Short mid-infrared band universal mercury-sulfur family colloidal quantum dot homojunction photovoltaic detector, preparation method and application thereof

Abstract

The present application relates to a kind of short mid-infrared band general-purpose sulfur mercury group colloidal quantum dot homojunction photovoltaic detector and its preparation method and application, belong to the technical field of photoelectric sensor.The detector includes bottom electrode, top electrode and intrinsic sulfur mercury group quantum dot layer, also includes p-type sulfur mercury group quantum dot layer and / or n-type sulfur mercury group quantum dot layer;Wherein, intrinsic sulfur mercury group quantum dot layer and p-type sulfur mercury group quantum dot layer form I-P or P-I homojunction;Intrinsic sulfur mercury group quantum dot layer and n-type sulfur mercury group quantum dot layer form I-N or N-I homojunction;P-type sulfur mercury group quantum dot layer, intrinsic sulfur mercury group quantum dot layer and n-type sulfur mercury group quantum dot layer form P-I-N or N-I-P homojunction.The detector has good responsivity, high specific detectivity and high external quantum efficiency for short mid-infrared wave at room temperature, and also has relatively wide detection temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to a sulfur-mercury group infrared colloidal quantum dot photovoltaic detector, belonging to the technical field of photoelectric sensors, and particularly relates to a short and medium infrared band universal sulfur-mercury group colloidal quantum dot homojunction photovoltaic detector and a preparation method and application thereof. BACKGROUND

[0002] Most of the existing photovoltaic type mercury telluride colloidal quantum dot detectors are formed by spin-coating silver telluride quantum dots and sulfur bismuth Bi2X3, such as Bi2Te3, Bi2Se3 or Bi2S3 nanocrystals on the surface of mercury telluride colloidal quantum dots to realize the corresponding regulation of p and n type doped heterojunction mode to form a PN junction. The existing photovoltaic type mercury telluride quantum dot detector structure is as shown in the figure, and sapphire is selected as the substrate because sapphire has high transmittance in the infrared band. The short-wave specific detectivity of the current photovoltaic detector can reach 2*10 Figure 11 10 Jones, the specific detectivity of the medium-wave infrared is 10 7 Jones, after being cooled to 80K by liquid nitrogen, the performance of the short-wave and medium-wave detectors can reach 10 10 Jones.

[0003] The specific doping process of silver telluride or sulfur bismuth on mercury telluride is as follows:

[0004] (1) Silver telluride realizes p-type doping: taking silver telluride as a p-doped layer doped on mercury telluride quantum dots as an example. Silver ions can diffuse to the surface of the mercury telluride film by spin-coating silver telluride on the mercury telluride quantum dot film to form p-doping. After spin-coating silver telluride, a mercury chloride solution is used for treatment, and through cation exchange, an insoluble silver chloride is formed on the surface of the mercury telluride film to fix the silver ions and form a stable and reliable p-doping.

[0005] (2) Sulfur bismuth realizes n-doping: sulfur bismuth nanocrystals are used as the n-doped layer of mercury telluride quantum dots due to their liquid phase treatment, energy band matching, high electron concentration and other characteristics. In the prior art, bismuth sulfide as an n-doped layer can form a pn junction with p-type lead sulfide to prepare a photovoltaic device. Moreover, after the bismuth sulfide is treated by ethanedithiol ligand exchange, the electron coupling and carrier mobility are improved, further improving the performance of the device. Bismuth selenide has the best plasmon resonance peak among sulfur bismuth and has the characteristics of high concentration nanosheet morphology, can form a stable surface, and is suitable for being used as an n-doped layer of mercury telluride quantum dots to transfer electrons through surface charge transfer to form stable n-type doping.

[0006] However, the above-mentioned doping methods have the following technical defects:

[0007] ​(1) The chalcogen bismuth, silver telluride nanocrystals can only provide single n-type doping or p-type doping, cannot control the doping state, doping concentration, and carrier concentration, cannot change the doping state according to the demand, and limits the application range of the mercury telluride colloidal quantum dot photovoltaic infrared detector.

[0008] (2) The chalcogen bismuth, silver telluride nanocrystals are sensitive to water oxygen and are easy to oxidize and deteriorate, meanwhile, the size and lattice of the nanocrystals do not match the mercury telluride quantum dots, and the doping effect on different waveband mercury telluride colloidal quantum dots is different, for example, the doping effect on short wave mercury telluride quantum dots is poor, which affects the performance of the photovoltaic detector.

[0009] (3) The generated photo-generated carrier mobility in the mercury telluride quantum dot is high, while the carrier mobility in the chalcogen bismuth, silver telluride is low, which will cause the band bending at the heterojunction interface, as shown in Figure 12 , causing the carrier transport to be mismatched and reducing the performance of the photovoltaic detector. SUMMARY

[0010] To solve the above technical problems, the application discloses a short and medium infrared waveband universal chalcogenide colloidal quantum dot homojunction photovoltaic detector and a preparation method and application thereof. The photovoltaic infrared detector prepared by the method has a small difference in carrier mobility and no band bending at the homojunction interface size and lattice matching, has relatively higher responsivity, specific detectivity and wider working temperature, and has good response capability to short and medium infrared waves.

[0011] To achieve the above technical purpose, the application discloses a short and medium infrared waveband universal chalcogenide colloidal quantum dot homojunction photovoltaic detector, which comprises a bottom electrode, a top electrode and an intrinsic chalcogenide quantum dot layer, and further comprises a p-type chalcogenide quantum dot layer and / or an n-type chalcogenide quantum dot layer.

[0012] The intrinsic chalcogenide quantum dot layer and the p-type chalcogenide quantum dot layer form an I-P or P-I homojunction.

[0013] The intrinsic chalcogenide quantum dot layer and the n-type chalcogenide quantum dot layer form an I-N or N-I homojunction.

[0014] The p-type chalcogenide quantum dot layer, the intrinsic chalcogenide quantum dot layer and the n-type chalcogenide quantum dot layer form a P-I-N or N-I-P homojunction.

[0015] Further, the n-type chalcogenide quantum dot layer is made of mercury salt doped chalcogenide semiconductor material, and the p-type chalcogenide quantum dot layer is made of sulfide doped chalcogenide semiconductor material.

