Photoelectric conversion elements and imaging elements

Abstract

A photoelectric conversion element (10A) according to an embodiment of the present disclosure includes: a first electrode (21); a second electrode (23) arranged opposite to the first electrode (21); and a photoelectric conversion layer (22) arranged between the first electrode (21) and the second electrode (23), the photoelectric conversion layer (22) including a hole transport material as a first organic semiconductor material, the hole transport material absorbing blue light.

Description

Technical Field

[0001] The present disclosure relates to, for example, a photoelectric conversion element using an organic material and an imaging element including the photoelectric conversion element. Background Art

[0002] For example, Patent Document 1 discloses a photoelectric conversion element in which a photoelectric conversion layer is formed using three materials. In this photoelectric conversion element, an organic semiconductor material having maximum absorption within a predetermined wavelength range is used as one of the three materials, and organic semiconductor materials each having high transmittance in the visible light region are used as the other two materials. Consequently, the photoelectric conversion element can achieve high photoelectric conversion efficiency within the predetermined wavelength range.

[0003] Reference List

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. WO 2017 / 159684 Summary of the Invention

[0006] Incidentally, the imaging device is required to have an extended absorption spectrum.

[0007] It is desirable to provide a photoelectric conversion element having a wide absorption spectrum and an imaging device having a wide absorption spectrum.

[0008] A photoelectric conversion element according to an embodiment of the present disclosure includes: a first electrode; a second electrode disposed opposite the first electrode; and a photoelectric conversion layer disposed between the first and second electrodes. The photoelectric conversion layer includes a hole transport material as a first organic semiconductor material. The hole transport material absorbs blue light.

[0009] Each of the plurality of pixels of the image pickup device according to the embodiment of the present disclosure includes one or more of the above-described photoelectric conversion elements according to the embodiment of the present disclosure.

[0010] In the photoelectric conversion element according to the embodiment of the present disclosure and the image pickup device according to the embodiment, the photoelectric conversion layer uses a hole transport material that absorbs blue light as the first organic semiconductor material, thereby expanding the absorption spectrum of the photoelectric conversion layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a cross-sectional schematic diagram illustrating an example of a schematic configuration of a photoelectric conversion element according to an embodiment of the present disclosure.

[0012] Figure 2 It shows that Figure 1 A block diagram showing the configuration of an imaging device including a photoelectric conversion element.

[0013] Figure 3 is a cross-sectional schematic diagram illustrating an example of a schematic configuration of a photoelectric conversion element according to Modification 1 of the present disclosure.

[0014] Figure 4 is a cross-sectional schematic diagram illustrating another example of the schematic configuration of the photoelectric conversion element according to Modification 1 of the present disclosure.

[0015] Figure 5 is a cross-sectional schematic diagram illustrating an example of a schematic configuration of a photoelectric conversion element according to Modification 2 of the present disclosure.

[0016] Figure 6 is a cross-sectional schematic diagram illustrating an example of a schematic configuration of a photoelectric conversion element according to Modification 3 of the present disclosure.

[0017] Figure 7 It shows that Figure 2 A block diagram showing an example of the configuration of electronic equipment of the imaging device shown.

[0018] Figure 8 is a diagram showing an example of a schematic configuration of an endoscopic surgery system.

[0019] Figure 9 : is a block diagram showing an example of the functional configuration of a camera head and a camera control unit (CCU).

[0020] Figure 10 is a block diagram showing an example of a schematic configuration of a vehicle control system.

[0021] Figure 11 It is a diagram for assisting in explaining an example of the installation positions of the vehicle exterior information detection unit and the imaging unit.

[0022] Figure 12 These are absorption spectra of the compound represented by formula (1-1) and the compound represented by formula (5).

[0023] Figure 13 It is the absorption spectrum of the three compounds that form the organic photoelectric conversion layer.

[0024] Figure 14 This is an absorption spectrum diagram of a ternary organic photoelectric conversion layer containing the compound represented by formula (1-1) or the compound represented by formula (5).

[0025] Figure 15 This is an absorption spectrum diagram of a binary organic photoelectric conversion layer containing the compound represented by formula (1-1) or the compound represented by formula (5).

[0026] Figure 16is an X-ray diffraction pattern of a thin film containing the compound represented by formula (1-1).

[0027] Figure 17 is an X-ray diffraction pattern of a ternary organic photoelectric conversion layer containing the compound represented by formula (1-1).

[0028] Figure 18 This is a diagram of the crystal structure of the compound represented by formula (1-1).

[0029] Figure 19 This is a diffraction pattern of the compound represented by formula (1-1). DETAILED DESCRIPTION

[0030] The following describes an embodiment of the present disclosure in detail with reference to the accompanying drawings. The following description is a specific example of the present disclosure, but the present disclosure is not limited to the following methods. In addition, the present disclosure is not limited to the arrangement, size, and dimensional ratio of the components shown in the various figures. It should be noted that the description is given in the following order.

[0031] 1. Embodiment (Example of a photoelectric conversion element having an organic photoelectric conversion layer containing a hole transport material that absorbs blue light)

[0032] 1-1. Structure of Photoelectric Conversion Element

[0033] 1-2. Structure of the Camera Device

[0034] 1-3. Actions and Effects

[0035] 2. Modification

[0036] 2-1. Modification 1 (Example with Addition of Spectrum Adjustment Layer)

[0037] 2-2. Modification 2 (Example of stacking an organic photoelectric conversion unit for detecting blue light and an inorganic photoelectric conversion unit for detecting red and green light)

[0038] 2-3. Modification 3 (Example of stacking organic photoelectric conversion layers having different spectral characteristics)

[0039] 3. Application examples

[0040] 4. Application Examples

[0041] 5. Examples

[0042] <1. Implementation Plan>

[0043] Figure 1 An example of a cross-sectional configuration of a photoelectric conversion element (photoelectric conversion element 10A) according to an embodiment of the present disclosure is shown. Figure 2 Shown include Figure 1The photoelectric conversion element 10A shown in FIG. 1 illustrates an example of the overall configuration of an imaging device (imaging device 1). The photoelectric conversion element 10A is included in one pixel (unit pixel P) of the imaging device 1, such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor used in electronic devices such as digital cameras or video cameras. The photoelectric conversion element 10A according to this embodiment includes an organic photoelectric conversion section 20. The organic photoelectric conversion layer 22 included in the organic photoelectric conversion section 20 is formed using a hole-transporting material that absorbs blue light.

[0044] (1-1. Structure of Photoelectric Conversion Element)

[0045] The photoelectric conversion element 10A includes, for example, a single organic photoelectric conversion section 20. The organic photoelectric conversion section 20 includes an organic photoelectric conversion layer 22 located between a lower electrode 21 (first electrode) and an upper electrode 23 (second electrode) disposed opposite each other. The organic photoelectric conversion layer 22 is formed using the aforementioned organic semiconductor material as an organic material. The organic photoelectric conversion section 20 detects part or all of the wavelengths in the visible light region (e.g., 400 nm to 760 nm).

[0046] In this embodiment, a color filter 51 (color filters 51R, 51G, and 51B) is provided above the organic photoelectric conversion unit 20 (on the light incident side) for each unit pixel P (unit pixels Pr, Pg, and Pb). The color filters 51 (color filters 51R, 51G, and 51B) selectively transmit red light (R), green light (G), and blue light (B). Therefore, in the unit pixel Pr provided with the color filter 51R, the organic photoelectric conversion unit 20 detects the red light passing through the color filter 51R and generates a signal charge corresponding to the red light (R). In the unit pixel Pg provided with the color filter 51G, the organic photoelectric conversion unit 20 detects the green light passing through the color filter 51G and generates a signal charge corresponding to the green light (G). In the unit pixel Pb provided with the color filter 51B, the organic photoelectric conversion section 20 detects blue light passing through the color filter 51B and generates signal charges corresponding to the blue light (B).

[0047] The photoelectric conversion element 10A further includes, for example, a single inorganic photoelectric conversion section 32. The inorganic photoelectric conversion section 32 is formed so as to be embedded in the semiconductor substrate 30. The inorganic photoelectric conversion section 32 detects light within a wavelength range different from that of the organic photoelectric conversion section 20 and performs photoelectric conversion. In other words, the organic photoelectric conversion section 20 and the inorganic photoelectric conversion section 32 each detect light within different wavelength ranges and perform photoelectric conversion. Specifically, the organic photoelectric conversion section 20 detects wavelengths in the visible light region, while the inorganic photoelectric conversion section 32 detects wavelengths in the infrared light region (e.g., from 700 nm to 1000 nm).

[0048] The organic photoelectric converter 20 and the inorganic photoelectric converter 32 are stacked vertically. Specifically, the organic photoelectric converter 20 is provided on the light incident side S1 and on the first surface 30A (back surface) of the semiconductor substrate 30 .

[0049] Therefore, part of the light in the visible light region of each of the color filters 51R, 51G, and 51B (R, G, and B) is absorbed by the organic photoelectric conversion unit 20, respectively. Other light passes through the organic photoelectric conversion unit 20. Specifically, light in the infrared light region passes through the organic photoelectric conversion unit 20. The inorganic photoelectric conversion unit 32 of each of the unit pixels Pr, Pg, and Pb detects this light in the infrared light region (hereinafter referred to as infrared light (IR)) that has passed through the organic photoelectric conversion unit 20. The unit pixels Pr, Pg, and Pb respectively generate signal charges corresponding to the infrared light (IR). In other words, the camera device 1 including the photoelectric conversion element 10A is capable of simultaneously generating visible light images and infrared light images.

[0050] Note that this embodiment describes the case where the electrons in a pair of electrons and holes (electron-hole pairs) generated by photoelectric conversion are read as signal charges (where the n-type semiconductor region serves as the photoelectric conversion layer). Furthermore, the "+ (plus sign)" added to "n" in the figure indicates a high concentration of n-type impurities.

[0051] The second surface 30B (front surface) of the semiconductor substrate 30 is provided with, for example, the charge holding portion 33, and unillustrated pixel transistors and a multilayer wiring layer 40. In the multilayer wiring layer 40, for example, wiring layers 41, 42, and 43 are stacked in an insulating layer 44.

[0052] Note that the figure shows the back surface (first surface 30A) side of the semiconductor substrate 30 as the light incident side S1 and the front surface (second surface 30B) side as the wiring layer side S2 .

[0053] As described above, the organic photoelectric conversion unit 20 has a configuration in which the lower electrode 21, the organic photoelectric conversion layer 22, and the upper electrode 23 are stacked in this order from the first surface 30A side of the semiconductor substrate 30. For example, the lower electrode 21 is formed separately for each photoelectric conversion element 10A. Figure 1 An example is shown in which the organic photoelectric conversion layer 22 and the upper electrode 23 are provided as a continuous layer common to the unit pixels Pr, Pg, and Pb, but like the lower electrode 21, the organic photoelectric conversion layer 22 and the upper electrode 23 may also be formed separately for the unit pixels Pr, Pg, and Pb.

[0054] For example, an interlayer insulating layer 34 is provided between the first surface 30A of the semiconductor substrate 30 and the organic photoelectric conversion unit 20. For example, a color filter 51 is provided above the upper electrode 23 as described above. Although not shown, an optical member such as a planarization layer and an on-chip lens is provided above the color filter 51.

[0055] For example, a through-electrode 35 is provided between the first surface 30A and the second surface 30B of the semiconductor substrate 30. The lower electrode 21 is electrically connected to the charge holding portion 33 via the through-electrode 35. In other words, the through-electrode 35 functions as a connector between the organic photoelectric conversion portion 20 and the charge holding portion 33, and also serves as a transmission path for signal charges generated in the organic photoelectric conversion portion 20. Therefore, the photoelectric conversion element 10A can effectively transmit signal charges (electrons in this case) generated by the organic photoelectric conversion portion 20 on the first surface 30A side of the semiconductor substrate 30 to the second surface 30B side of the semiconductor substrate 30 via the through-electrode 35, thereby improving characteristics. For example, an insulating film 36 is provided around the through-electrode 35. This electrically insulates the through-electrode 35 from the p-well 31.

