JP2005004188A - Light-emitting device and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device that can independently display images of both front and back sides, in a light emitting device that can display in the both sides and also to provide a light-emitting device in which the aperture ratio of both or either of front and back displays can be increased and the aperture ratio of the total of the front and back displays can be increased. <P>SOLUTION: The light-emitting device is arranged with a first light-emitting element and a second light-emitting element that are adjacent to each other are arranged in matrix; wherein the first light-emitting element can emit light to a first side of a substrate and the second light-emitting element can emit light to a second side that is opposite to the first side of the substrate. And light-emission of the first light-emitting element to the second side is shielded and light-emission of the second light-emitting element to the first side is shielded. In each light-emitting element, since a side opposite to a light-emitting side has a film having a light shielding effect, light-emission can be performed separately in each side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light-emitting device in which a pixel portion is formed using a light-emitting element having a light-emitting layer containing an electroluminescence (Electro-Luminescence) material between a pair of electrodes, and in particular, light emission that can be displayed on two surfaces. Relates to the device. Moreover, it is related with the electronic device which has a display surface on two surfaces.

  In recent years, research on a light-emitting device using a light-emitting element as a self-luminous light-emitting element has been activated. This light emitting device is also called an organic EL (Electro-Luminescence) display or an organic light emitting diode. These light-emitting devices have features such as fast response speed, low voltage, and low power consumption driving suitable for moving image display, so next-generation displays such as new-generation mobile phones and personal digital assistants (PDAs) It is attracting a lot of attention.

  A light-emitting element using an organic compound layer as a light-emitting layer has a structure in which a multilayer film in which at least one layer containing a light-emitting material is inserted is stacked over a substrate. This multilayer film is composed of a pair of electrodes formed of a light-transmitting conductive film, that is, an anode and a cathode, and a layer containing a light emitting material. By applying an electric field to the anode and the cathode, electroluminescence is emitted from the layer containing the luminescent material. Here, all layers provided between the cathode and the anode are collectively referred to as a layer containing a light-emitting substance.

  In many cases, the layer containing the light-emitting substance has a laminated structure represented by “hole transport layer / light-emitting layer / electron transport layer”. In addition, materials for forming a layer containing a light-emitting substance are roughly classified into a low molecular (monomer) material and a high molecular (polymer) material.

  A typical light-emitting element has a structure in which a transparent conductive film formed on a substrate by a sputtering method is used as an anode, and a layer containing a light-emitting substance and a cathode using a metal such as aluminum are stacked (hereinafter referred to as a lower surface). It is referred to as an emission type light emitting element). In the light-emitting element having this structure, light emission is extracted from the anode formed on the substrate. When a display using light emitting elements of this structure as pixels is displayed by active matrix driving, the driving elements on the substrate, for example, TFTs block light emitted through the anode, and the efficiency of light emission is greatly reduced.

  In addition, a light-emitting element having a structure in which a non-light-transmitting metal electrode is formed on a substrate as an anode and a layer containing a light-emitting substance and a light-transmitting conductive substance serving as a cathode are stacked thereon (hereinafter, referred to as a light-emitting element) Also referred to as a top emission element). In the light-emitting element having this structure, light emission is extracted from the cathode formed on the substrate. For this reason, even when the display is displayed by active matrix driving, the driving element on the substrate does not block light emission.

Further, a light emitting element having a structure in which light emission is extracted from both the cathode side and the anode side, that is, a structure in which one pixel is a top emission type and a bottom emission type element (hereinafter referred to as dual emission). (Referred to as a mold element) has also been proposed (Patent Document 1).
JP 20001-332392 A

  However, when the light emitting device having the dual emission element described in Patent Document 1 is driven and displayed, the mirror image is displayed on the other side of the image on one side. For this reason, there arises a problem that characters are reversed on either side.

  In addition, since both the anode side and cathode side electrodes have translucency in the dual emission type element, the anode side can be seen from the cathode side, and the back side can be seen from the anode side to the back side. It will end up. Therefore, in order to accurately recognize the displayed image, it is necessary to appropriately apply a light-shielding material to the entire back surface of the viewing surface. In that case, the images cannot be viewed simultaneously from both sides.

  Further, in the active matrix driving dual emission type element, the drive element of the bottom emission type element is provided in a part of the display portion (display area), and the aperture ratio in the bottom emission type element area is lowered. The problem is also mentioned.

  Therefore, in view of the above problems, the present invention can display images on two surfaces independently in a light emitting device capable of displaying on the front surface and the back surface, and each of the front surface and the back surface can have an aperture ratio. An improved light emitting device is provided. Furthermore, it aims at providing the light-emitting device which improved the total aperture ratio of the surface and a back surface.

  In one aspect of the present invention, adjacent first light emitting elements and second light emitting elements are arranged in a matrix, and the first light emitting elements can emit light on a first surface of a substrate, The second light emitting element is a light emitting device capable of emitting light on the second surface opposite to the first surface of the substrate. Further, light emitted from the first light emitting element toward the second surface is shielded from light, and light emitted from the second light emitting element toward the first surface is shielded from light. Each light-emitting element has a light-shielding film in the direction opposite to the light-emitting surface, so that each surface can emit light separately.

  According to another aspect of the present invention, in addition to the above structure, the first light-emitting element (an element that emits light toward the counter substrate) includes a semiconductor element that drives the first light-emitting element and a semiconductor that drives the second light-emitting element. It is a light emitting device characterized by covering an element. With this structure, in the second light-emitting element (an element that emits light toward the substrate side, that is, a bottom emission element), the area shielded by the semiconductor element that drives the light-emitting element is reduced, so that the aperture ratio on both sides is improved. Can do. That is, the aperture ratio of the entire display device can be improved. In addition, each of the first surface and the second surface, or one of the aperture ratios can be improved.

  Another embodiment of the present invention is a light-emitting device including a device for inputting a video signal to each light-emitting element in addition to the above structure. As a typical example, a source signal line and a driving element are provided for each light emitting element. Light emission and non-light emission of each light emitting element can be controlled by a signal input from each source signal line.

  Further, as other means for inputting a video signal to each light emitting element, a common source signal line and a switch that functions exclusively are provided for the two light emitting elements. By inputting a signal input to one source signal line to each light emitting element by a switch that functions exclusively, light emission and non-light emission of each light emitting element can be controlled. Note that control signals that are independently controlled may be used instead of the switches that function exclusively.

  With the above structure, each light emitting element can perform independent display, and a light emitting device capable of emitting light on each display surface can display an arbitrary image on each surface.

  Note that the light emitting device in this specification refers to a light emitting device or an image display device using a light emitting element. In addition, a module in which a connector such as an FPC (Flexible Printed Circuit) or TAB (Tape Automated Bonding) tape or TCP (Tape Carrier Package) is attached to the light emitting element, or a TAB tape or a module provided with a printed wiring board at the end of TCP Alternatively, a module in which an IC (integrated circuit) or CPU is directly mounted on a light emitting element by a COG (Chip On Glass) method is included in the light emitting device.

  The light emitting device of the present invention based on the gist of the present invention described above can include the following configurations.

  One embodiment of the present invention includes a first display surface on one surface of a substrate, a second display surface on a surface opposite to the one surface, and an image of the first display surface by the first light emitting element. And a second light emitting device for displaying an image on the second display surface, and independently controlling the image on the first display surface and the image on the second display surface. is there. Note that the first light emitting element covers the semiconductor element that drives the first light emitting element and the semiconductor element that drives the second light emitting element.

 One embodiment of the present invention includes a pixel portion in which first and second light-emitting elements adjacent to each other are arranged in a matrix, and the first light-emitting element emits light on a first surface of a substrate. The second light emitting element can emit light on the second surface opposite to the first surface of the substrate, and the light emission to the second surface side of the first light emitting element is shielded from light. The light emitting device is characterized in that light emitted to the first surface side of the second light emitting element is shielded from light. Note that the first light emitting element covers the semiconductor element that drives the first light emitting element and the semiconductor element that drives the second light emitting element.

   According to another aspect of the present invention, adjacent first light-emitting elements and second light-emitting elements are arranged in a matrix on a substrate provided with semiconductor elements that drive the first light-emitting elements and the second light-emitting elements. The first light-emitting element has a stacked structure in which a first light-transmitting electrode, a layer containing a light-emitting substance, and a second light-transmitting electrode are sequentially provided from the substrate side. The second light-emitting element has a stacked structure in which a third light-transmitting electrode, a layer containing a light-emitting substance, and a second light-transmitting electrode are sequentially provided from the substrate side, One light-emitting element is connected to the first semiconductor element, the second light-emitting element is connected to the second semiconductor element, and the first light-emitting element includes the first light-shielding film, the first semiconductor element, and the first The light emitting device is characterized in that the second light emitting element is covered with a second light shielding film.Note that the first light-transmitting electrode and the third light-transmitting electrode may be formed of the same material. The first light shielding film is covered with the first semiconductor element and the second semiconductor element.

