Infrared light sensor

Abstract

The invention relates to an infrared light sensor which comprises a substrate, and a first electrode, a light sensing unit and a second electrode which are sequentially formed from the surface of the substrate, and the substrate and the first electrode have infrared light penetrability. The light sensing unit is arranged on the surface, opposite to the substrate, of the first electrode, is used for absorbing and sensing infrared light, and is provided with a zinc oxide-based (ZnO-based) layer, a first lead sulfide-based (PbS-based) modified layer and a second lead sulfide-based (PbS-based) modified layer which are sequentially far away from the substrate from the surface of the first electrode, the first lead sulfide-based modified layer comprises a plurality of halogen ion modified lead sulfide nanoparticles, and the second lead sulfide-based modified layer comprises thiol molecule modified lead sulfide.

Description

Technical Field

[0001] The present invention relates to a sensor, in particular to an infrared light sensor. Background Art

[0002] Traditional image sensors primarily use silicon as a sensing material. However, silicon has insufficient light conversion efficiency for long wavelengths (>1100nm) and limited weak light sensing capabilities. Therefore, sensing devices using lead sulfide quantum dots (PbS-QDs) as long-wavelength light sensing materials have been developed to improve these issues. While PbS quantum dots (QDs) offer improved light conversion efficiency and good light sensing responsivity (R) at long wavelengths, typical photosensitive devices utilize a planar thin film transistor (TFT) structure with a large horizontal distance between electrodes. This results in higher drive voltages and slower response times, limiting the applicability of PbS-QDs in the field of light sensing.

[0003] To address the aforementioned shortcomings of planar photosensitive element structures, vertical photosensitive element structures have been developed to address these issues. However, the application of PbS-QD photosensitive elements remains limited due to the large number of trap states generated on the surface of PbS-QDs and at the carrier transfer interface between different materials in the photosensitive element. This affects the overall conductivity of the element, thus limiting their application. Summary of the Invention

[0004] The present invention aims to provide a lead sulfide (PbS)-based infrared light sensor having good electrical conductivity and photosensitivity (R).

[0005] The infrared light sensor of the present invention includes a substrate, a first electrode, a light sensing unit, and a second electrode.

[0006] The substrate is infrared light transparent.

[0007] The first electrode is disposed on one surface of the substrate and has infrared light transmittance.

[0008] The light sensing unit is disposed on a surface of the substrate opposite to the first electrode for absorbing and sensing infrared light. The light sensing unit comprises a zinc oxide (ZnO)-based layer, a first lead sulfide (PbS)-based modified layer, and a second lead sulfide (PbS)-based modified layer, which are sequentially located away from the substrate from the surface of the first electrode. The first lead sulfide-based modified layer comprises lead sulfide modified with halogen ions, and the second lead sulfide-based modified layer comprises lead sulfide modified with thiol molecules.

[0009] The second electrode is located on a surface of the substrate opposite to the light sensing unit, and the second electrode can cooperate with the light sensing unit and the first electrode to form a current channel.

[0010] The beneficial effects of the present invention lie in: utilizing the structural design of the light sensing unit, zinc oxide serves as a buffer layer between the first electrode and the first lead sulfide-based modified layer modified with halogen ions, thereby increasing compatibility with the zinc oxide-based layer and improving electron transfer efficiency. Furthermore, a second lead sulfide-based modified layer modified with thiol molecules, interposed between the first lead sulfide-based modified layer and the second electrode, increases the surface flatness of the light sensing unit and serves as a transition layer between the light sensing unit and the second electrode, thereby effectively enhancing the carrier transfer efficiency of the infrared light sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic diagram illustrating an embodiment of an infrared light sensor of the present invention;

[0012] Figure 2 is a schematic diagram illustrating another structural aspect of the electrode unit of this embodiment of the present invention;

[0013] Figure 3 is a current-voltage graph illustrating the electrical property measurement results of the sensing component at different ethanolamine contents;

[0014] Figure 4 SEM and current-voltage images illustrate the SEM cross-sectional structures of sensing elements using ZnO and EA-ZnO as electron transport layers, as well as electrical property measurement results of the sensing elements;

