JP5814293B2 - PHOTOELECTRIC CONVERSION ELEMENT AND IMAGING ELEMENT, PHOTOELECTRIC CONVERSION ELEMENT MANUFACTURING METHOD, AND IMAGING ELEMENT MANUFACTURING METHOD - Google Patents

Description

  The present invention relates to a photoelectric conversion element including a photoelectric conversion layer containing an organic substance, an imaging element using the photoelectric conversion element, a photoelectric conversion element, and a method for manufacturing the imaging element. Specifically, the present invention relates to a photoelectric conversion element and an image pickup element that can suppress an increase in dark current, a method for manufacturing the photoelectric conversion element, and a method for manufacturing the image pickup element.

  A photoelectric conversion element having a pair of electrodes and a photoelectric conversion layer using an organic compound provided between the pair of electrodes is known. Currently, development of photoelectric conversion elements and (solid) imaging elements using organic compounds is underway.

  For example, Patent Document 1 discloses a photoelectric conversion unit having a phosphor layer that emits light by absorbing radiation, an upper electrode, a lower electrode, and a photoelectric conversion film made of an organic photoelectric conversion material sandwiched between the upper and lower electrodes. A radiation imaging device is described. In this radiation imaging element, the photoelectric conversion film absorbs light emitted from the phosphor layer and generates charges, thereby capturing a radiation image.

Further, Patent Document 2 has a photoelectric conversion layer and a charge blocking layer made of an organic photoelectric conversion material between electrode pairs, and a glass transition temperature between the photoelectric conversion layer and the charge blocking layer. A photoelectric conversion element having an intermediate layer composed of an organic compound at 200 ° C. or higher and an imaging element using the photoelectric conversion element are described.
Furthermore, Patent Document 3 has a photoelectric conversion layer made of an organic photoelectric conversion material between electrode pairs, and the photoelectric conversion layer has an electron spin number of 1.0 × 10 ¹⁵ / cm ³ or less. A photoelectric conversion element and an imaging element using the photoelectric conversion element are described.

In such photoelectric conversion elements and image sensors, dark current is known as a cause of image quality degradation of images to be captured.
Further, in Patent Document 2 and Patent Document 3, after forming a photoelectric conversion layer made of an organic photoelectric conversion material, or further forming a protective layer or the like, heat treatment (annealing / annealing treatment) is performed, whereby dark current is reduced. It is described that it can be reduced.

JP 2009-32854 A JP 2011-187918 A JP 2011-199263 A

As shown in Patent Literature 2 and Patent Literature 3, dark current of a photoelectric conversion element or the like using an organic photoelectric conversion material can be reduced by performing heat treatment.
However, the dark current of the photoelectric conversion element and the image pickup element may increase during use. That is, the initial dark current can be reduced by performing heat treatment, but these conventional methods cannot suppress an increase in dark current that occurs after the product is completed.
Therefore, in a photoelectric conversion element or an image sensor having a photoelectric conversion layer using a conventional organic photoelectric conversion material, such as a photoelectric conversion element or an image sensor, noise gradually increases due to an increase in dark current and an image with a poor S / N ratio. It may become.

  An object of the present invention is to solve such a problem of the prior art, and is a photoelectric conversion element and an imaging element having a photoelectric conversion layer using an organic photoelectric conversion material, and suppressing an increase in dark current. It is an object to provide a photoelectric conversion element and an image sensor that can perform the above-described processes, and a method for manufacturing the photoelectric conversion element and the image sensor.

In order to achieve this object, the photoelectric conversion element of the present invention is formed by laminating a lower electrode, an organic layer including a photoelectric conversion layer, and an upper electrode in this order on a substrate, and a photoelectric conversion layer Is a photoelectric conversion element including an organic photoelectric conversion material having a bulk heterostructure of an N-type organic semiconductor composed of a P-type organic semiconductor and fullerene represented by the following general formula (1):
Provided is a photoelectric conversion element, wherein the degree of crystallinity of fullerene in the photoelectric conversion layer is 1 to 5%.
(In the general formula (1), Z ₁ represents a ring containing at least two carbon atoms and represents a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. L ₁ , L ₂ and L ₃ each independently represents an unsubstituted methine group or a substituted methine group, D ₁ represents an atomic group, and n represents an integer of 0 or more.)

  Moreover, the imaging device of this invention is an imaging device which has a photoelectric conversion element, Comprising: A photoelectric conversion element is a photoelectric conversion device of this invention, The imaging device characterized by the above-mentioned is provided.

Moreover, the manufacturing method of the photoelectric conversion element of the present invention is formed by laminating a lower electrode, an organic layer including a photoelectric conversion layer, and an upper electrode in this order on a substrate. A method for producing a photoelectric conversion element comprising an organic photoelectric conversion material having a bulk heterostructure of an N-type organic semiconductor composed of a P-type organic semiconductor and fullerene represented by the general formula (1),
After forming the photoelectric conversion layer and before irradiating the photoelectric conversion layer with X-rays, performing a process of improving the PL intensity of the photoelectric conversion layer by 10% or more when excited at an excitation wavelength of 532 nm. A method for producing a photoelectric conversion element is provided.
(In the general formula (1), Z ₁ represents a ring containing at least two carbon atoms, and represents a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. L ₁ , L ₂ and L ₃ each independently represents an unsubstituted methine group or a substituted methine group, D ₁ represents an atomic group, and n represents an integer of 0 or more.)

In such a method for producing a photoelectric conversion element of the present invention, the treatment for improving the PL intensity of the photoelectric conversion layer by 10% or more is preferably a heat treatment at 210 to 250 ° C.
Furthermore, it is preferable to have a sealing layer that covers the organic layer and the upper electrode, and after this sealing layer is formed, a process for improving the PL intensity of the photoelectric conversion layer by 10% or more is preferably performed.
Moreover, it is preferable that the photoelectric conversion element further includes a charge storage unit that stores charges generated by the photoelectric conversion layer, and a connection unit for transmitting charges generated by the photoelectric conversion layer to the charge storage unit.
Furthermore, it is preferable that the organic layer has an electron blocking layer for suppressing injection of electrons from the lower electrode to the photoelectric conversion layer under the photoelectric conversion layer.

  Moreover, the manufacturing method of the image pick-up element of this invention is a manufacturing method of the image pick-up element which has a photoelectric conversion element, Comprising: It has the process of manufacturing a photoelectric conversion element with the manufacturing method of the photoelectric conversion element of this invention, A method for manufacturing an imaging device is provided.

  According to the present invention having such a configuration, an increase in dark current of a photoelectric conversion element and an imaging element caused by X-rays to be described later can be suppressed, so that a high-quality image with low noise and a high SN ratio can be obtained over a long period of time. It is possible to obtain a photoelectric conversion element and an imaging element that can be stably obtained.

It is a figure which shows notionally an example of the photoelectric conversion element of this invention manufactured by the manufacturing method of the photoelectric conversion element of this invention. It is a figure which shows notionally an example of the image pick-up element of this invention manufactured by the manufacturing method of the image pick-up element of this invention. (A)-(c) is a conceptual diagram for demonstrating the manufacturing method of the image pick-up element of this invention. (A) And (b) is a conceptual diagram for demonstrating the manufacturing method of the image pick-up element of this invention.

  Hereinafter, the photoelectric conversion device and the imaging device of the present invention, and the method for manufacturing the photoelectric conversion device and the method for manufacturing the imaging device of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

In FIG. 1, an example of the photoelectric conversion element of this invention manufactured by the manufacturing method of the photoelectric conversion element of this invention is shown notionally.
In the photoelectric conversion element 100 illustrated in FIG. 1, a lower electrode 104 is formed on a substrate 102, and a photoelectric conversion unit 106 is formed on the lower electrode 104. An upper electrode 108 is formed on the photoelectric conversion unit 106. Further, a sealing layer 110 that seals the lower electrode 104, the upper electrode 108, and the photoelectric conversion unit 106 is provided so as to cover the upper electrode 108.
The photoelectric conversion unit 106 includes a photoelectric conversion layer 112 including an organic photoelectric conversion material described later and an electron blocking layer 114. In the photoelectric conversion unit 106, an electron blocking layer 114 is formed on the lower electrode 104.

  The substrate 102 is composed of, for example, a silicon substrate or a glass substrate.

The lower electrode 104 is an electrode for collecting holes in the electric charges generated in the photoelectric conversion unit 106.
Examples of the material of the lower electrode 104 include metals, metal oxides, metal nitrides, metal borides, organic conductive compounds, and mixtures thereof. Specifically, conductive metal oxides such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), indium tungsten oxide (IWO), and titanium oxide, titanium nitride (TiN) Metal nitrides such as gold (Au), platinum (Pt), silver (Ag), chromium (Cr), nickel (Ni), aluminum (Al), etc., and these metals and conductive metal oxides A mixture or laminate of the above, an organic conductive compound such as polyaniline, polythiophene, and polypyrrole, a laminate of these with ITO, and the like. The material of the lower electrode 104 is particularly preferably any of titanium nitride, molybdenum nitride, tantalum nitride, and tungsten nitride.

  In the present invention, a TiN substrate or a CMOS substrate on which electrodes are formed may be used as the substrate 102 and the lower electrode 104.

As described above, the photoelectric conversion unit 106 includes the upper photoelectric conversion layer 112 and the lower electron blocking layer 114.
The photoelectric conversion layer 112 is a layer that includes a photoelectric conversion material that receives light and generates a charge corresponding to the amount of light.
In the present invention, the photoelectric conversion layer 112 is an organic photoelectric conversion having a bulk heterostructure of a P-type organic semiconductor represented by the following general formula (1) and an N-type organic semiconductor composed of fullerene (fullerene and / or fullerene derivative). It is a layer made of a material (a layer mainly composed of this organic photoelectric conversion material).
(In the general formula (1), Z ₁ represents a ring containing at least two carbon atoms, and represents a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. L ₁ , L ₂ and L ₃ each independently represents an unsubstituted methine group or a substituted methine group, D ₁ represents an atomic group, and n represents an integer of 0 or more.)
This organic photoelectric conversion material will be described in detail later.

As will be described in detail later, the photoelectric conversion layer 112 (photoelectric conversion element 100) has a PL (Photoluminescence) intensity of 10% or more when excited at a wavelength of 532 nm before being irradiated with X-rays after formation. The process which improves is performed. This process is performed, for example, as the next process of the formation process of the sealing layer 110 described later.
Further, as will be described in detail later, the photoelectric conversion layer 112 that has been processed to improve the PL intensity by 10% or more has a crystallinity of 1-5% of fullerene, which is an N-type organic semiconductor.