[0016] Further, the chalcogenide semiconductor material includes any one of mercury sulfide, mercury selenide or mercury telluride,

[0017] The mercury salt is any one of mercury chloride, mercury perchlorate or mercury acetate, and the sulfide is ammonium sulfide.

[0018] Further, the bottom electrode material is ITO compounded on a sapphire substrate, and the top electrode material is a metal conductive material.

[0019] Further, the intrinsic chalcogenide quantum dot layer has a thickness greater than that of the p-type chalcogenide quantum dot layer and the n-type chalcogenide quantum dot layer.

[0020] Another object of the disclosed technical solution is to disclose a preparation method of the above short and medium infrared waveband universal chalcogenide colloidal quantum dot homojunction photovoltaic detector, which comprises the following steps:

[0021] 1) manufacturing a bottom electrode; it includes manufacturing an ITO thin film layer on a sapphire substrate.

[0022] 2) preparing intrinsic, n-type and / or p-type chalcogenide colloidal quantum dot ink:

[0023] 2.1) preparing a long-chain strong ligand coated chalcogenide colloidal quantum dot solution; long-chain strong ligands, mercury salts and sulfur precursors are used to synthesize a long-chain strong ligand coated chalcogenide colloidal quantum dot solution by a hot injection method; this step is to ensure the stability of the colloidal solution, but it also brings the technical problem of slow carrier transfer rate of the quantum dots, resulting in low light response rate of the optoelectronic device.

[0024] 2.2) normal temperature liquid phase mixed ligand exchange: the solution of step 1) is dispersed into n-hexane after cleaning, centrifugal drying treatment, 2-mercaptoethanol and phase transfer catalyst are added and mixed, N,N-dimethylformamide is further added to transfer the chalcogenide infrared colloidal quantum dots into N,N-dimethylformamide, and then the n-hexane is discarded; this step mainly uses the high binding energy between sulfur and mercury, uses short-chain 2-mercaptoethanol to connect with the mercury element on the surface of each quantum dot, replaces the long ligand of oleylamine on the surface of the sulfur-mercury quantum dots, and at the same time, uses the property that the hydroxyl group at the other end of 2-mercaptoethanol can be stabilized in a polar solution to transfer each quantum dot from a non-polar oily solution into a polar solution such as n-hexane and stably exist therein. The phase transfer catalyst is conducive to accelerating the above process.

[0025] 2.3) Surface dipole regulation: adding different amounts of mercury salt into the N,N-dimethylformamide solution of step 2.2) to prepare intrinsic, n-type and / or p-type chalcogenide colloidal quantum dot solution, which includes adding sulfide into the N,N-dimethylformamide solution of step 2) to prepare p-type chalcogenide colloidal quantum dot solution, and after washing and centrifugal drying, the solid precipitate of each quantum dot is dispersed in N,N-dimethylformamide to prepare the intrinsic, p-type and / or n-type chalcogenide colloidal quantum dot ink; this step is to realize different doping of each quantum dot, including adding different amounts of mercury salt to increase the enrichment degree of Hg 2+ on the surface of the quantum dot, and using the surface dipole field generated thereby to stabilize the electrons in the quantum dot and realize n-type doping of the quantum dot. Or adding sulfide, using S 2- to enrich on the surface of the quantum dot, generating a surface dipole field opposite to Hg 2+ , and realizing p-type doping of the quantum dot.

[0026] 3) Preparation of different types of homojunction semiconductor layers:

[0027] Coating the intrinsic chalcogenide colloidal quantum dot ink, p-type chalcogenide colloidal quantum dot ink prepared in step 2) on the surface of the bottom electrode of step 1) to form I-P homojunction semiconductor layer and / or P-I homojunction semiconductor layer;

[0028] Coating the intrinsic chalcogenide colloidal quantum dot ink, n-type chalcogenide colloidal quantum dot ink prepared in step 2) on the surface of the bottom electrode of step 1) to form I-N homojunction semiconductor layer and / or N-I homojunction semiconductor layer;

[0029] Coating the p-type chalcogenide colloidal quantum dot ink, intrinsic chalcogenide colloidal quantum dot ink, n-type chalcogenide colloidal quantum dot ink prepared in step 2) on the surface of the bottom electrode of step 1) to form P-I-N homojunction semiconductor layer and / or N-I-P homojunction semiconductor layer;

[0030] During the coating process, a mixture of 1,2-dithiol and hydrochloric acid is used for solid ligand replacement, and after each replacement, isopropanol is used for cleaning until the process is completed; this step includes solid ligand exchange after the formation of the above quantum dots, such as the exchange of ethanedithiol which has a similar length to the 2-mercaptoethanol ligand but does not contain a hydroxyl group and binds more strongly to the surface of the quantum dot, replacing the short-chain 2-mercaptoethanol on the surface of the quantum dot, and during the exchange process, low-concentration hydrochloric acid is added to stabilize the doping concentration of the quantum dot, and finally isopropanol is used to clean the excess ligand.

[0031] 4) Fabricating a top electrode on the surface of the homojunction semiconductor layer.

[0032] Further, in step 3), the volume ratio of 1,2-dithiol, hydrochloric acid, isopropyl alcohol is (0.8-1.2):(0.8-1.2):(15-25), preferably 1:1:20.

[0033] Further, in step 2.2), the volume of the 2-mercaptoethanol is 0.2-0.67% of the mass of the quantum dot solid precipitate after centrifugal drying in step 2.2), and the mass of the phase transfer catalyst is 66.7-120% of the mass of the quantum dot solid precipitate after centrifugal drying in step 2.2); the phase transfer catalyst is any one of tetrabutylammonium bromide, didodecyl dimethyl ammonium bromide, tetrabutylammonium chloride, tetramethylammonium chloride, and tetraethylammonium chloride.

[0034] Further, in step 2.3), the mass of the mercury salt for preparing the intrinsic type mercury-sulfur group infrared colloidal quantum dots is 20% of the mass of the mercury salt in step 2.1); the mass of the mercury salt for preparing the n-type mercury-sulfur group infrared colloidal quantum dots is 40% of the mass of the mercury salt in step 2.1); and the mass of the sulfide for preparing the p-type mercury-sulfur group infrared colloidal quantum dots is 10% of the mass of the mercury salt in step 2.1).

