JP6145872B2 - Method for forming photoelectric conversion layer - Google Patents

Description

  The present invention relates to a method for forming a photoelectric conversion layer formed on an organic photoelectric conversion element.

  Image sensors such as CCD sensors and CMOS sensors are widely known as image sensors used in digital still cameras, digital video cameras, mobile phone cameras, endoscope cameras, and the like. These elements include a photoelectric conversion element including a light receiving layer including a photoelectric conversion layer between a pair of electrodes. The photoelectric conversion element is an element that generates a charge in a photoelectric conversion layer in accordance with light incident from the transparent electrode side having light transparency among a pair of electrodes, and reads the generated charge as a signal charge from the electrode.

  An organic photoelectric conversion element using an organic compound in the photoelectric conversion layer and an image pickup element using the same have been proposed by the present applicants. Regardless of organic or inorganic, photoelectric conversion elements used for imaging elements are required to satisfy high standards in various performances such as S / N ratio of photocurrent / dark current, response speed, sensitivity, and afterimage characteristics. . In order to improve these performances, it is essential to improve the photoelectric conversion efficiency of the photoelectric conversion element.

  In the organic photoelectric conversion element, the applicant of the present invention provides a mixed layer (bulk hetero layer) of a p-type organic semiconductor and an n-type semiconductor such as fullerene or a fullerene derivative as an organic photoelectric conversion layer capable of obtaining good photoelectric conversion efficiency. (Patent Documents 1 and 2 etc.).

  The bulk hetero layer can be manufactured, for example, by co-evaporation (vacuum deposition) of a p-type organic semiconductor material and an n-type organic semiconductor material. In the co-evaporation, a film having a desired composition is formed by arranging a plurality of evaporation sources and controlling the speed and the like.

JP 2007-123707 A JP 2012-94660 A

Kosaka, “Radiation heat and its reduction during vacuum deposition”, Metal Surface Technology, 1977, Vol.28, No.6, p.330-335, 1977.

  However, an image sensor provided with a bulk hetero layer formed by co-evaporation as an organic photoelectric conversion layer has a problem that even if the composition is controlled, device performance tends to vary, and it is difficult to manufacture with a high yield.

  In particular, it has been confirmed by the present inventor that the degree of the afterimage phenomenon varies significantly only by using a different apparatus even when the film is formed under the same conditions in the film formation of the bulk hetero layer.

  In vacuum vapor deposition, it is known that the substrate temperature rises due to vapor deposition heat, and the substrate temperature gradually rises as vapor deposition proceeds (described in Non-Patent Document 1, etc.). This is considered to be due to the fact that the heat of vapor deposition is greatly affected by the radiation energy. Radiant energy varies depending on various factors such as the material of the substrate, the material of the film deposited on the surface of the substrate and the increase of the film thickness, the material of the inner surface of the vacuum vessel, the state of film adhesion on the surface, and the shape of the vacuum vessel. Therefore, precise control of the substrate temperature is difficult in vacuum deposition.

The present invention has been made in view of the above circumstances, and is an organic photoelectric conversion film capable of stably producing a bulk hetero layer that is easily changed by a film forming apparatus and has good film characteristics that directly affect afterimage characteristics. The object is to provide a film forming method.
Another object of the present invention is to produce an organic photoelectric conversion element having good afterimage characteristics with high yield.

The method for forming the organic photoelectric conversion layer of the present invention is as follows.
A method for forming an organic photoelectric conversion layer provided in an organic photoelectric conversion element,
Preparing a substrate and installing the substrate in a vacuum deposition chamber; and
The n-type organic semiconductor and the p-type organic semiconductor constituting the organic photoelectric conversion layer are co-deposited on the substrate while controlling the temperature of the installed substrate to be in a temperature range of 5 ° C. or more and 15 ° C. or less. A first photoelectric conversion layer forming step of forming a photoelectric conversion layer of,
There is a second photoelectric conversion layer forming step in which the control of the temperature of the substrate is stopped and co-evaporation is performed on the first photoelectric conversion layer to form a second photoelectric conversion layer.

  In this specification, the temperature of the substrate (substrate temperature) is the temperature of the substrate installation surface such as a substrate holder on which the substrate is installed. Further, “co-evaporation on the substrate” means both the case of co-evaporation directly on the substrate and the case of co-evaporation on the substrate via another layer such as an electrode.

In the method for forming an organic photoelectric conversion layer of the present invention, cooling can be preferably used for controlling the substrate temperature. In addition, the second photoelectric conversion layer preferably has a larger layer thickness than the first photoelectric conversion layer.
The ratio of the average layer thickness of the first photoelectric conversion layer to the average layer thickness of the second photoelectric conversion layer is preferably 1/2 or less, and more preferably 1/3 or less. When the total layer thickness of the first photoelectric conversion layer and the second photoelectric conversion layer is in the range of 0.2 μm to 1.0 μm, the average layer thickness of the first photoelectric conversion layer is 10 to 100 mm. Is preferred.

  The method for forming the organic photoelectric conversion layer of the present invention is preferably an embodiment in which the second photoelectric conversion layer forming step is performed under the condition that the maximum substrate temperature is 80 ° C. or higher.

  Moreover, in the film-forming method of the organic photoelectric conversion layer of this invention, after implementing a board | substrate installation process, before implementing a 1st photoelectric conversion layer formation process, the temperature of a board | substrate shall be 5 to 15 degreeC. An embodiment having a cooling step of cooling to a temperature is preferable.

The n-type organic semiconductor of the organic photoelectric conversion layer is preferably one having a fullerene or a fullerene derivative as a main component, and examples of the p-type organic semiconductor include compounds 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, and n represents an integer of 0 or more.)

The method for producing an organic photoelectric conversion element of the present invention is a method for producing an organic photoelectric conversion element having a light receiving layer including at least an organic photoelectric conversion layer sandwiched between a hole collecting electrode and an electron collecting electrode,
The organic photoelectric conversion layer is formed by the organic photoelectric conversion layer forming method of the present invention.

The organic film forming apparatus of the present invention is an apparatus for forming an organic film on a substrate by co-evaporation,
A vacuum deposition chamber;
A plurality of vapor deposition sources, each of which is disposed in the vacuum vapor deposition chamber so as to be opened on the substrate side, and includes a container for storing the raw material of the organic film, and a heating source for heating the container and evaporating the raw material in the container,
Substrate temperature control means for controlling the temperature of the substrate between 5 ° C. and 15 ° C. during co-evaporation is provided.
The substrate temperature control means is preferably a cooling means that is detachable during co-evaporation.

In the method for forming an organic photoelectric conversion layer of the present invention, the organic photoelectric conversion layer is co-deposited while controlling the temperature of the substrate to be in a temperature range of 5 ° C. to 15 ° C., and then the temperature of the substrate is controlled. It stops and forms by carrying out co-evaporation further. According to such a film forming method, it is possible to stably manufacture a bulk hetero layer that is easily changed by a film forming apparatus and has good film characteristics that directly affect afterimage characteristics.
Furthermore, by using the method for forming an organic photoelectric conversion layer of the present invention, an organic photoelectric conversion element having good afterimage characteristics can be produced with a high yield.

Sectional schematic diagram which shows one Embodiment of the organic photoelectric conversion element obtained by forming an organic photoelectric converting layer into a film by the film-forming method of the organic photoelectric converting layer of this invention Cross-sectional schematic diagram which shows one Embodiment of the film-forming method of the organic photoelectric converting layer of this invention (from a board | substrate installation process to the 1st photoelectric converting layer formation process) Sectional schematic diagram which shows one Embodiment of the film-forming method of the organic photoelectric converting layer of this invention (2nd photoelectric converting layer formation process) Schematic schematic diagram showing one embodiment of the organic film deposition apparatus of the present invention The figure which shows an example of the substrate temperature change in the film-forming method of the organic photoelectric converting layer of this invention The relationship between the afterimage current value of the organic photoelectric conversion element obtained by forming the organic photoelectric conversion layer without performing the first photoelectric conversion layer forming step and the maximum substrate temperature at the time of forming the organic photoelectric conversion layer Figure showing The figure which shows the relation between the degree of orientation of the vapor deposition film of organic material and the substrate temperature at the time of vapor deposition The afterimage current value of the organic photoelectric conversion element obtained by forming the organic photoelectric conversion layer by the method for forming an organic photoelectric conversion layer of the present invention and the maximum substrate temperature in the second photoelectric conversion layer forming step Diagram showing relationship The figure which shows the relationship between the orientation degree of the organic photoelectric converting layer of the organic photoelectric conversion element measured in FIG. 7, and the maximum temperature of the substrate temperature in a 2nd photoelectric converting layer formation process. Cross-sectional schematic diagram showing a schematic configuration of an example of an imaging device suitable for the organic photoelectric conversion device obtained by the present invention

“Method for Forming Organic Photoelectric Conversion Layer and Method for Manufacturing Organic Photoelectric Conversion Element”
With reference to drawings, the film-forming method of the organic photoelectric converting layer of one Embodiment concerning this invention and the manufacturing method of an organic photoelectric conversion element using the same are demonstrated. FIG. 1 is a schematic cross-sectional view of an organic photoelectric conversion element manufactured by the method for manufacturing an organic photoelectric conversion element of this embodiment. Moreover, FIG. 2A-FIG. 2B is a cross-sectional schematic diagram which shows the process of the film-forming method of the organic photoelectric converting layer of one Embodiment concerning this invention. In the drawings of this specification, the scale of each part is appropriately changed and shown for easy visual recognition.