  The thickness of the photoelectric conversion layer 112 is preferably 10 to 1000 nm or less, more preferably 50 to 800 nm or less, and particularly preferably 100 to 500 nm or less. By setting the thickness of the photoelectric conversion layer 112 to 10 nm or more, a suitable dark current suppressing effect can be obtained, and by setting the thickness of the photoelectric conversion layer 112 to 1000 nm or less, preferable photoelectric conversion efficiency can be obtained.

For example, the photoelectric conversion layer 112 is formed by a vapor deposition method such as vacuum deposition. Note that all the steps during film formation are preferably performed in a vacuum. This basically prevents the compound from coming into direct contact with oxygen and moisture in the outside air. It is preferable to use PI or PID control of the deposition rate using a film thickness monitor such as a quartz crystal resonator or an interferometer.
Further, since the photoelectric conversion layer 112 is a layer made of the P-type organic semiconductor and fullerene represented by the general formula (1), a co-evaporation method, a flash evaporation method, or the like in which two or more compounds are simultaneously deposited is preferably used. be able to.
Or you may form the photoelectric converting layer 112 by the apply | coating method using the coating material containing the P-type organic semiconductor and fullerene which are shown by the above-mentioned General formula (1). In addition, when using the apply | coating method, you may heat-process after drying or combining with drying as needed.

The electron blocking layer 114 is a layer for preventing electrons from being injected into the photoelectric conversion unit 106 from the lower electrode 104, and is configured of a single layer or a plurality of layers. The electron blocking layer 114 includes an organic material, an inorganic material, or both.
The electron blocking layer 114 may be composed of a single organic material film, or may be composed of a mixed film of a plurality of different organic materials. The electron blocking layer 114 is preferably formed of a material having a high electron injection barrier from the adjacent lower electrode 104 and a high hole transporting property. As an electron injection barrier, the electron affinity of the electron blocking layer 114 is preferably 1 eV or more, and more preferably 1.3 eV or less, and particularly preferably 1.5 eV or more, lower than the work function of the adjacent electrode. Is preferred.
The material for forming the electron blocking layer 114 will also be described in detail later.

The electron blocking layer 114 has a thickness of 20 nm or more in order to sufficiently suppress the contact between the lower electrode 104 and the photoelectric conversion layer 112 and avoid the influence of defects and dust existing on the surface of the lower electrode 104. preferable. The thickness of the electron blocking layer 114 is more preferably 40 nm or more, and particularly preferably 60 nm or more.
If the electron blocking layer 114 is too thick, the problem of increasing the supply voltage necessary for applying an appropriate electric field strength to the photoelectric conversion layer 112 and the carrier transport process in the electron blocking layer 114 may be caused by photoelectric conversion. There may be a problem that the performance of the element is adversely affected. Therefore, the total film thickness of the electron blocking layer 114 is preferably 300 nm or less, more preferably 200 nm or less, and further preferably 100 nm or less.
Various methods can be used to form the electron blocking layer 114 depending on the material.

The upper electrode 108 is an electrode that collects electrons out of charges generated in the photoelectric conversion unit 106. The upper electrode 108 is a conductive material having a sufficient transmittance with respect to light having a wavelength with which the photoelectric conversion unit 106 has sensitivity (light having an absorption wavelength of the photoelectric conversion layer 112) so that light is incident on the photoelectric conversion unit 106. Formed of material.
Further, by applying a bias voltage between the upper electrode 108 and the lower electrode 104, among the charges generated in the photoelectric conversion unit 106, holes can be moved to the lower electrode 104 and electrons can be moved to the upper electrode 108. it can.

For the upper electrode 108, a transparent conductive oxide is used in order to increase the absolute amount of light incident on the photoelectric conversion layer and increase the external quantum efficiency.
_{Specifically, ITO, IZO, SnO 2,} ATO ( antimony-doped tin oxide), ZnO, AZO (Al-doped zinc oxide), GZO (gallium-doped zinc oxide), TiO _2, FTO (fluorine-doped tin oxide) or the like Preferably exemplified.

  Various methods can be used to form the upper electrode 108 depending on the material, but a sputtering method is preferably exemplified.

The light transmittance of the upper electrode 108 is preferably 60% or more, more preferably 80% or more, still more preferably 90% or more, and 95% or more in the visible light wavelength. Particularly preferred.
The upper electrode 108 preferably has a thickness of 5 to 20 nm. By making the upper electrode 108 a film thickness of 5 nm or more, the lower layer can be sufficiently covered, and uniform performance can be obtained. On the other hand, when the thickness of the upper electrode 108 is 20 nm or more, the upper electrode 108 and the lower electrode 104 are locally short-circuited, and the dark current may increase. In addition, when the upper electrode 108 has a thickness of 20 nm or less, it is possible to suppress the occurrence of a local short circuit.

The sealing layer 110 is a layer for preventing a factor that degrades an organic material such as water and oxygen from entering the photoelectric conversion unit 106 containing the organic material.
In the illustrated example, the sealing layer 110 covers the lower electrode 104, the electron blocking layer 114, the photoelectric conversion unit 106, and the upper electrode 108, and seals between the substrate 102.

In the photoelectric conversion element 100 configured as described above, the upper electrode 108 is used as a light incident side electrode. When light L is incident from above the upper electrode 108, the light L is transmitted through the upper electrode 108 and the photoelectric conversion unit 106. Is incident on the photoelectric conversion layer 112, and charges are generated in the photoelectric conversion layer 112.
Holes in the generated charges move to the lower electrode 104. By converting the holes that have moved to the lower electrode 104 into a voltage signal corresponding to the amount of the holes and reading out the light, the light can be converted into a voltage signal and extracted.

  Hereinafter, by explaining the manufacturing method of the photoelectric conversion element 100, the photoelectric conversion element of the present invention and the manufacturing method of the photoelectric conversion element will be described in detail.

First, as the substrate 102 and the lower electrode 104, for example, a TiN substrate having a TiN electrode formed on the substrate is prepared. The TiN electrode as the lower electrode 104 is formed by depositing TiN on the surface of the substrate by sputtering or the like.
Next, an electron blocking material is formed on the lower electrode 104 by vacuum deposition to form the electron blocking layer 114. Examples of the electron blocking material include carbazole derivatives, and more preferably bifluorene derivatives. The film forming conditions may be set as appropriate according to the electron blocking material used.

Next, a p-type organic semiconductor material and fullerene (n-type organic semiconductor material) represented by the general formula (1) are vacuum-deposited (co-evaporated) on the electron blocking layer 114 as an organic photoelectric conversion material. The photoelectric conversion layer 112 constituting the photoelectric conversion unit 106 is formed.
Next, a transparent conductive oxide (for example, ITO) is formed on the photoelectric conversion layer 112 by a sputtering method to form the upper electrode 108.

Next, as the sealing material, for example, aluminum oxide is deposited on the upper electrode 108 and the substrate 102 by an atomic layer deposition method (ALD method). Further, a sealing layer 110 is formed thereon by further forming, for example, silicon nitride as a sealing material by magnetron sputtering.
The sealing layer 110 may be a single layer film.
Note that in the formation of each of the above layers, the film formation conditions may be set as appropriate according to the material used.

Here, in the method for producing a photoelectric conversion element of the present invention, photoelectric conversion when excited at an excitation wavelength of 532 nm after the photoelectric conversion layer 112 is formed and before the photoelectric conversion layer 112 is irradiated with X-rays. A treatment for improving the PL intensity of the layer 112 (hereinafter also simply referred to as “PL intensity”) by 10% or more, preferably 15% or more is performed.
In this example, as an example, the process of improving the PL intensity of the photoelectric conversion layer 112 by 10% or more is performed in the next process of the formation process of the sealing layer 110.
By having such a configuration, the manufacturing method of the present invention suppresses an increase in dark current caused by X-rays irradiated in various environments where photoelectric conversion elements (imaging elements) are placed.

Moreover, as described above, in the photoelectric conversion element 100 of the present invention, the photoelectric conversion layer 112 has a bulk heterostructure composed of the p-type organic semiconductor material represented by the general formula (1) and the fullerene that is the n-type organic semiconductor material. An organic photoelectric conversion material having the following is used.
Here, the photoelectric conversion layer 112 (organic photoelectric conversion material) is subjected to a treatment for improving the PL intensity by 10% or more, and as a result, the crystallinity of fullerene is improved. Specifically, in the photoelectric conversion element 100 of the present invention, the fullerene constituting the photoelectric conversion layer 112 has a crystallinity of 1 to 5%.

As described above, dark current is known as a cause of image quality degradation in photoelectric conversion elements (imaging elements). Further, as shown in Patent Document 2 and Patent Document 3, in the manufacturing process of the photoelectric conversion element, heat treatment is performed in order to reduce dark current of the finished product.
Here, according to the study by the present inventors, in the photoelectric conversion element using the organic photoelectric conversion material for the photoelectric conversion layer, the dark current increases for some reason during use. Often increased, resulting in an image with poor S / N. In particular, a photoelectric conversion element using an organic photoelectric conversion material having a bulk heterostructure composed of a p-type organic semiconductor material represented by the general formula (1) and a fullerene that is an n-type organic semiconductor material for the photoelectric conversion layer is excellent. While the photoelectric conversion performance is high, this dark current is greatly increased.

As a result of intensive studies, the present inventors have increased the dark current of the photoelectric conversion element when X-rays are irradiated to the photoelectric conversion element (photoelectric conversion layer), such as baggage inspection when boarding an aircraft, As a result, it has been found that noise increases and the image has a poor S / N.
This problem also occurs in a radiation imaging element using an organic photoelectric conversion material as disclosed in Patent Document 1. However, since the radiation imaging element has a large noise, an increase in dark current caused by X-ray irradiation is mixed with noise caused by X-rays. As a result, in a radiation imaging element using an organic photoelectric conversion material, image quality degradation caused only by the dark current of the photoelectric conversion layer is hardly a problem.
On the other hand, photoelectric conversion elements, in particular, imaging devices such as digital cameras and digital video cameras as described later, and imaging elements used for imaging modules of mobile phones, for example, baggage inspection when boarding an aircraft, etc. Even with X-ray irradiation due to, an increase in dark current that significantly affects image quality occurs. That is, the image quality after the inspection is clearly deteriorated before and after the baggage inspection by the X-ray.