[0056] In the organic photoelectric conversion unit 20 according to the present embodiment, light from the upper electrode 23 side is absorbed by the organic photoelectric conversion layer 22. The excitons thus generated move to the interface between the electron donor and the electron acceptor included in the organic photoelectric conversion layer 22, and exciton separation is performed. In other words, the excitons dissociate into electrons and holes. The charges (electrons and holes) thus generated are transferred to different electrodes by diffusion caused by the carrier concentration difference and the internal electric field caused by the work function difference between the anode (here the upper electrode 23) and the cathode (here the lower electrode 21). The transferred charge is detected as photocurrent. In addition, by applying a potential between the lower electrode 21 and the upper electrode 23, the transfer direction of electrons and holes can be controlled.

[0057] The structure and materials of each part are described below.

[0058] The organic photoelectric conversion section 20 is an organic photoelectric conversion element that absorbs light corresponding to a part or all of the wavelength range of the visible light region and generates electron-hole pairs.

[0059] The lower electrode 21 is used to attract electrons from the charges generated in the organic photoelectric conversion layer 22 as signal charges and transfer the attracted signal charges to the charge retention unit 33. The lower electrode 21 includes a light-transmitting conductive film. The lower electrode 21 includes, for example, ITO (indium tin oxide). However, in addition to ITO, a tin oxide (SnO2)-based material to which a dopant is added, or a zinc oxide-based material obtained by adding a dopant to zinc oxide (ZnO) can also be used as the material included in the lower electrode 21. Examples of zinc oxide-based materials include aluminum zinc oxide (AZO) to which aluminum (Al) is added as a dopant, gallium zinc oxide (GZO) to which gallium (Ga) is added, and indium zinc oxide (IZO) to which indium (In) is added. In addition, as the material included in the lower electrode 21, CuI, InSbO4, ZnMgO, CuInO2, MgIN2O4, CdO, ZnSnO3, or TiO2 can be used. In addition, a spinel oxide or an oxide having a YbFe2O4 structure can be used.

[0060] The organic photoelectric conversion layer 22 converts light energy into electrical energy. The organic photoelectric conversion layer 22 is formed to include, for example, two or more organic materials that serve as p-type semiconductors or n-type semiconductors, respectively. The organic photoelectric conversion layer 22 has a bulk heterojunction structure in the layer. The bulk heterojunction structure is a p / n junction surface formed by mixing a p-type semiconductor and an n-type semiconductor, and the excitons generated by absorbing light are separated into electrons and holes at the p / n junction interface. It should be noted that the p-type semiconductor relatively serves as an electron donor and the n-type semiconductor relatively serves as an electron acceptor. The organic photoelectric conversion layer 22 provides a field in which the excitons generated when light is absorbed are separated into electrons and holes. Specifically, the excitons are separated into electrons and holes at the interface (p / n junction surface) between the electron donor and the electron acceptor.

[0061] In addition to p-type and n-type semiconductors, organic photoelectric conversion layer 22 may also include three organic materials, or so-called dye materials, that photoelectrically convert light in a predetermined wavelength band while transmitting light in other wavelength bands. Preferably, the p-type semiconductor, n-type semiconductor, and dye material each have different maximum absorption wavelengths. This allows for broad absorption of light in the visible light range.

[0062] In this embodiment, a hole transport material that absorbs blue light is used as one of the two or three organic materials used to form the organic photoelectric conversion layer 22. For example, among the two or three organic materials forming the organic photoelectric conversion layer 22, this hole transport material that absorbs blue light has a maximum absorption wavelength on the shortest wavelength side. In addition, it is preferred that the hole transport material that absorbs blue light has a HOMO level that is shallower than the highest occupied molecular orbital (HOMO) level of the second organic semiconductor material included in the organic photoelectric conversion layer 22 described below. In addition, it is preferred that the hole transport material that absorbs blue light has crystallinity and, for example, has a herringbone molecular arrangement in the layer of the organic photoelectric conversion layer 22.

[0063] Examples of such hole transport materials that absorb blue light include dithieno[2,3-d:2',3'-d']benzo[1,2-b:4,5-b']dithiophene derivatives (hereinafter referred to as DTBDT derivatives) represented by the following general formula (1) or (2). The DTBDT derivatives represented by the general formula (1) or (2) correspond to specific examples of the "first organic semiconductor material" according to the present disclosure.

[0064] [Chemical Formula 1]

[0065]

[0066] (R1, R2, R3 and R4 each independently represent a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenylnaphthyl group, a biphenylnaphthyl group, a binaphthyl group, a thienyl group, a bithiphenyl group, a terthienyl group, a benzothienyl group, a phenylbenzothienyl group, a biphenylbenzothienyl group, a benzofuranyl group, a phenylbenzofuranyl group, an alkyl group, a cycloalkyl group, a fluorenyl group, a benzofluorenyl group, a carbazolyl group or a derivative thereof.)

[0067] Specific substituents introduced into R1, R2, R3 and R4 include the following formulas (A-1) to (A-53). In any of the formulas, the carbon atom bonded to A forms a bond with the carbon atom bonded to any one of R1, R2, R3 and R4 represented by general formula (1) or general formula (2).

[0068] [Chemical Formula 2]

[0069]

[0070] [Chemical Formula 3]

[0071]

[0072] [Chemical Formula 4]

[0073]

[0074] Specific examples of the DTBDT derivative represented by the above-mentioned general formula (1) or general formula (2) include compounds represented by the following formulas (1-1) to (1-5).

[0075] [Chemical Formula 5]

[0076]

[0077] The organic photoelectric conversion layer 22 may further include an organic semiconductor material having electron transport properties. Such an organic semiconductor material having electron transport properties corresponds to a specific example of the "second organic semiconductor material" according to the present disclosure. Examples of organic semiconductor materials having electron transport properties include fullerene C represented by the following formula (3): 60 Or fullerene C represented by formula (4) 70 or their derivatives, etc.

[0078] [Chemical Formula 6]

[0079]

[0080] The organic photoelectric conversion layer 22 may be formed using an organic material or a so-called dye material that photoelectrically converts light in a predetermined wavelength band in the visible light region and transmits light in other wavelength bands as one of the two or three organic materials used to form the organic photoelectric conversion layer 22. This dye material corresponds to a specific example of the “third organic semiconductor material” according to the present disclosure.

[0081] Examples of dye materials include subphthalocyanines, dipyrromethene, merocyanines or squarylium cyanines that absorb light in a wavelength band of 500 nm or more and 600 nm or less, or derivatives thereof. In addition, for example, any of naphthalene, anthracene, phenanthrene, tetracene, pyrene, perylene and fluoranthene or derivatives thereof can be used as dye materials. Alternatively, polymers such as phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene or diacetylene or derivatives thereof can be used. In addition, metal complex dyes, cyanine dyes, merocyanine dyes, phenylxanthene dyes, triphenylmethane dyes, rhodanine dyes, xanthene dyes, macrocyclic nitrogen heterocyclic dyes, azulene dyes, naphthoquinone, anthraquinone dyes, anthracene and pyrene, chain compounds formed by condensation of condensed polycyclic aromatic hydrocarbon groups such as anthracene and pyrene with aromatic rings or heterocyclic compounds, or cyanine dyes bonded via two nitrogen-containing heterocycles such as quinoline, benzothiazole, and benzoxazole having a squaryl group and a croconic methine as a bonding chain, or cyanine dyes bonded via a squaryl group and a croconic methine, etc. It should be noted that as the above-mentioned metal complex dyes, dithiol metal complex dyes, metal phthalocyanine dyes, metal porphyrin dyes, or ruthenium complex dyes are preferred, but are not limited thereto.

[0082] In this manner, the organic photoelectric conversion layer 22 is formed using a plurality of organic semiconductor materials each having a different maximum absorption wavelength, a hole transport material that absorbs blue light, fullerene or its derivative, and a so-called dye material in a specific term. Therefore, light in the visible light region can be widely absorbed.

[0083] Note that the above-mentioned organic semiconductor materials function as a p-type semiconductor or an n-type semiconductor depending on their combination.

[0084] For example, the organic photoelectric conversion layer 22 can be formed by mixing a plurality of organic semiconductor materials as described above and using a vacuum deposition method. Alternatively, for example, a spin coating technique or a printing technique can be used.

[0085] Like the lower electrode 21 , the upper electrode 23 includes a light-transmitting conductive film.

[0086] Other layers may be provided between the organic photoelectric conversion layer 22 and the lower electrode 21, and between the organic photoelectric conversion layer 22 and the upper electrode 23. Specifically, for example, an electron blocking film, the organic photoelectric conversion layer 22, a hole blocking film, and a work function adjustment layer may be stacked in this order from the lower electrode 21 side. Furthermore, an underlayer and a hole transport layer may be provided between the lower electrode 21 and the organic photoelectric conversion layer 22, and a buffer layer and an electron transport layer may be provided between the organic photoelectric conversion layer 22 and the upper electrode 23.

[0087] The semiconductor substrate 30 includes, for example, an n-type silicon (Si) substrate, and includes a p-well 31 in a predetermined region.

[0088] The inorganic photoelectric conversion unit 32 includes, for example, a PIN (Positive Intrinsic Negative) type photodiode PD and has a pn junction in a predetermined region of the semiconductor substrate 30. The inorganic photoelectric conversion unit 32 detects light (infrared light (IR)) within a wavelength range that is partially or entirely within the infrared light region. In addition to the charge retention unit 33, pixel transistors including a transfer transistor, an amplifier transistor, and a reset transistor are provided on the second surface 30B of the semiconductor substrate 30.

[0089] The interlayer insulating layer 34 includes, for example, silicon oxide (SiO x ), TEOS, silicon nitride (SiN x ) and silicon oxynitride (SiON) or a stacked film containing two or more of the above.

[0090] In addition to silicon-doped materials such as PDAS (Phosphorus Doped Amorphous Silicon), the through-electrode 35 can also be formed using metal materials such as aluminum (Al), tungsten (W), titanium (Ti), cobalt (Co), hafnium (Hf) and tantalum (Ta).

[0091] The insulating film 36 is used to electrically isolate the semiconductor substrate 30 and the through-electrode 35. Similar to the interlayer insulating layer 34, silicon oxide (SiO x ), TEOS, silicon nitride (SiN x ) and silicon oxynitride (SiON) etc. to form the insulating film 36.

[0092] (1-2. Structure of the Imaging Device)

[0093] The imaging device 1 is, for example, a CMOS image sensor. The imaging device 1 receives incident light (image light) from a subject through an optical lens system (not shown). The imaging device 1 converts the amount of incident light formed as an image on an imaging surface into an electrical signal in units of pixels, and outputs the electrical signal as a pixel signal. The imaging device 1 includes a pixel portion 100 serving as an imaging area on a semiconductor substrate 30. The imaging device 1 includes, in the peripheral area of ​​the pixel portion 100, for example, a vertical drive circuit 111, a column signal processing circuit 112, a horizontal drive circuit 113, an output circuit 114, a control circuit 115, and an input / output terminal 116.

[0094] The pixel unit 100 includes a plurality of unit pixels P arranged two-dimensionally, for example, in a matrix. These unit pixels P are provided with a pixel drive line Lread (specifically, a row select line and a reset control line) for each pixel row, and a vertical signal line Lsig for each pixel column. The pixel drive line Lread transmits a drive signal for reading a signal from the pixel. One end of the pixel drive line Lread is connected to an output terminal of the vertical drive circuit 111 corresponding to each row.

[0095] The vertical drive circuit 111 includes a shift register, an address decoder, and the like, and is a pixel driver that drives the individual unit pixels P of the pixel section 100, for example, in row units. Signals output from the individual unit pixels P in the pixel row selectively scanned by the vertical drive circuit 111 are supplied to the column signal processing circuit 112 via the respective vertical signal lines Lsig. Each column signal processing circuit 112 includes an amplifier and a horizontal selection switch, etc., provided for each vertical signal line Lsig.

[0096] The horizontal drive circuit 113 includes a shift register, an address decoder, and the like, and sequentially drives the respective horizontal selection switches of the column signal processing circuit 112 while scanning the horizontal selection switches. Through such selective scanning by the horizontal drive circuit 113, the signals of the respective pixels transmitted through the respective vertical signal lines Lsig are sequentially output to the horizontal signal lines 121, and the signals are transmitted to the outside of the semiconductor substrate 30 through the horizontal signal lines 121.