[0015] Figure 5 is a SEM image illustrating the surface morphology of PbS-I, PbS-EDT, and PbS-I / PbS-EDT films;

[0016] Figure 6 、 7 is a current-voltage graph illustrating electrical property measurement results of the infrared light sensor of the specific example of the present invention and Comparative Example 2;

[0017] Figure 8 、 9is a current-voltage graph illustrating electrical property measurement results of the infrared light sensor of the embodiment of the present invention and Comparative Example 1 at different irradiation powers;

[0018] Figure 10 、 11 is a current-voltage diagram illustrating the infrared light sensor of the specific example of the present invention and the comparative example 1 at a specific irradiation power (Pout = 310 μW / cm 2 )'s electrical measurement results. DETAILED DESCRIPTION

[0019] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. Before the present invention is described in detail, it should be noted that similar components are represented by the same numbers in the following description.

[0020] See Figure 1 An embodiment of the infrared light sensor of the present invention includes a substrate 2 , a first electrode 3 , a light sensing unit 4 , and a second electrode 5 .

[0021] The substrate 2 is infrared-transmissive and can be made of glass, sapphire, polyethylene terephthalate, or polyimide.

[0022] The first electrode 3 is disposed on a surface of the substrate 2 and is primarily composed of a transparent conductive oxide that is transparent to infrared light. The transparent conductive oxide can be selected from conductive metal oxides such as indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO), or antimony tin oxide (ATO). Furthermore, the transparent conductive oxide may include conductive dopants such as carbon nanotubes and silver nanowires.

[0023] The light sensing unit 4 is disposed on the surface of the first electrode 3 opposite the substrate 2 and is configured to absorb and sense infrared light. The light sensing unit 4 comprises a zinc oxide (ZnO)-based layer 41, a first lead sulfide (PbS)-based modified layer 42, and a second lead sulfide (PbS)-based modified layer 43, arranged sequentially from the surface of the first electrode 3 away from the substrate 2. The ZnO-based layer 41, the first lead sulfide-based modified layer 42, and the second lead sulfide-based modified layer 43 each comprise at least one quantum dot self-assembled film composed of a plurality of nanoparticles.

[0024] Preferably, the nanoparticles are assembled and arranged in a closest packing manner, and the particle size of the nanoparticles is between 1 and 30 nm.

[0025] In some embodiments, the thickness of the light sensing unit 4 is between 50 nm and 500 nm, and the thickness of the first lead sulfide-based modified layer 42 is greater than the thickness of the second lead sulfide-based modified layer 43 .

[0026] Specifically, the constituent material of the zinc oxide base layer 41 includes multiple amine-modified zinc oxide nanoparticles modified by amine molecules and zinc oxide nanoparticles. The amine-modified zinc oxide nanoparticles are obtained by reacting zinc oxide nanoparticles with amine molecules. The particle sizes of the zinc oxide nanoparticles and the amine-modified zinc oxide nanoparticles are between 1 and 30 nm. The zinc oxide base layer 41 has at least one quantum dot self-assembled film assembled by the zinc oxide nanoparticles and the amine-modified zinc oxide nanoparticles in a closest-packed manner, and the average surface roughness (Rq) of the zinc oxide base layer 41 is not greater than 1.5 nm.

[0027] In some embodiments, the thickness of the zinc oxide base layer 41 is between 1 and 30 nm.

[0028] Preferably, the amine molecule of the amine-modified zinc oxide is a primary amine with a single substituent, and the substituent is a straight-chain alkyl group with a carbon number not greater than 8. By controlling the carbon chain length of the substituent of the amine molecule, in addition to being used to modify the surface properties of zinc oxide, it can also minimize the change in the conductivity of the zinc oxide nanoparticles after amine molecule modification, and thus maintain the conductivity of the zinc oxide base layer 41.

[0029] In some embodiments, the amine molecule can be selected from ethanolamine (EA), ethylenediamine (EDA), n-butylamine, polyethyleneimine (PEI), and a combination of any of the foregoing.