[0035] The mercury salt is any one of mercury chloride, mercury perchlorate, and mercury acetate; the sulfide is ammonium sulfide; and the mercury-sulfur group includes any one of mercury sulfide, mercury selenide, and mercury telluride.

[0036] Compared with the prior art, the technical scheme provided by the embodiments of the present application has the following advantages:

[0037] 1. The homojunction photovoltaic infrared detector designed in the present application has a homojunction interface, and the dimensions and crystal lattices are matched, the carrier mobility difference is small, the energy band does not bend, the response rate is good at room temperature, the specific detectivity is high, the external quantum efficiency is high, and the detection temperature is relatively wide.

[0038] 2. In the process of preparing each quantum dot layer of the homojunction photovoltaic infrared detector designed in the present application, the normal temperature mixed ligand exchange, surface dipole control, and solid-state ligand exchange are adopted, which not only further improves the carrier mobility and enhances the electron transport performance in the quantum dot layer, but also realizes the adjustable doping of different types and different concentrations of quantum dots, thereby widening the application range of the mercury-sulfur group quantum dot photovoltaic infrared detector. BRIEF DESCRIPTION OF DRAWINGS

[0039] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate preferred embodiments of the present application and, together with the description, serve to explain the principles of the application.

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, for those skilled in the art, based on the drawings, other drawings can be obtained without creative labor.

[0041] Figure 1 Structure diagram of I-N homojunction photovoltaic infrared detector;

[0042] Figure 2 Structure diagram of P-I homojunction photovoltaic infrared detector;

[0043] Figure 3 Structure diagram of P-I-N homojunction photovoltaic infrared detector;

[0044] Figure 4 Structure diagram of I-P homojunction photovoltaic infrared detector;

[0045] Figure 5 Structure diagram of N-I homojunction photovoltaic infrared detector;

[0046] Figure 6 Structure diagram of N-I-P homojunction photovoltaic infrared detector;

[0047] Figure 7 Schematic diagram of carrier mobility of different types of mercury telluride quantum dot layers at different temperatures;

[0048] Figure 8 Test diagram of field effect tube constructed by different types of mercury telluride quantum dot layers;

[0049] Figure 9 Spectral response diagram of the detector prepared in Embodiment 1 of the present application to short infrared waves;

[0050] Figure 10 Spectral response diagram of the detector prepared in Embodiment 1 of the present application to middle infrared waves;

[0051] Figure 11 Structure diagram of the heterojunction photovoltaic infrared detector mentioned in the background art;

[0052] Figure 12 Energy band diagram of the heterojunction photovoltaic infrared detector of Figure 11

[0053] Figure 13 ​Band diagram of I-P homojunction photovoltaic infrared detector;

[0054] Figure 14 Band diagram of N-I homojunction photovoltaic infrared detector;

[0055] Figure 15 Band diagram of N-I-P homojunction photovoltaic infrared detector;

[0056] Figure 16 The detector designed according to the embodiment of the present application is used for drawing a diagram of the relationship between short-wave specific detectivity and temperature;

[0057] Figure 17 The detector designed according to the embodiment of the present application is used for drawing a diagram of the relationship between short-wave responsivity, external quantum efficiency and temperature;

[0058] Figure 18 The detector designed according to the embodiment of the present application is used for drawing a diagram of the relationship between middle-wave specific detectivity and temperature;

[0059] Figure 19 The detector designed according to the embodiment of the present application is used for drawing a diagram of the relationship between middle-wave responsivity, external quantum efficiency and temperature. DETAILED DESCRIPTION

[0060] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the scheme of the present application will be further described below.

[0061] The present application discloses a short and middle infrared band universal colloidal quantum dot homojunction photovoltaic detector of sulfur-mercury group, which comprises a bottom electrode, a top electrode and an intrinsic sulfur-mercury group quantum dot layer, further comprises a p-type sulfur-mercury group quantum dot layer and / or an n-type sulfur-mercury group quantum dot layer.

[0062] The intrinsic sulfur-mercury group quantum dot layer and the p-type sulfur-mercury group quantum dot layer form an I-P or P-I homojunction.

[0063] The intrinsic sulfur-mercury group quantum dot layer and the n-type sulfur-mercury group quantum dot layer form an I-N or N-I homojunction.

[0064] The p-type sulfur-mercury group quantum dot layer, the intrinsic sulfur-mercury group quantum dot layer and the n-type sulfur-mercury group quantum dot layer form a P-I-N or N-I-P homojunction.

[0065] Meanwhile, the p-type mercury sulfide quantum dot layer is made of a mercury salt-doped mercury sulfide semiconductor material, and the n-type mercury sulfide quantum dot layer is made of a sulfide-doped mercury sulfide semiconductor material. The mercury sulfide semiconductor material includes any one of mercuric sulfide, mercuric selenide, or mercuric telluride; the mercury salt is any one of mercuric chloride, mercuric perchlorate, or mercuric acetate; and the sulfide is ammonium sulfide. The bottom electrode material is ITO or FTO laminated on a sapphire substrate, and the top electrode material is a metallic conductive material, which is any one of gold, silver, copper, or aluminum.

[0066] Furthermore, the thickness of the intrinsic mercury sulfide quantum dot layer is greater than the thickness of the p-type mercury sulfide quantum dot layer and the thickness of the n-type mercury sulfide quantum dot layer, while the thickness of the p-type mercury sulfide quantum dot layer can be greater than, less than or equal to the thickness of the n-type mercury sulfide quantum dot layer.

[0067] like Figure 1 As shown, the detector protected by this invention comprises, from bottom to top, a bottom electrode, an n-type mercury sulfide quantum dot layer, an intrinsic mercury sulfide quantum dot layer, and a gold electrode.

[0068] like Figure 2 As shown, the detector protected by this invention comprises, from bottom to top, a bottom electrode, an intrinsic mercury sulfide quantum dot layer, a p-type mercury sulfide quantum dot layer, and a gold electrode.

[0069] like Figure 3 As shown, the detector protected by this invention comprises, from bottom to top, a bottom electrode, an n-type mercury sulfide quantum dot layer, an intrinsic mercury sulfide quantum dot layer, a p-type mercury sulfide quantum dot layer, and a gold electrode.