[0097] The output circuit 114 performs signal processing on the signals sequentially supplied from the column signal processing circuits 112 via the horizontal signal line 121 and outputs the signals. The output circuit 114 performs, for example, only buffering in some cases and performs black level adjustment, column variation correction, various digital signal processing, and the like in other cases.

[0098] The circuit portion including the vertical drive circuit 111, the column signal processing circuit 112, the horizontal drive circuit 113, the horizontal signal line 121, and the output circuit 114 may be formed directly on the semiconductor substrate 30, or may be provided in an external control IC. Alternatively, those circuits may be formed in another substrate connected via a cable or the like.

[0099] The control circuit 115 receives a clock supplied from outside the semiconductor substrate 30, data for instructions regarding an operation mode, and the like, and also outputs data such as internal information of the imaging device 1. The control circuit 115 also includes a timing generator that generates various timing signals, and the control circuit 115 controls the driving of peripheral circuits such as the vertical drive circuit 111, the column signal processing circuit 112, and the horizontal drive circuit 113 based on the various timing signals generated by the timing generator.

[0100] The input / output terminal 16 exchanges signals with the outside.

[0101] (1-3. Actions and Effects)

[0102] In the photoelectric conversion element 10A and the image pickup device 1 including the photoelectric conversion element 10A according to this embodiment, the absorption spectrum of the organic photoelectric conversion layer 22 can be expanded by forming the organic photoelectric conversion layer 22 with a hole transport material that absorbs blue light.

[0103] Image sensors using organic photoelectric conversion films have been developed for CCD (Charge Coupled Device) image sensors and CMOS image sensors. For example, an organic imaging device has been proposed that uses an organic photoelectric conversion film having a multilayer structure in which an organic photoelectric conversion film sensitive to blue light (B), an organic photoelectric conversion film sensitive to green light (G), and an organic photoelectric conversion film sensitive to red light (R) are sequentially stacked. This image sensor achieves improved sensitivity by extracting B / G / R signals from a single pixel. Furthermore, an imaging device has been proposed in which an organic photoelectric conversion film is stacked on a semiconductor substrate in which a photodiode is formed as an inorganic photoelectric conversion unit. As described above, this organic photoelectric conversion film is formed using one organic semiconductor material having maximum absorption within a predetermined wavelength range and two organic semiconductor materials having high transparency in the visible light region. In this imaging device, a signal for one color is extracted by the organic photoelectric conversion film, while signals for two colors are extracted by silicon (Si) bulk spectroscopy.

[0104] Incidentally, in recent years, there has been a demand for image sensors capable of capturing images using both visible and infrared (IR) light. For example, the use of the aforementioned organic imaging devices allows for absorption of a wider range of visible light, but this presents a problem: existing technologies make it difficult to manufacture commercial-sized imaging devices.

[0105] On the other hand, when the above-mentioned organic photoelectric conversion film comprising three organic semiconductor materials stacked on a semiconductor substrate in which a photodiode is formed as an inorganic photoelectric conversion portion is applied as a photoelectric conversion film of the above-mentioned image sensor for visible light, the organic photoelectric conversion film has a problem of not being able to provide sufficient sensitivity because the organic photoelectric conversion film is constructed to selectively absorb a predetermined range of visible light regions.

[0106] In contrast, in the present embodiment, a hole transport material that absorbs blue light is used as the organic material contained in the organic photoelectric conversion layer 22. Therefore, the absorption spectrum of the organic photoelectric conversion layer 22 can be expanded.

[0107] For example, the organic photoelectric conversion layer 22 is formed using such a hole transport material that absorbs blue light and one or two organic materials each having a maximum absorption wavelength different from the maximum absorption wavelength of the hole transport material. Therefore, compared with the case where the organic photoelectric conversion layer 22 is formed using one organic semiconductor material having maximum absorption in a predetermined wavelength range and the above-mentioned two organic semiconductor materials having high transparency in the visible light region, light absorption in the blue region is increased.

[0108] As described above, in the photoelectric conversion element 10A according to this embodiment, a hole transport material that absorbs blue light is used as the organic material contained in the organic photoelectric conversion layer 22. Therefore, it is possible to broaden the absorption spectrum of the organic photoelectric conversion layer 22. Therefore, it is possible to provide a photoelectric conversion element 10A having a wide absorption spectrum and an imaging device 1 including the photoelectric conversion element 10A.

[0109] Furthermore, in this embodiment, by selecting (as appropriate) a dye material to be used with the aforementioned hole-transporting material that absorbs blue light, it is possible to form an organic photoelectric conversion layer that detects blue light (B) and red light (R), as well as an organic photoelectric conversion layer that detects blue light and green light (G). Consequently, the number of organic photoelectric conversion films stacked in the aforementioned organic imaging device, which has three organic photoelectric conversion films stacked, can be reduced from three to two or one. In other words, a photoelectric conversion element 10A having broad light absorption and an imaging device 1 including this photoelectric conversion element 10A can be manufactured using simple steps.

[0110] Next, Modifications 1 to 3 of the present disclosure are described. Hereinafter, the same symbols are assigned to components similar to those of the above-described embodiment, and description thereof will be omitted as appropriate.

[0111] <2. Modifications>

[0112] (2-1. Modification 1)

[0113] Figure 3 An example of a cross-sectional configuration of a photoelectric conversion element (photoelectric conversion element 10B) according to Modification 1 of the present disclosure is shown. The photoelectric conversion element 10A described in the above embodiment may further be provided with, for example, a dual bandpass filter 71 as a spectrum adjustment layer.

[0114] The dual-bandpass filter 71 has transmission bands in the visible light region and the infrared light region, respectively. The dual-bandpass filter 71 is provided above the color filter 51 , for example.

[0115] As in the above-described embodiment, when color filters 51R, 51G, and 51B and the organic photoelectric converter 20 are provided above the first surface 30A of the semiconductor substrate 30, which serves as the light incident surface, the infrared light absorbed by the inorganic photoelectric converter 32 of each of the unit pixels Pr, Pg, and Pb is light that has passed through the color filters 51R, 51G, and 51B and the organic photoelectric converter 20. In other words, the infrared light absorbed by the inorganic photoelectric converter 32 of each of the unit pixels Pr, Pg, and Pb has a different spectrum. Therefore, the unit pixels Pr, Pg, and Pb have different sensitivities. This causes the problem that the unit pixels Pr, Pg, and Pb cannot function as IR pixels that generate the same infrared light image.

[0116] To this end, in this modified example, by providing a dual-bandpass filter 71, the infrared light (IR) detected by the inorganic photoelectric conversion unit 32 becomes light in the wavelength range of the passband of the dual-bandpass filter 71 on the infrared light region side. Therefore, the unit pixels Pr, Pg, and Pb are capable of detecting infrared light (IR) having a uniform spectrum. Therefore, the photoelectric conversion element 10B is capable of obtaining an IR image using IR signals obtained from the two-dimensionally arranged unit pixels Pr, Pg, and Pb. Therefore, in addition to the effects of the above-described embodiment, an imaging device 1 capable of obtaining an IR image with high resolution can also be provided.

[0117] In addition, as the spectrum adjustment layer, in addition to the dual-bandpass filter 71, for example, Figure 4 As shown in the photoelectric conversion element 10C, a multilayer film filter 81 can also be used. In the multilayer film filter 81, for example, films each comprising an inorganic material having a high refractive index and films each comprising an inorganic material having a low refractive index are periodically and alternately stacked in a repeating manner. Examples of inorganic materials having a high refractive index include silicon nitride (Si3N4) and titanium oxide (TiO2). Examples of inorganic materials having a low refractive index include silicon oxide (SiO2). For example, the multilayer film filter 81 can be provided between the organic photoelectric conversion unit 20 and the interlayer insulating layer 34.

[0118] In addition, for example, by providing a plasmon filter between the organic photoelectric conversion section 20 and the semiconductor substrate 30 , the same effect can be obtained.

[0119] (2-2. Modification 2)

[0120] Figure 5The cross-sectional configuration of a photoelectric conversion element (photoelectric conversion element 10D) according to Modification 2 of the present disclosure is schematically shown. The photoelectric conversion element 10D is included in a unit pixel P in an imaging device (imaging device 1) such as a CMOS image sensor that can capture images obtained, for example, from visible light without using any color filters. The photoelectric conversion element 10D according to this modification is a so-called vertical spectrum type photoelectric conversion element, in which, for example, one organic photoelectric conversion section 20 and two inorganic photoelectric conversion sections 32G and 32R are stacked in a vertical direction.

[0121] The organic photoelectric converter 20 and the inorganic photoelectric converters 32G and 32R selectively detect light within different wavelength ranges and perform photoelectric conversion. Specifically, the organic photoelectric converter 20, for example, obtains a blue color signal (B). The inorganic photoelectric converters 32G and 32R, respectively, obtain green (G) and red (R) color signals using different absorption coefficients. Thus, the imaging device 10 can obtain multiple types of color signals per pixel without using any color filters.

[0122] The inorganic photoelectric conversion portions 32G and 32R are formed so as to be buried in the semiconductor substrate 30 and are stacked in the thickness direction of the semiconductor substrate 30. The second surface (front surface) 30B of the semiconductor substrate 30 is provided with, for example, floating diffusion portions (floating diffusion layers) FD1, FD2, and FD3; transfer transistors Tr2 and Tr3; an amplifier transistor AMP; a reset transistor RST; a selection transistor SEL; and a multilayer wiring layer 40.

[0123] For example, interlayer insulating layer 34 and insulating layer 37 are provided between first surface 30A of semiconductor substrate 30 and lower electrode 21. Insulating layer 37 includes a layer having fixed charge (fixed charge layer) 37A and a dielectric layer 37B having insulating properties. A protective layer 52 is provided on upper electrode 23. A planarization layer (not shown) and optical components, such as on-chip lens layer 53 including on-chip lens 53L, are provided above protective layer 52.

[0124] In this manner, the present technology is also applicable to an imaging device that captures visible light images. Furthermore, in this modification, the photoelectric conversion element 10D has been described in which one organic photoelectric conversion section 20 and two inorganic photoelectric conversion sections 32R and 32G are stacked. However, the photoelectric conversion element according to the present technology may also have a configuration in which, for example, two organic photoelectric conversion sections that detect blue light (B) and green light (G), respectively, and one inorganic photoelectric conversion section that detects red light (R) are stacked.

[0125] (2-3. Modification 3)

[0126] Figure 6 The cross-sectional structure of a photoelectric conversion element (photoelectric conversion element 10E) according to Modification 3 of the present disclosure is shown. Like the photoelectric conversion element 10D according to Modification 2 described above, the photoelectric conversion element 10E is included in a unit pixel P in an imaging device (imaging device 1) such as a CMOS image sensor that can capture images obtained, for example, from visible light without using any color filters. The photoelectric conversion element 10E according to this modification has a structure in which a red photoelectric conversion portion 90R, a green photoelectric conversion portion 90G, and a blue photoelectric conversion portion 90B are stacked in this order on a semiconductor substrate 30 with an insulating layer 96 interposed therebetween.

[0127] The red photoelectric conversion unit 90R, the green photoelectric conversion unit 90G, and the blue photoelectric conversion unit 90B each include an organic photoelectric conversion layer 92R, 92G, and 92B between a pair of electrodes. Specifically, the red photoelectric conversion unit 90R, the green photoelectric conversion unit 90G, and the blue photoelectric conversion unit 90B each include an organic photoelectric conversion layer 92R, 92G, and 92B between a first electrode 91R and a second electrode 93R, between a first electrode 91G and a second electrode 93G, and between a first electrode 91B and a second electrode 93B, respectively.

[0128] An on-chip lens 98L is provided above the blue photoelectric conversion section 90B via a protective layer 97 and an on-chip lens layer 98. A red storage layer 310R, a green storage layer 310G, and a blue storage layer 310B are provided in the semiconductor substrate 30. Light entering the on-chip lens 98L is photoelectrically converted by the red photoelectric conversion section 90R, the green photoelectric conversion section 90G, and the blue photoelectric conversion section 90B. Signal charge is transferred from the red photoelectric conversion section 90R to the red storage layer 310R, from the green photoelectric conversion section 90G to the green storage layer 310G, and from the blue photoelectric conversion section 90B to the blue storage layer 310B. Although the signal charge can be electrons or holes generated by photoelectric conversion, the following description uses the case where electrons are read out as signal charge as an example.

