JP2006013109A - Organic semiconductor element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic semiconductor element technology which can prevent deterioration of an organic semiconductor layer with irradiation of light for a longer period of time and can also prevent, for a short period of time, behavior of change in the light irradiated as an unstable factor of the operation of an organic semiconductor element or a kind of noise. <P>SOLUTION: After an insulating film 212b is provided on a polycarbonate substrate 201 to which a carbon black is mixed in the 12 weight%, a cathode electrode 202 is formed and an organic semiconductor material 204 is formed thereon with vacuum evaporation or the like. Thereafter, an anode electrode 203 is formed on this organic semiconductor material 204. A polycarbonate is used in common as an electric insulating layer to the substrate material, and a light shielding layer is manufactured by coating a material in which a carbon black is mixed in about 12 weight% as a filler to the raw material (211a) of polycarbonate, to the rear surface side. An insulating film 212b may be provided between the organic semiconductor material, electrode and the light shielding polycarbonate, and moreover it is also possible to use the insulation property of the polycarbonate material of the substrate material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light-shielding protective film in a semiconductor element, a field effect transistor, or a switch element using an organic semiconductor material, and more particularly to an organic semiconductor switching element, an organic semiconductor element such as a MOS-TFT, which can be manufactured mainly using printing technology. . The organic semiconductor element according to the present invention can be applied to driving elements such as an organic EL display and a liquid crystal display.

  Conventionally, as a general application of a protective film, for example, many have been proposed that prevent deterioration of food quality against gas or moisture.

  There are many documents on the organic semiconductor element itself, but there is not much about a protective film against light (protective film for light shielding) of the organic semiconductor element, and Japanese Patent Application Laid-Open No. 8-116109 “Manufacturing method of organic thin film switching memory combined element and “Organic thin film switching / memory composite device” filed on October 14, 1994, applicant: Matsushita Giken Co., Ltd. (Patent Document 1).

The prior art described in Patent Document 1 will be described with reference to FIGS.
FIG. 5 is a configuration diagram of an organic thin film switching memory composite element described in Patent Document 1. Gold is deposited on a quartz glass substrate 311 to form a lower electrode 312 and a lead phthalocyanine (PbPc) thin film is formed. The organic thin film 314 is formed by vapor deposition, and gold is vapor-deposited thereon to form the upper electrode 313.

  As shown in FIG. 6, the characteristics of the organic thin film switching / memory composite element as shown in FIG. 5 are greatly increased by leaving the organic thin film 314 exposed to the air for several days. Changes occur. In particular, when irradiated with ultraviolet rays over a long period of time, the characteristics as a semiconductor, which is thought to be due to the decomposition of the polymer of the organic semiconductor material, are remarkably lost. Is lost.

  In addition, although it is slight, stray light from the surroundings (change) may affect the hysteresis operation of the organic thin film switching / memory composite element, which causes noise. In Patent Document 1, it is proposed to prevent the above-described change by covering the organic thin film switching / memory composite element with a fluororesin.

The problems in the prior art will be described below.
The above-described protective film in Patent Document 1 is proposed mainly with a fluororesin, but the fluororesin is extremely difficult to pass water and water vapor as polar molecules because of its extremely weak surface polarity. However, since it is a resin, there is a problem that a general gas passes relatively well and adhesion to a metal or the like is poor.

  The protection of the organic semiconductor material from light (light-shielding property) is important not only for preventing deterioration of the organic semiconductor material but also for preventing instability of carrier operation due to light entering from the outside. For example, in application to a driver element (TFT or the like) of a liquid crystal display, there is a problem that a light source is provided immediately adjacent to the liquid crystal display, which affects the operation of the material.

  The light-shielding protective film is generally electrically conductive as it is (especially remarkable in the case of carbon black) and cannot be used, and insulation between organic semiconductor materials is necessary. For example, a pigment is provided between the organic semiconductor and the insulating layer. It is conceivable to provide a resin layer that is not contained.

  The polyparaxylylene layer is a material having good characteristics as the insulating film. However, since polyparaxylylene is deposited by vapor deposition, it is difficult to deposit a vapor deposition film as a material containing a pigment.

  Therefore, as the light shielding material, it is necessary to use a polymer resin such as polycarbonate that can be applied and carbon black and share the function. Of course, there is no limitation to this as long as there is a material that can ensure good light-shielding properties and good insulating properties with the coating material. Both functions can be achieved with just one layer.

  In view of the above circumstances, the present invention prevents deterioration of the organic semiconductor layer due to light irradiation in the long term, and changes in the irradiated light in the short term are factors that cause unstable operation of the organic semiconductor element. It aims at providing the organic-semiconductor element technique which can prevent acting as noise.

