Organic photodiode for detecting SWIR, method for manufacturing the same and SWIR sensor including the same

Abstract

Provided are an organic photodiode for detecting SWIR, a method for manufacturing the organic photodiode, and an SWIR sensor including the organic photodiode, and more particularly, to an organic photodiode for SWIR detection, the organic photodiode comprising: a first electrode; a second electrode; and a photoelectric conversion layer between the first electrode and the second electrode. The photoelectric conversion layer includes a first photoelectric conversion layer and a second photoelectric conversion layer sequentially stacked, in which the first photoelectric conversion layer includes a polymer represented by Formula 1 and an organic dopant represented by Formula 2.

Description

[0001] This patent application claims priority to Korean Patent Application No. 10-2023-0073801 filed on June 8, 2023 and Korean Patent Application No. 10-2024-0060543 filed on May 8, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present disclosure herein relates to an organic photodiode for detecting SWIR, a method for manufacturing the organic photodiode, and a SWIR sensor including the organic photodiode.

[0003] This research was conducted with the support of Samsung Future Technology Promotion Project (Project No.: SRFC-TA1803-51). Background Art

[0004] Recently, photodetectors such as CMOS image sensors have become popular and are being used in many fields as a substitute for film-type imaging devices. Photodetectors are used not only in place of film-type imaging devices when capturing ordinary visible light, but are also used in large quantities when capturing invisible light such as ultraviolet rays, infrared rays, X-rays, and gamma rays.

[0005] A photodetector is a device that converts an optical signal into an electrical signal. The photodetector may include a photoelectric conversion layer. The photoelectric conversion layer may include a silicon-based photoelectric conversion layer and an organic material-based photoelectric conversion layer. The organic material-based photoelectric conversion layer may include a mixture of a p-type semiconductor material and an n-type semiconductor material. Organic material-based photodetectors have the problem of exhibiting high dark current properties. If the organic material-based photodetector includes any one of a p-type semiconductor material and an n-type semiconductor material, there is a problem that the photodiode has a low external quantum efficiency. Summary of the invention

[0006] The present disclosure provides an organic photodiode having excellent reactivity to SWIR.

[0007] The present disclosure also provides a method for manufacturing an organic photodiode having excellent reactivity to SWIR.

[0008] The present disclosure also provides a SWIR sensor including an organic photodiode having excellent reactivity to SWIR.

[0009] Embodiments of the inventive concept include an organic photodiode for detecting SWIR, the organic photodiode including: a first electrode; a second electrode; and a photoelectric conversion layer located between the first electrode and the second electrode. In an embodiment, the photoelectric conversion layer may include a first photoelectric conversion layer and a second photoelectric conversion layer stacked sequentially, wherein the first photoelectric conversion layer may include a polymer represented by Formula 1 below and an organic dopant represented by Formula 2 below.

[0010] [Formula 1]

[0011]

[0012] [Formula 2]

[0013]

[0014] In the above formula 1, R1 and R2 can be independently hydrogen or a substituted or unsubstituted C1-C 20 alkyl, and n may be an integer between 10 and 10,000, and in the above Formula 2, X1, X2, X3 and X4 may each independently be a halogen element selected from the group consisting of fluorine (F), chlorine (Cl), bromine (Br) and iodine (I), and L1, L2, L3 and L4 may each independently be a direct bond or a substituted or unsubstituted C1-C 10 Alkylene.

[0015] In an embodiment of the inventive concept, a SWIR sensor includes: a substrate; a first electrode located on the substrate; a photoelectric conversion layer located on the first electrode; and a second electrode located on the photoelectric conversion layer. In an embodiment, the photoelectric conversion layer may include a polymer represented by Formula 1 below and an organic dopant represented by Formula 2 below.

[0016] [Formula 1]

[0017]

[0018] [Formula 2]

[0019]

[0020] In the above formula 1, R1 and R2 can be independently hydrogen or a substituted or unsubstituted C1-C 20 alkyl, and n may be an integer between 10 and 10,000, and in the above Formula 2, X1, X2, X3 and X4 may each independently be a halogen element selected from the group consisting of fluorine (F), chlorine (Cl), bromine (Br) and iodine (I), and L1, L2, L3 and L4 may each independently be a direct bond or a substituted or unsubstituted C1-C 10 Alkylene.

[0021] In an embodiment of the inventive concept, a method for manufacturing a photoelectric conversion layer for detecting SWIR includes the following steps: preparing a film including a polymer represented by Formula 1 below; coating a first doping solution on the film to perform a primary doping process on the polymer; and coating a second doping solution on the film to perform a secondary doping process on the polymer. In an embodiment, each of the first doping solution and the second doping solution may include an organic dopant represented by Formula 2 below, and a first solvent of the first doping solution and a second solvent of the second doping solution are different from each other.

[0022] [Formula 1]

[0023]

[0024] [Formula 2]

[0025]

[0026] In the above formula 1, R1 and R2 can be independently hydrogen or a substituted or unsubstituted C1-C 20 alkyl, and n may be an integer between 10 and 10,000, and in the above Formula 2, X1, X2, X3 and X4 may each independently be a halogen element selected from the group consisting of fluorine (F), chlorine (Cl), bromine (Br) and iodine (I), and L1, L2, L3 and L4 may each independently be a direct bond or a substituted or unsubstituted C1-C 10 Alkylene. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are included to provide a further understanding of the inventive concept and are incorporated into and constitute a part of this specification. The accompanying drawings illustrate embodiments of the inventive concept and together with the description serve to explain the principles of the inventive concept. In the drawings:

[0028] Figure 1 is a cross-sectional view schematically illustrating an organic photodiode for detecting SWIR according to an embodiment of the inventive concept;

[0029] Figure 2 is a schematic diagram for explaining that an organic semiconductor material of the inventive concept has a polaron state due to an organic dopant;