[0129] The semiconductor substrate 30 includes, for example, a p-type silicon substrate. The red storage layer 310R, green storage layer 310G, and blue storage layer 310B provided in the semiconductor substrate 30 each include an n-type semiconductor region, and signal charges (electrons) provided from the red photoelectric conversion unit 90R, green photoelectric conversion unit 90G, and blue photoelectric conversion unit 90B are accumulated in these n-type semiconductor regions. The n-type semiconductor regions of the red storage layer 310R, green storage layer 310G, and blue storage layer 310B are formed, for example, by doping the semiconductor substrate 30 with n-type impurities such as phosphorus (P) or arsenic (As). It should be noted that the semiconductor substrate 30 may be provided on a supporting substrate (not shown) made of glass or the like.

[0130] The semiconductor substrate 30 includes a circuit for reading electrons from the red power storage layer 310R, the green power storage layer 310G, and the blue power storage layer 310B and transferring the read electrons to, for example, vertical signal lines ( Figure 2 The floating diffusion of the pixel transistor is provided in the semiconductor substrate 30 and is connected to the red power storage layer 310R, the green power storage layer 310G, and the blue power storage layer 310B. The floating diffusion includes an n-type semiconductor region.

[0131] The insulating layer 96 includes, for example, silicon oxide (SiO x ), silicon nitride (SiN x ), silicon oxynitride (SiON) and hafnium oxide (HfO x ) etc. The insulating layer 96 may include a plurality of laminated insulating films. The insulating layer 96 may include an organic insulating material. The insulating layer 96 is provided with plugs and electrodes for connecting the red power storage layer 310R and the red photoelectric conversion unit 90R, connecting the green power storage layer 310G and the green photoelectric conversion unit 90G, and connecting the blue power storage layer 310B and the blue photoelectric conversion unit 90B.

[0132] The red photoelectric conversion section 90R includes, in order from the position closest to the semiconductor substrate 30, a first electrode 91R, an organic photoelectric conversion layer 92R, and a second electrode 93R. The green photoelectric conversion section 90G includes, in order from the position closest to the red photoelectric conversion section 90R, a first electrode 91G, an organic photoelectric conversion layer 92G, and a second electrode 93G. The blue photoelectric conversion section 90B includes, in order from the position closest to the green photoelectric conversion section 90G, a first electrode 91B, an organic photoelectric conversion layer 92B, and a second electrode 93B. An insulating layer 94 is provided between the red photoelectric conversion section 90R and the green photoelectric conversion section 90G. An insulating layer 95 is provided between the green photoelectric conversion section 90G and the blue photoelectric conversion section 90B. The red photoelectric conversion unit 90R, the green photoelectric conversion unit 90G and the blue photoelectric conversion unit 90B selectively absorb red (for example, a wavelength of 600 nm to 700 nm), green (for example, a wavelength of 480 nm to 600 nm) and blue (for example, a wavelength of 400 nm to 480 nm) light and generate electron / hole pairs.

[0133] The first electrode 91R, the first electrode 91G, and the first electrode 91B respectively extract the signal charge generated in the organic photoelectric conversion layer 92R, the signal charge generated in the organic photoelectric conversion layer 92G, and the signal charge generated in the organic photoelectric conversion layer 92B. The first electrodes 91R, 91G, and 91B are provided, for example, for each pixel. The first electrodes 91R, 91G, and 91B each include, for example, a light-transmitting conductive material. Specifically, the first electrodes 91R, 91G, and 91B each include ITO. The first electrodes 91R, 91G, and 91B each may include, for example, a tin oxide-based material or a zinc oxide-based material. The tin oxide-based material is obtained by adding a dopant to tin oxide. Examples of zinc oxide-based materials include: aluminum zinc oxide in which aluminum is added as a dopant to zinc oxide; gallium zinc oxide in which gallium is added as a dopant to zinc oxide; and indium zinc oxide in which indium is added as a dopant to zinc oxide. In addition, IGZO, CuI, InSbO4, ZnMgO, CuInO2, MgIn2O4, CdO, and ZnSnO3 can also be used.

[0134] For example, an electron transport layer may be provided between the first electrode 91R and the organic photoelectric conversion layer 92R, between the first electrode 91G and the organic photoelectric conversion layer 92G, and between the first electrode 91B and the organic photoelectric conversion layer 92B. The electron transport layer facilitates the transfer of electrons generated in the organic photoelectric conversion layers 92R, 92G, and 92B to the first electrodes 91R, 91G, and 91B. The electron transport layer may include, for example, titanium oxide or zinc oxide. The electron transport layer may include a stack of titanium oxide and zinc oxide.

[0135] The organic photoelectric conversion layers 92R, 92G, and 92B each absorb light within a selective wavelength range for photoelectric conversion, while transmitting light within other wavelength ranges. The light within the selective wavelength ranges is, for example, light within a wavelength range of 600 nm to 700 nm in the organic photoelectric conversion layer 92R, light within a wavelength range of 480 nm to 600 nm in the organic photoelectric conversion layer 92G, and light within a wavelength range of 400 nm to 480 nm in the organic photoelectric conversion layer 92B.

[0136] The organic photoelectric conversion layers 92R, 92G, and 92B each have the same structure as the organic photoelectric conversion layer 12 according to the above-described embodiment. For example, the organic photoelectric conversion layers 92R, 92G, and 92B each include, for example, two or more organic semiconductor materials. Preferably, the organic photoelectric conversion layers 92R, 92G, and 92B each include, for example, one or both of a p-type semiconductor and an n-type semiconductor. For example, when the organic photoelectric conversion layers 92R, 92G, and 92B each include two organic semiconductor materials, a p-type semiconductor and an n-type semiconductor, for example, one of the p-type semiconductor and the n-type semiconductor is preferably a material that transmits visible light, and the other is preferably a material that performs photoelectric conversion of light within a selective wavelength range. Alternatively, the organic photoelectric conversion layers 92R, 92G, and 92B each preferably include three organic semiconductor materials, a material that performs photoelectric conversion of light within a selective wavelength range (a dye material), and an n-type semiconductor and a p-type semiconductor that transmit visible light, respectively.

[0137] For example, the organic photoelectric conversion layer 92R preferably uses a material (dye material) that can perform photoelectric conversion on light within a wavelength range of 600 nm to 700 nm. Examples of such materials include subnaphthalocyanine or its derivatives and phthalocyanine or its derivatives. For example, the organic photoelectric conversion layer 92G preferably uses a material (dye material) that can perform photoelectric conversion on light within a wavelength range of 480 nm to 600 nm. Examples of such materials include subnaphthalocyanine or its derivatives. The organic photoelectric conversion layer 92B preferably uses a material (dye material) that can perform photoelectric conversion on light within a wavelength range of 400 nm to 480 nm. Such materials include DTBDT derivatives represented by general formula (1) or general formula (2). In addition, in addition to the above materials, the organic photoelectric conversion layer 92B may also use, for example, a mixture of coumarin or its derivatives and porphyrin or its derivatives.

[0138] For example, a hole transport layer may be provided between the organic photoelectric conversion layer 92R and the second electrode 93R, between the organic photoelectric conversion layer 92G and the second electrode 93G, and between the organic photoelectric conversion layer 92B and the second electrode 93B. The hole transport layer is used to facilitate the provision of holes generated in the organic photoelectric conversion layers 92R, 92G, and 92B to the second electrodes 93R, 93G, and 93B. The hole transport layers may include, for example, molybdenum oxide, nickel oxide, or vanadium oxide. The hole transport layers may include organic materials such as PEDOT (poly(3,4-ethylenedioxythiophene)) and TPD (N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine).

[0139] The second electrode 93R, the second electrode 93G, and the second electrode 93B are used to extract holes generated in the organic photoelectric conversion layer 92R, the holes generated in the organic photoelectric conversion layer 92G, and the holes generated in the organic photoelectric conversion layer 92B, respectively. The holes extracted from the second electrodes 93R, 93G, and 93B are discharged to the p-type semiconductor region (not shown) in the semiconductor substrate 30, for example, through each transmission path (not shown). The second electrodes 93R, 93G, and 93B include, for example, conductive materials such as gold, silver, copper, and aluminum. Like the first electrodes 91R, 91G, and 91B, the second electrodes 93R, 93G, and 93B can each include a transparent conductive material. In the photoelectric conversion element 10E, the holes extracted from the second electrodes 93R, 93G, and 93B are discharged. For example, when a plurality of photoelectric conversion elements 10E are provided in the image pickup device 1 described below, the second electrodes 93R, 93G, and 93B may be provided in common to the respective photoelectric conversion elements 10E (unit pixels P).

[0140] Insulating layer 94 insulates second electrode 93R from first electrode 91G. Insulating layer 95 insulates second electrode 93G from first electrode 91B. Insulating layers 94 and 95 each include, for example, a metal oxide, a metal sulfide, or an organic substance. Examples of metal oxides include silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, zinc oxide, tungsten oxide, magnesium oxide, niobium oxide, tin oxide, and gallium oxide. Examples of metal sulfides include zinc sulfide and magnesium sulfide. Preferably, the material contained in each of insulating layers 94 and 95 has a band gap of 3.0 eV or greater.

[0141] As described above, the present technology is also applicable to a photoelectric conversion element (photoelectric conversion element 10E) in which a red photoelectric conversion unit 90R, a green photoelectric conversion unit 90G, and a blue photoelectric conversion unit 90B are stacked in this order. The red photoelectric conversion unit 90R, the green photoelectric conversion unit 90G, and the blue photoelectric conversion unit 90B each include a photoelectric conversion layer (organic photoelectric conversion layers 92R, 92G, and 92B). The photoelectric conversion layers (organic photoelectric conversion layers 92R, 92G, and 92B) each include an organic semiconductor material.

[0142] <3. Application Examples>

[0143] The above-described imaging device 1 is applicable to any type of electronic equipment having an imaging function, for example, camera systems such as digital cameras and video cameras, and mobile phones having an imaging function. Figure 7 A schematic configuration of an electronic device 1000 is shown.

[0144] The electronic device 1000 includes the imaging device 1 , a DSP (Digital Signal Processor) circuit 1001 , a frame memory 1002 , a display unit 1003 , a recording unit 1004 , an operation unit 1005 , and a power supply unit 1006 . These are connected to one another via a bus 1007 .

[0145] The DSP circuit 1001 is a signal processing circuit that processes a signal supplied from the image pickup device 1. The DSP circuit 1001 outputs image data obtained by processing the signal from the image pickup device 1. The frame memory 1002 temporarily retains the image data processed by the DSP circuit 1001 in units of frames.

[0146] The display unit 1003 includes, for example, a panel-type display device such as a liquid crystal panel or an organic EL (Electro Luminescence) panel, and the recording unit 1004 records moving images or still images captured by the camera 1 in a recording medium such as a semiconductor memory or a hard disk.

[0147] The operation unit 1005 outputs operation signals for various functions of the electronic device 1000 according to user operations. The power supply unit 1006 appropriately supplies various power supplies for the operation of the DSP circuit 1001, frame memory 1002, display unit 1003, recording unit 1004, and operation unit 1005.

[0148] <4. Application Examples>

[0149] <Application Examples of Endoscopic Surgery Systems>

[0150] The technology according to the present disclosure (the present technology) is applicable to various products. For example, the technology according to the present disclosure can be applied to an endoscopic surgery system.

[0151] Figure 8 : is a diagram showing an example of a schematic configuration of an endoscopic surgery system to which the technology according to an embodiment of the present disclosure (the present technology) can be applied.

[0152] exist Figure 8 , a surgeon (doctor) 11131 is shown performing surgery on a patient 11132 on a bed 11133 using an endoscopic surgery system 11000. As shown in the figure, the endoscopic surgery system 11000 includes an endoscope 11100, other surgical tools 11110 such as a pneumoperitoneum tube 11111 and an energy device 11112, a support arm device 11120 for supporting the endoscope 11100, and a cart 11200 on which various devices used for endoscopic surgery are installed.