The present inventor has intensively studied to solve this problem.
As a result, in the photoelectric conversion element 110 (imaging element) using the organic photoelectric conversion material composed of the p-type organic semiconductor material and fullerene represented by the general formula (1) for the photoelectric conversion layer 112, the photoelectric conversion layer 112 is After the formation, before the irradiation with X-rays, by performing a process for improving the PL intensity of the photoelectric conversion layer 112 by 10% or more, an increase in dark current can be suppressed even if the X-rays are irradiated thereafter. I found. Preferably, after the photoelectric conversion layer 112 is formed and before the X-ray is irradiated, the PL intensity of the photoelectric conversion layer 112 is improved by 15% or more, so that an increase in dark current can be more preferably suppressed.

Various treatments can be used for improving the PL intensity of the photoelectric conversion layer 112 by 10% or more as long as the PL intensity can be improved by 10% or more.
As a preferable treatment, after the photoelectric conversion layer 112 is formed, the photoelectric conversion layer 112 (photoelectric conversion element 100) is heat-treated at 210 to 250 ° C. (annealing / annealing treatment) before being irradiated with X-rays. Is done. In this example, as described above, heat treatment at 210 to 250 ° C. is performed as a process for improving the PL intensity of the photoelectric conversion layer 112 by 10% or more in the next process of the formation process of the sealing layer 110.

In addition, as also shown in Patent Document 2 and Patent Document 3, in a photoelectric conversion element and an imaging element using an organic photoelectric conversion material, it is possible to reduce dark current by forming a photoelectric conversion layer and then performing heat treatment. Well known.
However, this heat treatment in the present invention is not intended to reduce the dark current, but only to improve the PL intensity of the photoelectric conversion layer 112 using the predetermined organic photoelectric conversion material by 10% or more. It is in.
That is, even if heat treatment is performed after the photoelectric conversion layer is formed, if the PL intensity is not improved by 10% or more, the dark current reduction effect at that time can be obtained. It is not possible to suppress the increase.
This point will be clearly shown in later examples.

In the present invention in which the predetermined organic photoelectric conversion material is used for the photoelectric conversion layer 112, the PL intensity of the photoelectric conversion layer 112 is improved by 10% or more when the temperature of the heat treatment for improving the PL intensity is less than 210 ° C. It is difficult.
Conversely, when the temperature of the heat treatment exceeds 250 ° C., the photoelectric conversion layer 112 (the predetermined organic photoelectric conversion material) is deteriorated by heat, and the performance of the photoelectric conversion element such as a large increase in dark current is greatly increased. It will deteriorate.

  When the PL strength of the photoelectric conversion layer 112 is improved by heat treatment, the heat treatment time is not particularly limited, and the temperature of the heat treatment, the size of the photoelectric conversion element 100, the method of heat treatment, the heat treatment apparatus, and the photoelectric conversion layer 112 are adjusted. What is necessary is just to set suitably the heat processing time which can improve PL intensity | strength 10% or more according to the kind etc. of the said organic photoelectric conversion material to form.

  There is no particular limitation on the heat treatment method, and various known heat treatment methods such as a method using a thermostatic bath and a method using a hot plate can be used as long as the photoelectric conversion layer 112 can be heat treated.

In the present invention, the treatment for improving the PL strength by 10% or more is not limited to being performed in the next step of the step of forming the sealing layer 110. That is, this treatment can be performed at various timings after the photoelectric conversion layer 112 is formed and before the X-ray irradiation.
As an example, after forming the photoelectric conversion layer 112 or after forming the upper electrode 108, by performing heat treatment at 210 to 250 ° C. in an inert atmosphere, the PL intensity of the photoelectric conversion layer 112 is 10% or more, It may be improved. Or after the formation process of the sealing layer 110, after passing through one or more processes, and before the X-ray irradiation is expected, a process for improving the PL intensity by 10% or more may be performed. .
In view of the fact that treatment in an inert atmosphere is unnecessary, it is advantageous to perform treatment for improving the PL intensity by 10% or more after sealing with the sealing layer 110.

Further, in the photoelectric conversion element 100 of the present invention, the photoelectric conversion layer 112 (organic photoelectric conversion material) is a bulk heterostructure composed of a p-type organic semiconductor material represented by the general formula (1) and a fullerene that is an n-type organic semiconductor material. It has a structure.
Here, as described above, the photoelectric conversion layer 112 is subjected to a treatment for improving the PL intensity by 10% or more, whereby the fullerene constituting the photoelectric conversion layer 112 has a crystallinity of 1 to 5%.
That is, when the crystallinity of fullerene in the photoelectric conversion layer 112 is less than 1%, the PL intensity of the photoelectric conversion layer 112 is not improved by 10% or more. Further, when the degree of crystallinity of fullerene in the photoelectric conversion layer 112 exceeds 5%, the intensity of the treatment for improving the PL intensity is too strong, and the photoelectric conversion layer 112 is deteriorated, the dark current is greatly increased, etc. The performance of the photoelectric conversion element 100 is greatly deteriorated.

In addition, the crystallinity of fullerene can be measured by the area ratio of the intensity peak of the (111) plane of fullerene by X-ray diffraction (XRD) at 2θ = 11 °.
Fullerene is considered to have a crystallinity of 100% when subjected to heat treatment at 300 ° for 30 minutes.
Accordingly, the area of the intensity peak on the (111) plane of fullerene after the photoelectric conversion layer 112 (photoelectric conversion element 100) is heat-treated at 300 ° for 30 minutes is defined as a crystallinity of 100%. With respect to the area of the intensity peak with a crystallinity of 100%, the photoelectric conversion layer 112 is determined by what percentage the intensity peak area of the (111) plane of the fullerene of the photoelectric conversion layer 112 for measuring the degree of crystallinity. The degree of crystallinity of fullerenes can be measured.

FIG. 2 conceptually shows an example of the image sensor of the present invention manufactured by the method of manufacturing the image sensor of the present invention.
As an example, the image pickup device is mounted and used in an image pickup apparatus such as a digital camera or a digital video camera, an image pickup module of a mobile phone, an image pickup module of an electronic endoscope, or the like.

2 includes a substrate 12, an insulating layer 14, a pixel electrode 16, a photoelectric conversion unit 18, a counter electrode 20, a sealing layer (protective film) 22, a color filter 26, and a partition wall. 28, a light shielding layer 29, and a protective layer 30.
The pixel electrode 16 is the lower electrode 104 of the photoelectric conversion element 100, the counter electrode 20 is the upper electrode 108 of the photoelectric conversion element 100, and the photoelectric conversion unit 18 is the photoelectric element of the photoelectric conversion element 100. The sealing layer 22 corresponds to the sealing layer 110 of the photoelectric conversion element 100 described above.
In the image sensor 10, a read circuit 40 and a counter electrode voltage supply unit 42 are formed on the substrate 12.

As the substrate 12, for example, a glass substrate or a semiconductor substrate such as Si is used.
An insulating layer 14 made of a known insulating material is formed on the substrate 12. A plurality of pixel electrodes 16 are formed on the surface of the insulating layer 14. The pixel electrodes 16 are arranged in a one-dimensional or two-dimensional manner, for example.
In addition, a first connection portion 44 that connects the pixel electrode 16 and the readout circuit 40 is formed in the insulating layer 14. Furthermore, a second connection portion 46 that connects the counter electrode 20 and the counter electrode voltage supply unit 42 is formed. The second connection portion 46 is formed at a position not connected to the pixel electrode 16 and the photoelectric conversion portion 18. The 1st connection part 44 and the 2nd connection part 46 are formed with the electroconductive material.

A wiring layer 48 made of a conductive material for connecting the readout circuit 40 and the counter electrode voltage supply unit 42 to, for example, the outside of the imaging device 10 is formed inside the insulating layer 14.
As described above, the circuit board 11 is formed by forming the pixel electrodes 16 connected to the first connection portions 44 on the surface of the insulating layer 14 on the substrate 12. The circuit board 11 is also referred to as a CMOS substrate.

The photoelectric conversion unit 18 is formed so as to cover the plurality of pixel electrodes 16 and to avoid the second connection unit 46. The photoelectric conversion unit 18 includes a photoelectric conversion layer 50 including the predetermined organic photoelectric conversion material and an electron blocking layer 52. In the photoelectric conversion unit 18, the electron blocking layer 52 is formed on the pixel electrode 16 side, and the photoelectric conversion layer 50 is formed on the electron blocking layer 52.
As described above, since the photoelectric conversion unit 18 corresponds to the photoelectric conversion unit 106 of the photoelectric conversion element 100 illustrated in FIG. 1, the photoelectric conversion layer 50 and the electron blocking layer 52 are the photoelectric conversion layer 112 and the electron blocking layer, respectively. Corresponds to layer 114.

The electron blocking layer 52 is a layer for suppressing injection of electrons from the pixel electrode 16 to the photoelectric conversion layer 50.
The photoelectric conversion layer 50 generates charges according to the amount of light L received such as incident light, and is a p-type organic semiconductor material and an n-type organic semiconductor material represented by the general formula (1). It consists of a predetermined organic photoelectric conversion material having a bulk heterostructure composed of fullerene (main component). Here, as described above, the photoelectric conversion layer 50 is subjected to a treatment for improving the PL intensity by 10% or more before the X-ray irradiation. Furthermore, as described above, the photoelectric conversion layer 50 has a crystallinity of 1-5% of fullerene constituting the organic photoelectric conversion material.
Note that the photoelectric conversion layer 50 and the electron blocking layer 52 may have other film thicknesses as long as the film thickness is constant on the pixel electrode 16.
The material for forming the photoelectric conversion layer 50 will be described in detail later.

The counter electrode 20 is an electrode facing the pixel electrode 16 and is provided so as to cover the photoelectric conversion layer 50. A photoelectric conversion layer 50 is provided between the pixel electrode 16 and the counter electrode 20.
The counter electrode 20 is made of a conductive material that is transparent to incident light so that light enters the photoelectric conversion layer 50. The counter electrode 20 is electrically connected to the second connection portion 46 disposed outside the photoelectric conversion layer 50, and is connected to the counter electrode voltage supply portion 42 via the second connection portion 46. Yes.

  The counter electrode 20 can use the same material as the upper electrode 108. For this reason, the detailed description about the material of the counter electrode 20 is abbreviate | omitted.

  The counter electrode voltage supply unit 42 applies a predetermined voltage to the counter electrode 20 via the second connection unit 46. When the voltage to be applied to the counter electrode 20 is higher than the power supply voltage of the image sensor 10, the power supply voltage is boosted by a booster circuit such as a charge pump to supply the predetermined voltage.

The pixel electrode 16 is an electrode for collecting charges for collecting charges generated in the photoelectric conversion layer 50 between the pixel electrode 16 and the counter electrode 20 facing the pixel electrode 16. The pixel electrode 16 is connected to the readout circuit 40 via the first connection portion 44. The readout circuit 40 is provided on the substrate 12 corresponding to each of the plurality of pixel electrodes 16, and reads out a signal corresponding to the charge collected by the corresponding pixel electrode 16.
The pixel electrode 16 can use the same material as the lower electrode 104 described above. Therefore, a detailed description of the material of the pixel electrode 16 is omitted.