[0030] Figure 3 is a plan view schematically illustrating a first photoelectric conversion layer according to an embodiment of the inventive concept;

[0031] Figure 4 is a plan view schematically illustrating a first photoelectric conversion layer according to a comparative example of the inventive concept;

[0032] Figure 5is a schematic diagram for explaining a free polaron and a bound polaron according to an embodiment of the inventive concept;

[0033] Figure 6 and Figure 7 is a schematic diagram for explaining a mechanism in which a bound polariton is converted into a free polariton by SWIR light according to an embodiment of the inventive concept;

[0034] Figure 8 and Fig. 9 is a schematic diagram for explaining a method for manufacturing an organic photodiode for detecting SWIR according to an embodiment of the inventive concept;

[0035] Fig.10 is a graph showing d-spacing values ​​according to changes in dopant concentration in the film of Example 1 and the film of Comparative Example 1;

[0036] Fig.11A is a graph of χT according to temperature T in the film of Example 1 and the film of Comparative Example 1;

[0037] Fig. 11B is a graph showing the density of total polarons and the density of bound polarons in the film of Example 1 and the film of Comparative Example 1;

[0038] Fig. 12A is a graph showing EQE spectra of the organic photodiode of Example 1 and the organic photodiode of Comparative Example 1;

[0039] Fig. 12B is a graph showing the responsivity of the organic photodiode of Example 1 and the organic photodiode of Comparative Example 1;

[0040] Fig. 12C shows the results of measuring the JV properties of the organic photodiode of Example 1 and the organic photodiode of Comparative Example 1; and

[0041] Fig.13 is a cross-sectional view for explaining a SWIR sensor according to an embodiment of the inventive concept. DETAILED DESCRIPTION

[0042] In order to promote a full understanding of the structure and effect of the present invention, the preferred embodiments of the inventive concept will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments set forth below, and can be implemented in various forms and modified in many alternative forms. On the contrary, these embodiments are provided so that the disclosure of the present invention will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. It will be appreciated by those skilled in the art that the concept of the present invention can be performed in any suitable environment.

[0043] The terms used herein are for the purpose of describing the embodiments and are not intended to limit the present invention. In this specification, unless the context clearly indicates otherwise, the singular includes the plural. As used herein, the term "comprising" and / or its variations are intended to include the stated materials, steps, operations and / or devices, and do not exclude the possibility of the presence or addition of one or more other materials, steps, operations and / or devices.

[0044] In the present disclosure, when any film (or layer) is referred to as being on another film (or layer) or a substrate, it means that the film (or layer) can be directly formed on the other film (or layer) or the substrate, or a third film (or layer) can be placed between the film (or layer) and the other film (or layer) or the substrate.

[0045] Although the terms first, second, third, etc. are used in various embodiments of the present disclosure to describe various regions, films (or layers), etc., these regions, films (or layers), etc. should not be limited by these terms. These terms are only used to distinguish any predetermined region or film (or layer) from another region or film (or layer). Therefore, a film referred to as a first film in one embodiment may be referred to as a second film in another embodiment. Each embodiment described and illustrated herein also includes its supplementary embodiment. Throughout the specification, the same reference numerals refer to the same elements.

[0046] In addition, the embodiments described in this specification will be described with reference to the cross-sectional views and / or plan views as ideal illustrations of the present invention. In the accompanying drawings, the thickness of the film and the region is exaggerated for the effective description of the technical content. Therefore, the shape of the example diagram can be modified by manufacturing technology and / or tolerance. The embodiments of the present invention are not limited to the specific forms shown, but are intended to include changes in form resulting from the manufacturing process. For example, the etching area shown as a right angle may be circular (rounded) or may be in a shape with a predetermined curvature. Therefore, the area shown in the drawings has a schematic nature, and the shape of the area shown in the drawings is intended to illustrate the specific shape of the area of ​​the device, without intending to limit the scope of the inventive concept.

[0047] In the present specification, the alkyl group may be a linear alkyl group, a branched alkyl group or a cyclic alkyl group. The number of carbon atoms of the alkyl group is not particularly limited, but the alkyl group may be an alkyl group having 1 to 3 carbon atoms. Examples of the alkyl group may include a methyl group, an ethyl group, a propyl group, etc., but are not limited thereto. The aromatic ring compound may be monocyclic or polycyclic. The number of carbon atoms of the aromatic ring compound may be 5 to 20, but are not limited thereto. Examples of the aromatic ring compound may include a phenyl group, a biphenyl group, a naphthyl group and / or a fluorenyl group, but are not limited thereto.

[0048] In this specification, a direct bond may mean a single bond.

[0049] In the present specification, examples of the halogen element may include fluorine (F), chlorine (Cl), bromine (Br), and iodine (I), but are not limited thereto.

[0050] In this specification, "substituted or unsubstituted" may mean unsubstituted or substituted with one or more substituents selected from the group consisting of hydrogen atoms, deuterium atoms, halogen elements, ether groups, haloalkyl groups, haloalkoxy groups, haloether groups, alkyl groups, cyano groups, cyano-substituted alkyl groups, cyano-substituted aryl groups, cyano-substituted aromatic ring groups, and hydrocarbon ring groups. In addition, each of the substituents shown above may be substituted or unsubstituted. For example, biphenyl may be interpreted as an aryl group, and may be interpreted as a phenyl group substituted with a phenyl group.

[0051] Unless otherwise defined in a formula in the present specification, if a chemical bond is not drawn at a position where a chemical bond should be drawn, it may mean that a hydrogen atom is bound to the position.

[0052] In this specification, the same drawing reference numerals may refer to the same components throughout the specification.