[0153] Endoscope 11100 includes: a barrel 11101, a region having a predetermined length from the distal end of barrel 11101 being inserted into a body cavity of patient 11132; and a camera 11102 connected to the proximal end of barrel 11101. In the illustrated example, endoscope 11100 is configured as a rigid endoscope having a rigid barrel 11101. However, endoscope 11100 may also be configured as a flexible endoscope having a flexible barrel 11101.

[0154] An opening is provided at the distal end of the lens barrel 11101, and an objective lens is mounted in this opening. A light source device 11203 is connected to the endoscope 11100 so that light generated by the light source device 11203 is guided to the distal end of the lens barrel 11101 via a light guide extending within the lens barrel 11101, and this light is irradiated via the objective lens onto an observation target in the body cavity of the patient 11132. Note that the endoscope 11100 may be a forward-looking endoscope, or may be an oblique-looking endoscope or a side-looking endoscope.

[0155] The camera head 11102 is equipped with an optical system and an imaging element. Light reflected from an observation target (observation light) is focused onto the imaging element through the optical system. The observation light is photoelectrically converted by the imaging element, generating an electrical signal corresponding to the observation light—that is, an image signal corresponding to the observed image. This image signal is transmitted as raw data to the camera control unit (CCU) 11201.

[0156] The CCU 11201 includes a central processing unit (CPU) or a graphics processing unit (GPU), and controls the operation of the endoscope 11100 and the display device 11202 as a whole. In addition, the CCU 11201 receives an image signal from the camera 11102 and performs various image processing such as development processing (demosaicing processing) on ​​the image signal for displaying an image based on the image signal.

[0157] Under the control of the CCU 11201 , the display device 11202 displays an image based on an image signal that has been image-processed by the CCU 11201 .

[0158] The light source device 11203 includes a light source such as a light emitting diode (LED), for example, and supplies irradiation light to the endoscope 11100 when imaging a surgical site.

[0159] The input device 11204 is an input interface of the endoscopic surgery system 11000. The user can input various information or commands to the endoscopic surgery system 11000 through the input device 11204. For example, the user can input a command for changing the imaging conditions (type of irradiation light, magnification, or focal length) of the endoscope 11100.

[0160] The treatment tool control device 11205 controls the driving of the energy device 11112 for cauterizing or cutting tissue, sealing blood vessels, and the like. The pneumoperitoneum device 11206 delivers gas into the body cavity of the patient 11132 via the pneumoperitoneum tube 11111 to inflate the cavity, thereby ensuring the field of view of the endoscope 11100 and the surgeon's working space. The recorder 11207 is a device capable of recording various surgical information. The printer 11208 is a device capable of printing various surgical information in various formats, such as text, images, or charts.

[0161] Note that the light source device 11203 that provides irradiation light to the endoscope 11100 when imaging the surgical site may include a white light source, which includes, for example, an LED, a laser light source, or a combination of an LED and a laser light source. When the white light source includes a combination of red, green, and blue (RGB) laser light sources, the light source device 11203 can adjust the white balance of the captured image because the output intensity and output timing of each color (each wavelength) can be controlled with high precision. In addition, in this case, if the observation object is irradiated with laser beams from each of the RGB laser light sources in a time-division manner, and the drive of the imaging element of the camera 11102 is controlled in synchronization with the irradiation timing. It is also possible to capture images corresponding to R, G, and B respectively in a time-division manner. According to this method, a color image can be obtained even if a color filter is not provided in the imaging element.

[0162] Furthermore, the light source device 11203 can be controlled so that the output light intensity changes at predetermined intervals. By controlling the driving of the imaging element of the camera 11102 in synchronization with the timing of the light intensity change, acquiring images in a time-division manner, and then synthesizing the images, it is possible to produce a high dynamic range image without underexposed shadows or overexposed highlights.

[0163] Furthermore, the light source device 11203 can be configured to provide light of a predetermined wavelength band intended for special light observation. In special light observation, for example, narrowband observation (narrowband imaging) is performed by utilizing the wavelength dependence of light absorption in human tissue and illuminating light of a narrower band than that used for ordinary observation (i.e., white light). This allows for high-contrast imaging of predetermined tissue, such as blood vessels in the mucosal surface layer. Alternatively, special light observation can be performed using fluorescence observation, where images are obtained by illuminating excitation light to generate fluorescence. In fluorescence observation, fluorescence from human tissue can be observed by illuminating the tissue with excitation light (autofluorescence observation), or a fluorescence image can be obtained by locally injecting an agent, such as indocyanine green (ICG), into the tissue and illuminating the tissue with excitation light corresponding to the fluorescence wavelength of the agent. As described above, the light source device 11203 can be configured to provide such narrowband light and / or excitation light suitable for special light observation.

[0164] Figure 9 It shows Figure 8 A block diagram of an example of the functional configuration of the camera 11102 and CCU 11201 is shown.

[0165] The camera 11102 includes a lens unit 11401, an imaging unit 11402, a driving unit 11403, a communication unit 11404, and a camera control unit 11405. The CCU 11201 includes a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera 11102 and the CCU 11201 are communicably connected to each other via a transmission cable 11400.

[0166] The lens unit 11401 is an optical system provided at a position connected to the lens barrel 11101. Observation light obtained from the distal end of the lens barrel 11101 is guided to the camera 11102 and is incident on the lens unit 11401. The lens unit 11401 includes a combination of multiple lenses (including a zoom lens and a focus lens).

[0167] The number of imaging elements included in the imaging unit 11402 can be one (single-board type) or multiple (multi-board type). For example, in the case where the imaging unit 11402 is constructed as a multi-board type imaging unit, image signals corresponding to R, G and B respectively are generated by the imaging elements, and these image signals can be synthesized to obtain a color image. The imaging unit 11402 can also be constructed to have a pair of imaging elements for respectively acquiring a right-eye image signal and a left-eye image signal prepared for three-dimensional (3D) display. If 3D display is performed, the surgeon 11131 can more accurately grasp the depth of living tissue in the surgical site. It should be noted that in the case where the imaging unit 11402 is constructed as a stereoscopic type, a system of multiple lens units 11401 is provided corresponding to each imaging element.

[0168] In addition, the imaging unit 11402 does not have to be provided on the camera head 11102. For example, the imaging unit 11402 can be provided just behind the objective lens in the lens barrel 11101.

[0169] The drive unit 11403 includes an actuator and moves the zoom lens and focus lens of the lens unit 11401 by a predetermined distance along the optical axis under the control of the camera control unit 11405. Therefore, the magnification and focus of the image captured by the imaging unit 11402 can be appropriately adjusted.

[0170] The communication unit 11404 includes a communication device for transmitting and receiving various information to and from the CCU 11201. The communication unit 11404 transmits an image signal obtained from the imaging unit 11402 to the CCU 11201 through the transmission cable 11400 as raw data.

[0171] In addition, the communication unit 11404 receives a control signal for controlling the driving of the camera 11102 from the CCU 11201, and provides the control signal to the camera control unit 11405. For example, the control signal includes information related to imaging conditions, such as information specifying the frame rate of the captured image, information specifying the exposure value during imaging, and / or information specifying the magnification and focus of the captured image.

[0172] Note that imaging conditions such as frame rate, exposure value, magnification, or focus can be appropriately specified by the user, or can be automatically set based on the acquired image signal by the control unit 11413 of the CCU 11201. In the latter case, the endoscope 11100 includes an automatic exposure (AE) function, an automatic focus (AF) function, and an automatic white balance (AWB) function.

[0173] The camera control unit 11405 controls the driving of the camera 11102 based on the control signal received from the CCU 11201 through the communication unit 11404 .

[0174] The communication unit 11411 includes a communication device for transmitting and receiving various information to and from the camera 11102. The communication unit 11411 receives an image signal transmitted from the camera 11102 through the transmission cable 11400.

[0175] Furthermore, the communication unit 11411 transmits a control signal for controlling the driving of the camera 11102 to the camera 11102. The image signal and the control signal can be transmitted through electrical communication, optical communication, or the like.

[0176] The image processing unit 11412 performs various image processing on the image signal in the raw data format sent from the camera 11102 .

[0177] The control unit 11413 performs various controls related to imaging the surgical site, etc. through the endoscope 11100 and displaying the captured image obtained by imaging the surgical site, etc. For example, the control unit 11413 generates a control signal for controlling the driving of the camera head 11102 .

[0178] Furthermore, based on the image signal processed by the image processing unit 11412, the control unit 11413 controls the display device 11202 to display a captured image of the surgical site, etc. In this case, the control unit 11413 can utilize various image recognition technologies to identify various objects in the captured image. For example, by detecting the shape and color of the edges of objects included in the captured image, the control unit 11413 can identify surgical tools such as forceps, specific living body parts, bleeding, and mist during the use of the energy device 11112. When the control unit 11413 controls the display device 11202 to display the captured image, it can use the recognition results to display various surgical assistance information superimposed on the image of the surgical site. Displaying this surgical assistance information superimposed on the image of the surgical site and presenting it to the surgeon 11131 can reduce the burden on the surgeon 11131, allowing the surgeon 11131 to perform the surgery reliably.

[0179] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 to each other is an electric signal cable prepared for electric signal communication, an optical fiber prepared for optical communication, or a composite cable prepared for electric communication and optical communication.

[0180] Here, in the illustrated example, although communication is performed by wired communication using the transmission cable 11400, communication between the camera 11102 and the CCU 11201 may be performed by wireless communication.

[0181] An example of an endoscopic surgery system to which the technology of the present disclosure can be applied has been described above. The technology of the present disclosure can be applied to the imaging unit 11402 among the above components. By applying the technology of the present disclosure to the imaging unit 11402, detection accuracy is improved.

[0182] It should be noted that an endoscopic surgical system is used as an example for description herein, but the technology disclosed herein can also be applied to, for example, a microsurgery system.

[0183] <Application examples for mobile objects>

[0184] The technology according to the present disclosure is applicable to various products. For example, the technology according to the present disclosure can be implemented as a device installed on any type of mobile object, such as an automobile, an electric vehicle, a hybrid vehicle, a motorcycle, a bicycle, a personal mobile device, an airplane, a drone, a ship, a robot, construction machinery, or agricultural machinery (tractor).

[0185] Figure 10 : is a block diagram showing a schematic configuration example of a vehicle control system as an example of a mobile body control system to which the technology according to the embodiment of the present disclosure is applicable.

[0186] The vehicle control system 12000 includes a plurality of electronic control units connected to each other via a communication network 12001. Figure 10 In the illustrated example, a vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an exterior information detection unit 12030, an interior information detection unit 12040, and an integrated control unit 12050. Furthermore, the functional configuration of the integrated control unit 12050 includes a microcomputer 12051, a sound / image output unit 12052, and an in-vehicle network interface (I / F) 12053.

[0187] Drive system control unit 12010 controls the operation of devices related to the vehicle's drive system according to various programs. For example, drive system control unit 12010 functions as a control device for the following devices: a drive force generating device, such as an internal combustion engine or a drive motor, for generating drive force for the vehicle; a drive force transmission mechanism for transmitting drive force to the wheels; a steering mechanism for adjusting the vehicle's steering angle; and a braking device for generating braking force for the vehicle.

[0188] The body system control unit 12020 controls the operation of various devices installed on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for the following devices: a keyless entry system; a smart key system; power windows; or various lights such as headlights, taillights, brake lights, turn signals, and fog lights. In this case, radio waves transmitted from a mobile device that replaces a key or signals from various switches can be input to the body system control unit 12020. The body system control unit 12020 receives these input radio waves or signals and controls the vehicle's door locks, power windows, lights, and so on.

[0189] The vehicle exterior information detection unit 12030 detects information about the exterior of the vehicle, including the vehicle control system 12000. For example, the vehicle exterior information detection unit 12030 is connected to the camera unit 12031. The vehicle exterior information detection unit 12030 causes the camera unit 12031 to capture an image of the exterior of the vehicle and receives the captured image. Based on the received image, the vehicle exterior information detection unit 12030 can detect objects such as pedestrians, vehicles, obstacles, signs, or letters on the road surface, or perform distance detection processing.

[0190] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output this electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 can be visible light or non-visible light such as infrared light.