  A step corresponding to the film thickness of the pixel electrode 16 is steep at the end of the pixel electrode 16, there are significant irregularities on the surface of the pixel electrode 16, or minute dust (particles) adhere to the pixel electrode 16. As a result, a layer on the pixel electrode 16 becomes thinner than a desired film thickness or a crack occurs. When the counter electrode 20 (upper electrode 108) is formed on the layer in such a state, a pixel defect such as an increase in dark current or a short circuit occurs due to contact or electric field concentration between the pixel electrode 16 and the counter electrode 20 in the defective portion. . Further, the above-described defects may reduce the adhesion between the pixel electrode 16 and the layer above it and the heat resistance of the organic photoelectric conversion element 10.

  In order to prevent this defect and improve the reliability of the element, the surface roughness Ra of the pixel electrode 16 is preferably 0.6 nm or less. The smaller the surface roughness Ra of the pixel electrode 16, the smaller the surface unevenness, and the better the surface flatness. In order to remove particles on the pixel electrode 16, it is particularly preferable to clean the pixel electrode 16 and the like using a general cleaning technique used in a semiconductor manufacturing process before forming the electron blocking layer 52. preferable.

The readout circuit 40 is constituted by, for example, a CCD, a MOS circuit, or a TFT circuit, and is shielded from light by a light shielding layer (not shown) provided in the insulating layer 14. The readout circuit 40 is preferably a CCD or CMOS circuit for general image sensor applications, and is preferably a CMOS circuit from the viewpoint of noise and high speed.
Although not shown, for example, a high-concentration n region surrounded by a p region is formed on the substrate 12, and a connection portion 44 is connected to the n region. A read circuit 40 is provided in the p region. The n region functions as a charge storage unit that stores the charge of the photoelectric conversion layer 50. The signal charge accumulated in the n region is converted into a signal corresponding to the amount of charge by the readout circuit 40 and output to the outside of the image sensor 10 via the wiring layer 48, for example.

The sealing layer 22 is for protecting the photoelectric converting layer 50 containing organic substance from deterioration factors, such as a water molecule. The sealing layer 22 is formed so as to cover the counter electrode 20.
The following conditions are required for the sealing layer 22 (sealing layer 110).
First, it is possible to protect the photoelectric conversion layer by preventing the intrusion of factors that degrade the organic photoelectric conversion material contained in the solution, plasma, etc. in each manufacturing process of the device.
Second, after the device is manufactured, the penetration of factors that degrade the organic photoelectric conversion material such as water molecules is prevented, and the deterioration of the photoelectric conversion layer 50 is prevented over a long period of storage / use.
Third, when the sealing layer 22 is formed, the already formed photoelectric conversion layer is not deteriorated.
Fourth, since incident light reaches the photoelectric conversion layer 50 through the sealing layer 22, the sealing layer 22 must be transparent to light having a wavelength detected by the photoelectric conversion layer 50.

  The sealing layer 22 (sealing layer 110) can also be configured by a thin film made of a single material, but by providing a separate function to each layer in a multilayer configuration, stress relaxation of the entire sealing layer 22, It can be expected to produce effects such as suppression of defects such as cracks and pinholes due to dust generation during the manufacturing process, and optimization of material development. For example, the sealing layer 22 is formed by laminating a “sealing auxiliary layer” having a function that is difficult to achieve on the layer that serves the original purpose of preventing the penetration of deterioration factors such as water molecules. A two-layer structure can be formed. Although it is possible to have three or more layers, it is preferable that the number of layers is as small as possible in consideration of manufacturing costs.

Moreover, what is necessary is just to form the sealing layer 22 (sealing layer 110) as follows, for example.
The performance of organic photoelectric conversion materials is significantly deteriorated due to the presence of deterioration factors such as water molecules. Therefore, it is necessary to cover and seal the entire photoelectric conversion layer with a dense metal oxide film, metal nitride film, metal oxynitride film, or the like that does not allow water molecules to permeate. Conventionally, aluminum oxide, silicon oxide, silicon nitride, silicon nitride oxide, a laminated structure thereof, a laminated structure of them and an organic polymer, or the like is used as a sealing layer by various vacuum film forming techniques. The conventional sealing layer is a film compared to the flat part because the growth of the thin film is difficult (because the step becomes a shadow) at the step due to structures on the substrate surface, minute defects on the substrate surface, particles adhering to the substrate surface, etc. The thickness is significantly reduced. For this reason, the step portion becomes a path through which the deterioration factor penetrates. In order to completely cover this step with the sealing layer 22, it is necessary to form the film so as to have a film thickness of 1 μm or more in the flat portion, thereby increasing the thickness of the entire sealing layer 22.

  In the image sensor 10 having a pixel size of less than 2 μm, particularly about 1 μm, if the distance between the color filter 28 and the photoelectric conversion layer 50, that is, the film thickness of the sealing layer 22 is large, incident light is diffracted in the sealing layer 22. Or it diverges and color mixing occurs. For this reason, the imaging element 10 having a pixel size of about 1 μm requires a sealing layer material and a manufacturing method thereof that do not deteriorate the element performance even when the film thickness of the entire sealing layer 22 is reduced.

  The ALD (atomic layer deposition) method is a kind of CVD method, and adsorption / reaction of organometallic compound molecules, metal halide molecules, and metal hydride molecules, which are thin film materials, onto the substrate surface and unreacted groups contained in them. Is a technique for forming a thin film by alternately repeating decomposition. When the thin film material reaches the substrate surface, it is in the above-mentioned low molecular state, so that the thin film can be grown in a very small space where the low molecule can enter. Therefore, the step portion, which was difficult with the conventional thin film formation method, is completely covered (the thickness of the thin film grown on the step portion is the same as the thickness of the thin film grown on the flat portion), that is, the step coverage is very excellent. . Thereby, a step due to a structure on the substrate surface, a minute defect on the substrate surface, particles adhering to the substrate surface and the like can be completely covered, and such a step portion does not become an intrusion path of a deterioration factor of the photoelectric conversion material. When the sealing layer 22 is formed by the ALD method, the required sealing layer thickness can be effectively reduced as compared with the prior art.

  When the sealing layer 22 is formed by the ALD method, a material corresponding to the above-described preferable sealing layer can be appropriately selected. However, it is limited to a material capable of growing a thin film at a relatively low temperature so that the organic photoelectric conversion material does not deteriorate. According to the ALD method using alkyl aluminum or aluminum halide as a material, a dense aluminum oxide thin film can be formed at less than 200 ° C. at which the organic photoelectric conversion material does not deteriorate. In particular, when trimethylaluminum is used, an aluminum oxide thin film can be formed even at about 100 ° C., which is preferable. Silicon oxide and titanium oxide are also preferable because a dense thin film can be formed as the sealing layer 22 at a temperature lower than 200 ° C., similarly to aluminum oxide, by appropriately selecting materials.

  A thin film formed by the ALD method can achieve a high-quality thin film formation at a low temperature, which is unmatched from the viewpoint of step coverage and denseness. However, the thin film may be deteriorated by chemicals used in the photolithography process. For example, since an aluminum oxide thin film formed by the ALD method is amorphous, the surface is eroded by an alkaline solution such as a developer or a stripping solution. In such a case, a thin film having excellent chemical resistance is required on the aluminum oxide thin film formed by the ALD method. That is, a sealing auxiliary layer that becomes a functional layer for protecting the sealing layer 22 is necessary.

  In particular, the sealing layer 22 has a two-layer structure, and is formed on the first sealing layer by sputtering, and includes a second sealing containing any one of aluminum oxide, silicon oxide, silicon nitride, and silicon nitride oxide. A structure having a layer is preferable. At this time, the first sealing layer preferably has a thickness of 0.05 μm or more and 0.2 μm or less. Furthermore, the first sealing layer preferably contains any of aluminum oxide, silicon oxide, and titanium oxide.

  The color filter 26 is formed at a position facing each pixel electrode 16 on the sealing layer 22. The partition wall 28 is provided between the color filters 26 on the sealing layer 22 and is for improving the light transmission efficiency of the color filter 26. The light shielding layer 29 is formed in a region other than the region (effective pixel region) in which the color filter 26 and the partition wall 28 are provided on the sealing layer 22, and light is incident on the photoelectric conversion layer 50 formed outside the effective pixel region. This is to prevent this.

The protective layer 30 is for protecting the color filter 26 from subsequent processes and is formed so as to cover the color filter 26, the partition wall 28 and the light shielding layer 29. The protective layer 30 is also referred to as an overcoat layer.
In the image sensor 10, one pixel electrode 16, on which the photoelectric conversion unit 18, the counter electrode 20, and the color filter 26 are provided, is a pixel (unit pixel).

The protective layer 30 can be appropriately made of a polymer material such as acrylic resin, polysiloxane resin, polystyrene resin, or fluorine resin, or an inorganic material such as silicon oxide or silicon nitride.
When a photosensitive resin such as polystyrene is used, the protective layer 30 can be patterned by a photolithography method, so that it can be used as a photoresist when opening the peripheral light-shielding layer, sealing layer, insulating layer, etc. on the bonding pad. It is easy to process the protective layer 30 itself as a microlens, which is preferable. On the other hand, it is possible to use the protective layer 30 as an antireflection layer, and it is also preferable to form various low refractive index materials used as the partition walls of the color filter 26. Further, in order to pursue a function as a protective layer and a function as an antireflection layer with respect to the post-process, the protective layer 30 may have a structure of two or more layers combining the above materials.

In the illustrated example, the pixel electrode 16 is formed on the surface of the insulating layer 14. However, the configuration is not limited thereto, and the pixel electrode 16 may be embedded in the surface portion of the insulating layer 14.
Moreover, although the structure which provides the 2nd connection part 46 and the counter electrode voltage supply part 42 was made, it may be plural. For example, a voltage drop at the counter electrode 20 can be suppressed by supplying a voltage from both ends of the counter electrode 20 to the counter electrode 20. The number of sets of the second connection unit 46 and the counter electrode voltage supply unit 42 may be appropriately increased or decreased in consideration of the chip area of the element.

  Hereinafter, by explaining the manufacturing method of the imaging device 10, the imaging device of the present invention and the manufacturing method of the imaging device of the present invention will be described in detail.