[0053] Short-wave infrared (SWIR) may belong to a wavelength range between visible light and thermal radiation in the electromagnetic spectrum. The wavelength band of light in SWIR may be 900nm to 2,500nm, 900nm to 1,800nm, or 1,200nm to 1,800nm. SWIR may be located between mid-wave infrared (MWIR) and long-wave infrared (LWIR).

[0054] Typical organic photodiodes (i.e., organic semiconductors) generally use donor-acceptor (DA) push-pull copolymers to absorb low energy and narrow the wavelength range. The above method produces a complex state in which charges move within the molecule. Increasing the molecular weight of the polymer can lead to a narrower band gap, which can lead to better absorption of light with long wavelengths.

[0055] On the other hand, the above-mentioned DA type copolymer has a problem of difficulty in absorbing the SWIR region. Some previous studies have reported copolymers with extended absorption up to 1.5 μm, but in reality, absorption occurs only at 1.0 μm to 1.1 μm, and wavelengths exceeding it are rarely absorbed. Therefore, it is considered difficult for organic semiconductors to detect SWIR light with a wavelength of 1.5 μm or more.

[0056] On the other hand, doped organic semiconductors can absorb SWIR. However, doped polymers have too high conductivity. Due to the high dark current caused by high conductivity, it is difficult to use doped organic semiconductors as sensors for detecting SWIR.

[0057] Hereinafter, an organic photodiode for detecting SWIR and a SWIR sensor including the same according to the inventive concept will be described.

[0058] Figure 1 is a cross-sectional view schematically illustrating an organic photodiode for detecting SWIR according to an embodiment of the inventive concept. Figure 1 , the organic photodiode may include a first electrode ELT1, a conductive polymer layer CPL, a photoelectric conversion layer PRL, and a second electrode ELT2 sequentially stacked in a thickness direction (i.e., a third direction D3 perpendicular to the first direction D1). Although not shown, the organic photodiode may further include a substrate disposed under the first electrode ELT1. As an example, the substrate may include a semiconductor substrate (e.g., a silicon substrate), an organic substrate, or an inorganic substrate (e.g., a glass substrate). However, the material of the substrate is not limited thereto.

[0059] The first electrode ELT1 may include metal, doped polysilicon, or a conductive polymer. The first electrode ELT1 may be used as a lower electrode of an organic photodiode. The second electrode ELT2 may be disposed on the first electrode ELT1. The second electrode ELT2 may be spaced apart from the first electrode ELT1. The second electrode ELT2 may be used as an upper electrode of an organic photodiode.

[0060] The voltage applied to the second electrode ELT2 may be different from the voltage applied to the first electrode ELT1. Any one of the first electrode ELT1 and the second electrode ELT2 may be an anode, and the other one thereof may be a cathode. At least one of the first electrode ELT1 and the second electrode ELT2 may be a transparent electrode. For example, if light is incident through the first electrode ELT1, the first electrode ELT1 may be transparent. If light is incident through the second electrode ELT2, the second electrode ELT2 may be transparent.

[0061] The photoelectric conversion layer PRL may be disposed between the first electrode ELT1 and the second electrode ELT2. For example, the photoelectric conversion layer PRL may have a first surface and a second surface facing each other. The first electrode ELT1 may be disposed on the first surface of the photoelectric conversion layer PRL, and the second electrode ELT2 may be disposed on the second surface of the photoelectric conversion layer PRL.

[0062] According to an embodiment of the present invention, a conductive polymer layer CPL may be interposed between the photoelectric conversion layer PRL and the first electrode ELT1.

[0063] The conductive polymer layer CPL may perform a function of transferring charges between the first electrode ELT1 and the photoelectric conversion layer PRL.

[0064] As an example, the conductive polymer layer CPL may be formed of a transparent material together with the first electrode ELT1. Therefore, light may pass through the first electrode ELT1 and the conductive polymer layer CPL to be incident on the photoelectric conversion layer PRL. The conductive polymer layer CPL may serve as an adhesive layer for bonding the first electrode ELT1 and the photoelectric conversion layer PRL to each other.

[0065] The conductive polymer layer CPL may include a conductive polymer. For example, the conductive polymer layer CPL may include at least one selected from the group consisting of PEDOT:PSS, poly(3-hexylthiophene) (P3HT), and polyfluorene.

[0066] The photoelectric conversion layer PRL may include an organic semiconductor material. The organic semiconductor material may be an organic polymer. For example, the organic semiconductor material according to this embodiment may include polythiophene and / or its derivatives. The photoelectric conversion layer PRL may also include an organic dopant doped in the organic semiconductor material.

[0067] Specifically, the photoelectric conversion layer PRL may include a first photoelectric conversion layer PRL1 and a second photoelectric conversion layer PRL2. The first photoelectric conversion layer PRL1 and the second photoelectric conversion layer PRL2 may be sequentially stacked. The first photoelectric conversion layer PRL1 may be adjacent to the first electrode ELT1, and the second photoelectric conversion layer PRL2 may be adjacent to the second electrode ELT2.

[0068] The first photoelectric conversion layer PRL1 may include an organic dopant and an organic semiconductor material (ie, a conductive polymer). The second photoelectric conversion layer PRL2 may include an organic semiconductor material (ie, a conductive polymer). The second photoelectric conversion layer PRL2 may exclude the organic dopant. That is, the second photoelectric conversion layer PRL2 may be an undoped layer.

[0069] The organic semiconductor material in the photoelectric conversion layer PRL may include a polymer represented by Formula 1 below.

[0070] [Formula 1]

[0071]

[0072] In Formula 1, R1 and R2 may each independently be hydrogen or a substituted or unsubstituted C1-C 20 An alkyl group. n may be an integer between 10 and 10,000. The polymer of Formula 1 according to the present embodiment may have a molecular weight of 10,000 to 100,000. The molecular weight may refer to a weight average molecular weight.