  As shown in FIG. 1, the organic photoelectric conversion element 1 includes a substrate 10, a hole collection electrode 20 formed on the substrate 10, and an electron blocking layer 31 formed on the hole collection electrode 20. A photoelectric conversion layer 32 formed on the electron blocking layer 31, a hole blocking layer 33 formed on the photoelectric conversion layer 32, an electron collection electrode 40 formed on the hole blocking layer 33, and an electron And a sealing layer 50 that covers the surface of the collecting electrode 40 and the side surface of the laminate that is laminated from the hole collecting electrode 20 to the electron collecting electrode 40. The electron blocking layer 31, the photoelectric conversion layer 32, and the hole blocking layer 33 form the light receiving layer 30.

  In the photoelectric conversion element 1, the electron collection electrode 40 is a transparent electrode, and when light enters from above the electron collection electrode 40, the light passes through the electron collection electrode 40 and enters the photoelectric conversion layer 32. A charge is generated. Of the generated charges, holes move to the hole collecting electrode 20, and electrons move to the electron collecting electrode 40.

  By applying a bias voltage (external electric field) between the electron collection electrode 40 and the hole collection electrode 20, among the charges generated in the photoelectric conversion layer 32, holes are transferred to the hole collection electrode 20 and electrons are transferred. The electron collecting electrode 40 can be moved.

  The photoelectric conversion layer 32 is a photoelectric conversion layer made of a bulk hetero layer, and can be formed by co-evaporation. The photoelectric conversion layer composed of a bulk hetero layer has (1) carrier transportability in the bulk hetero layer, (2) visible light absorption rate, depending on the mixing ratio of the n-type organic semiconductor and the p-type organic semiconductor in the bulk hetero layer ( 3) Carrier transportability with the electron blocking layer and (4) heat resistance can be optimized. By making these characteristics favorable, a photoelectric conversion element having heat resistance and good response speed and sensitivity and low dark current can be obtained.

  The photoelectric conversion layer 32 is formed by the organic photoelectric conversion layer forming method of the present invention described below, and is formed in the first photoelectric conversion layer forming step, on the hole collecting electrode 20 side. It is comprised from the 1st photoelectric converting layer 32a and the 2nd photoelectric converting layer 32b by the side of the electron collection electrode 40 formed into a film in the 2nd photoelectric converting layer formation process.

As shown in FIGS. 2A to 2B, the organic photoelectric conversion layer forming method of the present embodiment prepares a substrate 10 in which a hole collecting electrode 20 and an electron blocking layer 31 are sequentially laminated, and the substrate. A n-type organic semiconductor that constitutes the organic photoelectric conversion layer while controlling the temperature of the installed substrate 10 to be in a temperature range of 5 ° C. or higher and 15 ° C. or lower; The first photoelectric conversion layer forming step in which the p-type organic semiconductor is co-evaporated on the substrate 10 to form the first photoelectric conversion layer 32a, and the temperature control of the substrate is stopped, and the first photoelectric conversion layer 32a is formed. The organic photoelectric conversion layer 32 is formed by performing a second photoelectric conversion layer forming step of forming a second photoelectric conversion layer 32b by performing co-evaporation.
The method of co-evaporation is not particularly limited, but is preferably performed using resistance heating vapor deposition, electron beam vapor deposition, flash vapor deposition, or the like.

  The method for forming an organic photoelectric conversion layer according to this embodiment can be preferably implemented by the organic film forming apparatus 200 shown in FIG. FIG. 3 is a schematic diagram of an organic film deposition apparatus 200 that is a vacuum deposition apparatus. As shown in the figure, the organic film deposition apparatus 200 is an apparatus for depositing an organic film on the substrate 10 by co-evaporation, and includes a vacuum deposition chamber 170 and a substrate holder 110 that holds the substrate 10 on the surface 110a. The container 151 (A, B) is arranged in the vacuum deposition chamber 170 so as to be opened to the substrate 10 side, and a heating source 152 for heating the container and evaporating the raw material in the container. (A, B) and a plurality of vapor deposition sources 150 (A, B), and substrate temperature control means 120 for controlling the temperature of the substrate 10 to 5 ° C. or more and 15 ° C. or less during co-deposition.

  In the organic film forming apparatus 200, the aspect in which the plurality of vapor deposition sources 150 are two is shown, but the number of vapor deposition sources 150 is not limited to two. In FIG. 3, the vapor deposition sources are respectively connected to the heating control means 160 (A, B) to control the evaporation of the raw materials, and the start and end of the vapor deposition of the respective raw materials are performed on the substrate side of the opening of the vapor deposition source. A shutter 140 (A, B) for controlling the above is provided.

  The substrate holder 110 includes a substrate holder position control means 130 for rotating the substrate holder and moving it in a three-dimensional direction in order to improve the in-plane uniformity of the composition and thickness of the organic film to be formed. And a substrate temperature control means 120 for controlling the temperature of the substrate holder surface 110a to 5 ° C. or more and 15 ° C. or less. In the present embodiment, the substrate temperature control unit 120 is shown as being configured by the cooling source 121 and the temperature control unit 122, but the substrate temperature control unit 120 is only used by the detachable cooling source 121 during co-evaporation. It may be configured.

<Board installation process>
In the substrate installation step, the substrate 10 on which the photoelectric conversion layer 32 is formed is prepared and installed in the vacuum vapor deposition chamber 170 of the organic film formation apparatus 200. In this embodiment, the substrate 10 in which the hole collection electrode 20 and the electron blocking layer 31 are sequentially laminated on the substrate surface 10 a is prepared, and the electron blocking layer is formed on the surface 110 a of the substrate holder 110 in the vacuum evaporation chamber 170. It installs so that the surface of 31 may become a film-forming surface. In FIG. 3, illustration of layers formed on the substrate 10 is omitted.

<First photoelectric conversion layer forming step>
Next, the n-type organic semiconductor and the p-type organic semiconductor constituting the organic photoelectric conversion layer are placed on the substrate 10 while controlling the temperature of the installed substrate 10 to be in a temperature range of 5 ° C. to 15 ° C. The first photoelectric conversion layer 32a is formed by co-evaporation on the deposited electron blocking layer 31.

  The n-type organic semiconductor and the p-type organic semiconductor constituting the organic photoelectric conversion layer 32 are not particularly limited, but one or both of the materials needs to have anisotropy in which molecules have a longitudinal long axis. It is. Suitable materials for the organic photoelectric conversion layer 32 will be described later.

  In the first photoelectric conversion layer forming step, an n-type organic semiconductor and a p-type organic semiconductor are co-evaporated while controlling the temperature of the substrate 10 to be in a temperature range of 5 ° C. or more and 15 ° C. or less, thereby The first bulk hetero layer (first organic photoelectric conversion layer) 32a is deposited, in which anisotropic molecules having the major axis are deposited in a state where the major axis is strongly oriented in the horizontal direction on the substrate surface.

  The first photoelectric conversion layer forming step is a step of co-evaporating an n-type organic semiconductor and a p-type organic semiconductor while controlling the temperature of the substrate 10 to be in a temperature range of 5 ° C. or higher and 15 ° C. or lower. When the film formation substrate is not in the temperature range of 5 ° C. or more and 15 ° C. or less in the substrate installation step, for example, when the first photoelectric conversion layer forming step is performed on the substrate 10 whose temperature is kept at room temperature. In this case, it is necessary to carry out a substrate cooling process.

  The cooling process may be performed before the substrate installation process, or may be performed on the substrate holder after the substrate installation process. In the first photoelectric conversion layer forming step, the temperature of the substrate 10 is set to be 5 ° C. or higher and 15 ° C. or lower from the beginning.

<Second photoelectric conversion layer forming step>
Next, the temperature control of the substrate 10 is stopped, and co-evaporation is subsequently performed on the first bulk hetero layer 32a using the same deposition source as that of the first bulk hetero layer 32a to form the second bulk hetero layer 32b. To do. In the formation of the second bulk hetero layer 32b, it may be the same as the film formation conditions of the first bulk hetero layer 32a except that the temperature control of the substrate 10 is stopped, but other conditions may be changed as necessary.