[0030] The constituent material of the first lead sulfide-based modified layer 42 includes lead sulfide nanoparticles and halogen-modified lead sulfide nanoparticles (PbS x X 1-x , where X is a halogen ion and 0 < X < 1). The halogen-modified lead sulfide nanoparticles are obtained by reacting lead sulfide nanoparticles with lead halide (PbX2). And the first lead sulfide-based modified layer 42 has at least one quantum dot self-assembled film assembled by the lead sulfide nanoparticles and / or the halogen-modified lead sulfide nanoparticles in a closest-packed manner.

[0031] Preferably, the particle sizes of the lead sulfide nanoparticles and the halogen-modified lead sulfide nanoparticles are between 1 and 30 nm. [[ID=​​​​​​1-x , where M is a thiol ion and 0 < M < 1). The thiol-modified lead sulfide nanoparticles are obtained by reacting lead sulfide nanoparticles with thiol molecules. The second lead sulfide-based modified layer 43 has at least one quantum dot self-assembled film formed by assembling the lead sulfide nanoparticles and / or the thiol-modified lead sulfide nanoparticles in a close-packed manner.

[0034] Preferably, the thiol molecule is selected from 1,2-ethanedithiol (EDT).

[0035] Specifically, for the preparation of the optoelectronic sensing layer 4, a zinc oxide mixture solution containing a solvent, zinc oxide nanoparticles, and an amino molecule is first coated on the first electrode 3 by spin coating or spray coating, and then the solvent is removed to obtain the zinc oxide base layer 41. The amino molecule is used for surface modification of the zinc oxide nanoparticles. The particle size of the zinc oxide nanoparticles ranges from 5 to 10 nm, and the weight percentage of the zinc oxide nanoparticles in the zinc oxide mixture solution is 1 to 10 wt%.

[0036] Preferably, the particle size of the zinc oxide nanoparticles ranges from 5 to 8 nm, and the weight percentage of the zinc oxide nanoparticles in the zinc oxide mixture solution is 3 to 6 wt%.

[0037] Next, a first lead sulfide mixed solution containing a solvent, lead sulfide nanoparticles, and lead halide (supersaturated concentration) for surface modification of the lead sulfide nanoparticles is coated on the zinc oxide base layer 41 by spin coating or spray coating, and then the solvent is removed to obtain the first lead sulfide-based modified layer 42. Finally, a second lead sulfide mixed solution containing a solvent, lead sulfide nanoparticles, and a thiol compound for surface modification of the lead sulfide nanoparticles is coated on the first lead sulfide-based modified layer 42 by spin coating or spray coating, etc., and then the solvent is removed to stack on the first lead sulfide-based modified layer 42 to form the second lead sulfide-based modified layer 43, and thus the optoelectronic sensing layer 4 can be obtained.

[0038] As mentioned above, when at least one of the zinc oxide base layer 41, the first lead sulfide-based modified layer 42, and the second lead sulfide-based modified layer 43 is to have a multi-layer nanoparticle self-assembled film, the desired number of layers of nanoparticle self-assembled film can be obtained by repeating the spray coating / spin coating and drying steps.

[0039] The solvent of the zinc oxide mixture is selected from water, methanol, ethanol, isopropanol, and at least one combination thereof. The volume content of the amino molecules in the zinc oxide mixture is between 0.01 and 1 vol%. Preferably, the volume content of the amino molecules in the zinc oxide mixture is between 0.05 and 0.5 vol%. Furthermore, to prevent excessive amino content in the zinc oxide mixture from forming excessive amino-modified zinc oxide nanoparticles and affecting the flatness and planarity of the zinc oxide base layer 41 after film formation, the volume content of the amino molecules in the zinc oxide mixture is more preferably between 0.05 and 0.2 vol%. Even more preferably, the volume content of the amino molecules in the zinc oxide mixture is between 0.05 and 0.1 vol%.

[0040] The solvent of the first lead disulfide mixed solution can be selected from toluene, dimethylformamide (DMF), or acetonitrile (ACN), and the particle size of the lead sulfide nanoparticles is between 3 and 10 nm. The content of the lead sulfide nanoparticles in the first lead disulfide mixed solution is between 4 and 10 wt %.