 According to another aspect of the present invention, adjacent first light-emitting elements and second light-emitting elements are arranged in a matrix on a substrate provided with semiconductor elements that drive the first light-emitting elements and the second light-emitting elements. The first light-emitting element has a stacked structure in which a first light-shielding electrode, a layer containing a light-emitting substance, and a first light-transmitting electrode are sequentially provided from the substrate side, The second light-emitting element has a stacked structure in which a second light-transmitting electrode, a layer containing a light-emitting substance, and a first light-transmitting electrode are sequentially provided from the substrate side. The light emitting element is connected to the first semiconductor element, the second light emitting element is connected to the second semiconductor element, the first light emitting element covers the first semiconductor element and the second light emitting element, The second light-emitting element is a light-emitting device that is covered with a second light-shielding film.

 According to another aspect of the present invention, adjacent first light-emitting elements and second light-emitting elements are arranged in a matrix on a substrate provided with semiconductor elements that drive the first light-emitting elements and the second light-emitting elements. The first light-emitting element has a stacked structure in which an electrode having a first light-transmitting property, a layer containing a light-emitting substance, and an electrode having a second light-transmitting property are sequentially provided from the substrate side, The second light-emitting element has a stacked structure in which a third light-transmitting electrode, a layer containing a light-emitting substance, and a first light-shielding electrode are sequentially provided from the substrate side, The light emitting element is connected to the first semiconductor element, the second light emitting element is connected to the second semiconductor element, and the first light emitting element includes the second light shielding film, the first semiconductor element, and the second semiconductor element. A light-emitting device characterized by covering a light-emitting element. Note that the first light-transmitting electrode and the third light-transmitting electrode may be formed of the same material. The second light shielding film is covered with the first semiconductor element and the second semiconductor element.

 According to another aspect of the present invention, adjacent first light-emitting elements and second light-emitting elements are arranged in a matrix on a substrate provided with semiconductor elements that drive the first light-emitting elements and the second light-emitting elements. The first light-emitting element has a stacked structure in which a first light-shielding electrode, a layer containing a light-emitting substance, and a first light-transmitting electrode are sequentially provided from the substrate side, The second light-emitting element has a stacked structure in which a second light-transmitting electrode, a layer containing a light-emitting substance, and a second light-shielding electrode are sequentially provided from the substrate side, and the first light-emitting element The element is connected to the first semiconductor element, the second light emitting element is connected to the second semiconductor element, and the first light emitting element covers the first semiconductor element and the second semiconductor element. The light emitting device is characterized.

 According to another aspect of the present invention, adjacent first light-emitting elements and second light-emitting elements are arranged in a matrix on a substrate provided with semiconductor elements that drive the first light-emitting elements and the second light-emitting elements. The first light-emitting element has a stacked structure in which a first light-shielding electrode, a layer containing a first light-emitting substance, and a first light-transmitting electrode are sequentially provided from the substrate side. The second light-emitting element has a stacked structure in which a second light-transmitting electrode, a layer containing a second light-emitting substance, and a second light-shielding electrode are sequentially provided from the substrate side. The first light emitting element is connected to the first semiconductor element, the second light emitting element is connected to the second semiconductor element, and the first light emitting element is the first semiconductor element or the second semiconductor element. And a second light-emitting element.

 According to another aspect of the present invention, adjacent first light-emitting elements and second light-emitting elements are arranged in a matrix on a substrate provided with semiconductor elements that drive the first light-emitting elements and the second light-emitting elements. The first light-emitting element has a stacked structure in which a first light-shielding electrode, a layer containing a first light-emitting substance, and a first light-transmitting electrode are sequentially provided from the substrate side. The second light-emitting element has a stacked structure in which a second light-transmitting electrode, a layer containing a second light-emitting substance, and a second light-shielding electrode are sequentially provided from the substrate side. The first light emitting element is connected to the first semiconductor element, the second light emitting element is connected to the second semiconductor element, and the first light emitting element is the first semiconductor element and the second semiconductor element. A light-emitting device characterized by covering an element. Note that the first light-transmitting electrode of the first light-emitting element and the second light-transmitting electrode of the second light-emitting element may be formed of the same material.

According to the present invention, in a light emitting device capable of displaying on both the front and back surfaces, it is possible to display images on the two surfaces independently, and to improve the aperture ratio of one or both of the front surface and the back surface. Furthermore, the total aperture ratio of the front surface and the back surface is improved. As a result, the aperture ratio of the entire display device can be improved.

  In addition, since the electronic device using the display device of the present invention can display images on both the front and back surfaces independently, it is possible to simultaneously view the same image on both display surfaces without a sense of incongruity. In addition, since different images can be browsed on both screens, a plurality of people can collect a large amount of information at the same time in a small space and at a low cost. In addition, the electric weight can be reduced and the thickness can be reduced, and operability is enhanced and high added value is realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, an active matrix driving element is used for description, but the driving method may be a simple matrix method. Further, although description is given using a thin film transistor (TFT) as a switching element and a driving element, there is no particular limitation. For example, a semiconductor element such as a MOS transistor, an organic transistor, or a molecular transistor may be used similarly. Furthermore, in this embodiment mode, a light-emitting region corresponding to one light-emitting element is used as one pixel.

(Embodiment 1)
In this embodiment mode, a structure of a light-emitting device of the present invention will be described with reference to FIG. FIG. 1 shows a cross-sectional view of a light emitting device in a region where two adjacent light emitting elements are formed. In the light-emitting element of this embodiment mode, an electrode formed on the substrate side is referred to as a first electrode, and an electrode formed on the counter substrate side is referred to as a second electrode.

  On the substrates 2007, 2107, 2207, 2307, 2407, and 2507, a layer in which a switch element, a drive element, and the like of the top emission light emitting element and the bottom emission light emitting element are formed (hereinafter referred to as a layer having a semiconductor element). .) 2001, 2101, 2201, 2301, 2401, 2501 are formed. Each of the top emission type light emitting element and the bottom emission type light emitting element is connected to at least a switch element, a drive element, and the like.

  An element that emits light above the layers 2001, 2101, 2201, 2301, 2401, and 2501 having a semiconductor element is a top emission light emitting element, and a light emitting element that emits light below the layer where the semiconductor element is formed is a bottom emission light emission. Element. That is, an element that emits light toward the substrate side is a bottom emission light emitting element. The light emitting areas of the top emission light emitting elements are 2021, 2121, 2221, 2231, 2421, and 2521, and the light emitting areas of the bottom emission light emitting elements are 2022, 2122, 2222, 2322, 2422, and 2522. Opposing substrates 2008, 2108, 2208, 2308, 2408, and 2508 are formed above each light emitting element, that is, on the side opposite to the substrate.

  Each light-emitting element includes a first electrode, a second electrode, and a layer containing a light-emitting substance formed between the two. Each light emitting element is controlled to emit light and not emit light by a switch element, a drive element, and the like.

  A light shielding film is formed below the top emission type light emitting element, that is, on the substrate side. Further, another light shielding film is formed above the bottom emission light emitting element, that is, on the counter substrate side. With this structure, light emitted from each light emitting element emits light only in one direction, so that each element can emit light in one direction. As a result, different images can be displayed in the two directions.

  Details of each structure will be described below.

  In FIG. 1A, the first electrode and the second electrode of the top emission light-emitting element, the first electrode and the second electrode of the bottom emission light-emitting element are formed using a light-transmitting conductive film. The structure in which a light shielding film is provided separately for each light emitting element is shown.

  A first light-shielding film 2005 is formed on the substrate 2007 of the top emission light emitting element, and a first insulating layer 2010 is formed on the substrate 2007 of the bottom emission light emitting element. In the light-emitting region 2021 of the top emission light-emitting element, a layer including a semiconductor element is formed over the first light-shielding film 2005. Note that the first light-shielding film 2005 can be formed by forming a film between a substrate and a layer having a semiconductor element or in a layer having a semiconductor element and etching the film into a desired shape. In addition, the film can be formed into a desired shape by an inkjet method or the like. Furthermore, a filter can be provided on the substrate surface. Note that in the case where the first light-shielding film is conductive, an insulating film is preferably formed between the layer having a semiconductor element and the first light-shielding film.

  In addition, first electrodes 2002a and 2002b of the light-emitting elements are formed over the layer 2001 having a semiconductor element and the first insulating layer 2010, respectively. A layer 2003 containing a light-emitting substance is formed over this, and a second electrode 2004 is formed thereover. The first electrode 2002a, 2002b, and the second electrode 2004 are formed using a light-transmitting conductive film.

  In the light emitting region 2022 of the bottom emission light emitting element, a second light shielding film 2006 is formed on the second electrode, and in the light emitting region 2021 of the top emission light emitting element, a second insulating layer 2011 is formed. ing. A counter substrate 2008 is provided over them. Note that the second light-shielding film 2006 can be formed by forming a film having a light-shielding property and etching the film into a desired shape. In addition, the film can be formed into a desired shape by an inkjet method or the like. A filter-like object can be provided on the surface of the counter substrate 2008. Note that when the second light-shielding film is conductive, an insulating film is preferably formed between the second electrode 2004 and the second light-shielding film 2006.