[0070] like Figure 4 As shown, the detector protected by this invention comprises, from bottom to top, a bottom electrode, a p-type mercury sulfide quantum dot layer, an intrinsic mercury sulfide quantum dot layer, and an aluminum electrode.

[0071] like Figure 5 As shown, the detector protected by this invention comprises, from bottom to top, a bottom electrode, an intrinsic mercury sulfide quantum dot layer, an n-type mercury sulfide quantum dot layer, and an aluminum electrode.

[0072] like Figure 6 As shown, the detector protected by this invention comprises, from bottom to top, a bottom electrode, a p-type mercury sulfide quantum dot layer, an intrinsic mercury sulfide quantum dot layer, an n-type mercury sulfide quantum dot layer, and an aluminum electrode.

[0073] This invention also discloses a method for fabricating a universal short-to-mid-infrared colloidal quantum dot homojunction photovoltaic detector, which includes the following steps:

[0074] 1) Fabricating bottom electrode: it includes fabricating ITO thin film layer on sapphire substrate. The present application preferably evaporates ITO thin film layer with thickness of 50nm on sapphire substrate. The present application chooses ITO because ITO as bottom electrode is because ITO has small resistance, and matches energy band of quantum dots, and has less infrared absorption.

[0075] 2) Preparing intrinsic, n-type and / or p-type chalcogenide colloidal quantum dot ink:

[0076] 2.1) Preparing long-chain strong ligand coated chalcogenide colloidal quantum dot solution: using long-chain strong ligand and adopting hot injection method to synthesize chalcogenide infrared colloidal quantum dot mixture, after solvent cleaning, centrifugal drying treatment to obtain dried chalcogenide infrared quantum dot precipitate; wherein, the long-chain strong ligand can be oleylamine, and can also be other long-chain ligand, the present application preferably is oleylamine, which is beneficial to ensure solution stability, but also brings technical problem of slow quantum dot carrier transfer rate leading to low photoelectric device light response rate. The chalcogenide is any one of mercury sulfide, mercury selenide or mercury telluride, and specific solvent cleaning is to place the mixture in a centrifuge tube, add appropriate amount of isopropanol and mix, after the mixture becomes turbid, place it in a centrifuge for centrifugal separation and precipitation, and the centrifuge speed, centrifugal treatment time and centrifugal treatment times can be discussed according to specific conditions, but all are within the protection scope of the present application, after complete centrifugal separation, discard the upper liquid, nitrogen gun can be used for drying the precipitated solid, or other drying methods can be used, all are within the protection scope of the present application.

[0077] 2.2) Ambient temperature liquid phase miscible ligand exchange: The HgS based IR QDs precipitate prepared in step 1) is dispersed into n-hexane, 2-mercaptoethanol and phase transfer catalyst are added and mixed by shaking, then N,N-dimethylformamide is added and mixed by shaking again to make the HgS based IR QDs completely transfer from n-hexane into N,N-dimethylformamide; after the transfer is completed, the n-hexane is discarded; wherein the volume of 2-mercaptoethanol is 0.2-0.67% of the mass of the QDs solid precipitate after centrifugal drying in step 2.2), and the mass of the phase transfer catalyst is 66.7-120% of the mass of the QDs solid precipitate after centrifugal drying in step 2.2); the phase transfer catalyst is any one of tetrabutylammonium bromide, didodecyl dimethyl ammonium bromide, tetrabutylammonium chloride, tetramethylammonium chloride, tetraethylammonium chloride; and the shaking is preferably ultrasonic shaking treatment, and can also be other mixing treatment modes, and the treatment time is mainly mixing. This step mainly utilizes the high binding energy between Hg-S bonds, uses short chain 2-mercaptoethanol to connect with the Hg element on the surface of each QD, replaces the long oleylamine ligand on the surface of the HgS based QD, and at the same time utilizes the property that the hydroxyl group at the other end of the 2-mercaptoethanol ligand can be stable in a polar solution to transfer each QD from a non-polar oil solution into a polar solution such as n-hexane and stably exist therein. The phase transfer catalyst is beneficial to accelerate the above process.

[0078] 2.3) Surface dipole regulation: adding different amounts of mercury salt into the N,N-dimethylformamide solution of step 2) to prepare intrinsic type, n-type and / or p-type chalcogenide colloidal quantum dot solution, also including adding ammonium sulfide into the N,N-dimethylformamide solution of step 2) to prepare p-type chalcogenide colloidal quantum dot solution; the N,N-dimethylformamide solution of the present application preferably adds mercury salt and / or ammonium sulfide, the amount of mercury salt for preparing intrinsic type chalcogenide colloidal quantum dot is 20% of the amount of mercury salt in step 2.1); the amount of mercury salt for preparing n-type chalcogenide colloidal quantum dot is 40% of the amount of mercury salt in step 2.1); the amount of sulfide for preparing p-type chalcogenide colloidal quantum dot is 10% of the amount of mercury salt in step 2.1); the sulfide is ammonium sulfide, and the mercury salt is any one of mercury chloride, mercury perchlorate and mercury acetate. After mixing, n-hexane is added for extraction, and after extraction is completed, n-hexane is discarded, and toluene is added for further centrifugal precipitation. The use amount of N,N-dimethylformamide, n-hexane and toluene is selected according to the specific circumstances, but any amount is within the protection scope of the present application. After complete centrifugal precipitation, the supernatant is separated, and the remaining solid precipitate is dried. The drying method can use nitrogen gun to dry the precipitated solid, or other drying methods, which are within the protection scope of the present application. This step is to realize different doping of quantum dots, including adding different amounts of mercury salt to improve the enrichment degree of Hg 2+ on the surface of quantum dots, using the generated surface dipole local electric field to stabilize the electrons in the quantum dots, realizing n-type doping of quantum dots. Or adding sulfide, using S 2- to enrich on the surface of quantum dots, generating a surface dipole electric field opposite to Hg 2+ , realizing p-type doping of quantum dots. After cleaning, centrifugal drying treatment of each solution, each quantum dot solid precipitate is prepared and dispersed in N,N-dimethylformamide to prepare intrinsic, p-type and / or n-type chalcogenide colloidal quantum dot ink.

