layer, a synergistic response organic layer, an electron transport layer, a cathode modification layer and a cathode are sequentially prepared on the surface of the substrate; specifically, when spin-coating the anode modification layer, a dispersion containing PEDOT:PSS is spin-coated on the surface of the substrate at 5000 revolutions per minute, and after annealing treatment, an anode modification layer is formed on the surface of the substrate; when evaporating the electron transport layer, C 60 is evaporated on the surface of the synergistic response organic layer at an evaporation rate of 0.02-0.08 nm / s to form an electron transport layer. When evaporating the cathode modification layer, BCP is evaporated on the surface of the electron transport layer at an evaporation rate of 0.02-0.08 nm / s to form a cathode modification layer. When evaporating the cathode, BCP is evaporated on the surface of the cathode modification layer at an evaporation rate of 0.05-0.15 nm / s to form a cathode.

[0034] By regulating the ratio of the electron donor and electron acceptor inside the organic heterojunction of the organism, and by affecting the uniformity of the organic heterojunction, synergistically regulating the energy level barrier of the perovskite / organic interface and the density of defect states of electrons and holes inside the device, the light extraction and carrier transport in the near-infrared band are balanced, and then applied in the perovskite / organic collaborative unit. The optimized device further improves the external quantum efficiency and responsivity of the narrow band in the near-infrared band and reduces the dark current. Among them, the perovskite / organic collaborative unit adopts Cs 0.05 FA 0.8075 MA 0.1425 Pb(I 0.85 Br 0.15 )3 / PTB7-Th:Y6 structure. The detector prepared by the present invention, without an external bias voltage, has a response range covering the first near-infrared band, realizes efficient narrow-band detection in the near-infrared, has a high external quantum efficiency and responsivity; realizes a reduction in dark current, improves the weak light detection ability, and has important significance in the field of detection imaging.

[0035] To make those skilled in the art understand the present invention more clearly, the following examples are now used to elaborate in detail a near-infrared spectral selective detector based on reducing dark current and its preparation method of the present invention.

[0036] Example 1 Step 1: Substrate pretreatment: Ultrasonically clean the ITO substrate in ethanol for 30 minutes, dry it with nitrogen, and place it in an ultraviolet ozone machine for 90 seconds; Step 2: Spin-coat the anode modification layer: The anode modification layer is PEDOT:PSS, the spin-coating rate is 5000 revolutions per minute, the spin-coating time is 20 seconds, and then it is annealed on a heating table at 150 °C for 10 minutes; Step 3: Prepare and spin-coat the built-in filtering perovskite layer: According to the elemental stoichiometric ratio of Cs 0.05 FA 0.8075 MA 0.1425 Pb(I 0.85 Br 0.15 )3, use CsI, FAI, MABr, PbI2 and PbBr2 as solutes, dissolve them in a solvent of DMF:DMSO at 4:1 to obtain a precursor solution of 2.5 mol / L, and heat and stir at 60 °C for 6 hours. After filtering the solution with a micron filter and spin-coating, when spin-coating, a two-stage spin-coating method is adopted. The spin-coating rate in the first stage is 400 revolutions per minute, and the spin-coating in the second stage is 1000 revolutions per minute, for a total of 120 seconds. At about 45 seconds, an appropriate amount of anti-solvent chlorobenzene is added. Then it is annealed on a heating platform at 100 °C for 30 minutes; Step 4: Prepare and spin-coat the collaborative response organic layer: Prepare a mixed solution of organic electron donor PTB7-Th and acceptor Y6 with a total concentration of 16 mg / ml, where the donor concentration is 7.28 mg / ml and the acceptor concentration is 8.72 mg / ml. The solvent is chloroform. Heat and stir at 60 °C for 10 hours, then use the one-step spin-coating method with a spin-coating rate of 1500 revolutions per minute for 60 seconds, and then anneal on a heating platform at 90 °C for 10 minutes; Step 5: Evaporate the electron transport layer: Evaporate the electron transport layer C 60 , with an evaporation rate of 0.05 nm / s and an evaporation thickness of 15 nm; Step 6: Evaporate the cathode modification layer: Evaporate the cathode modification layer BCP with an evaporation rate of 0.05 nm / s and an evaporation thickness of 9 nm; Step 7: Evaporate the cathode: Evaporate the cathode Ag with an evaporation rate of 0.1 nm / s and an evaporation thickness of 100 nm.

[0037] In this example, the mass ratio of the organic layer electron donor PTB7-Th to the acceptor Y6 in the mixed solution is 1:1.2.

[0038] Example 2 Steps 1 - 3 are the same as in Example 1; Step 4: Prepare and spin-coat the synergistic response organic layer: Prepare a mixed solution of organic electron donor PTB7-Th and acceptor Y6 with a total concentration of 16 mg / ml, where the donor concentration is 3.2 mg / ml and the acceptor concentration is 12.8 mg / ml. The solvent is chloroform. Heat and stir at 60 °C for 10 hours, then use the one-step spin-coating method with a spin-coating rate of 1500 revolutions per minute for 60 seconds, and then anneal on a heating platform at 90 °C for 10 minutes; Steps 5 - 7 are the same as in Example 1.