[0041] The second electrode 5 is disposed on a surface of the substrate 2 opposite to the light sensing unit 4 , and can form a current channel through the light sensing unit 4 in cooperation with the first electrode 3 .

[0042] Specifically, the second electrode 5 can be formed on the surface of the light sensing unit 4 by evaporation or coating, and has a first metal film 51 that is in direct contact with the surface of the light sensing unit 4 and can form an ohmic contact with the light sensing unit 4, thereby having a better electron conduction effect, and a second metal film 52 formed on the surface of the light sensing unit 4 opposite to the first metal film 51 and having better conductivity and / or not easy to oxidize and can protect the first metal film 51. The second metal film 52 can be formed on the entire surface of the first metal film 51, or formed on a portion of the surface of the first metal film 51. For example, the second metal film 52 can be formed on a portion of the surface of the first metal film 51, so as to form a Figure 1 Forked as shown, or as Figure 2 The grid arrangement shown is not particularly limited. In this embodiment, the first and second metal films 51 and 52 are formed of molybdenum oxide (MoO3) and aluminum (Al), respectively, and the second metal film 52 is formed on a portion of the surface of the first metal film 51 by evaporation.

[0043] See Figure 3 , Figure 3(a) is the electrical property measurement result of the sensing component (component structure: substrate / ITO / EA-ZnO / Al, wherein EA vol%: 0 to 0.2v%) containing zinc oxide modified layer (EA-ZnO) with different volume concentrations of ethanolamine-modified zinc oxide nanoparticles. Figure 3 (b) is Figure 3 A partial enlarged view of (a).

[0044] Depend on Figure 3 It can be seen that adding ethanolamine to modify zinc oxide nanoparticles can passivate the surface defects of zinc oxide nanoparticles and reduce the surface roughness of the zinc oxide modified layer, thereby improving carrier mobility and obtaining a higher current density. When the content of ethanolamine used for modification is 0.1 vol%, the device can show the highest carrier mobility, and the current density is 0.1 vol%. Figure 3 It can also be seen that when the ethanolamine addition exceeds 1.0 vol%, carrier mobility decreases, leading to a decrease in the device's current density. This is presumably due to a decrease in film flatness. This confirms that surface modification of zinc oxide nanoparticles with an appropriate amount of amine molecules can indeed improve device carrier mobility.

[0045] See also Figure 4 , Figure 4 The electrical properties of the sensing devices (represented by ZnO device and EA-ZnO device, respectively) were measured using halogen-modified lead sulfide (PbS-X) as the light sensing unit and unmodified zinc oxide (ZnO) and ethanolamine-modified zinc oxide (EA-ZnO) as the electron transport layer. Figure 4 (a) is the SEM cross-sectional structure of the component. Figure 4 (b) is the dark current of the component (I d ) and photocurrent (I p ) current density measurement results, Figure 4 (c) and (d) are the calculation results of the component's responsiveness (R) and detectivity (D), respectively.

[0046] Figure 4 In the equation, the responsivity (R) is calculated using the following formula:

[0047] R λ =I ph / P out

[0048] Sensitivity (D) is calculated using the following formula:

[0049]

[0050] Among them, S is the sensing area, q is the charge Figure 4 The results show that using an ethanolamine-modified zinc oxide layer (EA-ZnO) as an electron transport layer can passivate surface defects and inhibit carrier recombination, thereby increasing electron mobility and significantly improving the photocurrent of the device, so the response of the device can also be effectively improved. Figure 4 As shown in (c) and (d), the photocurrent of the EA-ZnO device increases significantly under high bias voltage (-4V to -6V), and it can show better responsivity and detectivity.

[0051] See also Figure 5 , Figure 5 (a) is a SEM photograph of a first lead sulfide-based modified layer (expressed as PbS-I) containing iodide-modified lead sulfide nanoparticles coated on a glass substrate. Figure 5 (b) is a SEM photograph of a second lead sulfide-based modified layer (denoted as PbS-EDT) formed on the surface of a glass substrate by coating a layer of 1,2-ethanedithiol (EDT)-modified lead sulfide nanoparticles, and Figure 5 (c) is a SEM photograph of the PbS-I and the PbS-EDT formed by sequentially coating on the surface of a glass substrate.