[0079] 3) Preparation of different types of homojunction semiconductor layers:

[0080] Coating the intrinsic chalcogenide colloidal quantum dot ink and / or p-type chalcogenide colloidal quantum dot ink prepared in step 2) on the surface of the bottom electrode of step 1) to form I-P homojunction semiconductor layer and / or P-I homojunction semiconductor layer;

[0081] Coating the intrinsic chalcogenide colloidal quantum dot ink and / or n-type chalcogenide colloidal quantum dot ink prepared in step 2) on the surface of the bottom electrode of step 1) to form I-N homojunction semiconductor layer and / or N-I homojunction semiconductor layer;

[0082] The p-type sulfide colloidal quantum dot ink, the intrinsic sulfide colloidal quantum dot ink, and the n-type sulfide colloidal quantum dot ink prepared in step 2) are coated on the surface of the bottom electrode in step 1) to form a P-I-N homojunction semiconductor layer and / or a N-I-P homojunction semiconductor layer.

[0083] During the coating process, the solid ligand replacement is performed by using a mixed solution of 1,2-dithiol and hydrochloric acid, and after each replacement, isopropanol is used for cleaning until the process is completed.

[0084] Taking the P-I-N homojunction semiconductor layer as an example:

[0085] Firstly, the n-type sulfide colloidal quantum dot ink is spin-coated on the surface of the ITO thin film layer in a nitrogen environment, and the appropriate rotation speed and spin-coating time are controlled; after each layer of spin-coating is completed and is fully infiltrated, the solid ligand replacement is performed by using a mixed solution of 1,2-dithiol and hydrochloric acid, and after each replacement is completed, isopropanol is used for cleaning until the n-type sulfide quantum dot layer with a suitable thickness is prepared.

[0086] The intrinsic sulfide colloidal quantum dot ink is spin-coated on the surface of the n-type sulfide quantum dot layer, and the appropriate rotation speed and spin-coating time are controlled; after each layer of spin-coating is completed and is fully infiltrated, the solid ligand replacement is performed by using a mixed solution of 1,2-dithiol and hydrochloric acid, and after each replacement is completed, isopropanol is used for cleaning until the intrinsic sulfide quantum dot layer with a suitable thickness is prepared.

[0087] The p-type sulfide colloidal quantum dot ink is spin-coated on the surface of the intrinsic sulfide quantum dot layer, and the appropriate rotation speed and spin-coating time are controlled; after each layer of spin-coating is completed and is fully infiltrated, the solid ligand replacement is performed by using a mixed solution of 1,2-dithiol and hydrochloric acid, and after each replacement is completed, isopropanol is used for cleaning until the p-type sulfide quantum dot layer with a suitable thickness is prepared.

[0088] The coating method can be point coating, spin coating, blade coating, spraying, etc., and the application preferably is spin coating, and the solid ligand replacement is performed more than once, and the application preferably uses the mixed solution of 1,2-dithiol and hydrochloric acid to replace the ligand after each layer of spin-coating is completed and is fully infiltrated, and isopropanol is used for cleaning after each replacement is completed; the volume ratio of 1,2-dithiol, hydrochloric acid, and isopropanol is (0.8-1.2):(0.8-1.2):(15-25), and preferably is 1:1:20.

[0089] 4) making top electrode on the surface of homojunction semiconductor layer. In the present application, a top metal electrode of certain thickness is preferably prepared on the surface of homojunction semiconductor layer by evaporation.

[0090] For the above-mentioned P-I-N homojunction detector, P-I homojunction detector and I-N homojunction detector, gold is preferably used as the top electrode because gold can match the energy band of intrinsic type and p-type quantum dots and allow holes to pass through. For the N-I-P homojunction detector, N-I homojunction detector and I-P homojunction detector, aluminum is preferably used as the top electrode because aluminum can match the energy band of intrinsic type and n-type quantum dots.

[0091] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other manners different from those described herein; it is apparent that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments.

[0092] Embodiment 1

[0093] The present embodiment discloses a P-I-N homojunction photovoltaic type mercury telluride infrared detector with the following characteristics: Figure 3 The preparation method of the P-I-N homojunction photovoltaic type mercury telluride infrared detector shown in the figure comprises the following specific preparation steps:

[0094] 1) making bottom electrode; ITO thin film layer with a thickness of 50 nm is evaporated on the sapphire substrate as the bottom electrode.

[0095] 2) preparing intrinsic, n-type and / or p-type mercury telluride colloidal quantum dot ink:

[0096] 2.1) preparing mercury telluride colloidal quantum dots coated with long-chain strong ligands; it comprises the following specific processes:

[0097] 2.1a) preparing heat balance solution: in a nitrogen environment glove box, take 27.2 mg (0.1 mmol) of mercury chloride, add 4 mL of oleylamine, place the mixture on a heating plate, put it into a magnetic stirrer to help accelerate dissolution, adjust the temperature of the heating plate to 100℃, heat at 100℃ for 1h until a transparent, light yellow solution is formed, then cool the solution to 80℃ as the synthesis temperature, and heat balance for about half an hour.

[0098] 2.1b) configuring quenching solution: take 0.5 mL of tri-n-octylphosphine and 4 mL of tetrachloroethylene in a glass bottle, mix well, and then store in a refrigerator;

[0099] 2.1c) preparing mercury telluride tri-n-octylphosphine solution: at room temperature, stir 0.1 mmol of tellurium powder and 0.1 mL of tri-n-octylphosphine in a nitrogen glove box to form a bright yellow solution.

[0100] 2.1d) Preparation of mercury telluride infrared colloidal quantum dot solution: quickly inject the thermal equilibrium solution of step 2.1a) into the solution of step 2.1c), the mixed solution gradually becomes dark and black, and the reaction is ended after a period of time, cool the reaction solution by using the quenching solution of step 2.1b), and take out the reaction solution from the glove box for water bath cooling.

[0101] 2.1e) Transfer the reaction solution cooled to room temperature in step 2.1d) to a centrifuge tube, add an appropriate amount of isopropanol and mix, wherein the amount of isopropanol is flexibly adjusted according to the number of centrifugation and the effect of centrifugation, place the mixed solution into a centrifuge for centrifugal separation and precipitation, control the centrifuge speed to be 7500 r / min, centrifugal treatment for 5-10 min, discard the supernatant, and dry the solid precipitate by using a nitrogen gun, and the drying time is determined according to the actual processing condition.