Next, the structure of FIG. 1B will be described. In FIG. 1B, the first electrode of the top emission light emitting element is formed of a light-shielding conductive film, the second electrode of the top emission light emitting element, and the first electrode of the bottom emission light emitting element. The electrode and the second electrode are formed of a light-transmitting conductive film. In addition, a structure in which a light shielding film is separately provided on the counter substrate side of the bottom emission light emitting element is shown.

  A layer 2101 having a semiconductor element is formed in the light emitting region 2121 of the top emission light emitting element over the substrate 2107, and a first insulating layer 2110 is formed in the light emitting region 2122 of the bottom emission light emitting element.

  In addition, first electrodes 2102a and 2102b of the light-emitting elements are formed over the layer 2101 having the semiconductor element and the second insulating layer 2110, respectively. A layer 2103 containing a light-emitting substance is formed over this, and a second electrode 2104 is formed thereover. The first electrode 2102a of the top emission light-emitting element is formed using a light-shielding conductive film, and can be typically formed using a drain electrode of a driving TFT or a conductive film connected thereto. Alternatively, a light-transmitting conductive film may be formed over the light-blocking conductive film. The first electrode 2102b of the bottom emission light-emitting element is formed using a light-transmitting conductive film. The second electrode 2104 of each light-emitting element is formed using a light-transmitting conductive film. Note that a light-transmitting film is formed over the layer 2101 having a semiconductor element and the first insulating layer 2110 and formed into the shape of each electrode, and then the first electrode region of the top emission light-emitting element. Impurities may be added to provide absorption in the visible region.

  In the light emitting region 2122 of the bottom emission light emitting element, a light shielding film 2106 is formed over the second electrode 2104, and in the light emitting region 2021 of the top emission light emitting element, a second insulating layer 2112 is formed. . A counter substrate 2108 is provided over them. Note that the formation method and position of the light-blocking film 2106 can be the same as those of the second light-blocking film 2006 in FIG.

Next, the structure of FIG. 1C will be described. In FIG. 1C, the first electrode, the second electrode, and the first electrode of the bottom emission light-emitting element are formed using a light-transmitting conductive film. The second electrode of the emission type light emitting element is formed of a conductive film having a light shielding property. In addition, a structure in which a light shielding film is separately provided on the substrate side of the top emission light emitting element is shown.

  A light shielding film 2205 is formed on the substrate 2207 of the top emission type light emitting element, and a first insulating layer 2210 is formed on the substrate 2207 of the bottom emission type light emitting element. In the light-emitting region 2221 of the top emission light-emitting element, a light-blocking film 2205 and a layer 2201 including a semiconductor element are formed.

  In addition, first electrodes 2202a and 2202b of the light-emitting elements are formed over the layer 2201 having a semiconductor element and the first insulating layer 2210, respectively, and a layer 2203 containing a light-emitting substance is formed thereover. ing. In the top emission type light emitting element, a second electrode 2204a is formed thereon, and in the bottom emission type light emitting element, a second electrode 2204b is formed. The first electrodes 2202a and 2202b of each light-emitting element are formed using a light-transmitting conductive film. The second electrode 2204a of the top emission light-emitting element is formed using a light-transmitting conductive film, and the second electrode 2204b of the bottom emission light-emitting element is formed using a light-shielding conductive film. ing. A counter substrate 2208 is provided over them. Note that the formation method and position of the light shielding film 2205 can be the same as those of the first light shielding film 2005 in FIG.

  Next, the structure of FIG. 1D will be described. In FIG. 1D, the first electrode of the top emission light-emitting element is formed using a light-shielding conductive film, and the second electrode of the top emission light-emitting element is formed using a light-transmitting conductive film. Has been. The first electrode of the bottom emission type light emitting element is formed of a light-transmitting conductive film, and the second electrode is formed of a light-shielding conductive film. In this structure, it is not necessary to provide a separate light shielding film.

  A layer 2301 having a semiconductor element is formed in the light emitting region 2321 of the top emission light emitting element over the substrate 2307, and a first insulating layer 2310 is formed in the light emitting region 2322 of the bottom emission light emitting element.

  In addition, first electrodes 2302a and 2302b of the light-emitting elements are formed over the layer 2301 having a semiconductor element and the first insulating layer 2310, respectively. The first electrode 2302a of the top emission light-emitting element is formed using a light-shielding conductive film, and can be typically formed using a drain electrode of a driving TFT or a conductive film connected thereto. Alternatively, a light-transmitting conductive film may be formed over the light-blocking conductive film. The first electrode 2302b of the bottom emission light-emitting element is formed using a light-transmitting conductive film. In addition, a light-transmitting film is formed over the semiconductor element-containing layer 2301 and the first insulating layer 2310 and formed into the shape of each electrode, and then the first electrode region of the top emission light-emitting element. Impurities may be added to 2301 to absorb in the visible region.

  A layer 2303 containing a light-emitting substance is formed over them, and second electrodes 2304a and 2304b are formed thereover. The second electrode 2304a of the top emission light-emitting element is formed using a light-transmitting conductive film. The second electrode 2304b of the bottom emission light emitting element is formed using a light-shielding conductive film. A counter substrate 2308 is provided over them.

  Next, the structure of FIG. In FIG. 1E, unlike FIGS. 1A to 1D, a layer containing two different light-emitting substances is formed, and the layer 2403a containing the light-emitting substance of the top emission light-emitting element is formed on the bottom surface. The light emitting area of the emission type light emitting element is covered. In addition, the first electrode 2405a of the top emission light-emitting element is formed using a light-shielding conductive film, and the second electrode 2404 of the top emission light-emitting element is formed using a light-transmitting conductive film. . In addition, the first electrode 2402b of the bottom emission light-emitting element is formed using a light-transmitting conductive film, and the second electrode 2405b is formed using a light-shielding conductive film. In this structure, it is not necessary to provide a separate light shielding film. In this structure, the top emission light emitting element covers the bottom emission light emitting element. For this reason, the top emission type light emitting element can emit light from above the region where the bottom emission type light emitting element is formed, and the sum of the aperture ratios on both sides increases.

  A layer 2401 having a semiconductor element is formed in the light emitting region 2421 of the top emission light emitting element over the substrate 2407, and a first insulating layer 2410 is formed in the light emitting region 2422 of the bottom emission light emitting element.

  A first electrode 2402b of a bottom emission light emitting element is formed over the first insulating layer 2410. The first electrode 2402b of the bottom emission light-emitting element is formed using a light-transmitting conductive film. A layer 2403b containing a first light-emitting substance is formed over the first electrode of the bottom emission light-emitting element. A second electrode 2405b is formed over the layer 2403b containing a light-emitting substance, and a second insulating layer 2412 is formed thereover. On the other hand, a third insulating layer 2411 is formed over the layer 2401 having a semiconductor element, and the first electrode 2405a of the top emission light-emitting element is formed over the second insulating layer and the third insulating layer. A layer 2403a containing a second light-emitting substance and a second electrode 2404 are formed. The second electrode 2405b of the bottom emission light emitting element and the first electrode 2405a of the top emission light emitting element are light-shielding conductive films, and the second electrode 2404 of the top emission light emitting element is a transparent electrode. It is formed of a conductive film having light properties. Note that the top emission light emitting element may be formed without being overlapped above the bottom emission light emitting element. In this case, the second electrode 2405a of the bottom emission light-emitting element and the first electrode 2405b of the top emission light-emitting element can be formed using the same material.

  A counter substrate 2408 is provided over the second electrode 2404 of the top emission light-emitting element.

  Next, the structure of FIG. In FIG. 1F, similarly to FIG. 1E, a layer including two different light-emitting substances is formed. The first electrode of the top emission type light emitting element is formed of a light-shielding conductive film, and the second electrode of the top emission type light emitting element is formed of a translucent conductive film. The first electrode of the bottom emission light emitting element is formed of a light-transmitting conductive film, and the second electrode is formed of a light-shielding conductive film. In this structure, it is not necessary to provide a separate light shielding film.

  A layer 2501 having a semiconductor element is formed over a substrate 2507 in a light emitting region 2521 of the top emission light emitting element, and a first electrode 2502a of the top emission light emitting element is formed thereover, and a first electrode 2502a is formed thereover. A layer 2503a containing one light-emitting substance is formed, and a second electrode 2504a is formed thereover. A first insulating layer 2511 is formed over the second electrode.

  In the light emitting region 2522 of the bottom emission light emitting element, a second insulating layer 2510 is formed on each of the substrates 2507. A first electrode 2502b of a bottom emission light-emitting element is formed over the second insulating layer 2510, a layer 2503b containing a second light-emitting substance is formed thereover, and a second electrode 2502b is formed thereover. An electrode 2504b is formed.

  The first electrode of the top emission light emitting element and the second electrode of the bottom emission light emitting element are formed of a light-shielding conductive film. The second electrode of the bottom emission light emitting element and the first electrode of the bottom emission light emitting element are formed of a light-transmitting conductive film.