  FIG. 4 shows the relationship between each step of the organic photoelectric conversion layer deposition method of the present embodiment and the substrate temperature when the substrate before the substrate installation step is held at room temperature. In FIG. 4, the horizontal axis indicates each process of the film forming method of the present embodiment, and the process proceeds from left to right. As shown in FIG. 4, the substrate temperature is set to 5 ° C. or higher and 15 ° C. or lower by the cooling step before the first photoelectric conversion layer forming step (10 ° C. in FIG. 4) while controlling the temperature to be maintained. The first photoelectric conversion layer forming step is performed, and then the temperature control is stopped and then the second photoelectric conversion layer forming step is performed. In FIG. 4, the substrate temperature is a constant value in the first photoelectric conversion layer forming step, but may vary as long as it is in the range of 5 ° C. to 15 ° C.

  FIG. 4 shows the case where the maximum temperature of the second photoelectric conversion layer forming step is 70 ° C., but in the second photoelectric conversion layer forming step, it should be equal to or lower than the melting point of the organic material constituting the photoelectric conversion layer. The maximum temperature is not particularly limited. However, from the viewpoint of long-term reliability of the film, it is preferably about 150 ° C. or lower. From the viewpoint of productivity, there may be a case where the atmospheric temperature is higher than the short-time film formation when the deposition film formation environment is operated continuously for a long time. For example, the second photoelectric conversion layer forming step is performed. In practice, the maximum substrate temperature may be 80 ° C. or higher.

  The ratio of the layer thickness of the first photoelectric conversion layer and the second photoelectric conversion layer is not particularly limited, but the layer thickness of the second photoelectric conversion layer is larger than the first photoelectric conversion layer that is formed at a low temperature. From the viewpoint of productivity. The ratio of the average layer thickness of the first photoelectric conversion layer to the average layer thickness of the second photoelectric conversion layer is preferably 1/2 or less, and more preferably 1/3 or less. When the total layer thickness of the first photoelectric conversion layer and the second photoelectric conversion layer is in the range of 0.2 μm to 1.0 μm, the average layer thickness of the first photoelectric conversion layer is 10 to 100 mm. , Sufficient orientation imparting effect can be obtained.

  In the examples described later, the total thickness of the first photoelectric conversion layer and the second photoelectric conversion layer was about 400 nm, and the thickness of the first photoelectric conversion layer was 6 to 7.5 nm.

In the method for forming an organic photoelectric conversion layer according to this embodiment, the organic photoelectric conversion layer 32 is co-evaporated while being controlled so that the temperature of the substrate is in a temperature range of 5 ° C. or more and 15 ° C. or less. The control is stopped and further co-evaporation is performed. According to such a film forming method, an organic photoelectric conversion element having good afterimage characteristics can be manufactured with a high yield.
Below, the mechanism which makes it possible to manufacture an organic photoelectric conversion element with good afterimage characteristics with a high yield by the above-mentioned method for forming an organic photoelectric conversion layer will be described.

  As described in the section “Problems to be solved by the present invention”, in the formation of an organic film by vacuum deposition, the substrate temperature depends on the material of the substrate, the material of the film deposited on the surface of the substrate, and the film thickness thereof. It is affected by radiant energy that varies depending on various factors such as the increase, the material of the inner surface of the vacuum vessel, the state of film adhesion on the surface, and the shape of the vacuum vessel.

  The present inventor paid attention to the possibility that the radiant energy, which is easily changed by the film forming apparatus, is one of the causes of variations in the afterimage characteristics of the film forming apparatus. The relationship was examined.

  Fig. 5 shows the deposition of an electron blocking layer and a bulk hetero layer on a substrate on which an ITO (indium tin oxide) electrode is formed using a commercially available vacuum deposition apparatus, and further forms an upper electrode by sputtering. Then, an organic photoelectric conversion element was produced, and the result of measuring the afterimage current value of the obtained element is shown. A plurality of organic photoelectric conversion elements were produced by changing only the substrate temperature at the time of vapor deposition of the bulk hetero layer. As already described, the substrate temperature during normal vapor deposition increases with time due to vapor deposition including radiant energy, and almost always reaches the maximum temperature at the end of film formation. Therefore, here, a plurality of organic photoelectric conversion elements having different substrate temperatures at the end of film formation were prepared, and the respective residual current values were measured.

  FIG. 5 shows that the remaining current value changes depending on the maximum substrate temperature. In this measurement, it is observed that the substrate temperature is greatly increased from 80 ° C., the afterimage current value is increased, and the characteristics are deteriorated.

  Next, the film characteristics of the bulk hetero layer affecting the afterimage current value were investigated. The bulk hetero layer is an amorphous film, and it is known that the orientation of organic molecules in the film thickness direction changes depending on the substrate temperature in an organic amorphous film containing organic molecules having a large anisotropy (Japanese Patent Application Laid-Open (JP-A)). 2010-212112 etc.). On the other hand, the orientation in the in-plane direction has not been confirmed.

  The inventor of the bulk hetero layer material used in FIG. 5 has a p-type organic semiconductor material (compound 6 described later) having a large molecular anisotropy, and an organic molecule orientation substrate in the film thickness direction of the deposited film. The dependence on temperature was evaluated.

  The orientation of organic molecules in the film thickness direction is described in non-patent literature (“Daisuke Yokoyama et al,“ Horizontal Orientation of linear-shaped organic molecules having bulky substituents in neat and doped vacuum-deposited amorphous films. ”Organic Electronics 10, pp. 127-137 2009.) and as disclosed in Japanese Patent Application Laid-Open No. 2010-212112, the orientation obtained from the polarization analysis of the deposited film by the multi-incidence angle spectroscopic ellipsometry method and the extinction coefficient obtained by the analysis. This was done by quantifying the degree parameter.

Specifically, the orientation degree parameter S shown in the following formula (a) was calculated from the calculated extinction coefficient, and the molecular orientation in the film was evaluated.
S = (− 2) × (k _z −k _xy ) / (k _z +2 k _xy ) (a)
(K _z is the extinction coefficient in the film thickness direction, and k _xy is the extinction coefficient in the in-plane direction of the substrate.)

  When the thin film has no optical anisotropy, that is, when the molecular orientation (alignment of the long axis of the organic molecule) is a completely random orientation, the S value is 0, and the molecular orientation direction in the thin film is completely with respect to the substrate The S value in the case of the vertical direction is -0.5, and 1 in the case of the complete horizontal alignment. Further, when the molecular orientation of the π-conjugated compound is controlled in the horizontal direction with respect to the substrate, the S value indicates a value in the range of 0 <S ≦ 1.

  Compound 6 (hereinafter referred to as organic dye molecule) is formed on a quartz substrate at various substrate temperatures, and the results of evaluating the respective orientation degrees S are shown in FIG. The substrate temperature was a method in which the substrate was directly heated, and was maintained at a constant temperature during film formation. Here, in order to accurately measure the degree of orientation, the thickness of the deposited film was set to 40 nm sufficient to accurately measure the absorption characteristics of the film.

  In FIG. 6, up to the substrate temperature of 15 ° C., the degree of orientation parameter of the deposited film is around 0.7, 20 ° C. to 60 ° C. around 0.6, and 100 ° C. cannot maintain the horizontal molecular orientation. It is shown to be closer to random.

Comparing FIG. 5 and FIG. 6, when the major axis of the organic dye molecule is strongly oriented in the horizontal direction with respect to the substrate (when closer to 1 in the range of 0.5 <S ≦ 1), the residual It is assumed that the current value tends to be low.
This is because the organic dye used in this evaluation is a donor-acceptor-coupled vertically long molecule and has a certain amount of dipole moment within the molecule. The inventor thinks.

When the long axis of the organic pigment molecules tends to tilt with respect to the substrate (horizontal orientation), it becomes easier to easily arrange the π conjugates between the molecules of the organic pigment molecules, and when the overlap of the π conjugates increases, Delivery becomes smoother, the afterimage current is small, that is, the response is improved.
On the other hand, when the molecular orientation becomes random (approaching S = 0), in addition to reducing the overlap as described above, there is a dipole moment within the molecule. The potential level inhibits the flow of charges, such as the formation of localized levels of the electrons and the trapping of charges.

  From the above, in order to enable stable production of an organic photoelectric conversion element with good afterimage characteristics, the present inventors strongly oriented the vertically long organic molecules constituting the bulk heterolayer in the horizontal direction with respect to the substrate. The present inventors have found that it is important to form the bulk hetero layer without being affected by changes in the substrate temperature.

  In order to form a film so that the vertically long organic molecules are strongly oriented in the horizontal direction with respect to the substrate, it is considered that the film may be formed while maintaining the substrate temperature at a lower temperature. Judging from FIG. 6, when the substrate temperature is set to 60 ° C. or lower, a bulk hetero layer in which vertically long organic molecules are oriented to some extent in the horizontal direction can be obtained, and when the substrate temperature is set to 15 ° C. or lower, the horizontal orientation is further improved. It is considered that an organic photoelectric conversion element having excellent afterimage characteristics can be obtained.