[0039] In this example, the mass ratio of the organic layer electron donor PTB7-Th to the acceptor Y6 in the mixed solution is 1:4.

[0040] Example 3 Steps 1 - 3 are the same as in Example 1; Step 4: Prepare and spin-coat the synergistic response organic layer: Prepare a mixed solution of organic electron donor PTB7-Th and acceptor Y6 with a total concentration of 16 mg / ml, where the donor concentration is 1.78 mg / ml and the acceptor concentration is 14.22 mg / ml. The solvent is chloroform. Heat and stir at 60 °C for 10 hours, then use the one-step spin-coating method with a spin-coating rate of 2000 revolutions per minute for 60 seconds. After that, anneal on a heating platform at 90 °C for 10 minutes; Steps 5 - 7 are the same as in Example 1.

[0041] In this example, the mass ratio of the organic layer electron donor PTB7-Th to the acceptor Y6 in the mixed solution is 1:8.

[0042] Perform performance tests on the detectors prepared in Examples 1 - 3. The results are shown in Figures 2 - 5 .

[0043] Figure 2 Shows the external quantum efficiency graph of the near-infrared spectral selective detector provided by the embodiment of the present invention. As Figure 2 shown, under the condition of no external bias voltage, in the device provided by Example 1, when the mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 is 1:1.2, the external quantum efficiency reaches up to 68.11% in the 700 - 930 nm band; in the device provided by Example 2, when the mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 is 1:4, the external quantum efficiency reaches up to 66.14% in the 700 - 930 nm band; in the device provided by Example 3, when the mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 is 1:8, the external quantum efficiency reaches up to 69.32% in the 700 - 930 nm band. It can be seen that the detector provided by the present invention has a relatively high external quantum efficiency performance (not less than 65%).

[0044] Figure 3 Shows the dark current curve graph of the near-infrared spectral selective detector provided by the embodiment of the present invention. As Figure 3 shown, in the device provided by Example 1, when the mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 is 1:1.2, the dark current at -0.1 V is 2.13E - 8 A / cm 2 ; in the device provided by Example 2, when the mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 is 1:4, the dark current at -0.1 V is 8.85E - 9 A / cm 2 ; in the device provided by Example 3, when the mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 is 1:8, the dark current at -0.1 V is 3.78E - 9 A / cm 2 . It can be seen that the detector provided by the present invention has a relatively low dark current (not higher than 2.13E - 8 A / cm at -0.1 V 2), indicating that the organic heterojunction with a high receptor ratio and the built-in filter layer play a positive role in suppressing dark current.

[0045] Figure 4 Shows the defect state density map of the near-infrared spectral selective detector provided by the embodiments of the present invention. As Figure 4 shown, in the device provided in Embodiment 1, when the mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 is 1:1.2, the hole defect density is 1.67E14 cm -3 , and the electron defect density is 1.38E14 cm -3 ; in the device provided in Embodiment 2, when the mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 is 1:4, the hole defect density is 5.90E13 cm -3 , and the electron defect density is 2.26E14 cm -3 ; in the device provided in Embodiment 3, when the mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 is 1:8, the hole defect density is 4.91E13 cm -3 , and the electron defect density is 3.14E14 cm -3 .

[0046] Figure 5 Shows the responsivity curve of the near-infrared spectral selective detector provided by the embodiments of the present invention. As Figure 5 shown, under the condition of no external bias voltage, in the device provided in Embodiment 1, when the mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 is 1:1.2, the device has a responsivity of 0.40 A / W at 800 nm; in the device provided in Embodiment 2, when the mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 is 1:4, the device has a responsivity of 0.43 A / W at 800 nm; in the device provided in Embodiment 3, when the mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 is 1:8, the device has a responsivity of 0.45 A / W at 800 nm.

[0047] It can be seen from Figures 2 - 5 that by adjusting the mass ratio of the electron donor PTB7-Th to the electron acceptor Y6, as the mass concentration of the electron acceptor Y6 decreases in the co-responsive organic layer, it affects the uniformity of the organic heterojunction, the energy level barriers at the perovskite / organic interface and the defect state densities of electrons and holes inside the device, thereby improving the external quantum efficiency and responsivity in the near-infrared narrowband band, as well as reducing the dark current by using the perovskite / organic co-unit. Finally, a higher external quantum efficiency and responsivity in the narrowband outside the band, as well as a lower dark current, are obtained at a mass ratio of 1:8 compared to other ratios.