[0191] The in-vehicle information detection unit 12040 detects information about the vehicle's interior. For example, the in-vehicle information detection unit 12040 is connected to a driver status detection unit 12041 for detecting the driver's condition. For example, the driver status detection unit 12041 includes a camera for capturing the driver's image. Based on the detection information input from the driver status detection unit 12041, the in-vehicle information detection unit 12040 can calculate the driver's level of fatigue or concentration, or determine whether the driver is dozing off.

[0192] Based on the information outside or inside the vehicle acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040, the microcomputer 12051 can calculate a control target value for the driving force generating device, the steering mechanism, or the braking device, and can output a control command to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control for implementing advanced driver assistance system (ADAS) functions, such as collision avoidance or impact mitigation, following driving based on a following distance, speed maintenance driving, vehicle collision warning, or lane departure warning.

[0193] In addition, the microcomputer 12051 is capable of controlling the driving force generating device, steering mechanism or braking device, etc. based on the information outside or inside the vehicle obtained by the outside information detection unit 12030 or the inside information detection unit 12040, thereby performing collaborative control for realizing automatic driving, etc., which enables the vehicle to drive autonomously without relying on the driver's operation.

[0194] In addition, based on information outside the vehicle acquired by the vehicle exterior information detection unit 12030, the microcomputer 12051 can output a control command to the body system control unit 12020. For example, the microcomputer 12051 controls the headlights and switches the high beam to the low beam based on the position of the preceding vehicle or oncoming vehicle detected by the vehicle exterior information detection unit 12030, thereby performing cooperative control for preventing glare.

[0195] The sound / image output unit 12052 transmits an output signal of at least one of sound and image to an output device, which can visually or auditorily notify information to passengers on the vehicle or outside the vehicle. Figure 10 In the example of FIG, as output devices, an audio speaker 12061, a display portion 12062, and an instrument panel 12063 are shown. For example, the display portion 12062 may include at least one of an in-vehicle display and a head-up display.

[0196] Figure 11 This is a diagram showing an example of the installation position of the camera unit 12031.

[0197] exist Figure 11 , the camera unit 12031 includes camera units 12101 , 12102 , 12103 , 12104 and 12105 .

[0198] For example, camera units 12101, 12102, 12103, 12104, and 12105 are located at the front nose, rearview mirror, rear bumper, and rear door of vehicle 12100, as well as at the upper portion of the windshield inside the vehicle. Camera unit 12101 located at the front nose and camera unit 12105 located at the upper portion of the windshield inside the vehicle primarily capture images in front of vehicle 12100. Camera units 12102 and 12103 located at the rearview mirror primarily capture images from the side of vehicle 12100. Camera unit 12104 located at the rear bumper or rear door primarily captures images from the rear of vehicle 12100. Camera unit 12105 located at the upper portion of the windshield inside the vehicle primarily detects vehicles ahead, pedestrians, obstacles, traffic lights, traffic signs, lanes, and the like.

[0199] By the way, Figure 11 Examples of the imaging ranges of imaging units 12101 to 12104 are shown. Imaging range 12111 represents the imaging range of imaging unit 12101, located on the front nose. Imaging ranges 12112 and 12113 represent the imaging ranges of imaging units 12102 and 12103, respectively, located on the rearview mirrors. Imaging range 12114 represents the imaging range of imaging unit 12104, located on the rear bumper or rear door. For example, by superimposing the image data acquired by imaging units 12101 to 12104, a bird's-eye view image of vehicle 12100 as viewed from above is obtained.

[0200] At least one of the imaging units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera composed of a plurality of imaging elements, or may be an imaging element having pixels for phase difference detection.

[0201] For example, microcomputer 12051 can determine the distance to each three-dimensional object within imaging ranges 12111-12114 and the change in this distance over time (relative speed to vehicle 12100) based on the distance information obtained from imaging units 12101-12104. This allows the microcomputer 12051 to identify the three-dimensional object closest to vehicle 12100 on the road and traveling in the same direction as vehicle 12100 at a predetermined speed (e.g., greater than or equal to 0 km / h) as the leading vehicle. Furthermore, microcomputer 12051 can pre-set a following distance to be maintained ahead of the leading vehicle and execute automatic braking control (including follow-up stop control) or automatic acceleration control (including follow-up start control). This allows for cooperative control, such as autonomous driving, that allows the vehicle to travel autonomously without relying on driver input.

[0202] For example, based on the distance information obtained from the imaging units 12101-12104, the microcomputer 12051 can classify 3D object data regarding 3D objects into 3D object data for two-wheeled vehicles, standard vehicles, large vehicles, pedestrians, utility poles, and other 3D objects, extract the classified 3D object data, and use the extracted 3D object data to automatically avoid obstacles. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 as those that the driver of the vehicle 12100 can visually identify and those that are difficult for the driver of the vehicle 12100 to visually identify. The microcomputer 12051 then determines a collision risk, indicating the risk of collision with each obstacle. If the collision risk is equal to or higher than a set value, indicating a possible collision, the microcomputer 12051 outputs a warning to the driver via the audio speaker 12061 or display unit 12062, and executes forced deceleration or evasive steering via the drive system control unit 12010. Thus, the microcomputer 12051 can assist in driving to avoid collisions.

[0203] At least one of the imaging units 12101-12104 may be an infrared camera for detecting infrared rays. For example, the microcomputer 12051 can identify a pedestrian by determining whether the pedestrian exists in the images captured by the imaging units 12101-12104. For example, this pedestrian identification is performed by extracting feature points from the images captured by the imaging units 12101-12104, which are infrared cameras; and performing pattern matching on a series of feature points representing the object's outline to determine whether the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian exists in the images captured by the imaging units 12101-12104 and identifies the pedestrian, the audio / video output unit 12052 controls the display unit 12062 to superimpose and display a rectangular outline on the identified pedestrian for emphasis. The audio / video output unit 12052 may also control the display unit 12062 to display an icon representing the pedestrian at a desired location.

[0204] <5. Examples>

[0205] Next, the embodiments of the present disclosure are described in detail. In Experiment 1, a thin film of the compound represented by the above formula (1-1) and the above organic photoelectric conversion layer 22 was formed into a hole transport material that absorbs blue light, and its spectral characteristics were evaluated. In Experiment 2, the crystallinity of the above film was evaluated. In Experiment 2, the crystal structure of the compound represented by the above formula (1-1) was evaluated. In Experiment 4, a device sample including the above organic photoelectric conversion layer 22 was prepared, and its electrical characteristics were evaluated.

[0206] (Experiment 1: Evaluation of Spectral Characteristics of Thin Films)

[0207] The sample for evaluating spectral characteristics was prepared using the following method. First, a quartz glass substrate cleaned in UV / ozone treatment was moved to a vacuum evaporation apparatus and heated at a substrate temperature of 0°C and a 1×10 -5 Pa or less, while rotating the substrate holder and using a resistance heating method, a film of the compound represented by formula (1-1) is formed. Evaporation is performed at a evaporation rate of 0.1nm / sec to provide a film thickness of 50nm (Experimental Example 1-1). Similarly, as with the compound represented by formula (1-1), a film of a compound (rBDT) represented by the following formula (5) (Experimental Example 1-2) that can be used as a hole transport material is formed. In addition, together with the compound represented by formula (1-1) and the compound represented by formula (5), a film of subphthalocyanine (SubPc) represented by the following formula (6) (Experimental Example 1-3) used as a material for an organic photoelectric conversion layer and a fullerene C represented by the above formula (3) are formed. 60 (Experimental Example 1-4) film.

[0208] [Chemical Formula 7]

[0209]

[0210] Similarly, a composite material containing a compound represented by formula (1-1), subphthalocyanine (SubPc) and fullerene C is formed. 60 The thin films of these three organic materials (Experimental Examples 1-5) were formed at evaporation rates of 0.5 nm / sec, 0.5 nm / sec, and 0.25 nm / sec, respectively, with a film thickness of 200 nm. Similarly, a film containing the compound represented by formula (5) (rBDT), subphthalocyanine (SubPc), and fullerene C was formed. 60 The thin films of these three organic materials (Experimental Examples 1-6) were deposited at evaporation rates of 0.5 nm / sec, 0.5 nm / sec, and 0.25 nm / sec, respectively, with a film thickness of 200 nm. Experimental Examples 1-5 and 1-6 were used as samples for evaluating the spectral characteristics of the ternary organic photoelectric conversion layer.

[0211] In addition, similarly, a thin film comprising two organic materials, a compound represented by formula (1-1) and subphthalocyanine (SubPc) was formed (Experimental Example 1-7). The evaporation rates were 0.5 nm / sec and 0.5 nm / sec, respectively, and the film thickness was 100 nm. Similarly, a thin film comprising two organic materials, a compound represented by formula (5) (rBDT) and subphthalocyanine (SubPc), was formed (Experimental Example 1-8). The evaporation rates were 0.5 nm / sec and 0.5 nm / sec, respectively, and the film thickness was 100 nm. Experimental Examples 1-7 and 1-8 were used as samples for evaluating the spectral characteristics of a binary organic photoelectric conversion layer.

[0212] As spectral characteristics, the transmittance and reflectance of each wavelength in the wavelength region corresponding to wavelength λ = 350nm to 700nm were measured using an ultraviolet-visible spectrophotometer to obtain the light absorptivity (%) absorbed by each film. By using the light absorptivity and film thickness of the film as parameters, the linear absorption coefficient α (cm2) of each film at each wavelength was evaluated according to the Lambert-Beer law. -1 ). max (nm) is the wavelength of the longest wavelength observed among wavelengths showing the maximum value of the linear absorption coefficient observed in a certain absorption spectrum.

[0213] Figure 12 Absorption spectra of a thin film containing the compound represented by formula (1-1) (Experimental Example 1-1) and a thin film containing the compound represented by formula (5) (rBDT) (Experimental Example 1-2) are shown. Figure 13 The films of Experimental Example 1-1 and subphthalocyanine (SubPc) (Experimental Example 1-3) and the films of Experimental Example 1-3 ... 60 Absorption spectra of the thin films (Experimental Examples 1-4). Figure 14 The absorption spectra of the thin films included in the ternary organic photoelectric conversion layers of Experimental Examples 1-5 and 1-6 are shown. Figure 15 The absorption spectra of the thin films included in the binary organic photoelectric conversion layers of Experimental Examples 1-7 and 1-8 are shown.

[0214] Figure 12 The compound represented by formula (1-1) is shown to have a higher linear absorption coefficient than the compound represented by formula (5) (rBDT) in the region of λ = 350 nm to 500 nm. In other words, it has been found that the compound represented by formula (1-1) is a hole transport material having an increased light absorption capability. For example, at λ = 450 nm, the α of the compound represented by formula (1-1) is 7.3 × 10 4 cm -1 , the α of the compound (rBDT) represented by formula (5) is 0.5×10 4 cm -1 . In other words, it has been found that the light absorption ability of the compound represented by formula (1-1) is improved by 15 times at this wavelength. In addition, it has been found that at λ = 450nm to 500nm, the α of the compound represented by formula (5) is almost 0 and does not absorb light. At the same time, the compound represented by formula (1-1) also exhibits light absorption in this wavelength range. This shows that the compound represented by formula (1-1) is a material with higher light absorption ability than the compound (rBDT) represented by formula (5).

[0215] Figure 13The compound represented by formula (1-1), subphthalocyanine (SubPc) and fullerene C are shown. 60 Each effectively absorbs different wavelength regions. For example, it has been found that the α of the compound represented by formula (1-1) is the highest in the blue region of 400nm to 430nm, and light in this range is effectively absorbed. It has been found that the α of subphthalocyanine (SubPc) is the highest in the green region of 500nm to 580nm, and light in this range is effectively absorbed. It has been found that fullerene C 60 The α is highest in the red region of 600nm to 650nm, and light in this range is efficiently absorbed.

[0216] In addition, Table 1 summarizes the compounds represented by formula (1-1), subphthalocyanine (SubPc) and fullerene C 60 λ max Table 1 shows the compound represented by formula (1-1), subphthalocyanine (SubPc) and fullerene C. 60 With different λ max (nm). Wherein, the λ of the compound represented by formula (1-1) max is the shortest wavelength.

