Active solid-state devices (e.g. – transistors – solid-state diode – Organic semiconductor material
Reexamination Certificate
2002-01-18
2002-11-19
Lee, Eddie (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Organic semiconductor material
Reexamination Certificate
active
06483123
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an organic electroluminescent (EL) device and a method for fabricating the same, and more particularly, to an organic EL device having an organic field effect transistor and an organic light-emitting diode incorporated therein, and a method for fabricating the same.
2. Description of the Related Art
Organic electroluminescent (EL) devices radiate light by electrical excitation generated by an externally applied electrical field. Among such organic EL devices, organic light-emitting diodes (LEDs) are expected to be widely used for flat-panel display purposes. This is because the organic LED can be fabricated with simplicity, at room temperature, and it can be fabricated over not only a crystalline substrate but also a bendable plastic or glass substrate. The organic LED can be formed over both a crystalline substrate or non-crystalline (amorphous) substrate. However, since transistors for driving organic LEDs are processed at high temperature, it is not easy to fabricate the organic LED over a plastic substrate. Thus, in order to drive an organic LED formed over a plastic substrate, there is a trend to use an organic field effect transistor (FET) that can be processed at low temperature of 100° C. or less.
FIG. 1
is a cross-sectional view showing an example of a conventional organic EL device having an organic FET and an organic LED incorporated therein.
Referring to
FIG. 1
, the conventional organic EL device includes an organic LED
110
and an organic FET
120
incorporated on a single substrate
100
.
The organic LED
110
includes a transparent electrode
111
, an organic light-emitting layer
112
and a metal electrode
113
sequentially formed on the substrate
100
. The organic FET
120
includes a gate electrode
121
formed on the substrate
100
, a dielectric layer
122
formed on the gate electrode
121
, an organic semiconducting layer
123
formed on the dielectric layer
122
and a source electrode
124
and a drain electrode
125
formed on the dielectric layer
122
at either side of the organic semiconducting layer
123
. The drain electrode
125
is connected to the transparent electrode
111
and organic light-emitting layer
112
of the organic LED
110
.
The organic EL device operates as follows. An electric field is applied to the organic semiconducting layer
123
by the gate electrode
121
of the organic FET
120
. A channel is formed in the organic semiconducting layer
123
between the source electrode
124
and the drain electrode
125
by the applied electric field. Carriers move from the source electrode
124
to the drain electrode
125
through the channel to be injected into the organic light-emitting layer
112
of the organic LED
110
. The carriers injected into the organic light-emitting layer
112
are combined to generate excitons. The generated excitons extinguish while emitting light corresponding to a lattice energy gap.
The organic LED
110
is parallel to the organic FET
120
in a horizontal direction, and, due to the positional relationship therebetween, the size of the organic FET
120
undesirably reduces an aperture ratio. In order to overcome the problem of a smaller aperture ratio, it is necessary to increase the light emission intensity of a unit pixel in a display device, which deteriorates a life characteristic of the display device.
SUMMARY OF THE INVENTION
To solve the above-described problems, it is an object of the present invention to provide an organic electroluminescent device having an organic field effect transistor and an organic light-emitting diode incorporated therein while having a high aperture ratio.
It is another object of the present invention to provide a method. for fabricating the organic electroluminescent device.
To accomplish the first object of the present invention, there is provided a an organic electroluminescent (EL) device including a substrate, a transparent electrode formed on the substrate, an organic light-emitting layer formed on the transparent electrode, a metal electrode formed on the organic light-emitting layer, a first insulating layer formed on the metal electrode, a gate electrode formed on the first insulating layer, a second insulating layer formed on the gate electrode, an organic semiconducting layer formed on the second insulating layer, a source electrode connected to one end of the organic semiconducting layer on the second insulating layer and connected to the metal electrode, and a drain electrode connected to the other end of the organic semiconducting layer on the second insulating layer.
The substrate is preferably a plastic, glass or crystalline substrate.
The transparent electrode may include indium tin oxide (ITO), indium zinc oxide (IZO) and aluminum zinc oxide (AZO).
The organic light-emitting layer may include an organic monomolecular component or an organic polymeric component.
The metal electrode may include at least one selected from the group consisting of aluminum (Al), magnesium (Mg), calcium (Ca), barium (Ba), lithium (Li), yttrium (Y), ytterbium (Yb), cesium (Cs) and silver (Ag).
The dielectric constant of the first insulating layer is preferably relatively lower than that of the second insulating layer.
The gate electrode may include at least one selected from the group consisting of gold (Ag), palladium (Pd), silver (Ag), platinum (Pt), aluminum (Al), copper (Cu) and titanium (Ti).
The source electrode and the drain electrode may include at least one selected from the group consisting of titanium (Ti), gold (Ag), palladium (Pd), chrome (Cr), platinum (Pt), aluminum (Al), calcium (Ca), barium (Ba), magnesium (Mg), silver (Ag), strontium (Sr) and lithium (Li).
The organic semiconducting layer is preferably either an n-type or a p-type.
According to another aspect of the present invention, there is provided an organic EL device including a metal substrate having a first, bottom surface and a second, top surface, an organic light-emitting layer formed on the first surface of the metal substrate, a transparent electrode formed on the organic light-emitting layer, a first insulating layer formed on the second surface of the metal substrate, a gate electrode formed on the first insulating layer, a second insulating layer formed on the gate electrode, an organic semiconducting layer formed on the second insulating layer, a source electrode connected to one end of the organic semiconducting layer on the second insulating layer and connected to the second surface of the metal substrate, and a drain electrode connected to the other end of the organic semiconducting layer on the second insulating layer.
The metal substrate is preferably formed of aluminum or stainless steel coated with one selected from the group consisting of Al, Ca, Sr, Y, Yb, Li and Mg.
According to still another aspect of the present invention, there is provided an organic EL device including an insulating substrate having a first, bottom surface and a second, top surface, a metal electrode formed on the first surface of the insulating substrate, an organic light-emitting layer formed on the metal electrode, a transparent electrode formed on the organic light-emitting layer, a gate electrode formed on the second surface of the insulating substrate, an insulating layer formed on the gate electrode, an organic semiconducting layer formed on the insulating layer, a source electrode connected to one end of the organic semiconducting layer on the insulating layer and connected to the metal substrate, and a drain electrode connected to the other end of the organic semiconducting layer on the insulating layer.
The insulating substrate is preferably a glass or plastic substrate.
To accomplish the second object of the present invention, there is provided a method for fabricating an organic EL device including the steps of sequentially forming a transparent electrode, an organic light-emitting layer and a metal electrode over a substrate to forming an organic LED, forming a first insulating layer on the metal electro
Chu Hye-yong
Do Lee-mi
Kim Seong-Hyun
Lee Hyo-young
Lee Jeong-Ik
Blakely & Sokoloff, Taylor & Zafman
Korea Electronics
Lee Eddie
Nguyen Joseph
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