  The present invention employs the following configuration in order to achieve the above object. Hereinafter, the structure for each claim will be described.

(1) The invention according to claim 1 is an organic semiconductor element using an organic semiconductor material, an organic semiconductor layer provided on a substrate, a first light shielding layer provided on the organic semiconductor layer, It has the 2nd light shielding layer provided in the opposite side to the 1st light shielding layer on both sides of an organic semiconductor layer.

(2) In the invention described in claim 2, an electrical insulating layer is provided between the first light-shielding layer and the organic semiconductor layer and between the second light-shielding layer and the organic semiconductor layer. It is characterized by that.

(3) The invention described in claim 3 is characterized in that the function of the second light shielding layer is provided in the substrate.

(4) The invention described in claim 4 is characterized in that the substrate has a function of an insulating layer provided between the second light-shielding layer and the organic semiconductor element.

The present invention has the following effects by adopting the above configuration. The effects of each claim will be described below.
(1) According to the first aspect of the present invention, the deterioration of the organic semiconductor layer due to long-term light irradiation can be prevented, and the change of the irradiated light is unstable in the operation of the organic semiconductor in the short term. No longer behaves as a factor or a kind of noise.

(2) According to the invention described in claim 2, the conductivity generated by mixing carbon black, which is a kind of pigment often used in light-shielding materials, can be prevented from affecting the characteristics of the organic semiconductor. It was.

(3) According to the invention described in claim 3, since the substrate also serves as a light shielding layer, the configuration is simplified and the manufacture is facilitated.

(4) According to the invention described in claim 4, since the substrate also serves as the electrical insulating layer, the configuration is simplified and the manufacture is facilitated.

  Hereinafter, examples of the organic semiconductor element according to the present invention will be described in detail with reference to the drawings. Here, an embodiment centering on an organic semiconductor switching element will be described.

  FIG. 1 is a cross-sectional view of an embodiment of an organic semiconductor element according to the present invention corresponding to FIG. 5 described in the prior art (Patent Document 1). FIG. 6 shows the voltage-current characteristics of the switching element of FIG. 5 as described above.

  This example is an example of IV characteristics of pentacene used as an organic semiconductor, but has hysteresis in the characteristics, and this hysteresis is used for switching display elements. As a material, in general, a material that is easily crystallized, such as a low-molecular organic semiconductor material, can relatively obtain such characteristics in many cases.

  As shown in FIG. 1, an organic semiconductor element according to the present invention is provided with an insulating film 212b on a polycarbonate substrate 201 mixed with 12% by weight of carbon black, and then a cathode electrode 202 is formed thereon. The semiconductor material 204 is produced by vapor deposition or the like. On top of that, an anode electrode 203 is fabricated. Gold was used as the material used for these electrodes. In the present invention, polycarbonate is used as a substrate material also as an electrical insulating layer, and is prepared by applying a mixture of about 12% by weight of carbon black as a filler to a polycarbonate raw material (211a) on the back side as a light shielding layer. .

  In general, when a pigment such as carbon black is mixed with a binder, conductivity is obtained. Therefore, an insulating film 212b may be provided between the organic semiconductor material and the electrode and the light-shielding polycarbonate. Insulation may be used.

  This insulating film (212b and 211b) can of course achieve a certain level of performance even if polycarbonate without carbon black is used, but it has a higher performance of insulation and air / water vapor blocking ability. Xylylene may be used. For polyparaxylylene, a known method by vapor deposition has been proposed, and it is difficult to produce a film in which a light-shielding pigment is mixed for vapor deposition.

  2 and 3 are modified embodiments in which a polycarbonate material containing 12% by weight of carbon black is applied to a substrate as a light-transmitting substrate material.

  2 is provided on the glass substrate 201 on the side where the organic semiconductor is applied, and FIG. 3 is provided on the back side of the polycarbonate substrate 201 (that is, the front side in FIG. 3). If necessary, an adhesive layer is provided between the substrate material and the light shielding material (not shown).

  In FIG. 2, the light-shielding material does not necessarily have good electrical or air / water vapor barrier properties, so polycarbonate (without pigments) as an insulating film, gas or other polyparaxylylene with particularly high barrier properties, etc. Was used between the organic semiconductor material and the light-shielding material (211b and 212b).