  It is considered that the substrate temperature is preferably low, but if it is less than 5 ° C., it is easy to incorporate moisture in the film forming environment, and a very small amount of gas components existing in the film forming environment such as oxygen and hydrogen into the film. There is a problem in terms.

  On the other hand, in consideration of the problem that the deposition rate is slow and the productivity is low when the deposition is performed at a low temperature of 15 ° C. or lower, which is lower than the room temperature, and that the substrate temperature is gradually increased by the deposition heat without control, the cost performance and Also from the viewpoint of process easiness, it is preferable that the low-temperature temperature control is performed for a short time. In addition, as shown in Examples and Comparative Examples described later, the present inventors have also confirmed that afterimage characteristics deteriorate in a bulk heterolayer formed while controlling the substrate temperature at 10 ° C.

  There have been some reports on the control of the orientation of organic molecules in the organic photoelectric conversion layer. For example, in Japanese Patent Laid-Open No. 2010-212112 already described, in a charge transporting amorphous film formed by vapor deposition of a single material, if the molecular orientation direction is horizontal, the charge mobility in the horizontal direction is It is described that the charge mobility in the vertical direction increases when the charge mobility in the vertical direction is compared with that in the vertical direction, and the substrate temperature is deposited at a constant temperature within the range of 0 ° C. to Tg (270 ° C. or 300 ° C.). It is described that a charge transport layer whose orientation is controlled by the above can be obtained. That is, it is described that the orientation control can be satisfactorily controlled even in high-temperature film formation up to about 300 ° C., as long as it is in the range of 0 ° C. to Tg.

  JP 2008-258421 A discloses that, in order to improve carrier mobility, part or all of a photoelectric conversion layer containing a photoconductive organic compound is formed in a vapor phase, and the substrate temperature is set to 60 ° C. An organic photoelectric conversion element including a photoelectric conversion layer in which at least one of a p-type organic semiconductor and an n-type organic semiconductor is controlled in orientation by forming a film at a constant temperature within a range of 250 ° C. is disclosed.

  In addition, the molecular orientation in the amorphous organic thin film is not easily affected by the lower layer, and the amorphous organic thin film is formed by layering the substrate at different temperatures. It is described in the above-mentioned non-patent document that modulation and control are possible.

  From these descriptions, the first photoelectric conversion layer is obtained when the substrate temperature during the film formation process changes as shown in FIG. 4 as in the method for forming the organic photoelectric conversion layer of the present embodiment. It is conceivable that films having different orientation, optical characteristics, and electrical characteristics are formed in the second photoelectric conversion layer 32b.

  As shown in Examples and Comparative Examples described later, the present inventor has repeatedly studied a method for forming a bulk hetero layer that can easily form a bulk hetero layer in which vertically long organic molecules are oriented in the horizontal direction with high productivity. As a result, in the formation of the organic photoelectric conversion layer, the film was first formed while controlling the substrate temperature at 5 ° C. to 15 ° C. so that an organic photoelectric conversion layer having high horizontal orientation was obtained, and then the substrate temperature was controlled. It was found that an organic photoelectric conversion element having good productivity, good cost performance, easy process and good afterimage characteristics can be produced by stopping ordinary vapor deposition.

  As can be seen from the description of Examples below, in the method of forming an organic photoelectric conversion layer of the present invention, the organic layer in the upper layer is aligned by the influence of the orientation of the organic molecule in the underlayer, and the photoelectric conversion with excellent orientation is achieved. Layers are being deposited. As described above, in the organic amorphous film, the method of controlling the orientation of the organic molecules in the upper layer by the orientation of the organic molecules in the underlying layer is a new technique not found in the technical common sense of the organic amorphous film.

Below, the structure of each layer of the organic photoelectric conversion element 1 is demonstrated.
<Substrate and electrode>
There is no restriction | limiting in particular as the board | substrate 10, A silicon substrate, a glass substrate, etc. can be used.

  The hole collection electrode 20 is an electrode for collecting holes out of the charges generated in the photoelectric conversion layer 32, and corresponds to a pixel electrode in the configuration of the imaging device described later. The hole collecting electrode 20 is not particularly limited as long as it has good conductivity. However, depending on the application, a material that does not have transparency but reflects light can be used. There are cases.

  Specific examples include metals, metal oxides, metal nitrides, metal borides, organic conductive compounds, and mixtures thereof. More specifically, tin oxide doped with antimony or fluorine (ATO, FTO), tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO) and other conductive metal oxides, gold, silver, chromium, nickel, titanium, tungsten, aluminum and other metals Conductive compounds such as oxides and nitrides of these metals (titanium nitride (TiN) is given as an example), a mixture or laminate of these metals and conductive metal oxides, copper iodide, copper sulfide, etc. And inorganic conductive materials, organic conductive materials such as polyaniline, polythiophene, and polypyrrole, and laminates of these with ITO or titanium nitride. Particularly preferred as the hole collecting electrode 20 is any material of titanium nitride, molybdenum nitride, tantalum nitride, and tungsten nitride.

  The electron collection electrode 40 is an electrode that collects electrons out of charges generated in the photoelectric conversion layer 32, and is a transparent electrode disposed on the light receiving side in the present embodiment. The electron collecting electrode 40 is not particularly limited as long as it is a conductive material that is sufficiently transparent to light having a wavelength with which the photoelectric conversion layer 32 has sensitivity in order to make light incident on the photoelectric conversion layer 32. In order to increase the absolute amount of light incident on the photoelectric conversion layer 32 and increase the external quantum efficiency, it is preferable to use a transparent conductive oxide (TCO). The electron collection electrode 40 corresponds to a pixel electrode in the configuration of the imaging device described later.

Specifically, as the electron collecting electrode 40, ITO, IZO, SnO ₂ , ATO (antimony-doped tin oxide), ZnO, AZO (Al-doped zinc oxide), GZO (gallium-doped zinc oxide), TiO ₂ , FTO Any material of (fluorine-doped tin oxide) is mentioned.

  The light transmittance of the electron collection electrode 40 is preferably 60% or more, more preferably 80% or more, more preferably 90% or more, and more preferably 95% or more in the visible light wavelength.

  The method for forming the electrodes (20, 40) is not particularly limited, and can be appropriately selected in consideration of appropriateness with the electrode material. Specifically, it can be formed by a wet method such as a printing method or a coating method, a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, or a chemical method such as CVD or plasma CVD method.

  When the material of the electrode is ITO, it can be formed by a method such as an electron beam method, a sputtering method, a resistance heating vapor deposition method, a chemical reaction method (such as a sol-gel method), or a dispersion of indium tin oxide. Furthermore, UV-ozone treatment, plasma treatment, or the like can be performed on a film formed using ITO. When the electrode material is TiN, various methods including a reactive sputtering method are used, and further, annealing treatment, UV-ozone treatment, plasma treatment, and the like can be performed.

  When a transparent conductive film made of TCO is used as the electron collecting electrode 40, a DC short circuit or an increase in leakage current may occur. One reason for this is thought to be that fine cracks introduced into the photoelectric conversion layer 32 are covered with a dense film such as TCO, and conduction between the lower electrode 20 on the opposite side is increased. Therefore, in the case of an electrode having a relatively poor film quality such as Al, an increase in leakage current is unlikely to occur. By controlling the film thickness of the electron collection electrode 40 with respect to the film thickness of the photoelectric conversion layer 32 (that is, the depth of cracks), an increase in leakage current can be largely suppressed. The thickness of the electron collection electrode 40 is desirably 1/5 or less, preferably 1/10 or less of the thickness of the photoelectric conversion layer 32.

  Usually, when the conductive film is made thinner than a certain range, a rapid increase in resistance value is caused. However, in the solid-state imaging device incorporating the photoelectric conversion element according to the present embodiment, the sheet resistance is preferably 100 to 10,000 Ω / □. Well, the degree of freedom in the range of film thickness that can be made thin is great. Further, the thinner the upper electrode 40 is, the less light is absorbed, and the light transmittance is generally increased. The increase in light transmittance is very preferable because it increases the light absorption in the photoelectric conversion layer 32 and increases the photoelectric conversion ability. Considering the suppression of leakage current, the increase in the resistance value of the thin film, and the increase in transmittance due to the thinning, the thickness of the electron collection electrode 40 is preferably 5 to 100 nm, and preferably 5 to 20 nm. Is more preferable.