[0102] 2.2) Liquid phase mixed ligand exchange at room temperature: re-disperse the above dried mercury telluride quantum dot solid precipitate into 6 mL of n-hexane, add 50 uL of 2-mercaptoethanol and 15 mg of tetrabutylammonium bromide, and then ultrasonically shake for 1 min to make the mercury telluride quantum dot solid completely dissolved; then add 2.5 mL of N,N-dimethylformamide and continue to ultrasonically shake for 1 min, mix to make the mercury telluride infrared colloidal quantum dots completely transferred from n-hexane to N,N-dimethylformamide; and then discard the n-hexane after complete transfer.

[0103] 2.3) Surface dipole control:

[0104] For the N,N-dimethylformamide solution of the above mercury telluride infrared colloidal quantum dots, different types of materials are prepared by the following process:

[0105] 2.3a) Preparation of intrinsic mercury telluride infrared colloidal quantum dots:

[0106] Dissolve 5 mg of mercury chloride in 0.5 mL of N,N-dimethylformamide, add the solution of step 2) after mixing, ultrasonically treat for about 1 min, then add 6 mL of n-hexane for cleaning, which can be cleaned by mixing thoroughly, and the number of extraction times can be selected according to the actual situation, one time, two times or more, and the upper n-hexane is discarded during each cleaning and extraction process, after cleaning, add 10 mL of toluene, and perform centrifugal separation treatment, control the centrifuge speed to be 7500 r / min, centrifugal treatment for 5-10 min, discard the supernatant, and dry the solid precipitate by using a nitrogen gun, and the drying time is determined according to the actual processing condition.

[0107] 2.3b) Preparation of n-type mercury telluride infrared colloidal quantum dots:

[0108] Take 20 mg of mercury chloride dissolved in 0.5 mL of N, N- dimethylformamide, after mixing, add the solution of step 2) above, ultrasonic treatment for about 1 minute, then add 6 mL of n-hexane for cleaning, which can be used by mixing the extraction method, extraction times can be selected according to the actual situation once, also can choose two times or more, each cleaning extraction process is discarded the upper n-hexane, after cleaning, add 10 mL of toluene, centrifugal separation treatment, control centrifuge speed is 7500 r / min, centrifugal treatment 5-10 min, discard the supernatant, the solid precipitate is dried by nitrogen gun, the drying time is determined according to the actual processing situation.

[0109] 2.3c) Preparation of p-type mercury telluride infrared colloidal quantum dots:

[0110] Take 5 mg of ammonium sulfide dissolved in 0.5 mL of N, N- dimethylformamide, after mixing, add the solution of step 2) above, ultrasonic treatment for about 1 minute, then add 6 mL of n-hexane for cleaning, which can be used by mixing the extraction method, extraction times can be selected according to the actual situation once, also can choose two times or more, each cleaning extraction process is discarded the upper n-hexane, after cleaning, add 10 mL of toluene, centrifugal separation treatment, control centrifuge speed is 7500 r / min, centrifugal treatment 5-10 min, discard the supernatant, the solid precipitate is dried by nitrogen gun, the drying time is determined according to the actual processing situation.

[0111] Take the intrinsic mercury telluride infrared colloidal quantum dots, n-type mercury telluride infrared colloidal quantum dots and p-type mercury telluride infrared colloidal quantum dots prepared in the above steps, respectively, and disperse them in 100 uL of N, N-dimethylformamide to obtain stable quantum dot ink.

[0112] 3) Preparation of P-I-N homojunction semiconductor layer:

[0113] First, take 20 uL of n-type mercury telluride colloidal quantum dot ink in a nitrogen environment and spin it on the surface of the ITO thin film layer, control the speed at 3000 rpm, spin for 1 minute, and after each layer is completed and fully infiltrated, use a mixture of 1, 2-dithiol + hydrochloric acid for solid ligand replacement, and then use isopropanol for cleaning after each replacement, until the n-type mercury telluride electron transport layer of 50 nm is prepared; wherein the volume ratio of 1, 2-dithiol, hydrochloric acid and isopropanol is preferably 1:1:20.

[0114] Take 20 uL of intrinsic mercury telluride colloidal quantum dot ink on the surface of the n-type mercury telluride electron transport layer spin coating, similarly, control the rotating speed of 3000 rpm, spin coating 1 minute, after each layer of spin coating and fully infiltrated, using 1,2-dithiol + hydrochloric acid mixed solution for solid ligand replacement, after each replacement, isopropanol is used for cleaning, until the preparation of 400 nm of intrinsic mercury telluride quantum dot layer; wherein, the volume ratio between 1,2-dithiol, hydrochloric acid and isopropanol is preferably 1:1:20.

[0115] Take 20 uL of p-type mercury telluride colloidal quantum dot ink on the surface of the above intrinsic mercury telluride quantum dot layer spin coating, similarly, control the rotating speed of 3000 rpm, spin coating 1 minute, after each layer of spin coating and fully infiltrated, using 1,2-dithiol + hydrochloric acid mixed solution for solid ligand replacement, after each replacement, isopropanol is used for cleaning, until the preparation of 100 nm of p-type mercury telluride quantum dot layer. Wherein, the volume ratio between 1,2-dithiol, hydrochloric acid and isopropanol is preferably 1:1:20.

[0116] 4) Fabricate the top electrode on the surface of the homojunction semiconductor layer: use the evaporation method of the coating machine to fabricate 30 nm thick metal gold as the top electrode on the surface of the above p-type mercury telluride colloidal hole transport layer.

[0117] Example 2

[0118] The embodiment discloses a preparation method of the N-I-P homojunction photovoltaic type mercury telluride infrared detector. Figure 6 The preparation method of the N-I-P homojunction photovoltaic type mercury telluride infrared detector is different from that in the above embodiment 1.

[0119] 3) Preparation of N-I-P homojunction semiconductor layer:

[0120] First, take 20 uL of p-type mercury telluride colloidal quantum dot ink and spin it on the surface of the ITO thin film layer in a nitrogen environment, control the rotating speed of 3000 rpm, spin coating 1 minute, after each layer of spin coating and fully infiltrated, using 1,2-dithiol + hydrochloric acid mixed solution for solid ligand replacement, after each replacement, isopropanol is used for cleaning, until the preparation of 50 nm of p-type mercury telluride quantum dot layer; wherein, the volume ratio between 1,2-dithiol, hydrochloric acid and isopropanol is preferably 1:1:20.