[0052] Depend on Figure 5 As shown in (a), the surface flatness of the PbS-I layer is poor, while the PbS-EDT layer containing thiol (EDT)-modified lead sulfide nanoparticles has better surface flatness. Therefore, by utilizing the stacked structure of the PbS-EDT layer and the PbS-I layer, the surface roughness of the PbS-I layer (the first lead sulfide-based modified layer) can be significantly reduced by the PbS-EDT layer (the second lead sulfide-based modified layer), thereby flattening the contact interface between the light sensing unit 4 and the second electrode 5, thereby achieving a better charge transfer effect.

[0053] Next, the electrical properties of the infrared light sensors produced in the following specific examples and comparative examples 1 to 3 are described.

[0054] The solutions used in this specific example and comparative examples 1 to 3 are described as follows:

[0055] Zinc oxide solution: solvent (isopropyl alcohol), zinc oxide nanoparticles (particle size: 5.8 nm, 4 wt %).

[0056] Zinc oxide modified solution: solvent (isopropyl alcohol), zinc oxide nanoparticles (particle size: 5.8 nm), ethanolamine (EA, 0.1 vol%).

[0057] Lead sulfide solution: solvent (DMF), lead sulfide nanoparticles (particle size: 3.4 nm, 5 wt%).

[0058] The first lead sulfide modification solution: solvent (DMF), lead sulfide nanoparticles (particle size: 3.4 nm), PbI2 (9 wt%).

[0059] The second lead sulfide modification solution: solvent (ACN), lead sulfide nanoparticles (particle size: 3.4 nm), and 1,2-ethanedithiol (EDT) (0.02 vol%).

[0060] Specific example

[0061] First, a zinc oxide solution was spin-coated onto a glass substrate with an ITO layer on the surface of the ITO layer to form a zinc oxide self-assembled coating. The solvent was then removed and dried at 150°C to obtain a 25nm thick zinc oxide-based layer, represented by ZnO-EA.

[0062] Next, the first lead sulfide-modified solution was applied to the surface of the zinc oxide substrate by spin coating to form a lead sulfide self-assembled coating. The solvent was then removed and dried at 60°C, resulting in a 200nm thick first lead sulfide-based modified layer, designated PbS-I.

[0063] The second lead sulfide modified solution was then applied to the surface of the first lead sulfide-based modified layer by spin coating to form a lead sulfide self-assembled coating. The solvent was then removed and dried at 60°C, resulting in a 144nm thick second lead sulfide-based modified layer, designated PbS-EDT.

[0064] Finally, a first metal layer composed of molybdenum oxide (MoO3) is formed on the surface of the second lead sulfide-based modified layer by vapor deposition, and a second metal layer composed of aluminum (Al) is formed on a portion of the surface of the first metal layer, completing the preparation of the infrared light sensor of this specific example.

[0065] The infrared light sensor structure of this specific example is:

[0066] Glass substrate / ITO / ZnO-EA / PbS-I / PbS-EDT / MoO3 / Al

[0067] Comparative Example 1

[0068] The preparation method of each film layer of the comparative example 1 is substantially the same as that of the specific example 1, except that the first and lead disulfide modified solutions are simultaneously replaced by lead sulfide solution, and only the lead sulfide layer (PbS) is formed.

[0069] The infrared light sensor structure of Comparative Example 1 is as follows:

[0070] Substrate / ITO / ZnO-EA / PbS / MoO3 / Al

[0071] Comparative Example 2

[0072] The preparation method of each film layer of Comparative Example 2 is substantially the same as that of Specific Example 1, except that a zinc oxide solution is used instead of the zinc oxide modified solution to obtain a zinc oxide layer (ZnO).

[0073] The infrared light sensor structure of Comparative Example 2 is as follows:

[0074] Substrate / ITO / ZnO / PbS-I / PbS-EDT / MoO3 / Al

[0075] Comparative Example 3

[0076] The preparation method of each film layer of Comparative Example 3 is substantially the same as that of Specific Example 1, except that a lead sulfide solution is used instead of the first lead sulfide reforming solution to obtain the lead sulfide layer (PbS).