[0048] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc., mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0049] For method embodiments, for the sake of simple description, they are all expressed as a series of combinations of actions. However, those skilled in the art should know that the present invention is not limited by the described order of actions, because according to the present invention, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0050] The above has introduced in detail a near-infrared spectral selective detector and a preparation method thereof based on reducing dark current. Specific examples are used herein to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A near-infrared spectral selective detector based on reducing dark current, including a perovskite / organic cooperative unit, characterized in that, The perovskite / organic cooperative unit is composed of a built-in filtering perovskite layer and a cooperative response organic layer; the composition of the built-in filtering perovskite layer is Cs 0.05 FA 0.8075 MA 0.1425 Pb(I 0.85 Br 0.15 )3; the composition of the cooperative response organic layer is an organic heterojunction formed by an electron donor PTB7-Th and an electron acceptor Y6; wherein, The electron donor PTB7-Th is poly([2,6′-4,8-bis(5-ethylhexylthiophenyl)benzo[1,2-b;3,3-b]dithiophene]{3-fluoro-2[(2-ethylhexyl)carbonyl]thiopheno[3,4-b]thiophenediyl}); The electron acceptor Y6 is 12,13-bis(2-ethylhexyl)-3,9-undecadiyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-E]thieno[2'',3'',4',5']thieno[2',3',4,5]pyrrolo[3,2-G]thieno[2',3',4,5]thieno[3,2-B]indole-2,10-bis(5,6-difluoro-3-(dicyanomethylene)indan-1-one); The mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 is 1:1.2 - 1:

8.

2. The near-infrared spectral selective detector based on reducing dark current according to claim 1, characterized in that The mass ratio of the electron donor PTB7-Th to the electron acceptor Y6 in the synergistic response organic layer is 1:

8.

3. The near-infrared spectral selective detector based on reducing dark current according to claim 1, wherein The thickness of the built-in filtering perovskite layer is 1400 - 1800 nanometers; The thickness of the synergistic response organic layer is 100 - 150 nanometers.

4. The near-infrared spectral selective detector based on reducing dark current according to claim 1, wherein The detector structure from bottom to top is successively a transparent ITO substrate, an anode modification layer, a built-in filtering perovskite layer, a synergistic response organic layer, an electron transport layer, a cathode modification layer, and a cathode; where The composition of the anode modification layer is a mixture of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate; The composition of the electron transport layer is C 60 ; The composition of the cathode modification layer is 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; The composition of the cathode is Ag.

5. The near-infrared spectral selective detector based on reducing dark current according to claim 1, wherein The external quantum efficiency of the detector at a working wavelength of 700 - 930 nm is not less than 65%; The dark current of the detector at -0.1V is not greater than 2.13E-9 A / cm 2 .

6. A method for preparing the near-infrared spectral selective detector based on reducing dark current according to any one of claims 1-5 above, characterized in that, including: successively preparing an anode modification layer, a perovskite / organic synergy unit, an electron transport layer, a cathode modification layer, and a cathode on the surface of a substrate; where the perovskite / organic synergy unit is composed of a built-in filtering perovskite layer and a synergistic response organic layer; The preparation steps of the built-in filtering perovskite layer include: spin-coating a precursor solution on the surface of the anode modification layer at a low speed of 300 - 500 revolutions per minute, then dropping an appropriate amount of chlorobenzene, continuing to spin-coat at 900 - 1200 revolutions per minute for 50 - 60 s, and after annealing treatment, forming the built-in filtering perovskite layer on the surface of the anode modification layer; The preparation steps of the synergistic response organic layer include: mixing the electron donor PTB7-Th and the electron acceptor Y6 with a mass ratio of 1:1.2 - 1:8 in chloroform, spin-coating the mixture on the surface of the built-in filtering perovskite layer at 1500 - 2000 revolutions per minute, and after annealing treatment, forming the synergistic response organic layer on the surface of the built-in filtering perovskite layer; The precursor solution is prepared according to the elemental stoichiometric ratio of Cs 0.05 FA 0.8075 MA 0.1425 Pb(I 0.85 Br 0.15 )3. CsI, FAI, MABr, PbI2, and PbBr2 are used as solutes and dissolved in a mixed solution composed of N,N-dimethylformamide and dimethyl sulfoxide.

7. The preparation method of the near-infrared spectral selective detector based on reducing dark current according to claim 6, wherein The preparation steps of the anode modification layer include: spin-coating a dispersion liquid containing poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate on the surface of the substrate at 5000 revolutions per minute, and after annealing treatment, forming the anode modification layer on the surface of the substrate.

8. The preparation method of the near-infrared spectral selective detector based on reducing dark current according to claim 6, characterized in that, The preparation steps of the electron transport layer include: evaporating C at an evaporation rate of 0.02 - 0.08 nanometers per second 60 onto the surface of the synergistic response organic layer to form the electron transport layer.

9. The preparation method of the near-infrared spectral selective detector based on reducing dark current according to claim 6, characterized in that, The preparation steps of the cathode modification layer include: depositing BCP on the surface of the electron transport layer at an evaporation rate of 0.02 - 0.08 nanometers per second to form the cathode modification layer.

10. The preparation method of the near-infrared spectral selective detector based on reducing dark current according to claim 6, wherein, The preparation steps of the cathode include: depositing BCP on the surface of the cathode modification layer at an evaporation rate of 0.05 - 0.15 nanometers per second to form the cathode.

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