<Light receiving layer>
The light receiving layer 30 is a layer including at least the photoelectric conversion layer 32, and includes an electron blocking layer 31 and a hole blocking layer 33 in the present embodiment. The method for forming the electron blocking layer 31 and the hole blocking layer 33 is not particularly limited, and can be formed by each dry film forming method or wet film forming method. Preferably, it is preferably carried out, and basically it is preferable that the compound does not come into direct contact with oxygen and moisture in the outside air. An example of such a film forming method is a vacuum deposition method. In the vacuum deposition method, it is preferable to perform PI or PID control of the deposition rate using a film thickness monitor such as a crystal resonator or an interferometer. In the case where two or more kinds of compounds are deposited at the same time, a co-evaporation method can be used as in the photoelectric conversion layer 32. The co-evaporation method is performed using resistance heating deposition, electron beam deposition, flash deposition, or the like. It is preferable to do.

When the light receiving layer 30 is formed by a dry film forming method, the degree of vacuum at the time of formation is preferably 1 × 10 ⁻³ Pa or less in consideration of preventing deterioration of element characteristics at the time of forming the light receiving layer. ⁻⁴ Pa or less is more preferable, and 1 × 10 ⁻⁴ Pa or less is particularly preferable.

  The thickness of the light receiving layer 30 is preferably 10 nm to 1000 nm, more preferably 50 nm to 800 nm, and particularly preferably 100 nm to 600 nm. By setting it to 10 nm or more, a suitable dark current suppressing effect is obtained, and by setting it to 1000 nm or less, suitable photoelectric conversion efficiency (sensitivity) is obtained.

<< Photoelectric conversion layer >>
The n-type organic semiconductor in the photoelectric conversion layer (bulk hetero layer) 32 is not particularly limited. 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 ₅₄₀ , mixed fullerene, fullerene nanotube and the like can be mentioned. A typical fullerene skeleton is shown below.
The fullerene derivative means a compound having a substituent added thereto. The substituent for the fullerene derivative is preferably an alkyl group, an aryl group, or a heterocyclic group. More preferably, the alkyl group is an alkyl group having 1 to 12 carbon atoms, and the aryl group and the heterocyclic group are preferably a 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, phenanthroline , 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.

In the bulk hetero layer 32, the organic p-type semiconductor mixed with the n-type organic semiconductor is not particularly limited, but the peak wavelength of the absorption spectrum may be 450 nm or more and 700 nm or less from the viewpoint of widely absorbing light in the visible region. It is preferably 480 nm to 700 nm, more preferably 510 nm to 680 nm. From the viewpoint of efficiently using light, the higher the molar extinction coefficient, the better. 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.

  A p-type organic semiconductor is a donor-type organic semiconductor (compound), which is mainly represented by a hole-transporting organic compound and has a property of easily donating electrons. More specifically, two organic materials are brought into contact with each other. Is an organic compound having a smaller ionization potential when used. Therefore, any organic compound can be used as the donor organic compound as long as it is an electron-donating organic compound.

  Examples of p-type organic semiconductors include triarylamine compounds, pyran compounds, quinacridone compounds, benzidine compounds, pyrazoline compounds, styrylamine compounds, hydrazone compounds, triphenylmethane compounds, carbazole compounds, polysilane compounds, thiophene compounds, phthalocyanine compounds, Cyanine compounds, merocyanine compounds, oxonol compounds, polyamine compounds, indole compounds, pyrrole compounds, pyrazole compounds, polyarylene compounds, condensed aromatic carbocyclic compounds (naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, Fluoranthene derivatives), metal complexes with nitrogen-containing heterocyclic compounds as ligands, and triarylamination Things, pyran compounds, quinacridone compounds, pyrrole compounds, phthalocyanine compounds, merocyanine compounds, fused aromatic carbocyclic compound.

Examples of suitable materials for the p-type organic semiconductor include compounds represented by the following general formula (1).
(In General Formula (1), Z ₁ represents an atomic group necessary for forming a 5- or 6-membered ring. L ₁ , L ₂ , and L ₃ are each independently an unsubstituted methine group or a substituted methine. D ₁ represents an atomic group, and n represents an integer of 0 or more.

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. . As a 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: Is mentioned.

(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 represented 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, a 2-thiobarbi acid nucleus, 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 , 4-imidazolidinedione nucleus, 2-thio-2,4-imidazolidinedione nucleus, 2-imidazolin-5-one nucleus, 3,5-pyrazolidinedione nucleus, benzothiophen-3-one nucleus, indanone nucleus And more preferably a 1,3-dicarbonyl nucleus, a 2,4,6-triketohexahydropyrimidine nucleus (including a thioketone body such as a barbituric acid nucleus, Rubituric 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 their Is a derivative.

In the general formula (1), 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 form a ring. A 6-membered ring (for example, benzene ring etc.) is mentioned as a ring. Examples of the substituent of the substituted methine group include the substituent W described later, and it is preferable that all of L ₁ , L ₂ and L ₃ are unsubstituted methine groups.

  In the general formula (1), n represents an integer of 0 or more, preferably 0 or more and 3 or less, more preferably 0. When n is increased, the absorption wavelength region can be made longer, but the decomposition temperature due to heat is lowered. N = 0 is preferable in that it has appropriate absorption in the visible region and suppresses thermal decomposition during vapor deposition.

In the general formula (1), D ₁ represents an atomic group. D ₁ is preferably a group containing —NR ^a (R ^b ), and D ₁ is preferably an aryl group substituted with —NR ^a (R ^b ) (preferably, may have a substituent, Preferred is a phenyl group or a naphthyl group. R ^a and R ^b each independently represent a hydrogen atom or a substituent, and examples of the substituent include a substituent W described later, and preferably an aliphatic hydrocarbon group (preferably having a substituent). An alkyl group or an alkenyl group), an aryl group, or a heterocyclic group.

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 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 Ra and Rb include a 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 good phenyl group), or a heterocyclic group.

  The aryl groups represented by Ra and Rb 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, 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. is there. Examples 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 Ra and Rb are each independently preferably 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 C3-18 heterocycle which may have a C1-4 alkyl group or a C6-18 aryl group. It is a group. The heterocyclic group represented by Ra and Rb is preferably a condensed ring structure, such as a furan ring, a thiophene ring, a selenophene ring, a silole ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, an oxazole ring, a thiazole ring, a triazole ring, A condensed ring structure of a combination of rings selected from an oxadiazole ring and a thiadiazole ring (which may be the same) is preferable. A quinoline ring, an isoquinoline ring, a benzothiophene ring, a dibenzothiophene ring, a thienothiophene ring, a bithienobenzene ring, A thienothiophene ring is preferred.

The arylene group and aryl group represented by D ₁ , Ra and Rb 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, a pyrene ring, A phenanthrene ring can be mentioned, a benzene ring, a naphthalene ring or an anthracene ring is more preferable, and a benzene ring or a naphthalene ring is still more preferable.

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, mercapto 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 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 (OPO (OH) 2)} , a sulfato group (-OSO ₃ H), and other known substituents.

  When Ra and Rb represent a substituent (preferably an alkyl group or an alkenyl group), the substituent is a hydrogen atom of an aromatic ring (preferably benzene ring) skeleton of an aryl group substituted by —NRa (Rb), or It may combine with a substituent to form a ring (preferably a 6-membered ring).

Ra and Rb may be bonded to each other to form a ring (preferably a 5- or 6-membered ring, more preferably a 6-membered ring), and Ra and Rb are each L (L ₁ , A ring (preferably a 5- or 6-membered ring, more preferably a 6-membered ring) may be formed by combining with a substituent in L ₂ or L ₃ .

  The compound represented by the general formula (1) is a compound described in JP 2000-297068 A, and a compound not described in the above publication can also be produced according to the synthesis method described in the above publication. .

The compound represented by the general formula (1) is preferably a compound represented by the following general formula (2).
(In the formula, Z ₂ , L ₂₁ , L ₂₂ , L ₂₃ , and n are synonymous with Z ₁ , L ₁ , L ₂ , L ₃ , and n in the general formula (1), and preferred examples thereof are also the same. D ₂₁ represents a substituted or unsubstituted arylene group, and 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 Ra and Rb, 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 the formula (3), Z ₃ represents any of the following A-1 to A-12. L ₃₁ represents methylene and n represents 0. D ₃₁ represents any of B-1 to B-9. D ₃₂ and D ₃₃ represent any one 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 following substituents, linking groups and partial structures in the general formula (3), but the present invention is not limited thereto. .
Here, A-1 to A-12, B-1 to B-9, and C-1 to C-16 are synonymous with those already shown.

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

  The photoelectric conversion layer 32 is a non-light-emitting layer, unlike an organic EL light-emitting layer (a layer that converts an electrical signal into light). The non-light emitting layer means a layer having a light emission quantum efficiency of 1% or less, preferably 0.5% or less, more preferably 0.1% or less in the visible light region (wavelength 400 nm to 730 nm). In the photoelectric conversion layer 32, if the emission quantum efficiency exceeds 1%, it is not preferable because it affects sensing performance or imaging performance when applied to a sensor or an imaging device.

<< Electron blocking layer >>
The electron blocking layer 31 is a layer for suppressing injection of electrons from the hole collection electrode 20 into the photoelectric conversion layer 32. It may be composed of a single organic material film, or may be composed of a mixed film of a plurality of different organic materials or inorganic materials.