[0077] The infrared light sensor structure of Comparative Example 3 is as follows:

[0078] Substrate / ITO / ZnO-EA / PbS / PbS-EDT / MoO3 / Al

[0079] Next, relevant electrical properties of the infrared light sensors prepared in the specific example and comparative examples 1 to 3 were measured.

[0080] See Figure 6 、 7 , Figure 6 、 7 The specific example and the comparative example 2 are respectively, when the irradiation wavelength is 940nm and the irradiation power (P out ) is: 310μW / cm 2 The electrical properties of the measured results are summarized in Table 1. In the figure, (a) to (d) are: (a) dark current (I d ), (b) Photocurrent (I p ), (c) responsiveness (R), (d) sensitivity (D), cell-1 to cell-4 represent the results of repeated experiments at different times.

[0081] Table 1

[0082] Specific example Comparative Example 2 <![CDATA[I d (A)]]> <![CDATA[10 -8 -10 -7 ]]> <![CDATA[10 -5 -10 -7 ]]> <![CDATA[I p (A)]]> <![CDATA[10 -5 -10 -4 ]]> <![CDATA[10 -5 -10 -4 ]]> R(A / W) <![CDATA[10 0 -10 1 ]]> <![CDATA[10 0 -10 1 ]]> D(Jones) <![CDATA[~10 12 ]]> <![CDATA[~10 11 ]]>

[0083] In Table 1, the calculation formulas for responsivity (R) and sensitivity (D) are as described above.

[0084] The results in Table 1 indicate that surface modification of the zinc oxide nanoparticles in the zinc oxide-based layer effectively enhances interfacial compatibility between the electrode (first electrode 3) and the light sensing unit 4, thereby improving electron transfer efficiency. Therefore, compared to the infrared light sensing element prepared in Comparative Example 2, the infrared light sensing element of the present invention exhibits superior responsiveness and sensitivity.

[0085] See also Figure 8 、 9 And Table 2, Figure 8 、 9 The specific example and the comparative example 1 are respectively, the irradiation wavelength is 940nm, and the irradiation power is: 19μW / cm 2 、84μW / cm 2 、190μW / cm 2 、310μW / cm 2 , the electrical properties obtained by measurement. Among them, (a) to (d) are: (a) dark current (I d ), (b) Photocurrent (I p ), (c) responsiveness (R), (d) sensitivity (D). Table 2 is based on Figure 8 , calculated results with a bias voltage of -1V.

[0086] Table 2

[0087]

[0088] See also Figure 10 、 11 And Table 3 below, Figure 10 、 11 The specific example and the comparative example 1 are respectively, at an irradiation wavelength of 940 nm and an irradiation power of 310 μW / cm 2 The electrical measurement results of Table 3 are based on Figure 10 、 11 Calculation results. Among them, (a) to (d) are: (a) dark current (I d ), (b) Photocurrent (I p ), (c) responsiveness (R), (d) sensitivity (D).

[0089] Table 3

[0090] Specific example Comparative Example 1 <![CDATA[I d (A)]]> <![CDATA[10 -6 ~10 -3 ]]> <![CDATA[10 -5 ~10 -4 ]]> <![CDATA[I ph (A)]]> <![CDATA[10 -6 ~10 -2 ]]> <![CDATA[10 -5 ~10 -4 ]]> R(A / W) <![CDATA[~10 4 ]]> <![CDATA[~10 3 ]]> D(Jones) <![CDATA[~10 14 ]]> <![CDATA[~10 13 ]]>

[0091] Depend on Figure 10 、 11 As can be seen from the results in Table 3, the infrared light sensing component prepared in the present invention has better responsiveness and sensitivity than the infrared light sensing component of the comparative example.