[0073] In an embodiment, the organic semiconductor material in the photoelectric conversion layer PRL may include poly(3-hexylthiophene) (P3HT).

[0074] In addition to the above-mentioned organic semiconductor material, the first photoelectric conversion layer PRL1 may further include an organic dopant. The organic dopant may be doped in the organic semiconductor material. The organic dopant may include a compound represented by Formula 2 below.

[0075] [Formula 2]

[0076]

[0077] In Formula 2, X1, X2, X3 and X4 may be independently a halogen element selected from the group consisting of fluorine (F), chlorine (Cl), bromine (Br) and iodine (I). L1, L2, L3 and L4 may be independently a direct bond or a substituted or unsubstituted C1-C 10 Alkylene.

[0078] In an embodiment, the organic dopant may include 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ).

[0079] In an embodiment, the concentration of the organic dopant in the first photoelectric conversion layer PRL1 may be 1 ppm to 100 ppm.

[0080] Figure 2 Schematic diagram for explaining that an organic semiconductor material of the inventive concept has a polaron state due to an organic dopant. Figure 2 , the organic semiconductor material of the first photoelectric conversion layer PRL1 may have a polaron state due to the organic dopant.

[0081] Specifically, the organic dopant of Formula 2 can be doped into the polymer of Formula 1 to generate anions. Electrons in the polymer of Formula 1 can be transferred to the organic dopant to generate an anionic dopant. Electrons in the polymer of Formula 1 can be transferred to the organic dopant to generate positive charges in the polymer chain. The positive charge can cause structural deformation in the polymer chain to generate a quinone structure in the polymer. In other words, the organic dopant can convert at least one of the aromatic rings in the polymer into a quinone ring.

[0082] The quinone structure and the radical cation may constitute a positive polaron. The positive polaron may include a singly occupied first energy level EL1 above the valence band edge and an unoccupied second energy level EL2 below the conduction band edge.

[0083] The positive polaron can cause strong ion gap absorption in the SWIR region P1 and the NIR region P2 through the above energy levels EL1 and EL2, respectively. The organic photodiode according to the present invention can be used as a photodiode capable of effectively detecting SWIR by using the property that the polaron in the first photoelectric conversion layer PRL1 can strongly absorb the SWIR region P1.

[0084] Figure 3 is a plan view schematically illustrating a first photoelectric conversion layer according to an embodiment of the inventive concept.

[0085] Figure 4 is a plan view schematically illustrating a first photoelectric conversion layer according to a comparative example of the inventive concept.

[0086] Figure 5 is a schematic diagram for explaining a free polaron and a bound polaron according to an embodiment of the inventive concept.

[0087] Figure 3 and Figure 4 yes Figure 1 An enlarged plan view of area M in FIG.

[0088] Reference Figure 3 , the first photoelectric conversion layer PRL1 may include a polymer chain PLC and an organic dopant AOD. The polymer chain PLC may include a crystallized domain CRD.

[0089] The organic dopant AOD may include a first organic dopant AOD1 located in the crystal domain CRD and a second organic dopant AOD2 located in a region other than the crystal domain CRD. In an embodiment, the second organic dopant AOD2 may be located in an amorphous domain of the polymer.

[0090] Reference Figure 3 and Figure 5 , the first organic dopant AOD1 can be positioned close to the radical unit RAU in the crystal domain CRD. A relatively strong Coulomb binding energy (BE) can be generated between the first organic dopant AOD1 and the radical unit RAU. Therefore, the first organic dopant AOD1 can form a bound polaron BOS that is fixed inside the polymer chain PLC and cannot move freely.

[0091] The second organic dopant AOD2 can be positioned away from the free radical unit RAU in the crystal domain CRD. A relatively weak Coulomb binding energy (BE) can be generated between the second organic dopant AOD2 and the free radical unit RAU. Therefore, the second organic dopant AOD2 can form a free polaron FRS that can move freely inside the polymer chain PLC.

[0092] Bound polarons BOS cannot move freely, and thus may not have a significant effect on the conductivity of first photoelectric conversion layer PRL1 . However, free polarons FRS can move freely, and thus may have a significant effect on the conductivity of first photoelectric conversion layer PRL1 .

[0093] In the first photoelectric conversion layer PRL1 according to the present embodiment, the ratio of bound polaritons to total polaritons may be relatively large. Specifically, the ratio of the density of bound polaritons to the density of total polaritons may be 10% to 50% or 20% to 40%. If the ratio of bound polaritons is within the above range, the dark current caused by the first photoelectric conversion layer PRL1 may be reduced, and at the same time, the responsiveness to SWIR may be improved.

[0094] Reference Figure 4 , the ratio of the first organic dopant AOD1 in the first photoelectric conversion layer PRL1 of the comparative example according to the present invention may be less than Figure 3 The ratio of the first organic dopant AOD1 in the first photoelectric conversion layer PRL1 of the example shown in . That is, the first photoelectric conversion layer PRL1 of the comparative example may have a relatively low ratio of bound polarons. Therefore, the first photoelectric conversion layer PRL1 of the comparative example may have a high conductivity due to doping, which may cause a problem of greatly generating dark current. Dark current may cause a major problem in a photodiode for detecting SWIR.

[0095] Return to reference Figure 3 , the first photoelectric conversion layer PRL1 according to the present embodiment has a high ratio of bound polarons, and thus can suppress the increase in conductivity due to doping. Therefore, it is possible to prevent the problem of greatly generating dark current. The first photoelectric conversion layer PRL1 according to the present embodiment can be effectively used for a photodiode detecting SWIR.

[0096] Figure 6 and Figure 7 is a schematic diagram for explaining a mechanism in which a bound polaron is converted into a free polaron by SWIR light according to an embodiment of the inventive concept.