[0121] Take 20 uL of intrinsic mercury telluride colloidal quantum dot ink on the surface of the p-type mercury telluride quantum dot layer spin coating, similarly, control the rotating speed of 3000 rpm, spin coating 1 minute, after each layer of spin coating and fully infiltrated, using 1,2-dithiol + hydrochloric acid mixed solution for solid ligand replacement, after each replacement, isopropanol is used for cleaning, until the preparation of 400 nm of intrinsic mercury telluride quantum dot layer; wherein, the volume ratio between 1,2-dithiol, hydrochloric acid and isopropanol is preferably 1:1:20.

[0122] Take 20uL n-type mercury telluride colloidal quantum dot ink on the surface of the above intrinsic mercury telluride quantum dot layer spin coating, similarly, control the rotating speed to be 3000rpm, spin coating for 1 minute, after each layer of spin coating is completed and is fully infiltrated, solid ligand replacement is carried out by using a mixed solution of 1,2-dithiol + hydrochloric acid, after each replacement is completed, isopropanol is used for cleaning, until the n-type mercury telluride electron transport layer of 100nm is prepared. The volume ratio among 1,2-dithiol, hydrochloric acid and isopropanol is preferably 1:1:20.

[0123] 4) Top electrode is made on the surface of the homojunction semiconductor layer: 50nm thick metal aluminum is made on the surface of the above n-type mercury telluride electron transport layer as a top electrode by using a plating film machine evaporation method.

[0124] In addition, the present application also discloses a detector with the structure shown in Figure 1 , Figure 2 , Figure 4 and Figure 5 . The difference may be that the preparation sequence and thickness of each semiconductor layer are different, and the others remain the same, and the present application will not be described in detail, and at the same time, the present application takes mercury telluride material as an example, and other sulfur mercury group materials are also within the protection scope of the present application, and the present application will not be described in detail.

[0125] The present application respectively measures the quantum carrier mobility of the n-type mercury telluride quantum dot layer, the intrinsic mercury telluride quantum dot layer and the p-type mercury telluride quantum dot layer prepared in the embodiment 1 at different temperatures, and the specific values are shown in Figure 7 , and it can be known from Figure 7 that the mobility of the quantum dot film of each type can reach 1cm 2 / Vs above at 100-300K.

[0126] The present application also constructs a field effect tube to measure the above semiconductor layer, and the obtained results are shown in Figure 8 , and it can be known from Figure 8 that the embodiment further verifies that the intrinsic semiconductor material film, the n-type doped semiconductor material film and the p-type doped semiconductor film are prepared.

[0127] In addition, the present application tests the spectral response capability of the detector prepared in the embodiment 1, and the detector is irradiated by a medium wave and a short wave respectively, and the obtained response results are shown in Figure 9 , Figure 10 , and it can be known from Figure 9 that the detector designed in the present application has better response capability to a short infrared wave at 80-300K, and the responsivity can reach 1.2-1.9A / W, and it can be known from Figure 10It can be known that the designed detector has better response capability to middle infrared waves at 80-300K, and the responsivity can reach 0.4-1.6A / W, which is greatly improved compared with the responsivity of 0.3A / W of a short-wave infrared heterojunction photovoltaic device and 0.15A / W of a middle-wave infrared heterojunction photovoltaic device.

[0128] The external quantum efficiency of the homojunction photovoltaic infrared detector is further detected, Figure 16 、 Figure 17 、 Figure 18 and Figure 19 , wherein the external quantum efficiency of the detector to short waves reaches 94%, and the external quantum efficiency of the detector to middle waves reaches more than 65%. Meanwhile, the specific detectivity of the designed homojunction photovoltaic infrared detector to middle infrared waves can reach 10 9 Jones at room temperature. 11 Jones. 10 Jones at 250K. 12 Jones.

[0129] The energy band of the I-P type homojunction detector is further explored, and the specific structure is shown in Figure 13 , and it can be known from Figure 12 and 13 that the energy band of the I type and the P type homojunction is not curved, and the carrier cannot appear transport mismatch between the homojunctions of the I type and the P type, which avoids the loss caused by the mismatch of the energy band and the mobility at the heterojunction interface, improves the trapping efficiency of the photo-generated carrier, and improves the quantum efficiency of the device.

[0130] The energy band of the N-I type homojunction detector is further explored, and the specific structure is shown in Figure 14 , and it can be known from Figure 12 and Figure 14 that the energy band of the N type and the I type homojunction is not curved, and the carrier cannot appear transport mismatch between the homojunctions of the N type and the I type, which avoids the loss caused by the mismatch of the energy band and the mobility at the heterojunction interface, improves the trapping efficiency of the photo-generated carrier, and improves the quantum efficiency of the device.

[0131] The energy band of the N-I-P type homojunction detector is further explored, and the specific structure is shown in Figure 12 and Figure 15It can be known that the two homojunction energy bands of N type, I type and P type are not bent, and the carrier will not appear transport mismatch between the homojunctions of N type, I type and P type, the loss caused by the mismatch of the energy band and the mobility of the carrier at the heterojunction interface is avoided, the trapping efficiency of the photo-generated carrier is improved, and the quantum efficiency of the device is improved.

[0132] In conclusion, the homojunction photovoltaic infrared detector designed in the application not only has good response rate, high specific detectivity and high external quantum efficiency to short and medium infrared waves at room temperature, but also has a relatively wide detection temperature.

[0133] It should be noted that in this document, the terms "comprising", "including", or any other variant thereof are intended to cover non-exclusive inclusions, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or inherent to such a process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article or device including the element.