When manufacturing the image pickup device 10, as an example, as shown in FIG. 3A, the first connection portion 44 and the substrate 12 on which the readout circuit 40 and the counter electrode voltage supply portion 42 are formed are formed. The second connecting portion 46 and the insulating layer 14 provided with the wiring layer 48 are formed, and the pixel electrode 16 connected to each first connecting portion 44 is formed on the surface 14a of the insulating layer 14. A circuit board 11 (CMOS substrate) is prepared.
In this case, as described above, the first connection unit 44 and the readout circuit 40 are connected, and the second connection unit 46 and the counter electrode voltage supply unit 42 are connected. The pixel electrode 16 is made of, for example, TiN.

Next, in the film forming chamber of the electron blocking layer 52, as shown in FIG. 3B, the electron blocking material is vacuumed, for example, so as to cover all the pixel electrodes 16 except for the second connection portion 46. The electron blocking layer 52 is formed by forming a film by vapor deposition.
As described above, examples of the electron blocking material include carbazole derivatives, and more preferably bifluorene derivatives. Also, the film forming conditions may be set appropriately as in the previous example.

Next, in the film formation chamber of the photoelectric conversion layer 50, as shown in FIG. 3C, the p-type organic semiconductor material and fullerene represented by the general formula (1) are applied to the surface 52a of the electron blocking layer 52. For example, the photoelectric conversion layer 50 is formed by film formation by co-evaporation (vacuum evaporation). The film forming conditions are set as appropriate as in the previous example.
The photoelectric conversion part 18 is formed by forming the photoelectric conversion layer 50.

Next, in the film formation chamber of the counter electrode 20, as shown in FIG. 4A, ITO is formed by sputtering, for example, by a pattern that covers the photoelectric conversion layer 18 and is formed on the second connection portion 46. The counter electrode 20 is formed by film formation.
The film forming conditions are set as appropriate as in the previous example.

Next, in the film forming chamber for the sealing layer 22, as shown in FIG. 4B, for example, an aluminum oxide film is formed on the surface 14 a of the insulating layer 14 as the sealing layer 22 so as to cover the counter electrode 20. Then, a laminated film made of a silicon nitride film is formed.
In this case, as described above, the aluminum oxide film is formed by depositing aluminum oxide on the surface 14a of the insulating layer 14 using the ALD method, and forming silicon nitride on the aluminum oxide film using the magnetron sputtering method. It is preferable to form a silicon nitride film.
The sealing layer 22 may be a single layer film as described above.

When the sealing layer 22 is formed in this way, a process for improving the PL intensity of the photoelectric conversion layer 50 by 10% or more is performed in the same manner as before.
As an example, after forming the sealing layer 22, as a next process of the forming process of the sealing layer 22, a laminated body (photoelectric conversion layer 50) in which the sealing layer 22 is formed using a thermostatic bath, a hot plate, or the like. Heat treatment is performed at 210 to 250 ° C. for a predetermined time.
Moreover, the PL intensity | strength of the photoelectric converting layer 50 improves 10% or more, and the crystallinity degree of the fullerene which comprises the photoelectric converting layer 50 (organic photoelectric converting material) will be 1-5%.

In addition, the process for improving the PL intensity by 10% or more is not limited to being performed as the next process of the formation process of the sealing layer 22, and after the photoelectric conversion layer 50 is formed and before being irradiated with X-rays. If so, it may be performed at various timings as described above.
For example, as the next step of the photoelectric conversion layer 50 forming step, a process for improving the PL intensity in an inert atmosphere may be performed, or, if possible in terms of heat resistance, following the step of forming the color filter 26. As a process, you may perform the process which improves PL intensity | strength.

Next, the color filter 26, the partition wall 28, and the light shielding layer 29 are formed on the surface 22a of the sealing layer 22 by using, for example, a photolithography method. As the color filter 26, the partition wall 28, and the light shielding layer 29, known ones used for imaging devices are used. The color filter 26, the partition wall 28, and the light shielding layer 29 may be formed by a known method.
Next, the protective film 30 is formed using, for example, a coating method so as to cover the color filter 26, the partition wall 28, and the light shielding layer 29. Thereby, the image sensor 10 shown in FIG. 2 can be formed. As the protective film 30, a known film used for an organic imaging element is used.
The protective film 30 may be formed by a known method.

As described above, in the manufacturing method of the present invention, the photoelectric conversion layer 50 and the photoelectric conversion layer 112 are made of an N-type organic semiconductor composed of a P-type organic semiconductor and a fullerene (fullerene derivative) represented by the general formula (1). An organic photoelectric conversion material having a bulk heterostructure is included (this organic photoelectric conversion material is a main component).
Further, this fullerene (fullerene derivative) has a crystallinity of 1 to 5%.

  Exciton dissociation efficiency can be increased by bonding a p-type organic semiconductor material and an n-type organic semiconductor material to form a donor-acceptor interface. For this reason, the photoelectric conversion layer of the structure which joined the p-type organic-semiconductor material and the n-type organic-semiconductor material expresses high photoelectric conversion efficiency. In particular, a photoelectric conversion layer in which a p-type organic semiconductor material and an n-type organic semiconductor material are mixed is preferable because the junction interface is increased and the photoelectric conversion efficiency is improved.

The p-type organic semiconductor material (compound) is a donor-type organic semiconductor material (compound), which is mainly represented by a hole-transporting organic compound and refers to an organic compound having a property of easily donating electrons. More specifically, an organic compound having a smaller ionization potential when two organic materials are used in contact with each other.
The n-type organic semiconductor material (compound) is an acceptor organic semiconductor material, and is mainly represented by an electron-transporting organic compound and refers to an organic compound having a property of easily accepting electrons. More specifically, an n-type organic semiconductor refers to an organic compound having a larger electron affinity when two organic compounds are used in contact with each other.

In the present invention, fullerene having excellent electron transport properties is used as the n-type organic semiconductor material forming the organic photoelectric conversion material.
Fullerene C ₆₀ , fullerene C ₇₀ , fullerene C ₇₆ , fullerene C ₇₈ , fullerene C ₈₀ , fullerene C ₈₂ , fullerene C ₈₄ , fullerene C ₉₀ , fullerene C ₉₆ , fullerene C ₂₄₀ , fullerene C ₅₄₀ , mixed Examples include fullerenes and fullerene nanotubes.

In the present invention, fullerene derivatives in which substituents are added to these fullerenes may be used as fullerenes.
The substituent for the fullerene derivative is preferably an alkyl group, an aryl group, or a heterocyclic group. The alkyl group is more preferably an alkyl group having 1 to 12 carbon atoms, and the aryl group and the heterocyclic group are preferably benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, fluorene ring, triphenylene ring, naphthacene ring. , Biphenyl ring, pyrrole ring, furan ring, thiophene ring, imidazole ring, oxazole ring, thiazole ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, indolizine ring, indole ring, benzofuran ring, benzothiophene ring, isobenzofuran Ring, benzimidazole ring, imidazopyridine ring, quinolidine ring, quinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinoxazoline ring, isoquinoline ring, carbazole ring, phenanthridine ring, acridine ring, phenanthroli Ring, thianthrene ring, chromene ring, xanthene ring, phenoxathiin ring, phenothiazine ring, or phenazine ring, more preferably a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, pyridine ring, imidazole ring, oxazole ring, Or a thiazole ring, particularly preferably a benzene ring, a naphthalene ring, or a pyridine ring. These may further have a substituent, and the substituents may be bonded as much as possible to form a ring. In addition, you may have a some substituent and they may be the same or different. A plurality of substituents may be combined as much as possible to form a ring.

When the photoelectric conversion layer 50 (112) includes fullerene, electrons generated by photoelectric conversion can be quickly transported to the pixel electrode 16 (104) or the counter electrode 20 (108) via the fullerene molecule.
When fullerene molecules are connected and an electron path is formed, the electron transport property is improved and high-speed response of photoelectric conversion can be realized. For this purpose, it is preferable that the fullerene is contained in the photoelectric conversion layer 50 by 40% (volume ratio) or more. On the other hand, if there is too much fullerene, the p-type organic semiconductor is reduced, the junction interface becomes smaller, and the exciton dissociation efficiency decreases.

  In the photoelectric conversion layer 50, the p-type organic semiconductor material mixed with fullerene or a fullerene derivative is a compound represented by the following general formula (1).

In the general formula (1), Z ₁ represents a ring containing at least two carbon atoms and represents a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. . L ₁ , L ₂ and L ₃ each independently represents an unsubstituted methine group or a substituted methine group. D ₁ represents an atomic group. n represents an integer of 0 or more.

Z ₁ is a ring containing at least two carbon atoms, and represents a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. As the condensed ring containing at least one of a 5-membered ring, a 6-membered ring, and a 5-membered ring and a 6-membered ring, those usually used as an acidic nucleus in a merocyanine dye are preferable.
Specific examples thereof include the following.

(A) 1,3-dicarbonyl nucleus: for example, 1,3-indandione nucleus, 1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-dioxane-4,6- Zeon etc.
(B) Pyrazolinone nucleus: for example 1-phenyl-2-pyrazolin-5-one, 3-methyl-1-phenyl-2-pyrazolin-5-one, 1- (2-benzothiazoyl) -3-methyl-2 -Pyrazolin-5-one and the like.
(C) isoxazolinone nucleus: for example, 3-phenyl-2-isoxazolin-5-one, 3-methyl-2-isoxazolin-5-one and the like.
(D) Oxindole nucleus: For example, 1-alkyl-2,3-dihydro-2-oxindole and the like.
(E) 2,4,6-triketohexahydropyrimidine nucleus: for example, barbituric acid or 2-thiobarbituric acid and its derivatives. Examples of the derivatives include 1-alkyl compounds such as 1-methyl and 1-ethyl, 1,3-dialkyl compounds such as 1,3-dimethyl, 1,3-diethyl and 1,3-dibutyl, 1,3-diphenyl, 1,3-diaryl compounds such as 1,3-di (p-chlorophenyl) and 1,3-di (p-ethoxycarbonylphenyl), 1-alkyl-1-aryl compounds such as 1-ethyl-3-phenyl, Examples include 1,3-di (2-pyridyl) 1,3-diheterocyclic substituents and the like.
(F) 2-thio-2,4-thiazolidinedione nucleus: for example, rhodanine and derivatives thereof. Examples of the derivatives include 3-alkylrhodanine such as 3-methylrhodanine, 3-ethylrhodanine and 3-allylrhodanine, 3-arylrhodanine such as 3-phenylrhodanine, and 3- (2-pyridyl) rhodanine. And the like.