[0097] Reference Figure 6 and Figure 7 , light hv in the SWIR region P1 may be incident on the first photoelectric conversion layer PRL1. The bound polaritons BOS may be excited by the incident light. Specifically, the electrons at the valence band edge of the radical unit RAU may be excited by the incident light to the first energy level EL1 (see Figure 2 ). Thereafter, holes HT can move from the radical unit RAU to the adjacent neutral unit due to the energy shift between the valence band maximum and the external bias.

[0098] Adjacent neutral units can be converted into free radical units, and free radical units can be converted into neutral units. At the same time, the position of the first organic dopant AOD1 can be fixed as it is. Therefore, when the light hv of the SWIR region P1 is irradiated, the free radical unit RAU can gradually move away from the first organic dopant AOD1. Therefore, the bound polaron BOS can be converted into a free polaron FRS. In other words, if the first photoelectric conversion layer PRL1 according to the present invention is irradiated with the light hv of the SWIR region P1, the bound polaron BOS in the first photoelectric conversion layer PRL1 can be converted into a free polaron FRS.

[0099] The free polaritons FRS are used as free holes to improve the photoconductivity of the organic photodiode. Due to the generation of the free polaritons FRS, the response to the light hv in the SWIR region P1 can become stronger.

[0100] Return to reference Figure 1 If SWIR is not incident, the organic photodiode according to the present invention may have low conductivity due to bound polaritons BOS even if the first photoelectric conversion layer PRL1 is a doped layer. Therefore, generation of dark current can be prevented.

[0101] On the other hand, if SWIR is incident on the organic photodiode, the first photoelectric conversion layer PRL1 can convert the bound polaron BOS into the free polaron FRS in response to the SWIR. Therefore, free charges are generated in the first photoelectric conversion layer PRL1, and current can flow in the organic photodiode composed of the first photoelectric conversion layer PRL1 and the second photoelectric conversion layer PRL2.

[0102] Figure 8 and Fig. 9 is a schematic diagram for explaining a method for manufacturing an organic photodiode for detecting SWIR according to an embodiment of the inventive concept.

[0103] Reference Figure 8 , an organic semiconductor film OSL may be disposed on the stage TAB. In an embodiment, the organic semiconductor film OSL may include a polymer represented by the above Formula 1. For example, the organic semiconductor film OSL may include P3HT.

[0104] The organic semiconductor film OSL may be doped once. A first doping solution DFS1 may be provided on the organic semiconductor film OSL by a rotating table TAB. The first doping solution DFS1 may include a first solvent and an organic dopant represented by the above formula 2. For example, the first solvent may include acetonitrile. When the first doping solution DFS1 is coated on the organic semiconductor film OSL, the organic dopant may be doped into a polymer in the organic semiconductor film OSL.

[0105] In an embodiment, the concentration of the organic dopant in the first doping solution DFS1 may be 0.5 mg / mL to 5 mg / mL or 0.5 mg / mL to 2 mg / mL.

[0106] As a result of the above-mentioned primary doping process, Figure 4 As shown in FIG. 1 , in the organic semiconductor film OSL, the ratio of the first organic dopant AOD1 located in the crystal domain CRD may be relatively small, and the ratio of the second organic dopant AOD2 located in the region other than the crystal domain CRD may be relatively large.

[0107] Reference Fig. 9 , the organic semiconductor film OSL may be secondarily doped. The second doping solution DFS2 may be provided on the organic semiconductor film OSL through the rotating table TAB. The second doping solution DFS2 may include a second solvent and an organic dopant represented by Formula 2 above.

[0108] The second solvent may be different from the first solvent. The second solvent can swell the polymer in the organic semiconductor film OSL. If the polymer swells due to the second solvent, the organic dopant can easily penetrate into the crystal domain CRD. For example, the second solvent may include chlorobenzene.

[0109] In an embodiment, the concentration of the organic dopant in the second doping solution DFS2 may be 0.5 mg / mL to 5 mg / mL or 0.5 mg / mL to 2 mg / mL.

[0110] As a result of the above secondary doping process, Figure 3 As shown in FIG. 1 , in the organic semiconductor film OSL, the ratio of the first organic dopant AOD1 located in the crystal domain CRD may become relatively large, and the ratio of the second organic dopant AOD2 located in the region other than the crystal domain CRD may become relatively small.

[0111] As a result of the above secondary doping process, the organic semiconductor film OSL can be used as the above reference Figure 1 The first photoelectric conversion layer PRL1 described. Through the secondary doping process, the first photoelectric conversion layer PRL1 prepared by the method according to the present invention can have a relatively high proportion of bound polarons. Therefore, compared with the organic semiconductor film to which only one doping process is performed, the first photoelectric conversion layer PRL1 according to the present invention can have low conductivity in a state where SWIR light is not incident.

[0112] Fig.13 1 is a cross-sectional view for explaining a SWIR sensor according to an embodiment of the inventive concept. Fig.13The SWIR sensor may include a substrate 100 , a wiring layer 200 , a first electrode ELT1 , a photoelectric conversion layer PRL, a second electrode ELT2 , a protective layer 400 , and a microlens layer 500 .

[0113] The substrate 100 may be a semiconductor substrate. For example, the substrate 100 may include silicon or silicon germanium. The substrate 100 may include a pixel region. The pixel region may be arranged in a two-dimensional form. In an embodiment, the pixel region of the substrate 100 may include a first pixel region PX1 and a second pixel region PX2.

[0114] In an embodiment of the present invention, the substrate 100 may be a substrate of a circuit chip. Specifically, an integrated circuit may be provided on the substrate 100. The integrated circuit on the substrate 100 may include a logic circuit, a memory circuit, or a combination thereof. The integrated circuit on the substrate 100 may include, for example, a transistor. The wiring layer 200 to be described later may be electrically connected to the integrated circuit on the substrate 100. The wiring layer 200 may electrically connect the integrated circuit on the substrate 100 and the photoelectric conversion layer PRL to each other.