[0134] The above is only a specific embodiment of the application, which enables those skilled in the art to understand or implement the application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the application. Therefore, the application will not be limited to these embodiments described herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for fabricating a universal short-to-mid-infrared colloidal quantum dot homojunction photovoltaic detector, characterized in that, It includes the following steps: 1) Fabricate the bottom electrode; 2) Preparation of intrinsic, n-type and / or p-type mercury thiosulfate colloidal quantum dot inks: 2.1) Preparation of long-chain strong ligand-coated thiomercurate colloidal quantum dot solution: Long-chain strong ligands, mercury salts, and sulfide precursors were synthesized into long-chain strong ligand-coated thiomercurate colloidal quantum dot solution by hot injection method. 2.2) Room temperature liquid phase miscible ligand exchange: Take the solution from step 2.1), wash, centrifuge and dry it, disperse it in n-hexane, add 2-mercaptoethanol and phase transfer catalyst and mix well, continue to add N,N-dimethylformamide to transfer the thiomercurate infrared colloidal quantum dots to N,N-dimethylformamide, and then discard the n-hexane. 2.3) Surface Dipole Control: Different amounts of mercury salts are added to the N,N-dimethylformamide solution in step 2.2) to prepare intrinsic thiomercury group infrared colloidal quantum dot solutions and / or n-type thiomercury group infrared colloidal quantum dot solutions. The method also includes adding sulfides to the N,N-dimethylformamide solution in step 2) to prepare p-type thiomercury group infrared colloidal quantum dot solutions. After washing, centrifugation, and drying, each solution yields a solid precipitate of quantum dots, which is then dispersed in N,N-dimethylformamide to prepare intrinsic, p-type, and / or n-type thiomercury group colloidal quantum dot inks. 3) Fabrication of different types of homojunction semiconductor layers: The intrinsic mercury thiocyanate colloidal quantum dot ink and p-type mercury thiocyanate colloidal quantum dot ink prepared in step 2) are coated on the bottom electrode surface in step 1) to form an IP homojunction semiconductor layer and / or a PI homojunction semiconductor layer. The intrinsic mercury thiocyanate colloidal quantum dot ink and n-type mercury thiocyanate colloidal quantum dot ink prepared in step 2) are coated on the bottom electrode surface in step 1) to form an IN homojunction semiconductor layer and / or an NI homojunction semiconductor layer. In step 1), the p-type mercury thiocyanate colloidal quantum dot ink, intrinsic mercury thiocyanate colloidal quantum dot ink, and n-type mercury thiocyanate colloidal quantum dot ink prepared in step 2) are coated on the bottom electrode surface to form a PIN homojunction semiconductor layer and / or a NIP homojunction semiconductor layer. During the coating process, a mixture of 1,2-dithiol and hydrochloric acid was used for solid ligand replacement. After each replacement, isopropanol was used for cleaning until the process was completed. 4) Fabricate a top electrode on the surface of a homojunction semiconductor layer.

2. The method for fabricating a universal short-to-mid-infrared colloidal quantum dot homojunction photovoltaic detector according to claim 1, characterized in that, In step 3), the volume ratio of 1,2-dithiol, hydrochloric acid, and isopropanol is (0.8~1.2):(0.8~1.2):(15~25).

3. The method for fabricating a universal short-to-mid-infrared colloidal quantum dot homojunction photovoltaic detector according to claim 1 or 2, characterized in that, In step 2.2), the volume of 2-mercaptoethanol is 0.2-0.67% of the mass of the quantum dot solid precipitate after centrifugation and drying in step 2.2), and the mass of the phase transfer catalyst is 66.7-120% of the mass of the quantum dot solid precipitate after centrifugation and drying in step 2.2); the phase transfer catalyst is any one of tetrabutylammonium bromide, didodecyldimethylammonium bromide, tetrabutylammonium chloride, tetramethylammonium chloride, and tetraethylammonium chloride.

4. The method for fabricating a universal short-to-mid-infrared colloidal quantum dot homojunction photovoltaic detector according to claim 1 or 2, characterized in that, In step 2.3), the amount of mercury salt used to prepare intrinsic mercury-sulfur infrared colloidal quantum dots is 20% of the amount of mercury salt used in step 2.1); the amount of mercury salt used to prepare n-type mercury-sulfur infrared colloidal quantum dots is 40% of the amount of mercury salt used in step 2.1); and the amount of sulfide used to prepare p-type mercury-sulfur infrared colloidal quantum dots is 10% of the amount of mercury salt used in step 2.1). The mercury salt is any one of mercuric chloride, mercuric perchlorate, and mercuric acetate; the sulfide is ammonium sulfide; and the mercuric sulfide group includes any one of mercuric sulfide, mercuric selenide, and mercuric telluride.

5. A universal short-to-mid-infrared colloidal quantum dot homojunction photovoltaic detector prepared by the preparation method described in claim 1, characterized in that, The detector includes a bottom electrode, a top electrode, and an intrinsic mercury sulfide quantum dot layer, and further includes a p-type mercury sulfide quantum dot layer and / or an n-type mercury sulfide quantum dot layer; wherein, the intrinsic mercury sulfide quantum dot layer and the p-type mercury sulfide quantum dot layer form an IP or PI homojunction; the intrinsic mercury sulfide quantum dot layer and the n-type mercury sulfide quantum dot layer form an IN or NI homojunction; the p-type mercury sulfide quantum dot layer, the intrinsic mercury sulfide quantum dot layer, and the n-type mercury sulfide quantum dot layer form a PIN or NIP homojunction; The n-type mercury thiocyanate quantum dot layer is made of mercury salt-doped mercury thiocyanate semiconductor material, and the p-type mercury thiocyanate quantum dot layer is made of sulfide-doped mercury thiocyanate semiconductor material.

6. The universal short-to-mid-infrared colloidal quantum dot homojunction photovoltaic detector according to claim 5, characterized in that, The mercury sulfide semiconductor material is made of any one of mercury sulfide, mercury selenide, or mercury telluride, the mercury salt is any one of mercuric chloride, mercuric perchlorate, or mercuric acetate, and the sulfide is ammonium sulfide.

7. The universal short-to-mid-infrared colloidal quantum dot homojunction photovoltaic detector according to claim 5 or 6, characterized in that, The bottom electrode is made of ITO laminated on a sapphire substrate, and the top electrode is made of a metallic conductive material.

8. The universal short-to-mid-infrared colloidal quantum dot homojunction photovoltaic detector according to claim 5 or 6, characterized in that, The thickness of the intrinsic mercury sulfide quantum dot layer is greater than that of the p-type mercury sulfide quantum dot layer and the n-type mercury sulfide quantum dot layer.

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