  The second electrode 2504a of the top emission light-emitting element and the first electrode 2502b of the bottom emission light-emitting element are light-transmitting conductive films and can be formed using the same material.

  A counter substrate 2508 is provided over the first insulating layer 2511 formed in the top emission light-emitting element and the second electrode 2504b formed in the bottom emission light-emitting element.

(Embodiment 2)
An example of the dual emission type light emitting device of the present invention will be described with reference to FIGS. Note that this embodiment corresponds to the structure of FIG. 1B described in Embodiment 1.

  FIG. 2 is a diagram showing a cross section of a part of the pixel portion. In FIG. 2, 101 is a substrate, 102, 109 and 111 are insulating layers, 107a and 107b are TFTs, 110a and 110b are first electrodes (110a is a light-shielding conductive layer and 110b is a transparent conductive layer, respectively), and 112 is light emitting. A layer containing a substance, 113 is a second electrode, 114 is a light shielding layer, 115 is a transparent protective layer, 116 is a sealant, 117 is a counter substrate, 141 is a light emitting region of a top emission light emitting element, and 142 is a bottom emission light emission. This is a light emitting region of the element. Details of the structure of the light-emitting element will be described below.

  In this embodiment mode, a top emission light-emitting element is formed using the first electrode 110a, the first light-emitting substance-containing layer 112, and the second electrode 113, and the first electrode 110b and the first light-emitting substance are used. The included layer 112 and the second electrode 113 form a bottom emission light emitting element.

  TFTs 107 a and 107 b (p-channel TFTs) are formed on the substrate 101 with an insulating layer 102 interposed therebetween. Each TFT is provided between channel formation regions 103a and 103b, low-concentration impurity regions 104a and 104b, high-concentration impurity regions (source regions or drain regions) 105a and 105b, and between the semiconductor region and the gate electrode. These are formed by a gate insulating film (not shown), gate electrodes 106a and 106b, and drain electrodes (or source electrodes) 108a and 108b.

  Although not shown, wiring such as a power supply line (a wiring for supplying a constant voltage or a constant current) and a source wiring are formed at the same time in the same process as the drain electrodes 108a and 108b. In addition, although the example which forms a 1st electrode and a drain electrode separately was shown, you may form with the same layer. In this case, the drain electrode is formed in the light emitting region of the top emission type light emitting element. In this case, a drain electrode in which a titanium film, a titanium nitride film, a film containing aluminum as a main component, and a titanium nitride film are sequentially stacked may be used.

  An insulating layer 109 made of an organic material or an inorganic material is formed between the semiconductor region and the drain electrodes (or source electrodes) 108a and 108b. Although not shown here, one or more other TFTs (n-channel TFTs or p-channel TFTs) are provided in one pixel. Although a TFT having one channel formation region 103a and 103b is shown here, the TFT is not particularly limited and may be a TFT having a plurality of channels. Although the TFT having the low concentration impurity regions 104a and 104b is shown here, the present invention is not limited to this. The TFT having the channel formation regions 103a and 103b and the high concentration impurity regions (source region and drain region) 105a and 105b. It is good.

The semiconductor region can be formed of an amorphous semiconductor region or a crystalline semiconductor region. As a material for the semiconductor region, a single element or alloy of a semiconductor element (silicon, germanium, or the like), an organic semiconductor material, or the like can be used. An organic semiconductor material is an organic compound exhibiting semiconducting electrical properties with a specific resistance of about 10 ⁻² to 10 ¹⁶ Ωcm, and its structure is a π-electron conjugate whose skeleton is composed of conjugated double bonds. Polymeric materials of the system are desirable. Specifically, it is a soluble polymer material such as polythiophene, poly (3-alkylthiophene), and polythiophene derivatives.

Examples of the substrate 101 and the counter substrate 117 include alkali-free glass substrates such as aluminoborosilicate glass, barium borosilicate glass, and aluminosilicate glass, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PES (polyether sulfide), and polypropylene. A plastic substrate such as polypropylene sulfide, polycarbonate, polyetherimide, polyphenylene sulfide, polyphenylene oxide, polysulfone, or polyphthalamide can be used.

  The first electrodes 110a and 110b are anodes (or cathodes) of the light emitting element, 110a is made of a light-shielding conductive film, and the first electrode 110b is made of a transparent conductive film. In this embodiment mode, the first electrode 110a made of a light-shielding conductive film covers the light-emitting region 141 of the top emission light-emitting element. The first electrode 110b made of a transparent conductive film covers the light emitting region 142 of the bottom emission light emitting element. That is, the first electrode 110a made of a light-shielding conductive film covers a portion other than the drain electrode 108b of the TFT 107a of the top emission light emitting element and the TFT 107b of the bottom emission light emitting element. With this structure, the area of the light emitting region 142 of the bottom emission light emitting element can be increased. Note that the first electrode 110a made of a light-shielding conductive film may have a two-layer structure or a stacked structure with a transparent conductive film.

  Details of the material of the conductive film having a light-blocking property are described in Embodiment 4.

  The first electrodes 110a and 110b are connected to the drain electrodes 108a and 108b through the insulating layer 111 covering the insulating layer 109, respectively. Therefore, the top emission light emitting element can be formed on a TFT connected to the bottom emission light emitting element. As the insulating layer 111, an inorganic material (silicon oxide, silicon nitride, silicon oxynitride, or the like), a photosensitive or non-photosensitive organic material (polyimide, acrylic, polyamide, polyimide amide, resist, or benzocyclobutene), or a material thereof Lamination etc. can be used.

  The layer 112 containing a light-emitting substance is formed by an evaporation method, a spin coating method, a coating method such as inkjet. When the light emitting material is a low molecular weight material, the vapor deposition method is mainly used, and when the light emitting material is a medium molecule or high molecular weight, the coating method is mainly used. Here, the layer 112 containing a light-emitting substance is formed with a vapor deposition apparatus to obtain a uniform film thickness. Note that in order to improve reliability, it is preferable to perform deaeration by performing vacuum heating (100 ° C. to 250 ° C.) immediately before formation of the layer 112 containing a light-emitting substance.

The second electrode 113 is made of a conductive film and is a cathode (or an anode) of the light emitting element. Details of the material of the cathode (or the anode) of the light-emitting element are described in Embodiment Mode 4. Here, since it is a dual emission type that emits light through the second electrode, an Ag film of 1 nm to 10 nm or an MgAg alloy film is used. In addition, a light-transmitting layer (film thickness: 1 nm to 5 nm) made of CaF ₂ , MgF ₂ , or BaF ₂ may be formed as a cathode buffer layer before forming an Ag film of 1 nm to 10 nm.

In order to reduce the resistance of the cathode, a transparent conductive film (ITO (indium oxide tin oxide alloy), indium zinc oxide alloy (In ₂ O ₃ —ZnO), zinc oxide (ZnO) is formed on a metal thin film of 1 nm to 10 nm. ) Etc.) may be formed with a film thickness of 50 nm to 200 nm. In forming the cathode, an evaporation method or a resistance heating method may be used, and it may be selectively formed using an evaporation mask.

The light shielding film 114 is provided so that light emitted from the bottom emission light emitting element does not leak to the top surface. The light shielding film may be formed of non-translucent resin material including Al, Ti, Mo, other metals, and pigments. By using a light-shielding film as the conductive film, it also has the function of an auxiliary electrode, and the resistance of the cathode can be reduced.

  The transparent protective layer 115 is formed by sputtering or vapor deposition, and serves as a sealing film that protects the second electrode 113 and the light shielding layer 114 made of a metal thin film and prevents moisture from entering. As the transparent protective layer 115, a silicon nitride film, a silicon oxide film, a silicon oxynitride film (SiNO film (composition ratio N> O) or SiON film (composition ratio N <O)) obtained by sputtering or CVD, carbon A thin film (for example, a DLC film or a CN film) whose main component is can be used.

  The transparent protective layer 115 thus formed is optimal as a sealing film for a light-emitting element in which a layer containing an organic compound is used as a layer containing a light-emitting substance.

  Further, the counter substrate 117 and the substrate 101 are bonded to each other with a sealant 116. The sealing agent contains a gap material for securing the gap between the substrates, and is disposed so as to surround the pixel portion.

  Next, FIG. 4 shows a top view of two adjacent pixels (a top emission light emitting element and a bottom emission light emitting element) shown in this embodiment mode. FIG. 4 is a top view after the formation of the first electrodes 110a and 110b in FIG. 2 (that is, before the formation of the layer 112 containing a light-emitting substance). Components similar to those in FIG. 2 are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 4, the pixels of two adjacent pixels in this embodiment include a first source signal line 121, a second source signal line 122, and a power supply line (wiring for supplying a constant voltage or a constant current). 123 and a gate signal line 124. The first source signal line 121 is a source signal line of the top emission type light emitting element 151, and the second source signal line 122 is a source signal line of the bottom emission type light emitting element 152. Further, the power supply line (wiring for supplying a constant voltage or constant current) 123 and the gate signal line 124 are provided in common in each light emitting element, but may be provided for each light emitting element.