(G) 2-thio-2,4-oxazolidinedione (2-thio-2,4- (3H, 5H) -oxazoledione nucleus: for example, 3-ethyl-2-thio-2,4-oxazolidinedione and the like.
(H) Tianaphthenone nucleus: For example, 3 (2H) -thianaphthenone-1,1-dioxide and the like.
(I) 2-thio-2,5-thiazolidinedione nucleus: for example, 3-ethyl-2-thio-2,5-thiazolidinedione and the like.
(J) 2,4-thiazolidinedione nucleus: for example, 2,4-thiazolidinedione, 3-ethyl-2,4-thiazolidinedione, 3-phenyl-2,4-thiazolidinedione, and the like.
(K) Thiazolin-4-one nucleus: For example, 4-thiazolinone, 2-ethyl-4-thiazolinone and the like.
(L) 2,4-imidazolidinedione (hydantoin) nucleus: for example, 2,4-imidazolidinedione, 3-ethyl-2,4-imidazolidinedione, etc.
(M) 2-thio-2,4-imidazolidinedione (2-thiohydantoin) nucleus: for example, 2-thio-2,4-imidazolidinedione, 3-ethyl-2-thio-2,4-imidazolidinedione etc.
(N) Imidazolin-5-one nucleus: for example, 2-propylmercapto-2-imidazolin-5-one and the like.
(O) 3,5-pyrazolidinedione nucleus: for example, 1,2-diphenyl-3,5-pyrazolidinedione, 1,2-dimethyl-3,5-pyrazolidinedione and the like.
(P) Benzothiophen-3-one nucleus: for example, benzothiophen-3-one, oxobenzothiophen-3-one, dioxobenzothiophen-3-one and the like.
(Q) Indanone nucleus: For example, 1-indanone, 3-phenyl-1-indanone, 3-methyl-1-indanone, 3,3-diphenyl-1-indanone, 3,3-dimethyl-1-indanone, and the like.

The ring formed by Z ₁ is preferably a 1,3-dicarbonyl nucleus, a pyrazolinone nucleus, a 2,4,6-triketohexahydropyrimidine nucleus (including a thioketone body, for example, a barbituric acid nucleus, 2-thiobarbitur tool) Acid nucleus), 2-thio-2,4-thiazolidinedione nucleus, 2-thio-2,4-oxazolidinedione nucleus, 2-thio-2,5-thiazolidinedione nucleus, 2,4-thiazolidinedione nucleus, 2, In 4-imidazolidinedione nucleus, 2-thio-2,4-imidazolidinedione nucleus, 2-imidazolin-5-one nucleus, 3,5-pyrazolidinedione nucleus, benzothiophen-3-one nucleus, indanone nucleus More preferably 1,3-dicarbonyl nucleus, 2,4,6-triketohexahydropyrimidine nucleus (including thioketone, for example, barbituric acid nucleus, 2-thiovale nucleus, Tool acid nucleus), 3,5-pyrazolidinedione nucleus, benzothiophen-3-one nucleus, indanone nucleus, more preferably 1,3-dicarbonyl nucleus, 2,4,6-triketohexahydropyrimidine Nuclei (including thioketone bodies, such as barbituric acid nuclei, 2-thiobarbituric acid nuclei), particularly preferably 1,3-indandione nuclei, barbituric acid nuclei, 2-thiobarbituric acid nuclei and derivatives thereof. is there.

L ₁ , L ₂ , and L ₃ each independently represent an unsubstituted methine group or a substituted methine group. The substituted methine groups may be bonded to each other to form a ring (eg, a 6-membered ring such as a benzene ring). Although the substituent W of the substituted methine group includes the substituent W, it is preferable that all of L ₁ , L ₂ and L ₃ are unsubstituted methine groups.
L _{1 to} L ₃ may be linked to each other to form a ring, and preferred examples of the ring formed include a cyclohexene ring, a cyclopentene ring, a benzene ring, and a thiophene ring.

  n represents an integer of 0 or more, preferably 0 or more and 3 or less, and more preferably 0. When n is increased, the absorption wavelength region can be made longer, or the thermal decomposition temperature is lowered. N = 0 is preferable in that it has appropriate absorption in the visible region and suppresses thermal decomposition during vapor deposition.

D ₁ represents an atomic group. D ₁ is preferably a group containing —NR ^a (R ^b ), and more preferably, —NR ^a (R ^b ) represents an substituted arylene group. R ^a and R ^b each independently represent a hydrogen atom or a substituent.

The arylene group represented by D ₁ is preferably an arylene group having 6 to 30 carbon atoms, and more preferably an arylene group having 6 to 18 carbon atoms. The arylene group may have a substituent W described later, and is preferably an arylene group having 6 to 18 carbon atoms which may have an alkyl group having 1 to 4 carbon atoms. Examples thereof include a phenylene group, a naphthylene group, an anthracenylene group, a pyrenylene group, a phenanthrenylene group, a methylphenylene group, and a dimethylphenylene group, and a phenylene group or a naphthylene group is preferable.

Examples of the substituent represented by R ^a and R ^b include the substituent W described later, and preferably an aliphatic hydrocarbon group (preferably an alkyl group or alkenyl group which may be substituted) or an aryl group (preferably substituted). A phenyl group which may be substituted), or a heterocyclic group.

The aryl groups represented by R ^a and R ^b are each independently preferably an aryl group having 6 to 30 carbon atoms, and more preferably an aryl group having 6 to 18 carbon atoms. The aryl group may have a substituent, and is preferably an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 18 carbon atoms which may have an aryl group having 6 to 18 carbon atoms. . Examples thereof include a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, a phenanthrenyl group, a methylphenyl group, a dimethylphenyl group, and a biphenyl group, and a phenyl group or a naphthyl group is preferable.

The heterocyclic groups represented by R ^a and R ^b are preferably each independently a heterocyclic group having 3 to 30 carbon atoms, and more preferably a heterocyclic group having 3 to 18 carbon atoms. The heterocyclic group may have a substituent, preferably a C3-C18 heterocyclic group which may have a C1-C4 alkyl group or a C6-C18 aryl group. It is. The heterocyclic group represented by R ^a and R ^b is preferably a condensed ring structure, and is a furan ring, thiophene ring, selenophene ring, silole ring, pyridine ring, pyrazine ring, pyrimidine ring, oxazole ring, thiazole ring, triazole. A condensed ring structure of a ring combination selected from a ring, an oxadiazole ring, and a thiadiazole ring (which may be the same) is preferable. A bithienothiophene ring is preferred.

The arylene group and aryl group represented by D ₁ , R ^a , and R ^b are preferably a benzene ring or a condensed ring structure, more preferably a condensed ring structure containing a benzene ring, a naphthalene ring, an anthracene ring, pyrene A benzene ring, a naphthalene ring or an anthracene ring, more preferably a benzene ring or a naphthalene ring.

As the substituent W, a halogen atom, an alkyl group (including a cycloalkyl group, a bicycloalkyl group, and a tricycloalkyl group), an alkenyl group (including a cycloalkenyl group and a bicycloalkenyl group), an alkynyl group, an aryl group, and a heterocyclic group (May be referred to as a heterocyclic group), cyano group, hydroxy group, nitro group, carboxy group, alkoxy group, aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyl group, aryl Oxycarbonyl group, amino group (including anilino group), ammonio group, acylamino group, aminocarbonylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfamoylamino group, alkyl and arylsulfonylamino group, mercap Group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, sulfo group, alkyl and arylsulfinyl group, alkyl and arylsulfonyl group, acyl group, aryloxycarbonyl group, alkoxycarbonyl group, carbamoyl group, aryl and heterocyclic ring Azo group, imide group, phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, phosphono group, silyl group, hydrazino group, ureido group, boronic acid group (-B (OH) ₂ ), phosphato group (-OPO (OH) _2), a sulfato group (-OSO ₃ H), and other known substituents.

When R ^a and R ^b represent a substituent (preferably an alkyl group or an alkenyl group), the substituent is an aromatic ring (preferably benzene ring) skeleton of an aryl group substituted by —NR ^a (R ^b ). It may combine with a hydrogen atom or a substituent to form a ring (preferably a 6-membered ring).
R ^a and R ^b may be bonded to each other to form a ring (preferably a 5- or 6-membered ring, more preferably a 6-membered ring), and R ^a and R ^b are each L A ring (preferably a 5-membered or 6-membered ring, more preferably a 6-membered ring) may be formed by combining with a substituent in (representing any of L ₁ , L ₂ , L ₃ ).

  The compound represented by the general formula (1) is a compound described in Japanese Patent Application Laid-Open No. 2000-297068, and a compound not described in the above publication can be produced according to the synthesis method described in the above publication. it can. The compound represented by the general formula (1) is preferably a compound represented by the general formula (2).

In the general formula (2), Z ₂ , L ₂₁ , L ₂₂ , L ₂₃ , and n are the same as Z ₁ , L ₁ , L ₂ , L ₃ , and n in the general formula (1), and preferred examples thereof Is the same. D ₂₁ represents a substituted or unsubstituted arylene group. D ₂₂ and D ₂₃ each independently represents a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group.

The arylene group represented by D ₂₁ has the same meaning as the arylene ring group represented by D ₁ , and preferred examples thereof are also the same. The aryl group represented by D ₂₂ and D ₂₃ is independently the same as the heterocyclic group represented by R ^a and R ^b , and preferred examples thereof are also the same.

  Although the preferable specific example of a compound represented by General formula (1) below is shown using General formula (3), this invention is not limited to these.

In General Formula (3), Z ₃ represents any one of A-1 to A-12 in Chemical Formula 4 shown below. L ₃₁ represents methylene and n represents 0. D ₃₁ is any one of B-1 to B-9, and D ₃₂ and D ₃₃ each represent any of C-1 to C-16. Z ₃ is preferably A-2, D ₃₂ and D ₃₃ are preferably selected from C-1, C-2, C-15, and C-16, and D ₃₁ is B-1 or B- 9 is preferred.

  Particularly preferred p-type organic materials include dyes or materials not having 5 or more condensed ring structures (materials having 0 to 4, preferably 1 to 3 condensed ring structures). When using a pigment-based p-type material generally used in organic thin-film solar cells, the dark current tends to increase at the pn interface, and the light response is slow due to trapping at the crystalline grain boundary. Since it tends to be, it is difficult to use for an image sensor. For this reason, a dye-based p-type material that is difficult to crystallize, or a material that does not have five or more condensed ring structures can be preferably used for the imaging element.

  More preferred specific examples of the compound represented by the general formula (1) are combinations of the substituents, linking groups and partial structures shown below in the general formula (3), but the present invention is not limited to these. Absent.

In addition, A-1 to A-12, B-1 to B-9, and C-1 to C-16 in the chemical formula 5 have the same meanings as those shown in the chemical formula 4.
Although the especially preferable specific example of a compound represented by General formula (1) below is shown, this invention is not limited to these.