  The electron blocking layer 31 may be composed of a plurality of layers. By doing in this way, an interface is formed between each layer which comprises the electron blocking layer 31, and a discontinuity arises in the intermediate level which exists in each layer. As a result, it becomes difficult for the charge to move through the intermediate level and the like, so that the electron blocking effect can be enhanced. However, if the layers constituting the electron blocking layer 31 are made of the same material, the intermediate levels existing in the layers may be exactly the same. Therefore, in order to further enhance the electron blocking effect, the materials constituting the layers are different. It is preferable to make it.

  The electron blocking layer 31 is preferably made of a material having a high electron injection barrier from the hole collection electrode 20 and a high hole transport property. As the electron injection barrier, the electron affinity of the electron blocking layer is preferably 1 eV or less, more preferably 1.3 eV or more, and particularly preferably 1.5 eV or more than the work function of the adjacent electrode.

  The electron blocking layer 31 sufficiently suppresses the contact between the hole collecting electrode 20 and the photoelectric conversion layer 32, and also avoids the influence of defects and dust existing on the surface of the hole collecting electrode 20 at 20 nm or more. It is preferable that it is 40 nm or more.

  An electron-donating organic material can be used for the electron blocking layer 31. 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. Polyphyrin compounds, triazole derivatives, oxa Zazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, fluorene derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, silazane derivatives, etc. 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 a compound having a sufficient hole transporting property, it is possible to use it, and specifically, for example, the compounds described in JP-A-2008-72090 are preferred. Can be used.

An example of a compound suitable as the electron blocking layer 31 is shown below.
An inorganic material can also be used as the electron blocking layer 31. In general, since an inorganic material has a dielectric constant larger than that of an organic material, a large voltage is applied to the photoelectric conversion layer 32 when the electron blocking layer 31 is used, and the photoelectric conversion efficiency (sensitivity) is increased. Can do. Materials that can be the electron blocking layer 31 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.

When the electron blocking layer 31 is a single layer, the layer can be a layer made of an inorganic material, or in the case of a plurality of layers, one or more layers can be a layer made of an inorganic material. it can.
<< Hole blocking layer >>
In the photoelectric conversion element 1, the hole blocking layer 33 is a layer that suppresses injection of holes from the electron collection electrode 40 when an external voltage is applied, and is a layer formed on the layer (in this embodiment, the electron collection electrode 40). When the film is formed, it has a function of protecting the photoelectric conversion layer 32 and suppressing film formation damage.

  An electron-accepting organic material can be used for the hole blocking layer. Although the electron-accepting material is not particularly limited, oxadiazole derivatives such as 1,3-bis (4-tert-butylphenyl-1,3,4-oxadiazolyl) phenylene (OXD-7), anthraquinodimethane derivatives, Diphenylquinone derivatives, bathocuproine, bathophenanthroline, and derivatives thereof, triazole compounds, tris (8-hydroxyquinolinato) aluminum complexes, bis (4-methyl-8-quinolinato) aluminum complexes, distyrylarylene derivatives, silole compounds, etc. Can be used. Moreover, even if it is not an electron-accepting organic material, it can be used if it is a material which has sufficient electron transport property. A porphyrin-based compound or a styryl-based compound such as DCM (4-dicyanomethylene-2-methyl-6- (4- (dimethylaminostyryl))-4H pyran) or a 4H pyran-based compound can be used.

  If the charge blocking layer composed of the hole blocking layer 33 and the electron blocking layer 31 is too thick, the supply voltage necessary for applying an appropriate electric field strength to the photoelectric conversion layer is increased, The carrier transport process in the charge blocking layer may cause a problem that adversely affects the performance of the photoelectric conversion element. Accordingly, the total film thickness of the hole blocking layer 33 and the electron blocking layer 31 is preferably designed to be 300 nm or less. The total film thickness is more preferably 200 nm or less, and still more preferably 100 nm or less.

<Sealing layer>
The sealing layer 50 prevents entry of factors that degrade the photoelectric conversion material such as water molecules and oxygen molecules after the photoelectric conversion element 1 or the imaging element 100 described later, and can be stored and used for a long period of time. It is a layer for preventing deterioration of the photoelectric conversion layer. In addition, the sealing layer 50 protects the photoelectric conversion layer by preventing intrusion of factors that degrade the photoelectric conversion layer included in the solution, plasma, and the like in the manufacturing process of the imaging element 100 after the sealing layer is formed. It is also a layer.

  The sealing layer 50 is formed so as to cover the hole collection electrode 20, the electron blocking layer 31, the photoelectric conversion layer 32, the hole blocking layer 33, and the electron collection electrode 40.

  In the photoelectric conversion element 1, since incident light reaches the photoelectric conversion layer 32 through the sealing layer 50, the photoelectric conversion layer 32 is sensitive to the sealing layer 50 in order to allow light to efficiently enter the photoelectric conversion layer 32. It is necessary to be sufficiently transparent to light having a wavelength. Examples of the sealing layer 50 include ceramics such as dense metal oxide, metal nitride, and metal nitride oxide that do not allow water molecules to permeate, diamond-like carbon (DLC), and the like. Conventionally, aluminum oxide, silicon oxide, Silicon nitride, silicon nitride oxide, a laminated film thereof, a laminated film of them and an organic polymer, or the like is used.

  The sealing layer 50 can be composed of a thin film made of a single material, but by providing a separate function for each layer in a multi-layer structure, the stress relaxation of the entire sealing layer 50 and dust generation during the manufacturing process Such effects as the suppression of defects such as cracks and pinholes caused by the above, and the optimization of material development can be expected. For example, the sealing layer 50 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.

  The formation method of the sealing layer 50 is not particularly limited, and is preferably formed by a method that does not deteriorate the performance and film quality of the already formed photoelectric conversion layer 32 and the like as much as possible.

  The performance of organic photoelectric conversion materials is significantly deteriorated due to the presence of deterioration factors such as water molecules and oxygen molecules. Therefore, it is necessary to cover and seal the entire photoelectric conversion layer with a dense metal oxide, metal nitride oxide or the like that does not permeate deterioration factors. 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.

However, the conventional sealing layer is difficult to grow a thin film at a step due to a structure on the substrate surface, minute defects on the substrate surface, particles adhering to the substrate surface, etc. As a result, the film thickness is significantly reduced. For this reason, the step portion becomes a path through which the deterioration factor penetrates. In order to completely cover the step with the sealing layer, it is necessary to form the film so as to have a film thickness of 1 μm or more in the flat portion, and to increase the thickness of the entire sealing layer. The degree of vacuum when forming the sealing layer is preferably 1 × 10 ³ Pa or less, and more preferably 5 × 10 ² Pa or less.

  In the case of an imaging device having a pixel size of less than 2 μm, particularly about 1 μm, if the sealing layer 50 is thick, the distance between the color filter and the photoelectric conversion layer increases, and incident light is diffracted / Diversity and color mixing may occur. Therefore, when considering application to an image sensor having a pixel size of about 1 μm, a sealing layer material / manufacturing method is required that does not deteriorate the device performance even if the thickness of the sealing layer 50 is reduced.

  The atomic layer deposition (ALD) 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 therein. 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. For this reason, 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 high. Excellent. For this reason, steps due to structures on the substrate surface, minute defects 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 for a deterioration factor of the photoelectric conversion material. When the sealing layer 50 is formed by the atomic layer deposition method, the required sealing layer thickness can be effectively reduced as compared with the prior art.

  In the case of forming the sealing layer 50 by the atomic layer deposition method, a material corresponding to the ceramics preferable for the sealing layer 50 described above can be appropriately selected. However, since the photoelectric conversion layer of the present invention uses an organic photoelectric conversion material, 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 atomic layer deposition method using alkyl aluminum or aluminum halide as the 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. Silicon oxide and titanium oxide are also preferable because a dense thin film can be formed at less than 200 ° C., similarly to aluminum oxide, by appropriately selecting materials.

  The sealing layer preferably has a thickness of 10 nm or more in order to sufficiently prevent the entry of factors that degrade the photoelectric conversion material such as water molecules. In the imaging device, when the sealing layer has a large film thickness, incident light is diffracted or diverged in the sealing layer, and color mixing occurs. The film thickness of the sealing layer is preferably 200 nm or less.

  In addition, the thin film formed by the atomic layer deposition method can achieve a high-quality thin film formation at a low temperature that is unparalleled from the viewpoint of step coverage and denseness. However, the physical properties of the thin film material may be deteriorated by chemicals used in the photolithography process. For example, since an aluminum oxide thin film formed by atomic layer deposition is amorphous, the surface is eroded by an alkaline solution such as a developer or a stripping solution.