[0115] The wiring layer 200 may be disposed on the substrate 100. The wiring layer 200 may include an insulating layer and stacked wiring patterns 640. The insulating layer may be a single layer or multiple layers. The wiring pattern 640 may be disposed in the insulating layer. The wiring pattern 640 may include a conductive material such as a metal.

[0116] The second electrodes ELT2 may be disposed in the wiring layer 200. The second electrodes ELT2 may be electrically connected to the wiring patterns 640, respectively. In an embodiment, the second electrodes ELT2 may be exposed through the upper surface of the wiring layer 200. The second electrodes ELT2 may be disposed in the first pixel region PX1 and the second pixel region PX2, respectively. The second electrodes ELT2 may each be a pixel electrode.

[0117] The insulating layer 250 may be disposed on the wiring layer 200. The photoelectric conversion layer PRL may be disposed in the insulating layer 250. The photoelectric conversion layer PRL may be disposed in the first pixel region PX1 and the second pixel region PX2, respectively. Each of the photoelectric conversion layers PRL may be connected to the reference pixel region PX1. Figure 1 The described photoelectric conversion layers PRL are substantially the same. The photoelectric conversion layers PRL may include an organic semiconductor material. Each of the photoelectric conversion layers PRL may be responsive to incident SWIR light.

[0118] The first electrodes ELT1 may be respectively disposed on the photoelectric conversion layer PRL. Each of the first electrodes ELT1 may be electrically connected to the corresponding photoelectric conversion layer PRL. The voltage applied to the first electrode ELT1 may be different from the voltage applied to the second electrode ELT2. If the second electrode ELT2 is an anode, the first electrode ELT1 may be a cathode. If the second electrode ELT2 is a cathode, the first electrode ELT1 may be an anode. The first electrode ELT1 may be a transparent electrode.

[0119] The protective layer 400 may be disposed on the insulating layer 250. The protective layer 400 may be disposed on the plurality of first electrodes ELT1. The protective layer 400 may have an insulating property. The protective layer 400 may include, for example, an organic material such as a polymer. The protective layer 400 may be transparent.

[0120] The color filters CF and the barrier pattern 300 may be disposed on the protective layer 400. In an embodiment, the barrier pattern 300 may be disposed between two adjacent color filters CF to separate the color filters CF from each other. For example, the color filters CF may be physically and optically separated from each other by the barrier pattern 300.

[0121] In an embodiment, the barrier pattern 300 may have a mesh shape. When viewed in a plan view, the barrier pattern 300 may surround each of the first pixel region PX1 and the second pixel region PX2. The barrier pattern 300 may surround each of the color filters CF.

[0122] The fence pattern 300 may include a first fence pattern 310 and a second fence pattern 320. The first fence pattern 310 may be disposed between the insulating layer 250 and the second fence pattern 320. The first fence pattern 310 may include a conductive material such as a metal and / or a metal nitride. For example, the first fence pattern 310 may include titanium and / or titanium nitride.

[0123] The second barrier pattern 320 may be disposed on the first barrier pattern 310. The second barrier pattern 320 may include a material different from that of the first barrier pattern 310. The second barrier pattern 320 may include an organic material. The second barrier pattern 320 includes a low refractive material and may have an insulating property.

[0124] The microlens layer 500 may be disposed on the color filter CF. The microlens layer 500 may include a plurality of protruding microlenses 510. In an embodiment, the microlenses 510 may be disposed at positions corresponding to the photoelectric conversion layer PRL, respectively. In an embodiment, the microlenses 510 may be disposed on the color filter CF, respectively, and may correspond to the color filter CF, respectively.

[0125] When viewed in a plan view, the microlenses 510 may be arranged in a two-dimensional array. Each of the microlenses 510 may have a protruding shape. Each of the microlenses 510 may have a hemispherical cross-section. The microlenses 510 may condense incident light.

[0126] The microlens layer 500 is transparent and thus can transmit light. The microlens layer 500 may include an organic material such as a polymer. For example, the microlens layer 500 may include a photoresist material or a thermosetting resin.

[0127] The organic photodiode for detecting SWIR according to the present invention can be used in a SWIR camera. The SWIR camera can provide thermal imaging and can even be used at night.

[0128] The organic photodiode for detecting SWIR according to the present invention can be used as a sensor for detecting the properties of a material. For example, the SWIR sensor can detect defective materials or materials containing specific chemicals. The SWIR sensor can be used to evaluate the health status of plants.

[0129] SWIR sensors can be used to detect defects and check quality in the semiconductor chip manufacturing process. This can help improve the efficiency of the semiconductor process and improve the reliability of semiconductor devices.

[0130] Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are only illustrative of the present invention and are not intended to limit the scope of the present invention.

[0131] Example 1: Preparation of dual-doped films

[0132] The P3HT film was fixed to the stage of the spin coating equipment. The stage was rotated at a spin speed of 1,000 rpm. The P3HT film was heat treated at 150°C for 10 minutes.

[0133] A first doping solution (F4-TCNQ and acetonitrile) was prepared. The concentration of the dopant (F4-TCNQ) of the first doping solution was 0.1 mg / mL. The first doping solution (primary doping) was provided on the P3HT film.

[0134] A second doping solution (F4-TCNQ and chlorobenzene) was prepared. The concentration of the dopant (F4-TCNQ) of the second doping solution was 1 mg / mL. After the primary doping, a second doping solution (secondary doping) was provided on the P3HT film.

[0135] Comparative Example 1: Preparation of single doped film

[0136] The secondary doping process was omitted, and only the P3HT film was subjected to a primary doping process. At this time, the concentration of the doping solution was 1 mg / mL.