(Molecular weight)
The compound represented by the general formula (1) preferably has a molecular weight of 300 to 1500, more preferably 350 to 1200, and still more preferably 400 to 900 from the viewpoint of film forming suitability. When the molecular weight is too small, the film thickness of the formed photoelectric conversion film decreases due to volatilization. Conversely, when the molecular weight is too large, vapor deposition cannot be performed, and a photoelectric conversion element cannot be manufactured.

(Melting point)
The compound represented by the general formula (1) has a melting point of preferably 200 ° C. or higher, more preferably 220 ° C. or higher, and further preferably 240 ° C. or higher from the viewpoint of vapor deposition stability. If the melting point is low, it melts before vapor deposition, and in addition to being unable to form a stable film, the decomposition product of the compound increases, so the photoelectric conversion performance deteriorates.

(Absorption spectrum)
The peak wavelength of the absorption spectrum of the compound represented by the general formula (1) is preferably 400 nm to 700 nm from the viewpoint of widely absorbing light in the visible region.

(Molar extinction coefficient of peak wavelength)
The higher the molar extinction coefficient is, the better the compound represented by the general formula (1) is from the viewpoint of efficiently using light. Absorption spectrum (chloroform solution), in the visible region of the wavelength 400nm to 700 nm, the molar absorption coefficient preferably 20000 ^-1 cm ^-1 or more, more preferably 30000 m ^-1 cm ^-1 or more, 40000M ^-1 cm ^-1 or more Is more preferable.

An electron donating organic material can be used for the electron blocking layer 52 which comprises the photoelectric conversion part 18 (106) with the photoelectric converting layer 50 which consists of the above-mentioned organic photoelectric converting material.
Specifically, in a low molecular material, N, N′-bis (3-methylphenyl)-(1,1′-biphenyl) -4,4′-diamine (TPD) or 4,4′-bis [N Aromatic diamine compounds such as-(naphthyl) -N-phenyl-amino] biphenyl (α-NPD), oxazole, oxadiazole, triazole, imidazole, imidazolone, stilbene derivative, pyrazoline derivative, tetrahydroimidazole, polyarylalkane, butadiene 4,4 ′, 4 ″ -tris (N- (3-methylphenyl) N-phenylamino) triphenylamine (m-MTDATA), porphine, tetraphenylporphine copper, phthalocyanine, copper phthalocyanine, titanium phthalocyanine oxide, etc. Porphyrin compounds, triazole derivatives, oxazizazo Derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, annealed amine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, silazane derivatives, carbazole derivatives, bifluorenes Derivatives and the like can be used. As the polymer material, polymers such as phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, diacetylene, and derivatives thereof can be used.
Even if it is not an electron-donating compound, it can be used as long as it has a sufficient hole transporting property.

An inorganic material can also be used for the electron blocking layer 52.
In general, since an inorganic material has a dielectric constant larger than that of an organic material, when it is used for the electron blocking layer 52, a large voltage is applied to the photoelectric conversion layer, and the photoelectric conversion efficiency can be increased. Materials that can be the electron blocking layer 52 include calcium oxide, chromium oxide, chromium oxide copper, manganese oxide, cobalt oxide, nickel oxide, copper oxide, gallium copper oxide, strontium copper oxide, niobium oxide, molybdenum oxide, indium copper oxide, Examples include indium silver oxide and iridium oxide.

  As described above, the photoelectric conversion element and the image pickup element of the present invention, and the method for manufacturing the photoelectric conversion element and the method for manufacturing the image pickup element of the present invention have been described in detail, but the present invention is not limited to the above-described examples. Of course, various improvements and changes may be made without departing from the scope of the invention.

Hereinafter, the present invention will be described in more detail by showing specific examples of the present invention.
[Example 1]
A general CMOS substrate on which pixel electrodes were formed was prepared.
This CMOS substrate was mounted on a substrate holder in an organic vapor deposition chamber, the organic vapor deposition chamber was closed, and the interior was depressurized to 1 × 10 ⁻⁴ Pa. Then, while rotating the substrate holder, the following compound 5 is vacuum-deposited on the pixel electrode by a resistance heating method at a deposition rate of 0.1 to 0.12 nm / Sec to form an electron blocking layer having a thickness of 100 nm. did.

On this electron blocking layer, the following compound 1 and fullerene C60 were vacuum-deposited (co-evaporated) by resistance heating at a deposition rate of 0.16-0.18 nm / Sec and 0.25-0.25 nm / Sec, respectively. Thus, a photoelectric conversion layer having a thickness of 400 nm was formed.
In addition, the main absorption wavelength of this photoelectric conversion layer is 500 to 600 nm.

The CMOS substrate on which the photoelectric conversion layer was formed was taken out from the organic vapor deposition chamber and mounted on the substrate holder in the sputtering chamber. In the sputtering chamber, an ITO film was formed on the photoelectric conversion layer by RF magnetron sputtering to form a counter electrode having a thickness of 10 nm.
The CMOS substrate on which the counter electrode was formed was taken out of the sputtering chamber and mounted on the substrate holder in the ALD chamber. In the ALD chamber, an aluminum oxide film was formed by ALD on the counter electrode to form a sealing layer (first sealing layer) having a thickness of 200 nm.
The CMOS substrate on which the sealing layer was formed was taken out from the ALD chamber and mounted on the substrate holder in the sputtering chamber. In the sputtering chamber, a SiON film was formed on the sealing layer by RF magnetron sputtering to form a stress relaxation layer (second sealing layer) having a thickness of 100 nm.

The CMOS substrate on which the stress relaxation layer was formed was taken out of the sputtering chamber, placed on a hot plate adjusted to 210 ° C., and subjected to heat treatment at 210 ° C. for 30 minutes, thereby producing an image sensor.
The PL strength of the photoelectric conversion layer before and after heat treatment was measured using a Nanofinder manufactured by Tokyo Instruments. The PL intensity was measured by exciting a photoelectric conversion layer (imaging device) with a laser beam having a wavelength of 532 nm and detecting fluorescence with a CCD detector.
As a result, the PL strength after the heat treatment was improved by 10% compared with that before the heat treatment.

Further, the crystallinity of fullerene (fullerene C60) of the photoelectric conversion layer with improved PL intensity was measured by X-ray diffraction (2θ = 11 °). As a result, the crystallinity was 1%.
Note that, as described above, the crystallinity is the (111) plane of fullerene C60, where the area of the intensity peak of the (111) plane of fullerene when heat treatment is performed at 300 ° C. for 30 minutes is defined as 100% crystallinity. The intensity peak area ratio was measured.

[Example 2]
An imaging device was manufactured in the same manner as in Example 1 except that the temperature of the heat treatment was 220 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was improved by 11% compared to that before the heat treatment, and the crystallinity of fullerene C60 was 2%.

[Example 3]
An imaging device was produced in the same manner as in Example 1 except that the temperature of the heat treatment was 230 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was 12% higher than that before the heat treatment, and the crystallinity of fullerene C60 was 3%.

[Example 4]
An imaging device was manufactured in the same manner as in Example 1 except that the temperature of the heat treatment was 240 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was 13% higher than that before the heat treatment, and the crystallinity of fullerene C60 was 4%.

[Example 5]
An imaging device was manufactured in the same manner as in Example 1 except that the heat treatment temperature was 250 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was improved by 15% compared to that before the heat treatment, and the crystallinity of fullerene C60 was 5%.

[Example 6]
An imaging device was produced in the same manner as in Example 1 except that the photoelectric conversion layer was formed using the following compound 2 instead of the compound 1.
The main absorption wavelength of this photoelectric conversion layer is 600 to 700 nm.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was 10% higher than that before the heat treatment, and the crystallinity of fullerene C60 was 1%.

[Example 7]
An imaging device was produced in the same manner as in Example 1 except that the photoelectric conversion layer was formed using Compound 2 instead of Compound 1 and the temperature of the heat treatment was 220 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was improved by 11% compared to that before the heat treatment, and the crystallinity of fullerene C60 was 2%.

[Example 8]
An imaging device was produced in the same manner as in Example 1 except that instead of Compound 1, a photoelectric conversion layer was formed using Compound 2, and the temperature of the heat treatment was changed to 230 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was 12% higher than that before the heat treatment, and the crystallinity of fullerene C60 was 3%.

[Example 9]
An imaging device was produced in the same manner as in Example 1 except that the photoelectric conversion layer was formed using Compound 2 instead of Compound 1 and the temperature of the heat treatment was 240 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was 13% higher than that before the heat treatment, and the crystallinity of fullerene C60 was 4%.

[Example 10]
An imaging device was produced in the same manner as in Example 1 except that the photoelectric conversion layer was formed using Compound 2 instead of Compound 1 and the temperature of the heat treatment was 250 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was improved by 15% compared to that before the heat treatment, and the crystallinity of fullerene C60 was 5%.

[Example 11]
An imaging device was produced in the same manner as in Example 1 except that the photoelectric conversion layer was formed using the following compound 3 instead of the compound 1.
In addition, the main absorption wavelength of this photoelectric conversion layer is 400-500 nm.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was 10% higher than that before the heat treatment, and the crystallinity of fullerene C60 was 1%.

[Example 12]
An imaging device was fabricated in the same manner as in Example 1 except that the photoelectric conversion layer was formed using Compound 3 instead of Compound 1 and the temperature of the heat treatment was 220 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was improved by 11% compared to that before the heat treatment, and the crystallinity of fullerene C60 was 2%.

[Example 13]
An imaging device was produced in the same manner as in Example 1 except that the photoelectric conversion layer was formed using Compound 3 instead of Compound 1 and the temperature of the heat treatment was 230 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was 12% higher than that before the heat treatment, and the crystallinity of fullerene C60 was 3%.

[Example 14]
An imaging device was produced in the same manner as in Example 1 except that the photoelectric conversion layer was formed using Compound 3 instead of Compound 1 and the temperature of the heat treatment was set to 240 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was 13% higher than that before the heat treatment, and the crystallinity of fullerene C60 was 4%.

[Example 15]
An imaging device was produced in the same manner as in Example 1 except that the photoelectric conversion layer was formed using Compound 3 instead of Compound 1 and the temperature of the heat treatment was 250 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was improved by 15% compared to that before the heat treatment, and the crystallinity of fullerene C60 was 5%.

[Example 16]
An imaging device was produced in the same manner as in Example 1 except that the photoelectric conversion layer was formed using the following compound 4 instead of the compound 1.
The main absorption wavelength of this photoelectric conversion layer is 400 to 600 nm.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was 10% higher than that before the heat treatment, and the crystallinity of fullerene C60 was 1%.