  In addition, thin films formed by CVD, such as atomic layer deposition, often have tensile stresses with very large internal stress, such as processes that repeat intermittent heating and cooling, such as semiconductor manufacturing processes, Due to storage / use in a high temperature / high humidity atmosphere for a period, deterioration of the thin film itself may occur.

  Therefore, when the sealing layer 50 formed by the atomic layer deposition method is used, it is preferable to form a sealing auxiliary layer that has excellent chemical resistance and can cancel the internal stress of the sealing layer 50.

  Examples of the auxiliary sealing layer include any of ceramics such as metal oxide, metal nitride, and metal nitride oxide that are excellent in chemical resistance formed by physical vapor deposition (PVD) such as sputtering. Or a layer containing one of them. Ceramics formed by a PVD method such as sputtering often has a large compressive stress, and can cancel the tensile stress of the sealing layer 50 formed by an atomic layer deposition method.

In the photoelectric conversion element 1, as an external electric field applied between the hole collection electrode 20 and the electron collection electrode 40 in order to obtain excellent characteristics in photoelectric conversion efficiency (sensitivity), dark current, and light response speed. Is preferably 1 V / cm or more and 1 × 10 ⁷ V / cm or less. The external electric field is a value obtained by dividing the voltage applied from the outside to the pair of electrodes by the distance between the electrodes.

  In the photoelectric conversion element 1, the light receiving layer 30 is formed by the electron blocking layer 31, the photoelectric conversion layer 32, and the hole blocking layer 33. In the present embodiment, the mode including the hole blocking layer 33 is shown. However, since the hole blocking layer 33 does not contribute to the flow of holes, the present invention can be used regardless of the presence or absence of the hole blocking layer 33. An effect can be obtained.

"Image sensor"
Next, the configuration of the image sensor 100 including the photoelectric conversion element 1 will be described with reference to FIG. FIG. 9 is a schematic cross-sectional view illustrating a schematic configuration of an image sensor for explaining an embodiment of the present invention. This imaging device is used by being mounted on an imaging device such as a digital camera or a digital video camera, an imaging module such as an electronic endoscope or a mobile phone, or the like.

  The image pickup device 100 is a circuit board on which a plurality of organic photoelectric conversion elements 1 configured as shown in FIG. 1 and a readout circuit that reads out signals corresponding to charges generated in the photoelectric conversion layer of each organic photoelectric conversion element are formed. And a plurality of organic photoelectric conversion elements are arranged one-dimensionally or two-dimensionally on the same surface above the circuit board.

  The image sensor 100 includes a substrate 101, an insulating layer 102, a connection electrode 103, a pixel electrode 104, a connection portion 105, a connection portion 106, a light receiving layer 107, a counter electrode 108, a buffer layer 109, a sealing layer. A stop layer 110, a color filter (CF) 111, a partition wall 112, a light shielding layer 113, a protective layer 114, a counter electrode voltage supply unit 115, and a readout circuit 116 are provided.

  The pixel electrode 104 has the same function as the hole collection electrode 20 of the organic photoelectric conversion element 1 shown in FIG. The counter electrode 108 has the same function as the electron collection electrode 40 of the organic photoelectric conversion element 1 shown in FIG. The light receiving layer 107 has the same configuration as the light receiving layer 30 provided between the hole collecting electrode 20 and the electron collecting electrode 40 of the organic photoelectric conversion element 1 shown in FIG. The sealing layer 110 has the same function as the sealing layer 50 of the organic photoelectric conversion element 1 shown in FIG. The pixel electrode 104, a part of the counter electrode 108 facing the pixel electrode 104, the light receiving layer 107 sandwiched between the electrodes, and the buffer layer 109 and the part of the sealing layer 110 facing the pixel electrode 104 are subjected to organic photoelectric conversion. The element is configured.

  The substrate 101 is a glass substrate or a semiconductor substrate such as Si. An insulating layer 102 is formed on the substrate 101. A plurality of pixel electrodes 104 and a plurality of connection electrodes 103 are formed on the surface of the insulating layer 102.

  The light receiving layer 107 is a layer common to all the organic photoelectric conversion elements provided on the plurality of pixel electrodes 104 so as to cover them.

  The counter electrode 108 is one electrode provided on the light receiving layer 107 and common to all organic photoelectric conversion elements. The counter electrode 108 is formed up to the connection electrode 103 disposed outside the light receiving layer 107 and is electrically connected to the connection electrode 103.

  The connection part 106 is embedded in the insulating layer 102 and is a plug or the like for electrically connecting the connection electrode 103 and the counter electrode voltage supply part 115. The counter electrode voltage supply unit 115 is formed on the substrate 101 and applies a predetermined voltage to the counter electrode 108 via the connection unit 106 and the connection electrode 103. When the voltage to be applied to the counter electrode 108 is higher than the power supply voltage of the image sensor, the power supply voltage is boosted by a booster circuit such as a charge pump to supply the predetermined voltage.

  The readout circuit 116 is provided on the substrate 101 corresponding to each of the plurality of pixel electrodes 104, and reads out a signal corresponding to the charge collected by the corresponding pixel electrode 104. The reading circuit 116 is configured by, for example, a CCD, a MOS circuit, or a TFT circuit, and is shielded from light by a light shielding layer (not shown) disposed in the insulating layer 102. The readout circuit 116 is electrically connected to the corresponding pixel electrode 104 via the connection unit 105.

  The buffer layer 109 is formed on the counter electrode 108 so as to cover the counter electrode 108. The sealing layer 110 is formed on the buffer layer 109 so as to cover the buffer layer 109. The color filter 111 is formed at a position facing each pixel electrode 104 on the sealing layer 110. The partition wall 112 is provided between the color filters 111 and is for improving the light transmission efficiency of the color filter 111.

  The light shielding layer 113 is formed in a region other than the region where the color filter 111 and the partition 112 on the sealing layer 110 are provided, and prevents light from entering the light receiving layer 107 formed outside the effective pixel region. The protective layer 114 is formed on the color filter 111, the partition 112, and the light shielding layer 113, and protects the entire image sensor 100.

  In the imaging device 100 configured as described above, when light is incident, the light is incident on the light receiving layer 107, and charges are generated here. Holes in the generated charges are collected by the pixel electrode 104, and a voltage signal corresponding to the amount is output to the outside of the image sensor 100 by the readout circuit 116.

The manufacturing method of the image sensor 100 is as follows.
On the circuit substrate on which the common electrode voltage supply unit 115 and the readout circuit 116 are formed, the connection units 105 and 106, the plurality of connection electrodes 103, the plurality of pixel electrodes 104, and the insulating layer 102 are formed. The plurality of pixel electrodes 104 are arranged on the surface of the insulating layer 102 in a square lattice pattern, for example.

  Next, the light receiving layer 107, the counter electrode 108, the buffer layer 109, and the sealing layer 110 are sequentially formed on the plurality of pixel electrodes 104. The formation method of the light receiving layer 107, the counter electrode 108, and the sealing layer 110 is as described in the description of the photoelectric conversion element 1. The buffer layer 109 is formed by, for example, a vacuum resistance heating vapor deposition method. Next, after forming the color filter 111, the partition 112, and the light shielding layer 113, the protective layer 114 is formed, and the imaging element 100 is completed.

"Design changes"
As mentioned above, although the film-forming method of the organic photoelectric conversion layer of this invention, the manufacturing method of the organic photoelectric conversion element using the same, and the organic film film-forming apparatus were demonstrated in detail, this invention is not limited to the said embodiment, this Changes can be made as appropriate without departing from the spirit of the invention.

Example 1
A CMOS substrate in which an ITO electrode was patterned on a Si substrate was prepared, placed on a substrate holder in an organic vapor deposition chamber, and the pressure in the vapor deposition chamber was reduced to 1.0 × 10 ⁻⁴ Pa or less. Thereafter, while rotating the substrate holder, the compound 2 was deposited as an electron blocking layer on the ITO electrode at a deposition rate of 1.0 to 1.2 mm / sec to a thickness of 30 nm by a resistance heating deposition method.

Next, the compound 7 and C ₆₀ are respectively installed in the container of the vapor deposition source in the organic vapor deposition chamber having the configuration shown in FIG. 3 and cooled by the cooling block until the substrate temperature becomes 10 ° C. Film formation was started under the condition that the ratio of C ₆₀ was 1: 3 in terms of the film thickness ratio. The first photoelectric conversion layer forming step was carried out by co-evaporation while controlling the substrate temperature so that the substrate temperature was in the range of 5 ° C. to 15 ° C. for 30 seconds from the start of film formation. In the first photoelectric conversion layer forming step, the vapor deposition rate in the co-deposited film combining the two materials was 2.0 to 2.5 liters / Sec.

  After the elapse of 30 seconds from the start of film formation, the cooling block was removed, and the second photoelectric conversion layer forming step was performed by co-evaporation until the thickness of the bulk hetero layer reached about 400 nm. In the second photoelectric conversion layer forming step, the maximum substrate temperature was set to 100 ° C.