[0137] Comparative Example 2: Preparation of undoped film

[0138] Undoped P3HT films were prepared without the need for a doping process.

[0139] Organic photodiodes

[0140] An organic photodiode was manufactured using the film of Example 1 and the film of Comparative Example 1. Specifically, a PEDOT:PSS solution was spin coated on a patterned ITO substrate. The coated PEDOT:PSS solution was heat treated at 140°C for 20 minutes to form a PEDOT:PSS intermediate film. A doped film (Example 1 and Comparative Example 1) was set on the PEDOT:PSS intermediate film. An undoped P3HT film was formed on the doped film. An undoped P3HT film was formed using spin coating.

[0141] An aluminum electrode was formed on the undoped P3HT film. The aluminum electrode was formed using thermal evaporation. The area of ​​the active region of the fabricated SWIR organic photodiode was about 0.09 cm 2 .

[0142] Experimental Example 1: Evaluation of the influence of doping solvent on the location of dopant

[0143] For the film of Example 1 and the film of Comparative Example 1, the d-spacing values ​​according to the change of dopant concentration were calculated. Fig.10 The d-spacing values ​​were calculated using 2D-GIXD measurements. The 2D-GIXD measurements were performed at the Pohang Accelerator Laboratory in the Republic of Korea.

[0144] Reference Fig.10 , when chlorobenzene is used as the second doping solvent as in Example 1, it can be confirmed that the d-spacing value changes from arrive On the other hand, when doping was performed only once using acetonitrile as the first doping solvent as in Comparative Example 1, the d-spacing value hardly changed.

[0145] When chlorobenzene was used for doping as in Example 1, it was confirmed that the F4-TCNQ dopant could effectively penetrate into the crystalline domain of the polymer. On the other hand, when only acetonitrile was used for doping as in Comparative Example 1, it was confirmed that the F4-TCNQ dopant was mainly located in the amorphous domain. This confirmed that chlorobenzene swelled the P3HT polymer, thereby ensuring space for the dopant to penetrate into the crystalline domain of the polymer.

[0146] Experimental Example 2: Polaron Behavior Properties

[0147] ESR measurements were performed according to temperature for the film of Example 1 and the film of Comparative Example 1. Using a reference sample of CuSO4.5H2O, spin susceptibility χ was calculated from the ESR measurement results.

[0148] Fig.11A A graph of χT according to temperature T is shown in FIG. Fig.11A , the degree of localization of the polarons of the film of Example 1 and the film of Comparative Example 1 can be confirmed.

[0149] The Curie constant of Example 1 and the Curie constant of Comparative Example 1 were obtained from the slope of each graph. It was confirmed that the Curie constant (C) of Example 1 was significantly greater than the Curie constant (C) of Comparative Example 1.

[0150] Using the following equation 1, calculate the density n of bound polarons 束缚极化子 .

[0151] [Equation 1]

[0152] C=n 束缚极化子 ·μ B 2 ·k B -1

[0153] μB is the Bohr magneton.

[0154] For the film of Example 1 and the film of Comparative Example 1, the density of total polarons and the density of bound polarons were calculated. The results are Fig. 11B Shown in.

[0155] Reference Fig. 11B , it was confirmed that the film of Comparative Example 1 had a very small ratio of bound polarons to total polarons (which was about 3%). It was confirmed that the film of Example 1 had a relatively large ratio of bound polarons to total polarons (which was about 33%).

[0156] Experimental Example 3: Properties of Organic Photodiodes

[0157] For the organic photodiode of Example 1 and the organic photodiode of Comparative Example 1, the EQE spectrum and the responsivity were measured, and the EQE spectrum and the responsivity were measured at Fig. 12A and Fig. 12B For the organic photodiode of Example 1 and the organic photodiode of Comparative Example 1, the JV properties were measured and the results were as follows. Fig. 12C Shown in.

[0158] The EQE spectrum and JV properties were measured using a setup in which a Keithley 2450 source meter and a 150W QTH lamp were combined with an Oriel Cornerstone monochromator. The experimental setup was controlled with a LabView program. The LDR of the device was determined using the same EQE / JV measurement setup, and the intensity of the light was adjusted using various neutral density filters (3.12×10 -6 W cm -2 to 3.12×10 -9 W cm -2 ).

[0159] Reference Fig. 12A and Fig. 12B , it can be confirmed that both the organic photodiode of Example 1 and the organic photodiode of Comparative Example 1 have a photoresponse to SWIR between 1,200 nm and 1,800 nm.

[0160] Specifically, it can be confirmed that the two devices have similar EQE values ​​in the visible light range. However, it can be confirmed that in the SWIR range (1,200nm to 1,800nm), the EQE value of the organic photodiode of Example 1 is greater than the EQE value of the organic photodiode of Comparative Example 1. It can be confirmed that in the SWIR range (1,200nm to 1,800nm), the responsivity of the organic photodiode of Example 1 is greater than the responsivity of the organic photodiode of Comparative Example 1.

[0161] For example, at 1800 nm, the EQE value of the organic photodiode of Example 1 is 77%, and the responsivity is 1,120 AW -1 This is 150% of the EQE value and responsivity of the organic photodiode of Comparative Example 1.

[0162] In summary, it can be confirmed that the organic photodiode according to the embodiment of the present invention has high photoresponsivity and high light efficiency with respect to SWIR.

[0163] Reference Fig. 12C It can be seen that the dark current of the organic photodiode of Example 1 is measured to be much lower than the dark current of the organic photodiode of Comparative Example 1. This is because the first photoelectric conversion layer PRL1 of the organic photodiode according to the present invention has relatively small conductivity due to a high proportion of bound polarons.