[0217] [Table 1]

[0218] <![CDATA[λ max (nm)]]> <![CDATA[C 60 ]]> 612 Formula (1-1) 367 SubPc 563

[0219] The above shows that the three organic materials forming the ternary organic photoelectric conversion layer 22 absorb light in different wavelength regions respectively, thereby effectively improving the light absorption capacity of the organic photoelectric conversion layer. Figure 14 It can be seen in.

[0220] in addition, Figure 14 It is shown that when the compound represented by formula (1-1) is used as a hole transport material, the binary organic photoelectric conversion layer has a larger light absorption coefficient in the range of 350 nm to 500 nm than when the compound represented by formula (5) (rBDT) is used. Figure 12 It can be seen that this is due to the fact that the light absorption coefficient of the compound represented by formula (1-1) in the range of 350nm to 500nm is higher than that of the compound (rBDT) represented by formula (5). In other words, it has been found that by using a compound with strong light absorption ability represented by formula (1-1) as a hole transport material, the ternary organic photoelectric conversion layer 22 can have a full-color spectrum shape. It should be noted that in this organic photoelectric conversion layer 22 (Experimental Example 1-5), the hole transport material is used to absorb light in the blue region, the dye is used to absorb light in the green region, and the electron transport material is used to absorb light in the red region.

[0221] also, Figure 15 It is shown that when the compound represented by formula (1-1) is used as a hole transport material, the light absorption coefficient in the range of 350nm to 500nm is greater than that in the case of using the compound represented by formula (5). As with the ternary organic photoelectric conversion layer (Experimental Example 1-5), this is because the light absorption coefficient of the compound represented by formula (1-1) in the range of 350nm to 500nm is higher than that of the compound represented by formula (5). In other words, it has been found that by using a compound with a strong light absorption ability represented by formula (1-1) as a hole transport material, the binary organic photoelectric conversion layer 22 is able to have a full-color spectrum shape. It should be noted that in this organic photoelectric conversion layer 22 (Experimental Example 1-7), the hole transport material is used to absorb light in the blue region, and the dye is used to absorb light in the green region.

[0222] (Experiment 2: Evaluation of the Crystallinity of Thin Films)

[0223] The following method was used to prepare samples for evaluating the crystallinity of thin films. First, a 50 nm thick ITO film was formed on a glass substrate using a sputtering device. The ITO film was patterned by photolithography and etching, and used as an ITO electrode. Subsequently, the glass substrate provided with the ITO electrode was cleaned in a UV / ozone treatment, and then the substrate temperature was set at 20°C and 1×10 -5 A film of the compound represented by formula (1-1) was formed using a vacuum evaporation apparatus under reduced pressure of 1.5 Pa or less, using a resistance heating method while rotating the substrate holder. Vacuum evaporation was performed at a vacuum evaporation rate of 0.1 nm / sec to provide a film thickness of 50 nm. This served as a sample for evaluating the crystallinity of a thin film of the compound represented by formula (1-1) (Experimental Example 2-1).

[0224] Similarly, when the substrate temperature is 20°C and the -5 Under reduced pressure conditions of Pa or less, the compound represented by formula (1-1), subphthalocyanine (SubPc) and fullerene C were deposited by a vacuum deposition apparatus using a resistance heating method while rotating the substrate holder. 60 Co-evaporation was performed on a glass substrate. The glass substrate had been cleaned using UV / ozone treatment. The film thickness of the glass substrate was 50 nm and the glass substrate had an ITO electrode. The evaporation rates were 0.5 nm / sec, 0.5 nm / sec, and 0.25 nm / sec, respectively, and the film thickness was 230 nm. This was used as a sample for evaluating the crystallinity of the ternary thin film (Experimental Example 2-2).

[0225] To evaluate the crystallinity of the thin film, X-ray irradiation was performed using an X-ray diffraction apparatus whose X-ray source was CuKα, and X-ray diffraction in the out-of-plane direction was measured in the range of 2θ=2° to 30° using an oblique incidence method.

[0226] Figure 16 An X-ray diffraction pattern of a thin film containing the compound represented by formula (1-1) (Experimental Example 2-1) is shown. Figure 17 The compound represented by formula (1-1), subphthalocyanine (SubPc) and fullerene C are shown. 60 X-ray diffraction pattern of the thin film (Experimental Example 2-2).

[0227] It was found that all samples had about three clear peaks in the range of 2θ = 18° to 29°. In addition, no peaks were found in other regions of all samples. Figure 16 These three clear peaks are shown. This indicates that these peaks are derived from the compound represented by formula (1-1). In other words, it has been found that the compound represented by formula (1-1) has crystallinity in the case of thin films. In addition, Figure 17 These peaks are shown at similar positions. This indicates that the compound represented by formula (1-1) also has crystallinity in the ternary organic photoelectric conversion layer.

[0228] In addition, the peak positions and crystallite sizes of Experimental Examples 2-1 and 2-2 were evaluated using the following method: Three clear peaks are defined as the first peak, the second peak, and the third peak in order from the low angle side.

[0229] The peak positions of the first peak, the second peak and the third peak are obtained respectively from the spectrum fitting each peak through background subtraction using Pearson VII function. The second peak is obtained by fitting the second peak with Pearson VII function, and the half-peak width is substituted into the Scherrer formula, thereby obtaining crystallite size. In this case, 0.94 is used as the Scherrer constant K.

[0230] Table 2 summarizes the peak positions and crystallite sizes of the first, second, and third peaks.

[0231] [Table 2]

[0232]

[0233] The peak position of the first peak, the peak position of the second peak and the peak position of the third peak of the thin film of the compound represented by formula (1-1) (Experimental Example 2-1) and the ternary thin film (Experimental Example 2-2) are 19.0° and 19.0°, 23.4° and 23.4°, and 27.9° and 27.9°, respectively. The peak positions of the first peak, the second peak and the third peak of Experimental Example 2-1 and Experimental Example 2-2 do not change. This means that the first peak, the second peak and the third peak are respectively derived from the compound represented by formula (1-1). The crystallite sizes of the first peak of Experimental Example 2-1 and Experimental Example 2-2 are 13.8nm and 15.2, the crystallite sizes of the second peak are 10.9nm and 16.7nm, and the crystallite sizes of the third peak are 10.5nm and 12.8nm, respectively. It has been found that the particle size of the ternary thin film generally increases. This indicates that the compound represented by formula (1-1) is a stable material that does not change in crystallinity even when the compound is mixed with another material and used as a co-evaporated film.

[0234] (Experiment 3: Evaluation of Crystal Structure)

[0235] Experiment 3 investigated what molecular arrangement characteristics of the compound represented by formula (1-1) led to the first peak, the second peak, and the third peak observed in Experiment 2.

[0236] (Experiment 3)

[0237] As a sample for evaluating the crystal structure, a single crystal of the compound represented by formula (1-1) having a block shape of 0.13 mm × 0.09 mm × 0.07 mm was prepared by sublimation purification. For this sample, X-ray structural analysis was performed using XtaLab AFC11 (RINC), where the wavelength was MoKα radiation was used as the X-ray source. A total of 14,584 reflections were measured in the range of θ = 2.067° to 27.484°. The structure was solved using the direct method SIR-2004 using the collected diffraction data. The structure factor F was calculated using the least squares method. 2 Structural optimization was performed, and a powder X-ray diffraction pattern was obtained from the structural optimization results using CuKα as an X-ray source.

[0238] Table 3 summarizes the crystal data and structure optimization results of the compound represented by formula (1-1). Figure 18 The molecular arrangement of the compound represented by formula (1-1) observed from the c-axis is shown. Figure 19 A powder X-ray diffraction pattern of the compound represented by formula (1-1) in the case where CuKα is used as an X-ray source was simulated.

[0239] [Table 3]

[0240]

[0241] Table 3 shows that the R1 factor obtained by structural optimization is 6.28%, which indicates that the structure of the compound represented by formula (1-1) can be analyzed without any problem.

[0242] Figure 18 It is shown that the compound represented by formula (1-1) has a molecular arrangement called herringbone. In the a-axis direction, there is an interaction and π-π stacking caused by the overlap of the π electrons of the compound skeleton represented by formula (1-1). In the b-axis direction, there is a CH-π interaction caused by the interaction between the hydrogen atoms of the compound skeleton represented by formula (1-1) and the π electrons of the skeleton. Due to the presence of these interactions, the compound represented by formula (1-1) forms a molecular arrangement called herringbone.

[0243] As Figure 19 The simulation results show that when CuKα is used as the X-ray source, strong diffraction peaks are determined at 19.03°, 23.67°, and 28.09°. These three diffraction peaks correspond to diffraction peaks from the plane orientations (111), (020), and (121), respectively. These diffraction peaks are all peaks indicating the formation of a herringbone structure. Therefore, it was found that in the case of thin films and ternary thin films, the compound represented by formula (1-1) has a herringbone structure in each film.

[0244] In addition, for photoelectric conversion elements, the hole transport material has a herringbone structure in the organic photoelectric conversion layer, so that the molecules are located in a spatially closer position than the randomly dispersed hole transport material. Therefore, it is expected to improve the charge transport performance in the organic photoelectric conversion layer.

[0245] (Experiment 4: Evaluation of Electrical Characteristics)

[0246] Next, a device sample for evaluation of electrical characteristics was prepared using the following method, and its dark current characteristics and external quantum efficiency (EQE) were evaluated.

[0247] First, as Experimental Example 3-1, a 100 nm thick ITO film was formed on a quartz glass substrate using a sputtering device. This ITO film was patterned by photolithography and etching, and used as an ITO electrode. Subsequently, the quartz glass substrate with the ITO electrode was cleaned in a UV / ozone treatment, and then the quartz glass substrate was moved to a vacuum evaporation device. -5 Under reduced pressure conditions of less than Pa, the substrate holder is rotated while using the resistance heating method to The electron blocking material film represented by the following formula (7) was formed at a deposition rate of 5 nm to form an electron blocking layer. Next, as an organic photoelectric conversion layer, C was formed at a substrate temperature of 20°C and film formation rates of 0.025 nm / sec, 0.050 nm / sec, and 0.050 nm / sec, respectively. 60 A film of fullerene (the above formula (3)), subphthalocyanine (SubPc) represented by the following formula (6) and a compound represented by the following formula (1-1) was prepared to obtain a mixed layer having a thickness of 230 nm. Thus, a film having a composition ratio of 20 vol% (C 60 Fullerene): 40 vol% (SubPc): 40 vol% (Formula (1-1)) of the organic photoelectric conversion layer. A hole-blocking material film represented by the following formula (8) was formed at a deposition rate of 5 nm to form a hole-blocking layer. Finally, a 100 nm thick AlSiCu film was formed on the hole-blocking layer by evaporation, and this AlSiCu film served as the upper electrode. Using the above-described manufacturing method, a photoelectric conversion element (Experimental Example 3-1) having a 1 mm × 1 mm photoelectric conversion region was prepared.

[0248] [Chemical Formula 8]

[0249]

[0250] In Experimental Example 3-2, a photoelectric conversion element was prepared using a method similar to Experimental Example 3-1, except that the compound represented by Formula (5) (rBDT) was used as a hole transport material instead of the compound represented by Formula (1-1).

[0251] A semiconductor parameter analyzer was used to evaluate the EQE and dark current characteristics. Specifically, the light intensity of the light irradiated from the light source to the photoelectric conversion element through the filter was measured to be 1.62 μW / cm 2 The current value (luminous current value) obtained when a bias voltage of -2.6 V is applied between the electrodes is the same as that when the light amount is set to 0 μW / cm 2 The current value (dark current value) obtained when the EQE and dark current characteristics were calculated based on these values. The wavelength of light irradiating the element was selected to correspond to the maximum absorption wavelength of each organic photoelectric conversion layer in the visible range. In both Experimental Examples 3-1 and 3-2, the selected irradiation wavelength was 560 nm.

[0252] Table 4 summarizes the EQE and dark current characteristics of Experimental Example 3-1 and Experimental Example 3-2. The numerical value of Experimental Example 3-1 is a relative value based on Experimental Example 3-2 as a benchmark (1.0). The results show that Experimental Example 3-1 has the same EQE as Experimental Example 3-2, and Experimental Example 3-1 has more favorable dark current characteristics than Experimental Example 3-2. This shows that using the compound represented by formula (1-1) as a material contained in the organic photoelectric conversion layer, excellent EQE and dark current characteristics can be obtained.