  The top emission light emitting element is provided with a switching TFT and a driving TFT, and a semiconductor region is formed of 125 and 135, respectively. Similarly, a bottom emission type light emitting element is provided with a switching TFT and a driving TFT, and semiconductor regions are formed of 126 and 136, respectively. In the source region of the switching TFT, the source signal lines 121 and 122 are electrically connected. Further, the gate signal line 124 covers the channel formation regions of the semiconductor regions 125 and 126, respectively. Further, drain electrodes 129 and 130 are connected to the drain region of the switching TFT, respectively, and are connected to gate wirings 127 and 128 of the driving TFT. The gate wirings 127 and 128 cover the channel formation regions of the semiconductor regions 135 and 136 of the driving TFT. The source region of the driving TFT is connected to a power supply line (wiring for supplying constant voltage or constant current) 123, and the drain region is connected to the first electrodes 110a and 110b via the drain electrodes 108a and 108b, respectively. Connected to.

  The semiconductor regions 131 and 132 form a capacitive element and are electrically connected to the power supply line 123. A first capacitor is formed by the first semiconductor region 131, the first gate wiring 127, the power supply line 123, and the insulating film formed therebetween. Further, the second capacitor element is formed by the second semiconductor region 132, the second gate wiring 128, the power supply line 123, and the insulating layer formed therebetween. Note that these capacitive elements are formed between the gate wiring and the source region of each driving TFT.

  Thereafter, a layer 112 containing a light-emitting substance and a second electrode 113 are formed on each first electrode, and a light-shielding film 114 is formed on the second electrode of the bottom emission light-emitting element. In other words, images can be displayed on the upper surface and the lower surface.

  As shown in FIG. 4, the first electrode 110 a of the top emission light emitting element 151 covers the light emitting region of the top emission light emitting element 151. In this region, a switching TFT and a driving TFT of the bottom emission type light emitting element 152 are formed, and covers a portion excluding the connection portion 133 of the first electrode of the bottom emission type light emitting element 152. For this reason, the aperture ratio of the bottom emission light emitting element 152 is improved. Further, since the source signal lines 121 and 122 are provided for the respective light emitting elements, different images can be displayed for the respective light emitting elements.

(Embodiment 3)
In this embodiment, a display device capable of displaying images on two sides with a structure different from that in Embodiment 2 will be described with reference to FIGS. Note that this embodiment corresponds to the structure of FIG. 1E described in Embodiment 1. In addition, about the site | part similar to FIG. 2, the same code | symbol is used and detailed description is abbreviate | omitted.

  In this embodiment mode, a top-emission light-emitting element is formed using the first electrode 214, the layer 215 containing the second light-emitting substance, and the second electrode 216, and the first electrode 211 and the first light-emitting substance are used. The included layer 212 and the second electrode 213 form a bottom emission light-emitting element.

    Similarly to Embodiment Mode 2, TFTs 107a and 107b are formed over the substrate 101, and the first emission of the bottom emission light emitting element is formed over the second insulating layer 109 and the drain electrodes (or source electrodes) 108a and 108b. , That is, an anode (or cathode) 211 of a bottom emission light emitting element is formed. The first electrode 211 is formed of a light-transmitting conductive film, similarly to the first electrode 110b of the second embodiment.

  On the end portion of the first electrode 211, the second insulating layer 109, and the drain electrodes (or source electrodes) 108a and 108b, a third insulator 209 (bank, partition wall, barrier, bank, etc.) covering them is called. )have.

  As the insulating layer 209, an inorganic material (silicon oxide, silicon nitride, silicon oxynitride, or the like), a photosensitive or non-photosensitive organic material (polyimide, acrylic, polyamide, polyimide amide, resist, or benzocyclobutene), or a material thereof Lamination etc. can be used. Note that positive photosensitive acrylic may be used as the organic resin material, and only the upper end portion of the insulator may have a curved surface having a radius of curvature. As the insulator, either a negative type that becomes insoluble in an etchant by photosensitive light or a positive type that becomes soluble in an etchant by light can be used.

  A layer 212 containing a first light-emitting substance is formed in the light-emitting region 242 of the bottom emission light-emitting element by a vapor deposition method, a spin coating method, or a coating method such as inkjet. Next, the second electrode 213 of the bottom emission light emitting element is formed.

  Next, a fourth insulating layer 210 that covers the third insulating layer 209 and the second electrode 213 is formed. Thereafter, contact holes are formed in the third insulating layer 209 and the fourth insulating layer 210, and the first electrode 214 of the top emission light emitting element connected to the drain electrode 108a of the TFT 107a is formed. Thereafter, a layer 215 containing a second light emitting material is formed on the first electrode 214 of the top emission light emitting element, and the second electrode is formed on the fourth insulating layer 210 and the layer 215 containing the second light emitting material. 216 is formed. The second electrode 216 is formed of the same material as the second electrode 113 of the second embodiment. A region where the first electrode 214, the layer 215 containing the second light-emitting substance, and the second electrode 216 overlap with each other is a light-emitting region 241 of the top emission light-emitting element. A top emission light emitting element can be formed over the TFT and the bottom emission light emitting element through the fourth insulating layer. For this reason, the area of the light emitting region of the top emission type light emitting element increases.

  Thereafter, the transparent protective layer 115 is formed on the fourth insulating layer 210 and the second electrode 216 as in the second embodiment. Thereafter, the substrate 101 and the counter substrate 117 are attached to each other with a sealant 116.

  In the present embodiment, the second electrodes 213 and 216 are separated from each other, but they may be connected outside the light emitting region.

  The light emitting device having the above light emitting element can display the same or different display objects on two surfaces at the same time. In addition, since the bottom emission type light emitting element TFT and the bottom emission type light emitting element are located below the first electrode (light-shielding electrode) of the top emission type light emitting element, the aperture ratio of the bottom emission type light emitting element is remarkably improved. To do. In addition, since the top emission light emitting element covers the bottom emission light emitting element, the light emission area of the top emission light emitting element is increased. For this reason, the aperture ratio of the entire display device increases.

  Note that the first electrode 214 of the top emission light emitting element may be formed simultaneously with the formation of the second electrode 213 of the bottom emission light emitting element. In this case, the top emission light-emitting element does not cover the bottom emission light-emitting element, but the number of types of materials for forming two types of electrodes can be reduced without providing a separate process, and the cost can be reduced. It is.

  Note that the other light-emitting device shown in FIG. 1 is also formed as in the second embodiment or the third embodiment.

(Embodiment 4)
In this embodiment, a structure of a light-emitting element that can be applied in Embodiments 1 to 3 will be described with reference to FIGS.

  The light-emitting element includes a pair of an anode and a cathode, and a layer containing a light-emitting substance sandwiched between the anode and the cathode. Hereinafter, the electrode provided on the substrate side is referred to as a first electrode, and the electrode provided on the opposite side of the substrate is referred to as a second electrode.

  The layer containing a light-emitting substance includes at least a light-emitting layer, and includes any one or a plurality of layers having different functions for carriers, such as a hole injection layer, a hole transport layer, a blocking layer, an electron transport layer, and an electron injection layer. It is formed by combining and laminating.

  FIG. 5 illustrates an example of a cross-sectional structure of the light-emitting element.

  In FIG. 5A, a layer 1303 containing a light-emitting substance includes a hole injection layer 1304, a hole transport layer 1305, a light-emitting layer 1306, an electron transport layer 1307, and an electron injection over the first electrode (anode) 1301. A layer 1308 is stacked, and a second electrode (cathode) 1302 is provided in contact with the electron injection layer 1308. This structure is referred to herein as a progressive stacking element.

  In FIG. 5B, the layer 1313 containing a light-emitting substance is formed over the first electrode (cathode) 1311 with an electron injection layer 1318, an electron transport layer 1317, a light-emitting layer 1316, a hole transport layer 1315, A hole injection layer 1314 is stacked, and a second electrode (anode) 1312 is provided in contact with the hole injection layer 1314. This structure is referred to herein as a reverse stacked element.

  In this embodiment mode, the first light-emitting element and the second light-emitting element may take any of the forms shown in FIGS. Either the first light emitting element or the second light emitting element may form a forward stacking element or a reverse stacking element, or one may be a forward stacking element and the other a reverse stacking element. May be. The former layer structure is preferable in the case of the light emitting element shown in FIG. 2, and the latter layer structure is preferable in the case of the light emitting element shown in FIG.

  The present embodiment is not limited to this, and various light-emitting element structures such as anode / hole injection layer / light-emitting layer / electron transport layer / cathode, anode / hole injection layer / hole transport layer / Light emitting layer / electron transport layer / electron injection layer / cathode, anode / hole injection layer / hole transport layer / light emission layer / hole blocking layer / electron transport layer / cathode, anode / hole injection layer / hole transport A structure such as a layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode may be used. Note that examples of the arrangement of the light emitting regions, that is, the arrangement of the pixel electrodes include a stripe arrangement, a delta arrangement, and a mosaic arrangement.

  Hereinafter, materials of a light-emitting element capable of emitting light on the substrate side and the counter substrate side, that is, the front and back surfaces will be described below.