  In FIG. 3, an insulating layer 212b made of a polyparaxylylene film is formed by vapor deposition on the side of the polycarbonate substrate 201 on which the organic semiconductor material is applied, and about 12% by weight of carbon black is formed on the opposite side of the polycarbonate substrate 201. The mixed coating material (light shielding layer) 212a is applied. Gold was deposited as the cathode electrode 202 on the substrate 201 thus obtained, and then an organic semiconductor material 204 was applied.

  Further on this, gold was vapor-deposited as the anode electrode 203, and after heating and drying, an insulating layer 211b made of polyparaxylylene was formed by vapor deposition.

  On top of this, a light-shielding film 211a in which about 12% by weight of carbon black was mixed with a polycarbonate raw material was applied.

  FIG. 4 shows the organic semiconductor layer on the substrate surface while utilizing the electrical insulation function (the substrate 201 has an insulation function (referred to as “201 (212b)” in FIG. 4)) that the substrate 201 also functions in FIG. In this example, a light shielding film (212a) in which about 12% by weight of carbon black is mixed with a polypropylene resin raw material is applied to the side opposite to the side to be manufactured.

  In general, compared to polycarbonate, polyparaxylylene has low permeability for gases such as air and water vapor as well as electrical insulation, and is suitable for protecting organic semiconductors. In this way, organic semiconductors that cause unstable operation such as noise in the short term due to light and that deteriorate due to light in the long term must be used with a highly light-shielding material. .

  The organic semiconductor element has been described above by taking the switching element as an example, but application to other semiconductor elements (organic TFT, organic MOS transistor, etc.) using an organic semiconductor material is also possible.

The features and cautions of the embodiment of the present application are listed below.
(1) A polycarbonate having a relatively high strength is easy to use. In particular, since it can be applied, it is convenient to apply carbon black as a filler to a polycarbonate raw material as a binder material and apply it through an insulating film that has little influence on the organic semiconductor material. Of course, the pigment is not limited to carbon black. A pigment having appropriate spectral absorption characteristics may be used. The insulating films (211b and 212b) can be omitted as long as the conductivity of the resin and the organic semiconductor are not affected.

(2) For the insulating film, for example, a material such as polyparaxylylene, particularly diparaxylylene and derivatives thereof (parylene (registered trademark) may be used) may be used.
(3) Since a filler is used, it can be applied to many other materials as long as the binder resin that can be applied is sufficient for adhesion.

(4) When the substrate on which the organic semiconductor material is applied is not light-shielding such as a glass substrate or a transparent resin substrate, these materials are applied on the back surface of the substrate, directly below the organic semiconductor, or on the back surface side of the substrate. Applying a light-shielding material to the back side of the substrate is easier to fabricate than applying it to the front side of the substrate because it is not in direct contact with the organic semiconductor, and is suitable for covering the entire organic semiconductor element at the end. In the case shown in FIG. 3, it is necessary to pay attention because light that enters along the substrate may not be completely shielded.

It is a figure which shows the Example of the organic-semiconductor element based on this invention. This is a modified example in which a polycarbonate material containing 12% by weight of carbon black is applied to a light transmissive substrate (part 1). This is a modified example in which a polycarbonate material containing 12% by weight of carbon black is applied to a light transmissive substrate (part 2). In FIG. 1, a light-shielding film in which about 12% by weight of carbon black is mixed with a polypropylene resin raw material is applied on the side opposite to the side on which the organic semiconductor layer is formed on the side of the substrate while being used as an electrical insulating function that also serves as the substrate It is an example. 1 is a configuration diagram of an organic thin film switching / memory combined element described in Patent Document 1. FIG. It is a figure which shows the characteristic of the organic thin film switching memory composite element shown in FIG.

Explanation of symbols

201: Substrate 202: Cathode electrode 203: Anode electrode 204: Organic semiconductor material 211a, 212a: Light shielding layer 211b, 212b: Insulating layer 311: Substrate 312: Lower electrode 313: Upper electrode 314: Organic thin film

Claims (4)

  In an organic semiconductor element using an organic semiconductor material, an organic semiconductor layer provided on a substrate, a first light shielding layer provided on the organic semiconductor layer, and the first light shielding layer sandwiching the organic semiconductor layer An organic semiconductor element comprising a second light-shielding layer provided on a side opposite to the layer.   The electrical insulating layer is provided between the first light-shielding layer and the organic semiconductor layer, and between the second light-shielding layer and the organic semiconductor layer. Organic semiconductor element.   The organic semiconductor element according to claim 1, wherein the substrate has a function of the second light shielding layer.   4. The organic semiconductor element according to claim 2, wherein the substrate has a function of an insulating layer provided between the second light shielding layer and the organic semiconductor element.

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