[0164] The organic semiconductor according to the present invention has a relatively large proportion of bound polarons and thus has excellent responsivity to SWIR while being able to significantly reduce dark current. The organic semiconductor according to the present invention can be used as an organic photodiode for detecting SWIR. The organic photodiode of the present invention can have high external quantum efficiency and high responsivity in the SWIR region.

Claims

1. An organic photodiode for detecting SWIR, the organic photodiode include: a first electrode; a second electrode; as well as a photoelectric conversion layer, located between the first electrode and the second electrode, The photoelectric conversion layer includes a first photoelectric conversion layer and a second photoelectric conversion layer stacked sequentially. Wherein, the first photoelectric conversion layer includes a polymer represented by the following formula 1 and an organic dopant represented by the following formula 2: [Formula 1] [Formula 2] Wherein, in the above formula 1, R 1 and R 2 are independently hydrogen or substituted or unsubstituted C 1 -C 20 alkyl, and n is an integer between 10 and 10,000, and Wherein, in the above formula 2, X 1 , X 2 , X 3 and X 4 are independently a halogen element selected from the group consisting of fluorine, chlorine, bromine and iodine, and L 1 , L 2 , L 3 and L 4 are independently a direct bond or a substituted or unsubstituted C 1 -C 10 Alkylene.

2. The organic photodiode according to claim 1, in, The organic dopant forms bound polarons and free polarons in the first photoelectric conversion layer, and Wherein, the ratio of the density of the bound polarons to the density of the total polarons in the first photoelectric conversion layer is 10% to 50%.

3. The organic photodiode according to claim 2, in, When SWIR light is incident on the first photoelectric conversion layer, the bound polaritons are converted into the free polaritons in response to the SWIR light.

4. The organic photodiode according to claim 2, in, The organic dopant includes a first organic dopant and a second organic dopant, wherein the first organic dopant is located in the crystal domain of the polymer, The second organic dopant is located in the amorphous domains of the polymer, The first organic dopant forms the bound polaron, and The second organic dopant forms the free polaron.

5. The organic photodiode according to claim 1, in, The second photoelectric conversion layer includes the polymer, and Wherein, the second photoelectric conversion layer is an undoped layer.

6. The organic photodiode according to claim 1, in, The polymer includes poly(3-hexylthiophene).

7. The organic photodiode according to claim 1, in, The organic dopant includes 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane.

8. The organic photodiode according to claim 1, in, The polymer of the first photoelectric conversion layer includes a radical cation having a quinone structure, and Wherein, the organic dopant is an anion dopant.

9. The organic photodiode according to claim 8, in, The radical cation having the quinone structure constitutes a positive polaron. 10 . The organic photodiode according to claim 1 , further comprising a conductive polymer layer, wherein the conductive polymer layer is located between the first electrode and the first photoelectric conversion layer.

11. A SWIR sensor, wherein the SWIR sensor include: substrate; A first electrode, located on the substrate; A photoelectric conversion layer, located on the first electrode; as well as A second electrode is located on the photoelectric conversion layer. Wherein, the photoelectric conversion layer includes a polymer represented by the following formula 1 and an organic dopant represented by the following formula 2: [Formula 1] [Formula 2] Wherein, in the above formula 1, R 1 and R 2 are independently hydrogen or substituted or unsubstituted C 1 -C 20 alkyl, and n is an integer between 10 and 10,000, and Wherein, in the above formula 2, X 1 , X 2 , X 3 and X 4 are independently a halogen element selected from the group consisting of fluorine, chlorine, bromine and iodine, and L 1 , L 2 , L 3 and L 4 are independently a direct bond or a substituted or unsubstituted C 1 -C 10 Alkylene.

12. The SWIR sensor according to claim 11, in, The photoelectric conversion layer comprises: A first photoelectric conversion layer including the polymer and the organic dopant; and The second photoelectric conversion layer includes the polymer, Wherein, the second photoelectric conversion layer is an undoped layer.

13. The SWIR sensor according to claim 11, in: The polymer includes a radical cation having a quinone structure, and The organic dopant is an anion dopant.

14. The SWIR sensor according to claim 11, further comprising: include: a color filter, located on the second electrode; as well as A microlens is located on the color filter.

15. The SWIR sensor according to claim 11, in, The organic dopant forms bound polarons and free polarons in the photoelectric conversion layer, and Wherein, the ratio of the density of the bound polarons to the density of the total polarons in the photoelectric conversion layer is 10% to 50%.

16. A method for manufacturing a photoelectric conversion layer for detecting SWIR, the method The following steps are involved: preparing a film including a polymer represented by the following Formula 1; coating a first doping solution on the film to perform a primary doping process on the polymer; as well as coating a second doping solution on the film to perform a secondary doping process on the polymer, wherein each of the first doping solution and the second doping solution includes an organic dopant represented by the following Formula 2, and Wherein, the first solvent of the first doping solution and the second solvent of the second doping solution are different from each other: [Formula 1] [Formula 2] Wherein, in the above formula 1, R 1 and R 2 are independently hydrogen or substituted or unsubstituted C 1 -C 20 alkyl, and n is an integer between 10 and 10,000, and Wherein, in the above formula 2, X 1 , X 2 , X 3 and X 4 are independently a halogen element selected from the group consisting of fluorine, chlorine, bromine and iodine, and L 1 , L 2 , L 3 and L 4 are independently a direct bond or a substituted or unsubstituted C 1 -C 10 Alkylene.

17. The method according to claim 16, in, The second solvent is capable of swelling the polymer.

18. The method according to claim 16, in, The organic dopant forms bound polarons and free polarons in the film, wherein a ratio of a density of the bound polarons to a density of total polarons in the film is 10% to 50%.

19. The method according to claim 18, in, When SWIR light is incident on the film, the bound polaritons are converted into the free polaritons in response to the SWIR light.

20. The method according to claim 16, in, The coating of the first doping solution and the coating of the second doping solution both include a spin coating process.

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