As an anode material, it is preferable to use a conductive material having a large work function. If the anode side is the light extraction direction, a transparent conductive material such as indium-tin oxide (ITO) or indium-zinc oxide (IZO) may be used. In addition, if the anode side is made light-shielding, a laminate of titanium nitride and a film mainly composed of aluminum in addition to a single layer film such as TiN, ZrN, Ti, W, Ni, Pt, Cr, Al, A three-layer structure of a titanium nitride film, a film containing aluminum as its main component, and a titanium nitride film can be used. Or the method of laminating | stacking the transparent conductive material mentioned above on the film | membrane which has said light-shielding property may be sufficient.

Moreover, it is preferable to use a conductive material having a small work function as the material of the cathode. Specifically, alkaline metals such as Li and Cs, alkaline earth metals such as Mg, Ca, and Sr, and these are used. In addition to alloys including Mg (Ag, Al: Li, etc.), rare earth metals such as Yb and Er can also be used. Further, LiF, CsF, in the case of using an electron injecting layer such as CaF _2, Li ₂ O, may be used usual conductive thin film such as aluminum. When the cathode side is the light extraction direction, an ultrathin film containing an alkali metal such as Li or Cs and an alkaline earth metal such as Mg, Ca, or Sr, and a transparent conductive film (ITO, IZO, ZnO, etc.) ) And a stacked structure may be used. Alternatively, an electron injection layer in which an alkali metal or an alkaline earth metal and an electron transport material are co-evaporated may be formed, and a transparent conductive film (ITO, IZO, ZnO, or the like) may be stacked thereon.

  As a material for forming the layers 1303 and 1313 containing a light-emitting substance, a known organic compound having a low molecular weight, a high molecular weight, or a medium molecular weight typified by an oligomer or a dendrimer can be used. Alternatively, a light-emitting material (fluorescent material or singlet compound) that emits light (fluorescence) by singlet excitation or a light-emitting material (phosphorescent material or triplet compound) that emits light (phosphorescence) by triplet excitation can be used.

  Specific examples of materials for forming the layers 1303 and 1313 containing a light-emitting substance are shown below.

As a hole injection material for forming the hole injection layers 1304 and 1314, porphyrin compounds are effective as long as they are organic compounds, and phthalocyanine (hereinafter referred to as H ₂ -Pc), copper phthalocyanine (hereinafter referred to as Cu--). And the like can be used. In addition, a material obtained by chemically doping a conductive polymer compound can also be used. Polyethylenedioxythiophene (hereinafter referred to as PEDOT) doped with polystyrene sulfonic acid (hereinafter referred to as PSS), polyaniline, Examples thereof include polyvinyl carbazole (hereinafter referred to as PVK). In addition, an inorganic semiconductor thin film such as vanadium pentoxide or an ultra-thin film of an inorganic insulator such as aluminum oxide is also effective.

  As the hole transporting material for forming the hole transporting layers 1305 and 1315, an aromatic amine-based compound (that is, a compound having a benzene ring-nitrogen bond) is preferable. As a widely used material, for example, N, N′-bis (3-methylphenyl) -N, N′-diphenyl-1,1′-biphenyl-4,4′-diamine (abbreviation: TPD), 4,4'-bis [N- (1-naphthyl) -N-phenyl-amino] -biphenyl (abbreviation: α-NPD) which is a derivative thereof. In addition, 4,4 ′, 4 ″ -tris (N, N-diphenyl-amino) -triphenylamine (abbreviation: TDATA) and 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) ) -N-phenyl-amino] -triphenylamine (abbreviation: MTDATA) and the like.

Specific examples of a light emitting material for forming the light emitting layers 1306 and 1316 include tris (8-quinolinolato) aluminum (hereinafter referred to as Alq ₃ ), tris (4-methyl-8-quinolinolato) aluminum (hereinafter referred to as Almq _3). ), Bis (10-hydroxybenzo [h] -quinolinato) beryllium (hereinafter referred to as BeBq ₂ ), bis (2-methyl-8-quinolinolato)-(4-hydroxy-biphenylyl) -aluminum (hereinafter referred to as BAlq). ), Bis [2- (2-hydroxyphenyl) -benzoxazolate] zinc (hereinafter referred to as Zn (BOX) ₂ ), bis [2- (2-hydroxyphenyl) -benzothiazolate] zinc (hereinafter referred to as There are metal complexes such as Zn (BTZ) ₂ ), and various fluorescent dyes are effective. A triplet light emitting material is also possible, and is mainly a complex having platinum or iridium as a central metal. As the triplet light emitting material, tris (2-phenylpyridine) iridium (hereinafter referred to as Ir (ppy) ₃ ), 2,3,7,8,12,13,17,18-octaethyl-21H, 23H-porphyrin -Platinum (hereinafter referred to as PtOEP) is known.

As an electron transport material for forming the electron transport layers 1307 and 1317, tris (8-quinolinolato) aluminum (abbreviation: Alq ₃ ), tris (4-methyl-8-quinolinolato) aluminum (abbreviation: Almq ₃ ), bis (10 -Hydroxybenzo [h] -quinolinato) beryllium (abbreviation: BeBq ₂ ), bis (2-methyl-8-quinolinolato)-(4-hydroxy-biphenylyl) -aluminum (abbreviation: BAlq), bis [2- (2- Metal complexes such as hydroxyphenyl) -benzoxazolate] zinc (abbreviation: Zn (BOX) ₂ ) and bis [2- (2-hydroxyphenyl) -benzothiazolate] zinc (abbreviation: Zn (BTZ) ₂ ). . In addition to metal complexes, 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis [5- Oxadiazole derivatives such as (p-tert-butylphenyl) -1,3,4-oxadiazol-2-yl] benzene (abbreviation: OXD-7), 3- (4-tert-butylphenyl) -4 -Phenyl-5- (4-biphenylyl) -1,2,4-triazole (abbreviation: TAZ), 3- (4-tert-butylphenyl) -4- (4-ethylphenyl) -5- (4-biphenylyl) ) -1,2,4-triazole (abbreviation: p-EtTAZ) derivative, 2,2 ′, 2 ″-(1,3,5-benzenetriyl) tris [1-phenyl-1H-benzimidazole ] An imidazole derivative such as (abbreviation: TPBI), a phenanthroline derivative such as bathophenanthroline (abbreviation: BPhen), and bathocuproin (abbreviation: BCP) can be used.

As the electron injecting material that can be used for the electron injecting layers 1308 and 1318, the above-described electron transporting materials can be used. In addition, an ultra-thin film of an insulator such as an alkali metal halide such as LiF or CsF, an alkaline earth halide such as CaF ₂ , or an alkali metal oxide such as Li ₂ O is often used. In addition, alkali metal complexes such as lithium acetylacetonate (abbreviation: Li (acac) and 8-quinolinolato-lithium (abbreviation: Liq) are also effective.

  For the light-emitting elements described in any of Embodiments 1 to 3, the structures and materials described above can be selected as appropriate.

  In the case where the light-emitting device of this embodiment mode is used for full-color display, a material layer that emits red, green, and blue light can be deposited on the layers 1303 and 1313 containing a light-emitting substance using a deposition mask. Further, instead of this method, a film can be selectively formed as appropriate, such as a spin coating method or an ink jet method.

  Further, a layer containing a light emitting substance may emit white light, and a full color display may be performed by separately providing a color filter. Alternatively, a layer containing a light emitting substance may emit blue light, and a full color display may be performed by separately providing a color conversion layer or the like.

(Embodiment 5)
Next, the driving method of the light emitting device of the present invention shown in Embodiments 1 to 4 will be described below.

  In this embodiment mode, since the source region and the drain region of the TFT are difficult to separate depending on the structure and operating conditions, one is described as a first electrode and the other as a second electrode. The first light emitting element is a top emission light emitting element, and the second light emitting element is a bottom emission light emitting element.

  An example of this embodiment is shown in FIG. Here, an example in which light emission and non-light emission control of the first light emitting element 3007 and the second light emitting element 3008 is performed by the first and second driving TFTs 3005a and 3005b, respectively.

  A region surrounded by a dotted frame 3000 is a repeating unit of the light emitting device, and includes a first source signal line 3001a, a second source signal line 3001b, a gate signal line 3002, and a power supply line (a wiring for supplying a constant voltage or a constant current). ) 3003, a first switching TFT 3004a, a second switching TFT 3004b, a first driving TFT 3005a, a second driving TFT 3005b, a first light emitting element 3007, and a second light emitting element 3008. In each pixel, a region where the emitted light of the first light emitting element 3007 is obtained is a first region, and a region where the emitted light of the second light emitting element 3008 is obtained is a second region. Included one by one. Note that the first region is top emission and the second region is bottom emission.