[0253] [Table 4]

[0254] Quantum efficiency Dark current Experimental Example 3-1 1.0 0.6 Experimental Example 3-2 1.0 1.0

[0255] In addition, the results of Experiment 1 showed that the organic photoelectric conversion layer of Experimental Example 3-1 was able to absorb wavelengths over a wide range. These results indicate that by using the compound represented by General Formula (1) or General Formula (2) as the material contained in the organic photoelectric conversion layer, a photoelectric conversion element having excellent electrical characteristics and high light absorption capacity can be prepared.

[0256] Although the description is given with reference to the embodiment, modification examples 1 to 3, examples, applicable examples, and application examples, the content of the present disclosure is not limited to the above-mentioned embodiment, etc. The present disclosure can be modified in various ways. For example, the components, arrangement, and number of the photoelectric conversion element 10A, etc., illustrated in the above-mentioned embodiment, etc. are merely examples. Not all components must be provided. In addition, other components may also be included.

[0257] In the above-described embodiment and the like, examples are described in which the organic photoelectric conversion section 20 that detects visible light and the inorganic photoelectric conversion section 32 that detects light in the infrared region are stacked, but the organic photoelectric conversion section 20 alone may be used.

[0258] In addition, in the above-mentioned embodiments, etc., an example in which the lower electrode 21 includes one electrode is described, but two or three or more electrodes may be used. In addition, in the above-mentioned embodiments, etc., the present technology is described with reference to an example of a so-called back-illuminated image sensor in which the multilayer wiring layer 40 is provided on the front surface (second surface 30B) side of the semiconductor substrate 30 and light is incident from the back surface (first surface 30A) side, but the present technology is also applicable to a front-illuminated image sensor.

[0259] Furthermore, in the above-described second modification, as the photoelectric conversion element 10D that detects visible light, an example is described in which red light (R) and green light (G) are detected in the semiconductor substrate 30, and blue light (B) is detected above the semiconductor substrate 30. However, the present invention is not limited thereto. For example, red light (R) may be detected in the semiconductor substrate 30, and two organic photoelectric conversion units may be provided above the semiconductor substrate 30, each detecting green light (G) and blue light (B).

[0260] It should be noted that the effects described herein are merely examples and are not intended to be limiting. In addition, there may be other effects.

[0261] It is important to note that the present disclosure may also have the following configuration. According to this technology having the following configuration, a hole-transporting material that absorbs blue light is used as the first organic semiconductor material to form the photoelectric conversion layer. This broadens the absorption spectrum of the photoelectric conversion layer, allowing for the provision of a photoelectric conversion element and an imaging device each having a broad absorption spectrum. [1]

[0263] A photoelectric conversion element, comprising:

[0264] a first electrode;

[0265] a second electrode disposed opposite to the first electrode; and

[0266] A photoelectric conversion layer is provided between the first electrode and the second electrode, wherein the photoelectric conversion layer includes a hole transport material as a first organic semiconductor material, and the hole transport material absorbs blue light. [2]

[0268] The photoelectric conversion element according to [1], wherein

[0269] The photoelectric conversion layer includes a plurality of organic semiconductor materials having mutually different maximum absorption wavelengths, and

[0270] The maximum absorption wavelength of the hole transport material is the shortest among the plurality of organic semiconductor materials. [3]

[0272] The photoelectric conversion element according to [1] or [2], wherein the hole transport material has crystallinity. [4]

[0274] The photoelectric conversion element according to any one of [1] to [3], wherein the hole transport material has a herringbone molecular arrangement. [5]

[0276] The photoelectric conversion element according to any one of [1] to [4], wherein the photoelectric conversion layer further includes a second organic semiconductor material having a maximum absorption wavelength different from that of the first organic semiconductor material. [6]

[0278] The photoelectric conversion element according to any one of [1] to [4], wherein the photoelectric conversion layer further includes a third organic semiconductor material having a maximum absorption wavelength different from that of the first organic semiconductor material. [7]

[0280] The photoelectric conversion element according to any one of [1] to [4], wherein the photoelectric conversion layer includes a second organic semiconductor material and a third organic semiconductor material, the second organic semiconductor material and the third organic semiconductor material having a maximum absorption wavelength different from the maximum absorption wavelength of the first organic semiconductor material. [8]

[0282] The photoelectric conversion element according to [7], wherein

[0283] The first organic semiconductor material, the second organic semiconductor material and the third organic semiconductor material have different maximum absorption wavelengths, respectively, and

[0284] The maximum absorption wavelength of the first organic semiconductor material is the shortest. [9]

[0286] The photoelectric conversion element according to any one of [5] to [8], wherein

[0287] The second organic semiconductor material includes fullerene or a fullerene derivative, and

[0288] The first organic semiconductor material has a HOMO (Highest Occupied Molecular Orbital) energy level that is shallower than a HOMO energy level of the second organic semiconductor material.

[10]

[0290] The photoelectric conversion element according to any one of [1] to [9], wherein the hole transport material contains a dithieno[2,3-d:2',3'-d']benzo[1,2-b:4,5-b']dithiophene derivative represented by the following general formula (1) or (2).

[0291] [Chemical Formula 1]

[0292]

[0293] (R1, R2, R3 and R4 each independently represent a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenylnaphthyl group, a biphenylnaphthyl group, a binaphthyl group, a thienyl group, a bithiphenyl group, a terthienyl group, a benzothienyl group, a phenylbenzothienyl group, a biphenylbenzothienyl group, a benzofuranyl group, a phenylbenzofuranyl group, a biphenylbenzothienyl group, an alkyl group, a cycloalkyl group, a fluorenyl group, a benzofluorenyl group, a carbazolyl group or a derivative thereof.)

[11]

[0295] The photoelectric conversion element according to any one of [1] to [9], wherein the hole transport material includes a compound represented by the following formula (1-1) to formula (1-5).

[0296] [Chemical Formula 2]

[0297]

[12]

[0299] An imaging element, comprising:

[0300] A plurality of pixels, each pixel being provided with a photoelectric conversion element as one or more organic photoelectric conversion parts, wherein

[0301] The photoelectric conversion elements respectively include:

[0302] a first electrode;

[0303] a second electrode disposed opposite to the first electrode; and

[0304] A photoelectric conversion layer is provided between the first electrode and the second electrode, wherein the photoelectric conversion layer includes a hole transport material as a first organic semiconductor material, and the hole transport material absorbs blue light.

[13]

[0306] The imaging element according to

[12] , wherein the one or more organic photoelectric conversion units and the one or more inorganic photoelectric conversion units are stacked in each pixel, and the one or more inorganic photoelectric conversion units perform photoelectric conversion in a wavelength range different from the wavelength range of each of the organic photoelectric conversion units.

[14]

[0308] The imaging element according to

[13] , wherein

[0309] The inorganic photoelectric conversion unit is formed so as to be buried in the semiconductor substrate, and

[0310] The organic photoelectric conversion portion is formed on the first surface side of the semiconductor substrate.

[15]

[0312] The image pickup element according to

[14] , wherein the semiconductor substrate has a second surface opposite to the first surface, and a plurality of wiring layers are formed on the second surface side.

[16]

[0314] The imaging element according to any one of

[13] to

[15] , wherein

[0315] The organic photoelectric conversion parts each perform photoelectric conversion in the visible light region, and

[0316] The inorganic photoelectric conversion parts each perform photoelectric conversion in the infrared light region.

[17]

[0318] The imaging element according to any one of

[12] to

[16] , wherein a plurality of the organic photoelectric conversion units are stacked in each pixel, and the plurality of organic photoelectric conversion units perform photoelectric conversion in mutually different wavelength ranges.

[0319] This application claims the benefit of Japanese Patent Application No. 2019-200097 filed with the Japan Patent Office on November 1, 2019, the entire contents of which are incorporated herein by reference.

[0320] Those skilled in the art should understand that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors as long as these modifications, combinations, sub-combinations and alterations are within the scope of the appended claims or the equivalents thereof.

Claims

1. A photoelectric conversion element, comprising: a first electrode; a second electrode, disposed opposite to the first electrode; and a photoelectric conversion layer disposed between the first electrode and the second electrode, the photoelectric conversion layer including a hole transport material as a first organic semiconductor material, the hole transport material absorbing blue light, The hole transport material comprises a dithieno[2,3-d:2',3'-d']benzo[1,2-b:4,5-b']dithiophene derivative represented by the following general formula (1) or (2): [Chemical Formula 1] wherein R1, R2, R3 and R4 each independently represent a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenylnaphthyl group, a biphenylnaphthyl group, a binaphthyl group, a thienyl group, a dithienyl group, a terthienyl group, a benzothienyl group, a phenylbenzothienyl group, a biphenylbenzothienyl group, a benzofuranyl group, a phenylbenzofuranyl group, an alkyl group, a cycloalkyl group, a fluorenyl group, a benzofluorenyl group, a carbazolyl group or a derivative thereof.

2. The photoelectric conversion element according to claim 1, wherein The photoelectric conversion layer includes a plurality of organic semiconductor materials having mutually different maximum absorption wavelengths, and The maximum absorption wavelength of the hole transport material is the shortest among the plurality of organic semiconductor materials.

3. The photoelectric conversion element according to claim 1, wherein The hole transport material has crystallinity.

4. The photoelectric conversion element according to claim 1, wherein The hole transport material has a herringbone molecular arrangement.

5. The photoelectric conversion element according to any one of claims 1 to 4, wherein The photoelectric conversion layer further includes a second organic semiconductor material having a maximum absorption wavelength different from that of the first organic semiconductor material.

6. The photoelectric conversion element according to any one of claims 1 to 4, wherein The photoelectric conversion layer further includes a third organic semiconductor material having a maximum absorption wavelength different from that of the first organic semiconductor material.

7. The photoelectric conversion element according to any one of claims 1 to 4, wherein The photoelectric conversion layer includes a second organic semiconductor material and a third organic semiconductor material, the second organic semiconductor material and the third organic semiconductor material having a maximum absorption wavelength different from a maximum absorption wavelength of the first organic semiconductor material.

8. The photoelectric conversion element according to claim 7, wherein The first organic semiconductor material, the second organic semiconductor material, and the third organic semiconductor material have mutually different maximum absorption wavelengths, and The maximum absorption wavelength of the first organic semiconductor material is the shortest.

9. The photoelectric conversion element according to claim 5, wherein The second organic semiconductor material includes fullerene or a fullerene derivative, and The first organic semiconductor material has a highest occupied molecular orbital (HOMO) energy level shallower than a highest occupied molecular orbital (HOMO) energy level of the second organic semiconductor material.

10. The photoelectric conversion element according to claim 1, wherein The dithieno[2,3-d:2',3'-d']benzo[1,2-b:4,5-b']dithiophene derivatives include compounds represented by the following formulas (1-1) to (1-5), [Chemical Formula 2] 11. An imaging element, comprising: A plurality of pixels each provided with the photoelectric conversion element according to any one of claims 1 to 10 as one or more organic photoelectric conversion portions.

12. The imaging element according to claim 11, wherein In each pixel, the one or more organic photoelectric conversion sections and the one or more inorganic photoelectric conversion sections are stacked, and the one or more inorganic photoelectric conversion sections each perform photoelectric conversion in a wavelength range different from that of each of the organic photoelectric conversion sections.

13. The imaging element according to claim 12, wherein The inorganic photoelectric conversion unit is formed so as to be buried in the semiconductor substrate, and The organic photoelectric conversion portion is formed on the first surface side of the semiconductor substrate.

14. The imaging element according to claim 13, wherein The semiconductor substrate has a second surface opposite to the first surface, and a multilayer wiring layer is formed on the second surface side.

15. The imaging element according to claim 12, wherein The organic photoelectric conversion parts each perform photoelectric conversion in the visible light region, and The inorganic photoelectric conversion parts each perform photoelectric conversion in the infrared light region.

16. The imaging element according to claim 11, wherein A plurality of the organic photoelectric conversion units are stacked in each pixel, and the plurality of organic photoelectric conversion units perform photoelectric conversion in mutually different wavelength ranges.

Images