[Example 17]
An imaging device was fabricated in the same manner as in Example 1 except that the photoelectric conversion layer was formed using Compound 4 instead of Compound 1 and the temperature of the heat treatment was 220 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was improved by 11% compared to that before the heat treatment, and the crystallinity of fullerene C60 was 2%.

[Example 18]
An imaging device was fabricated in the same manner as in Example 1 except that the photoelectric conversion layer was formed using Compound 4 instead of Compound 1 and the temperature of the heat treatment was 230 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was 12% higher than that before the heat treatment, and the crystallinity of fullerene C60 was 3%.

[Example 19]
An imaging device was produced in the same manner as in Example 1 except that the photoelectric conversion layer was formed using Compound 4 instead of Compound 1 and the temperature of the heat treatment was 240 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was 13% higher than that before the heat treatment, and the crystallinity of fullerene C60 was 4%.

[Example 20]
An imaging device was produced in the same manner as in Example 1 except that the photoelectric conversion layer was formed using Compound 4 instead of Compound 1 and the temperature of the heat treatment was 250 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was improved by 15% compared to that before the heat treatment, and the crystallinity of fullerene C60 was 5%.

[Comparative Example 1]
An image sensor was manufactured in the same manner as in Example 1 except that the heat treatment was not performed.
In the same manner as in Example 1, the crystallinity of fullerene C60 was measured. As a result, it was 0%.

[Comparative Example 2]
An imaging device was manufactured in the same manner as in Example 1 except that the temperature of the heat treatment was 200 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after heat treatment was 8% higher than that before heat treatment, and the crystallinity of fullerene C60 was 0%.

[Comparative Example 3]
An imaging device was manufactured in the same manner as in Example 1 except that the temperature of the heat treatment was 260 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was significantly lower than that before the heat treatment, and the crystallinity of fullerene C60 was 6% or more. Furthermore, when the dark current after the heat treatment was measured by the method described later, the dark current was significantly increased after the heat treatment.

[Comparative Example 4]
An imaging device was produced in the same manner as in Example 1 except that the photoelectric conversion layer was formed using Compound 2 instead of Compound 1 and the temperature of the heat treatment was 200 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after heat treatment was 8% higher than that before heat treatment, and the crystallinity of fullerene C60 was 0%.

[Comparative Example 5]
An imaging device was produced in the same manner as in Example 1 except that the photoelectric conversion layer was formed using Compound 2 instead of Compound 1 and the temperature of the heat treatment was 260 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was significantly lower than that before the heat treatment, and the crystallinity of fullerene C60 was 6% or more. Furthermore, when the dark current after the heat treatment was measured by the method described later, the dark current was significantly increased after the heat treatment.

[Comparative Example 6]
An imaging device was fabricated in the same manner as in Example 1 except that the photoelectric conversion layer was formed using Compound 3 instead of Compound 1 and the temperature of the heat treatment was 200 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after heat treatment was 8% higher than that before heat treatment, and the crystallinity of fullerene C60 was 0%.

[Comparative Example 7]
An imaging device was produced in the same manner as in Example 1 except that the photoelectric conversion layer was formed using Compound 3 instead of Compound 1 and the temperature of the heat treatment was 260 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was significantly lower than that before the heat treatment, and the crystallinity of fullerene C60 was 6% or more. Furthermore, when the dark current after the heat treatment was measured by the method described later, the dark current was significantly increased after the heat treatment.

[Comparative Example 8]
An imaging device was produced in the same manner as in Example 1 except that the photoelectric conversion layer was formed using Compound 4 instead of Compound 1 and the temperature of the heat treatment was 200 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after heat treatment was 8% higher than that before heat treatment, and the crystallinity of fullerene C60 was 0%.

[Comparative Example 9]
An imaging device was produced in the same manner as in Example 1 except that the photoelectric conversion layer was formed using Compound 4 instead of Compound 1 and the temperature of the heat treatment was 260 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was significantly lower than that before the heat treatment, and the crystallinity of fullerene C60 was 6% or more. Furthermore, when the dark current after the heat treatment was measured by the method described later, the dark current was significantly increased after the heat treatment.

[Comparative Example 10]
Instead of compound 5, a 50 nm electron blocking layer is formed using the following compound 6, and compound 5 is vacuum-deposited by resistance heating on this electron blocking layer to form a 3 nm thick intermediate layer. An imaging element was produced in the same manner as in Example 1 except that the temperature of the heat treatment was 200 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after heat treatment was 8% higher than that before heat treatment, and the crystallinity of fullerene C60 was 0%.

[Comparative Example 11]
Instead of compound 5, a compound 6 is used to form an electron blocking layer having a thickness of 50 nm, and compound 5 is vacuum-deposited on the electron blocking layer by a resistance heating method to form an intermediate layer having a thickness of 3 nm. An imaging device was manufactured in the same manner as in Example 1 except that the temperature of the heat treatment was 260 ° C.
In the same manner as in Example 1, the PL strength before and after the heat treatment and the crystallinity of fullerene C60 were measured. As a result, the PL strength after the heat treatment was significantly lower than that before the heat treatment, and the crystallinity of fullerene C60 was 6% or more. Furthermore, when the dark current after the heat treatment was measured by the method described later, the dark current was significantly increased after the heat treatment.

[Measurement of dark current]
The dark current was measured for each image pickup device thus manufactured, and then the following X-ray irradiation was performed. The dark current was measured again, and the increase rate of the dark current after the X-ray irradiation was calculated.
For X-ray irradiation, 20 KVp (no filter) / 20 mA X-ray irradiation was performed 0.16 sec, 50 times at 30 sec intervals. In this irradiation method, the amount of X-ray irradiation is 1600 mR.
The dark current was measured by applying an electric field of 2 × 10 ⁵ V / cm. Note that the dark current was a value when a positive bias was applied to the counter power of the manufactured image sensor and holes were taken out from the pixel electrode.
The following table shows the measurement results of the structure of the electron blocking layer and the photoelectric conversion layer, the temperature of the heat treatment, the increase rate of PL intensity by the heat treatment, and the increase rate of dark current by the X-ray irradiation.

As shown in the above table, the imaging device of the present invention in which the crystallinity of the fullerene (fullerene C60) of the photoelectric conversion layer, which has been subjected to a treatment for improving the PL intensity by 10% or more by heat treatment, is 1 to 5%, Regardless of the material for forming the photoelectric conversion layer (absorption wavelength), the dark current never increased even after irradiation with X-rays.
On the other hand, Comparative Example 1, in which heat treatment was not performed, and Comparative Examples 2, 4, 6 in which the PL intensity increase rate was less than 10% and the fullerene crystallinity of the photoelectric conversion layer was 0%. , 8 and 10, the dark current is increased by 200% or more by irradiation with X-rays.
Further, in Comparative Examples 3, 5, 7, 9 and 11, which were heat-treated at 260 ° C., the heat treatment temperature was too high, the photoelectric conversion layer was damaged by the heat treatment, and the PL intensity was lowered. The crystallinity of the fullerene in the photoelectric conversion layer was 6% or more, and the dark current was greatly increased by the heat treatment.
From the above results, the effects of the present invention are clear.

DESCRIPTION OF SYMBOLS 10 Image sensor 12 Board | substrate 14 Insulating layer 16 Pixel electrode 18 Photoelectric conversion part 20 Counter electrode 22 Sealing layer 26 Color filter 30 Protection layer 40 Reading circuit 42 Counter electrode voltage supply part 44 1st connection part 46 2nd connection part 50 Photoelectric conversion layer 52 Electron blocking layer 100 Photoelectric conversion element 102 Substrate 104 Lower electrode 106 Photoelectric conversion unit 108 Upper electrode 110 Sealing layer 112 Photoelectric conversion layer 114 Electron blocking layer

Claims (8)

A P-type organic semiconductor in which a lower electrode, an organic layer including a photoelectric conversion layer, and an upper electrode are stacked in this order on a substrate, and the photoelectric conversion layer is represented by the following general formula (1). And a photoelectric conversion element comprising an organic photoelectric conversion material having an N-type organic semiconductor bulk heterostructure composed of fullerene,
The photoelectric conversion element, wherein the fullerene crystallinity of the photoelectric conversion layer is 1 to 5%.
(In the general formula (1), Z ₁ represents a ring containing at least two carbon atoms and represents a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. L ₁ , L ₂ and L ₃ each independently represents an unsubstituted methine group or a substituted methine group, D ₁ represents an atomic group, and n represents an integer of 0 or more.) An image sensor having a photoelectric conversion element,
The said photoelectric conversion element is a photoelectric conversion element described in Claim 1, The imaging element characterized by the above-mentioned. A P-type organic semiconductor in which a lower electrode, an organic layer including a photoelectric conversion layer, and an upper electrode are stacked in this order on a substrate, and the photoelectric conversion layer is represented by the following general formula (1). And a method for producing a photoelectric conversion element comprising an organic photoelectric conversion material having an N-type organic semiconductor bulk heterostructure composed of fullerene,
After forming the photoelectric conversion layer and before irradiating the photoelectric conversion layer with X-rays, a process of improving the PL intensity of the photoelectric conversion layer by 10% or more when excited at an excitation wavelength of 532 nm is performed. A method for producing a photoelectric conversion element.
(In the general formula (1), Z ₁ represents a ring containing at least two carbon atoms and represents a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. L ₁ , L ₂ and L ₃ each independently represents an unsubstituted methine group or a substituted methine group, D ₁ represents an atomic group, and n represents an integer of 0 or more.)   The method for producing a photoelectric conversion element according to claim 3, wherein the treatment for improving the PL intensity of the photoelectric conversion layer by 10% or more is a heat treatment at 210 to 250 ° C.   Furthermore, it has a sealing layer which covers the said organic layer and an upper electrode, and after forming this sealing layer, the process which improves PL intensity | strength of the said photoelectric converting layer 10% or more is performed. A method for producing a photoelectric conversion element.   The photoelectric conversion element further includes a charge storage unit that stores charges generated by the photoelectric conversion layer, and a connection unit for transmitting charges generated by the photoelectric conversion layer to the charge storage unit. The manufacturing method of the photoelectric conversion element of any one of -5.   The said organic layer has an electron blocking layer for suppressing that an electron is inject | poured into the photoelectric converting layer from the said lower electrode in the lower layer of the said photoelectric converting layer. A method for producing a photoelectric conversion element. A method of manufacturing an image sensor having a photoelectric conversion element,
It has the process of manufacturing the said photoelectric conversion element with the manufacturing method of the photoelectric conversion element of any one of Claims 3-7, The manufacturing method of the image pick-up element characterized by the above-mentioned.