  The gate electrode of the first switching TFT 3004a is electrically connected to the gate signal line 3002, the first electrode is electrically connected to the first source signal line 3001a, and the second electrode is The driving TFT 3005a is electrically connected to the gate electrode. The first electrode of the first driving TFT 3005a is electrically connected to a power supply line (wiring for supplying a constant voltage or a constant current) 3003, and the second electrode is a first electrode of the first light emitting element 3007. It is electrically connected to the electrode. The gate electrode of the second switching TFT 3004b is electrically connected to the gate signal line 3002, the first electrode is electrically connected to the second source signal line 3001b, and the second electrode is The driving TFT 3005b is electrically connected to the gate electrode. The first electrode of the second driving TFT 3005b is electrically connected to a power supply line (wiring for supplying a constant voltage or a constant current) 3003, and the second electrode is connected to the first light emitting element 3008. It is electrically connected to the electrode. The second electrode of the first light-emitting element 3007 and the second electrode of the second light-emitting element 3008 are counter electrodes 3009 and 3010 having a potential difference from a power supply line (a wiring for supplying a constant voltage or a constant current), respectively. Are connected to each. The counter electrodes 3009 and 3010 may be a common electrode.

  The video signal output to the first source signal line 3001a is input to the gate electrode of the first driving TFT 3005a at the timing when the first switching TFT 3004a is turned on. A current is supplied to the second light emitting elements 3007 and 3008 to emit light. Similarly, the video signal output to the second source signal line 3001b is input to the gate electrode of the second driving TFT 3005b at the timing when the second switching TFT 3004b is turned on. A current is supplied to the first and second light emitting elements 3007 and 3008 to emit light. As described above, outgoing light is obtained from the front and back of the substrate in each of the first region and the second region.

    In FIG. 6, the light emitting elements 3007 and 3008 share a gate signal line 3002 and a power supply line (wiring for supplying a constant voltage or a constant current) 3003. However, the present invention is not limited to this structure. Each may have a gate signal line and a power supply line. Further, although the example in which the driving TFT for controlling light emission and non-light emission of each light emitting element is provided in the pixel is shown, the present invention is not limited to this, and the driving TFT may be provided outside the pixel portion (peripheral portion). Further, an external IC chip or the like may be used.

  A driving method different from that in FIG. 6 will be described with reference to FIG. Here, a structure is shown in which a switch for exclusively turning on and off each light emitting element is provided. In FIG. 7, a region surrounded by a dotted line frame 4000 is a repeating unit of the light emitting device, and includes a source signal line 4001, a gate signal line 4002, a power supply line (wiring for supplying a constant voltage or a constant current) 4003, a switching TFT 4004, A first driving TFT 4005, a second driving TFT 4006, a first light emitting element 4007, and a second light emitting element 4008 are included. In each pixel, the region from which the emitted light from the first light emitting element 4007 is obtained is the first region, and the region from which the emitted light from the second light emitting element 4008 is obtained is the second region. Included one by one.

  The gate electrode of the switching TFT 4004 is electrically connected to the gate signal line 4002, the first electrode is electrically connected to the source signal line 4001, and the second electrode is used for the first and second driving. The gate electrodes of the TFTs 4005 and 4006 are electrically connected. A first electrode of the first driving TFT 4005 is electrically connected to a power supply line (wiring for supplying a constant voltage or a constant current) 4003, and a second electrode is a first electrode of the first light emitting element 3007. It is electrically connected to the electrode. A first electrode of the second driving TFT 4006 is electrically connected to a power supply line (wiring for supplying a constant voltage or a constant current) 4003, and the second electrode is a first electrode of the second light emitting element 4008. It is electrically connected to the electrode. The second electrode of the first light-emitting element 4007 and the second electrode of the second light-emitting element 4008 are counter electrodes 4009 and 4010 having a potential difference from a power supply line (a wiring for supplying a constant voltage or a constant current), respectively. And are electrically connected.

  Analog switches 4011 and 4012 that operate exclusively are provided between a power supply line (wiring for supplying constant voltage or constant current) 4003 and the first electrodes of the first and second driving TFTs 4005 and 4006, respectively. By controlling ON / OFF by the display surface control signal, the analog switch 4011 is turned ON for a certain period, and when current is supplied to the first light emitting element 4007, emitted light is obtained in the first region. . On the other hand, the analog switch 4012 that operates exclusively with the analog switch 4011 is OFF at this time, and the current supply path to the second light emitting element 4008 is cut off. Therefore, the second region does not emit light. On the other hand, in a period in which the analog switch 4012 is turned on, current is supplied to the second light emitting element 4008, and an image is displayed in the second region, the analog switch 4011 is turned off and the first light emitting element 4007 is turned on. Shut off the current supply path. Therefore, the first region does not emit light. For this reason, since the first region and the second region emit light alternately, if the video signal to be displayed in each region is alternately input to the source signal line 4001, different light can be emitted in each region. As a result, different images can be displayed on the front and back sides.

    Here, an analog switch is used as a switch for exclusively turning on and off each light emitting element. However, the present invention is not limited to this, and a TFT, a mechanical switch, or the like can also be used. In addition, although an example in which a switch for exclusively turning on and off each light emitting element is provided in the pixel is shown, the present invention is not limited to this, and an external IC chip or the like outside the pixel may be used. .

  Further, instead of operating the analog switches 4011 and 4012 exclusively, as shown in FIG. 8, the first inverter 5013, the second inverter 5014, the first analog switch 4011, the second analog switch 4012, You may control independently using the display surface control signal 1 and the display surface control signal 2. FIG. According to this configuration, both the first area and the second area can be arbitrarily switched between display and non-display.

  As a method of displaying different images in the first area and the second area using the configuration shown in FIGS. 7 and 8, for example, in the one frame period, the display of the first area is performed in odd frames. For example, the second area may be displayed in an even frame. At this time, the display surface control signal may be inverted every frame period, and the analog switches 4011 and 4012 in FIG. 7 and the analog switches 4011 and 4012 in FIG. 8 may be switched ON / OFF for each frame.

  In the configuration shown in FIG. 7, the display surface control signal is output when the user performs some operation, and the display surface may be switched or used (for example, the terminal is folded). The switching operation may be automatically performed depending on whether it is open or not.

    By the above driving method, different images can be displayed simultaneously on the first area and the second area, that is, on the front and back of the light emitting device. For this reason, when viewing the display device from both directions, one can view the same image at the same time without looking at the mirror image of the other. It is also possible to see completely different images in both directions.

  In this example, electric appliances having the light-emitting device formed in Embodiment Modes 1 to 5 are described. Typically, a video camera, a digital camera, a notebook personal computer, a portable information terminal (such as a mobile computer, a mobile phone, a portable game machine, or an electronic book), and an image reproducing device (specifically, a digital device) provided with a recording medium And a television receiver, an electronic bulletin board, an electronic book, and the like. Typical examples of these are shown below.

  In this embodiment, an example in which the light emitting device of the present invention is applied to a typical mobile phone in a portable information terminal is shown.

  9A and 9B are schematic views of a mobile phone according to the present invention, in which FIG. 9A is a perspective view in an opened state, and FIG. 9B is a perspective view in a closed state of the same, It is the perspective view seen from the 1st housing | casing side provided with the 2nd display surface.

  In the mobile phone, two housings (a first housing 8000a and a second housing 8000b) are connected by a hinge 8101, and can be rotated around the hinge 8101.

  The first housing 8000a is provided with a first display surface 8001a, a second display surface 8001b, operation buttons 8002b, speakers 8003a and 8003b, an antenna 8004, a camera lens 8005, and the like.

  On the other hand, the second housing 8000b includes operation buttons 8002a, a microphone 8102, and the like.

  When the mobile phone is open, the first display surface 8001a is used as a main display surface. The screen operation is performed using the operation button 8002a. When the cellular phone is closed, the second display surface 8001b is used as a main display surface. In this case, the display information is operated by an operation button 8002b provided on the first housing.

  FIG. 9C is a cross-sectional view of the mobile phone in FIG. 9A viewed from the side. Inside the first housing 8000a, a display controller 8008 connected to the display unit is provided to control display contents. In addition, a battery 8010 and a main body driving module 8009 are provided in the second casing 8000b, and the display unit, the display controller 8008, the main body driving module 8009, and the like are driven using the power generated in the battery 8010. To do.

  FIG. (D) is an enlarged view of region A in FIG. 9 (C). The first display surface 8001a and the second display surface 8001b display images emitted from the display portion 8013 (including a light emitting element formed between the substrate 8011 and the counter substrate 8012) on each display surface. ing.

  The light-emitting device described in any of Embodiments 1 to 5 can be used for the display portion 8013 of this example.

  If the first display surface 8001a and the second display surface 8001b are displayed at the same time, the monitor image can be viewed from both the photographer 8006 side and the photographed person 8007 side, and the photographing intention such as the angle is satisfied. It is also possible for the photographer to release the shutter after the photographed person confirms whether or not. In such shooting, the communication between the photographer and the person to be photographed is smooth, and there is an effect of reducing shooting failures.

  Further, even when shooting with the lens 8005 facing forward, shooting can be performed while monitoring on the second display surface 8001b having a wide display area.

  Conventionally, two display devices are required to display the first display surface and the second display surface, but in this embodiment, display is performed on different display surfaces with one display device. Therefore, the volume of the mobile phone can be reduced, and the size of the device can be reduced.