[0092] In summary, the lead sulfide-based infrared sensor of the present invention modifies the zinc oxide particles within the zinc oxide-based layer 41, which directly contacts the photoelectric sensing layer 4 and the first electrode 3. The zinc oxide particles constituting the zinc oxide-based layer 41 are surface-modified with amine molecules. The amine molecules fill oxygen vacancies in the zinc oxide crystal lattice, passivating the surface defects of the zinc oxide nanoparticles. This inhibits carrier recombination and improves the carrier mobility of the zinc oxide-based layer 41. Furthermore, because zinc oxide is highly hydrophilic and lead sulfide nanoparticles are highly lipophilic, the interface between zinc oxide and lead sulfide can be compromised, which can affect charge transfer. Therefore, modifying the zinc oxide nanoparticles with amine groups increases the lipophilicity of the zinc oxide surface, improving compatibility with lead sulfide molecules and enhancing charge transfer. The lead sulfide-based light absorbing material is modified with different functional groups to form a first lead sulfide-based modified layer 42 comprising halogen-modified lead sulfide nanoparticles, which is directly in contact with the zinc oxide base layer 41 to improve electron injection efficiency. The second lead sulfide-based modified layer 43 comprising thiol-modified lead sulfide nanoparticles is then used for protection and planarization. This allows the contact surface between the light sensing unit 4 and the second electrode 5 to have better flatness, thereby enhancing electron transmission efficiency and improving the overall responsiveness and sensitivity of the infrared light sensing component, thereby effectively achieving the objectives of the present invention.

Claims

1. An infrared light sensor, characterized in that: The infrared light sensor includes: a substrate having infrared light transmittance; A first electrode is disposed on one surface of the substrate and has infrared light transparency; a light sensing unit disposed on a surface of the substrate opposite to the first electrode for absorbing and sensing infrared light, comprising a zinc oxide (ZnO)-based layer, a first lead sulfide (PbS)-based modified layer, and a second lead sulfide (PbS)-based modified layer, which are sequentially located away from the substrate from the surface of the first electrode, wherein the first lead sulfide-based modified layer comprises lead sulfide modified with halogen ions, and the second lead sulfide-based modified layer comprises lead sulfide modified with thiol molecules; and The second electrode is located on a surface of the substrate opposite to the light sensing unit. The second electrode cooperates with the light sensing unit and the first electrode to form a current channel.

2. The infrared light sensor according to claim 1, wherein: The halogen ion used to modify the lead sulfide is selected from chloride ion, bromide ion or iodide ion, and the thiol molecule used to modify the lead sulfide is selected from 1,2-ethanedithiol.

3. The infrared light sensor according to claim 1, wherein: The zinc oxide base layer, the first lead sulfide-based modified layer, and the second lead sulfide-based modified layer respectively have self-assembled films assembled from a plurality of nanoparticles.

4. The infrared light sensor according to claim 3, wherein: The zinc oxide base layer is composed of a self-assembled film composed of a plurality of nanoparticles. The nanoparticles are assembled and arranged in a densest packing manner, and the particle size of the nanoparticles is between 1 and 30 nm.

5. The infrared light sensor according to claim 1, wherein: The zinc oxide base layer comprises amino-modified zinc oxide nanoparticles modified with amino molecules.

6. The infrared light sensor according to claim 5, wherein: The amino molecule is a primary amine with a single substituent, and the substituent is a straight-chain alkyl group with a carbon number not greater than 8.

7. The infrared light sensor according to claim 6, wherein: The zinc oxide base layer is formed by coating a zinc oxide mixture and removing the solvent. The zinc oxide mixture contains the solvent, zinc oxide nanoparticles, and amino molecules. Based on 100 vol% of the volume of the zinc oxide mixture, the volume content of the amino molecules is between 0.05 and 0.5 vol%.

8. The infrared light sensor according to claim 7, wherein: The solvent is selected from water, methanol, ethanol, isopropyl alcohol, and at least one combination thereof, and the surface average roughness (Rq) of the zinc oxide-based layer is no greater than 1.5 nm.

9. The infrared light sensor according to claim 1, wherein: The thickness of the light sensing unit is between 50 nm and 500 nm, and the thickness of the first lead sulfide-based modified layer is greater than the thickness of the second lead sulfide-based modified layer.

10. The infrared light sensor according to claim 1, wherein: The substrate is glass, the material of the first electrode is selected from transparent conductive oxides, and the second electrode comprises a conductive metal oxide layer formed on the surface of the second lead sulfide-based modified layer opposite to the first electrode and a patterned metal layer formed on the surface of the conductive metal oxide layer.

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