Next, the film was transferred to a sputtering chamber, and ITO was sputtered on the second photoelectric conversion layer as a counter electrode so as to have a thickness of 10 nm by RF magnetron sputtering. Thereafter, the film was transferred to an ALD (Atomic Layer Deposition) chamber, and an Al ₂ O ₃ film was formed as a protective film to a thickness of 2000 mm by an atomic layer deposition method.
Thereafter, the film was transferred to a sputtering chamber, and a SiON film as a stress relaxation layer was formed to a thickness of 1000 mm by a planer type sputtering to produce an imaging device.

(Example 2)
In the second photoelectric conversion layer forming step, an imaging device was manufactured in the same manner as in Example 1 except that the maximum substrate temperature was set to 35 ° C.

(Example 3)
In the second photoelectric conversion layer forming step, an imaging element was manufactured in the same manner as in Example 1 except that the maximum substrate temperature was set to 60 ° C.

Example 4
In the second photoelectric conversion layer forming step, an imaging device was manufactured in the same manner as in Example 1 except that the maximum substrate temperature was set to 80 ° C.

(Example 5)
Compound 7 and 1 percentage thickness ratio of C _60: except for using 2 become vapor deposition conditions to produce an image sensor in the same manner as in Example 1.

(Example 6)
An imaging device was fabricated in the same manner as in Example 1 except that the deposition conditions were such that the ratio of the compound 7 and C ₆₀ was 1: 1 in terms of the film thickness ratio.

(Example 7)
An imaging device was produced in the same manner as in Example 1 except that Compound 6 was used instead of Compound 7.

(Comparative Example 1)
An imaging device was manufactured in the same manner as in Example 1 except for the method of forming the bulk hetero layer. The bulk hetero layer is formed by transferring the substrate temperature from about 20 ° C. in the room temperature environment to the film forming chamber before the start of film formation, and soon the ratio of compound 7 and C ₆₀ is 1: Film formation was started under vapor deposition conditions of 3. In the bulk hetero layer co-deposition, the maximum temperature of the substrate was 100 ° C., and the deposition rate was 2.0 to 2.5 liters / Sec.

(Comparative Example 2)
An imaging device was produced in the same manner as in Example 2 except for the method for forming the bulk hetero layer. The bulk hetero layer is formed by transferring the substrate temperature from about 20 ° C. in the room temperature environment to the film forming chamber before the start of film formation, and soon the ratio of compound 7 and C ₆₀ is 1: Film formation was started at an evaporation rate of 3. In the bulk hetero layer co-deposition, the maximum temperature of the substrate was 35 ° C., and the deposition rate was 2.0 to 2.5 liters / Sec.

(Comparative Example 3)
An imaging device was manufactured in the same manner as in Example 1 except for the method of forming the bulk hetero layer. The bulk hetero layer is formed by cooling the substrate before starting the film formation, and controlling the substrate temperature to be in the range of 5 ° C. to 15 ° C., while the ratio of the compound 1 to C ₆₀ is 1 in the film thickness ratio. : A bulk hetero layer was formed under vapor deposition conditions of 3.

(Comparative Example 4)
An imaging device was manufactured in the same manner as in Example 1 except for the method of forming the bulk hetero layer. The bulk hetero layer is formed by transferring the substrate temperature from about 20 ° C. in the room temperature environment to the film forming chamber before the start of film formation, and soon the ratio of compound 7 and C ₆₀ is 1: Film formation was started under vapor deposition conditions of 3. In the co-deposition of the bulk hetero layer, the deposition rate of the co-deposition film combining the two materials was 2.0 to 2.5 liters / sec, and the maximum substrate temperature during the bulk hetero film formation was 80 ° C. It was.

(Comparative Example 5)
An imaging device was manufactured in the same manner as in Example 1 except for the method of forming the bulk hetero layer. The bulk hetero layer is formed by transferring the substrate temperature from about 20 ° C. in the room temperature environment to the film forming chamber before the start of film formation, and soon the ratio of compound 7 and C ₆₀ is 1: Film formation was started under vapor deposition conditions of 3. In the co-deposition of the bulk hetero layer, the deposition rate of the co-deposited film combining the two materials was 2.0 to 2.5 liters / sec, and the maximum substrate temperature during the bulk hetero film formation was 60 ° C. It was.

(Evaluation)
The residual current values were measured for the image sensors of the above examples and comparative examples. The residual current value was measured by irradiating an LED with an output of 1 W for 1 second or more and then turning off, and measuring the residual current after 20 msec. As a result, in Examples 1 to 7, the residual current values were all about 10 pA.

  The results of Examples 1 to 4 and Comparative Example 3 having different substrate maximum temperatures in the second photoelectric conversion layer forming step are collectively shown in FIG. Moreover, about the photoelectric converting layer of Example 1- Example 4 and Comparative Example 3, the result of having measured the orientation degree parameter is put together in FIG. 7 and FIG. 8, the organic photoelectric conversion layer of the present invention in which the substrate temperature is controlled in the range of 5 ° C. to 15 ° C. at the initial stage of film formation and co-evaporation is performed after this temperature control is stopped. Depending on the film formation method, the vertical organic molecules in the organic photoelectric conversion layer are strongly oriented in the horizontal direction with respect to the substrate surface without depending on the maximum substrate temperature, resulting in a low afterimage current. It was confirmed that an organic photoelectric conversion element having a value was obtained. This indicates that according to the present invention, an organic photoelectric conversion element having a low afterimage current value can be stably manufactured without depending on the temperature rise characteristic of the film forming apparatus.

  The organic photoelectric conversion layer deposition method of the present invention is an organic light-emitting device mounted on an organic imaging device mounted on a digital camera, a mobile phone camera, an endoscope camera, or the like, an organic EL display, an organic EL illumination, or the like. It can be preferably applied to the film formation of a photoelectric conversion layer of an organic photoelectric conversion element used in an element, an organic thin film transistor mounted on an electronic paper, a wireless tag, or the like, or an optical sensor.

1 Organic photoelectric conversion device (photoelectric conversion device)
10 Substrate 20 Hole collecting electrode (electrode)
30 Photosensitive layer 31 Electron blocking layer 32 Photoelectric conversion layer (bulk hetero layer)
32a First photoelectric conversion layer 32b Second photoelectric conversion layer 33 Hole blocking layer 40 Electron collecting electrode (electrode)
50 Sealing layer 120 Substrate temperature control means 150 Deposition source 151 Container 152 Heat source 170 Vacuum deposition chamber 200 Organic film forming apparatus

Claims (9)

A method for forming an organic photoelectric conversion layer provided in an organic photoelectric conversion element,
Preparing a substrate and installing the substrate in a vacuum deposition chamber; and
The n-type organic semiconductor and the p-type organic semiconductor constituting the organic photoelectric conversion layer are co-deposited on the substrate while cooling so that the temperature of the installed substrate is in a temperature range of 5 ° C. to 15 ° C. A first photoelectric conversion layer forming step of forming a first photoelectric conversion layer;
An organic photoelectric conversion layer forming method including a second photoelectric conversion layer forming step in which the cooling is stopped and the co-evaporation is performed on the first photoelectric conversion layer to form a second photoelectric conversion layer.   The method for forming an organic photoelectric conversion layer according to claim 1, wherein the second photoelectric conversion layer forming step is performed under a condition that the maximum temperature of the substrate is 80 ° C. or more. The second film forming method according to claim 1 or 2, organic photoelectric conversion layer according photoelectric conversion layer has a thickness greater than said first photoelectric conversion layer. The method for forming an organic photoelectric conversion layer according to claim 3 , wherein a ratio of an average layer thickness of the first photoelectric conversion layer to an average layer thickness of the second photoelectric conversion layer is 1/2 or less. The method for forming a photoelectric conversion layer according to claim 4 , wherein a ratio of an average layer thickness of the first photoelectric conversion layer to an average layer thickness of the second photoelectric conversion layer is 1/3 or less. After the substrate placing step, prior to performing the first photoelectric conversion layer forming step, according to claim 1 to 5 having a cooling step of cooling so that the temperature of the substrate is the temperature range of 5 ° C. or higher 15 ℃ less The film-forming method of the organic photoelectric converting layer of any one of Claims 1. The n-type organic semiconductor according to claim 1-6 any one method of forming the organic photoelectric conversion layer according as a main component fullerene or a fullerene derivative. The p-type organic semiconductor is represented by the following general formula (1) are those containing a compound represented by the claims 1-7 any one method of forming the organic photoelectric conversion layer according.
(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.) A method for producing an organic photoelectric conversion element having a light receiving layer including at least an organic photoelectric conversion layer sandwiched between a hole collection electrode and an electron collection electrode on a substrate,
The manufacturing method of the organic photoelectric conversion element which forms the said organic photoelectric converting layer with the film-forming method of the organic photoelectric converting layer of any one of Claims 1-8 .