Conventionally, the display unit having the second display surface can be incorporated only with a small display area because of space, but according to the present invention, the display unit having the same display size as the first display surface 8001a can be provided. Since the second display surface 8001b can be provided, it is possible to browse e-mails, web pages, and the like without opening the mobile phone. For this reason, the complexity of operation can be reduced.

  Note that the light-emitting device of the present invention can also be implemented in a digital camera or a digital video camera, and has the same effect as a mobile phone.

  An example in which the light-emitting device of the present invention is applied to a notebook personal computer is shown in FIG.

  10A and 10B are schematic views of a notebook personal computer according to the present invention. FIG. 10A is a side view in an opened state, and FIG. 10B is a user (explainer) 9005. FIG. 10C is a perspective view seen from the side of the first display surface facing the keyboard when the two housings are closed, and FIG. 10C shows the same thing as the listener 9006, that is, the opposite side of the first display surface. It is the perspective view seen from the display surface (second display surface) 9002b.

  The notebook personal computer has two housings (first housing 9000 a and second housing 9000 b) connected by a hinge 9001, and can be rotated around the hinge 9001.

  The first housing 9000a is provided with a display panel, operation buttons, speakers, a display unit driving module (not shown), and the like. The display panel includes a first display surface 9002a and a second display surface 9002b. Have

  On the other hand, the second housing 9000b includes a keyboard 9003, an open / close button 9004, a main body driving module (not shown), and the like.

  Note that since the notebook personal computer including the light-emitting device of the present invention can have two display surfaces with one display device, the thickness of the display portion can be suppressed, and the weight of the display portion is reduced. However, the thickness is reduced. That is, the laptop personal computer can be reduced in weight and size. In addition, since the listener 9006 can see the same image as the image viewed by the person (explainer) 9005 who operates the personal computer on the opposite side, the images can be viewed without any sense of incongruity when explaining in a face-to-face manner. be able to.

  Note that the light-emitting device of the present invention can be provided in a television receiver, a DVD player, or the like. In this case, the same effect as that of the notebook personal computer can be obtained. Furthermore, since it is possible to display completely different images on the first display surface and the second display surface, it is possible to view multiple images on a single TV receiver, DVD player, etc. It is.

  An example in which the display device of the present invention is applied to an electric bulletin board is shown in FIG.

  FIG. 11 is an electric bulletin board that displays train times, and is provided with a housing 7001, a display portion 7002, and a drive device (not shown) for driving the display portion. In addition, the electronic bulletin board is fixed to a ceiling, a wall, a pillar, or the like by a support 7003.

  By adapting the light emitting device of the present invention to the display unit, train information such as train type, departure time, destination, number of vehicles can be displayed on the front and back, so the weight of the electric bulletin board can be reduced. It is. In addition, since different information can be displayed on each surface, the number of electronic bulletin boards can be reduced, and the cost can be reduced.

  The present invention can also be applied to an electric light guide plate instead of the electric bulletin board. In this case, the same effect as the electronic bulletin board can be obtained.

FIG. 6 illustrates a cross section of a light-emitting device of the present invention. FIG. 6 illustrates a cross section of a light-emitting device of the present invention. FIG. 6 illustrates a cross section of a light-emitting device of the present invention. FIG. 6 illustrates a top surface of a light-emitting device of the present invention. 4A and 4B illustrate a light-emitting element of the present invention. The figure explaining the drive method of this invention. The figure explaining the drive method of this invention. The figure explaining the drive method of this invention. 8A and 8B each illustrate an example of an electronic device of the invention. 8A and 8B each illustrate an example of an electronic device of the invention. 8A and 8B each illustrate an example of an electronic device of the invention.

Claims (11)

A pixel portion in which adjacent first light emitting elements and second light emitting elements are arranged in a matrix,
The first light emitting element can emit light on a first surface of the substrate, and the second light emitting element can emit light on a second surface opposite to the first surface of the substrate,
Light emission to the second surface side of the first light emitting element is shielded, light emission to the first surface side of the second light emitting element is shielded,
The first light emitting element is connected to a first semiconductor element, the second light emitting element is connected to a second semiconductor element, and the first semiconductor element and the second semiconductor element are connected to the first semiconductor element. A light-emitting device covered with a light-emitting element or the second light-emitting element. Adjacent first light emitting element and second light emitting element are arranged in a matrix on a substrate provided with semiconductor elements for driving the first light emitting element and the second light emitting element,
The first light-emitting element has a laminated structure in which an electrode having a first light-transmitting property, a layer containing a light-emitting substance, and an electrode having a second light-transmitting property are sequentially provided from the substrate side,
The second light-emitting element has a stacked structure in which a third light-transmitting electrode, a layer containing the light-emitting substance, and the second light-transmitting electrode are sequentially provided from the substrate side. And
The first light emitting element is connected to the first semiconductor element, the second light emitting element is connected to the second semiconductor element,
The first light emitting element covers the first light shielding film, the first semiconductor element and the second semiconductor element,
The light-emitting device, wherein the second light-emitting element is covered with a second light-shielding film.   The light-emitting device according to claim 2, wherein the first light-transmitting electrode and the third light-transmitting electrode are formed of the same material. Adjacent first light emitting element and second light emitting element are arranged in a matrix on a substrate provided with semiconductor elements for driving the first light emitting element and the second light emitting element,
The first light-emitting element has a stacked structure in which a first light-shielding electrode, a layer containing a light-emitting substance, and a first light-transmitting electrode are sequentially provided from the substrate side,
The second light-emitting element has a stacked structure in which a second light-transmitting electrode, a layer containing the light-emitting substance, and the first light-transmitting electrode are sequentially provided from the substrate side. And
The first light emitting element is connected to the first semiconductor element, the second light emitting element is connected to the second semiconductor element,
The first light emitting element covers the first semiconductor element and the second semiconductor element,
The light-emitting device, wherein the second light-emitting element is covered with a second light-shielding film. Adjacent first light emitting element and second light emitting element are arranged in a matrix on a substrate provided with semiconductor elements for driving the first light emitting element and the second light emitting element,
The first light-emitting element has a laminated structure in which an electrode having a first light-transmitting property, a layer containing a light-emitting substance, and an electrode having a second light-transmitting property are sequentially provided from the substrate side,
The second light-emitting element has a stacked structure in which a third light-transmitting electrode, a layer containing the light-emitting substance, and a first light-shielding electrode are sequentially provided from the substrate side,
The first light emitting element is connected to the first semiconductor element, the second light emitting element is connected to the second semiconductor element,
The light-emitting device, wherein the first light-emitting element covers a second light-shielding film, the first semiconductor element, and the second semiconductor element.   6. The light-emitting device according to claim 5, wherein the first light-transmitting electrode and the third light-transmitting electrode are formed of the same material. Adjacent first light emitting element and second light emitting element are arranged in a matrix on a substrate provided with semiconductor elements for driving the first light emitting element and the second light emitting element,
The first light-emitting element has a stacked structure in which a first light-shielding electrode, a layer containing a light-emitting substance, and a first light-transmitting electrode are sequentially provided from the substrate side,
The second light-emitting element has a stacked structure in which a second light-transmitting electrode, a layer containing the light-emitting substance, and a second light-shielding electrode are sequentially provided from the substrate side,
The first light emitting element is connected to the first semiconductor element, the second light emitting element is connected to the second semiconductor element,
The first light-emitting element covers the first semiconductor element and the second semiconductor element. Adjacent first light emitting element and second light emitting element are arranged in a matrix on a substrate provided with semiconductor elements for driving the first light emitting element and the second light emitting element,
The first light-emitting element has a stacked structure in which a first light-shielding electrode, a layer containing a first light-emitting substance, and a first light-transmitting electrode are sequentially provided from the substrate side. And
The second light-emitting element has a stacked structure in which a second light-transmitting electrode, a layer containing a second light-emitting substance, and a second light-shielding electrode are sequentially provided from the substrate side. And
The first light emitting element is connected to the first semiconductor element, the second light emitting element is connected to the second semiconductor element,
The first light-emitting element covers the first semiconductor element, the second semiconductor element, and the second light-emitting element. Adjacent first light emitting element and second light emitting element are arranged in a matrix on a substrate provided with semiconductor elements for driving the first light emitting element and the second light emitting element,
The first light-emitting element has a stacked structure in which a first light-shielding electrode, a layer containing a first light-emitting substance, and a first light-transmitting electrode are sequentially provided from the substrate side. And
The second light-emitting element has a stacked structure in which a second light-transmitting electrode, a layer containing a second light-emitting substance, and a second light-shielding electrode are sequentially provided from the substrate side. And
The first light emitting element is connected to the first semiconductor element, the second light emitting element is connected to the second semiconductor element,
The first light-emitting element covers the first semiconductor element and the second semiconductor element.   10. The first light-transmitting electrode of the first light-emitting element and the second light-transmitting electrode of the second light-emitting element are formed of the same material according to claim 9. Light-emitting device. An electronic apparatus comprising the light emitting device according to claim 1.

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