US-20260130104-A1 - DISPLAY DEVICE

US20260130104A1US 20260130104 A1US20260130104 A1US 20260130104A1US-20260130104-A1

Abstract

Provided is a display device. The display device comprises a first flexible substrate, a second flexible substrate including a first area, a second area, and a third area, and an intermediate layer between the first flexible substrate and the second flexible substrate. A plurality of pixels is disposed in the first area, and the plurality of pixels includes a first transistor including a polycrystalline semiconductor and a first gate electrode, a second transistor including an oxide semiconductor and a second gate electrode composed of a first metal layer, a second metal layer, and a third metal layer, and a third transistor including the polycrystalline semiconductor disposed in the second area, and a plurality of dams, a first line, a second line, and a cathode are disposed in the third area, and the cathode extends to the first area and the second area.

Inventors

Pyungho Choi
Hyunseok Na
HyoungSun Park
Hyunchyol Shin
Seongsoo Cho

Assignees

LG DISPLAY CO., LTD.

Dates

Publication Date: 20260507
Application Date: 20251219
Priority Date: 20220616

Claims (19)

1 . A display device, comprising: a flexible substrate including a first substrate, an intermediate layer, and a second substrate, the second substrate including a first area, a second area, and a third area; a plurality of pixels being disposed in the first area, each of the plurality of pixels having a first transistor that includes a polycrystalline semiconductor, a first source electrode, a first drain electrode, and a first gate electrode, and a second transistor that includes an oxide semiconductor, a second source electrode, a second drain electrode, and a second gate electrode; a third transistor including a polycrystalline semiconductor and a third gate electrode in the second area; and one or more dams in the third area, wherein the second gate electrode is composed of at least two metal layers including a first metal layer and a second metal layer on the first metal layer, and the second metal layer has a greater width than that of the first metal layer.
2 . The display device according to claim 1 , wherein each of the first gate electrode and the third gate electrode is a single layer made of one or more of silver (Ag), molybdenum (Mo), copper (Cu), titanium (Ti), aluminum (Al), chromium (Cr), nickel (Ni), neodymium (Nd), tungsten (W), or gold (Au), or an alloy thereof.
3 . The display device according to claim 1 , wherein the first area is a display area, and the second area and the third area are each a non-display area.
4 . The display device according to claim 1 , further comprising: a metal layer disposed below the oxide semiconductor of the second transistor, and wherein the second transistor is disposed on the first gate electrode of the first transistor.
5 . The display device according to claim 4 , wherein the metal layer is a lower gate of the second transistor.
6 . The display device according to claim 4 , further comprising: metal blocking layers below the polycrystalline semiconductors.
7 . The display device according to claim 1 , wherein the second gate electrode further includes a third metal layer between the first metal layer and the second metal layer.
8 . The display device according to claim 1 , wherein each of the plurality of pixels comprises a capacitor including a first capacitor electrode and a second capacitor electrode, and the first capacitor electrode is on a same layer as the first gate electrode.
9 . The display device according to claim 1 , wherein the first source and drain electrodes are on a same layer as the second source electrode or the second drain electrode.
10 . The display device according to claim 1 , further comprising: a first planarization layer and a second planarization layer on the first transistor and the second transistor; and a connection electrode between the first planarization layer and the second planarization layer.
11 . The display device according to claim 10 , wherein the connection electrode electrically connects the first transistor and a light-emitting diode on the second planarization layer.
12 . The display device according to claim 1 , further comprising: a light-emitting diode on the first transistor and the second transistor, wherein the light-emitting diode includes an anode, an emission layer, and a cathode.
13 . The display device according to claim 12 , wherein the cathode extends to the second area and the third area, and electrically connects to signal lines in the third area.
14 . A display device, comprising: a flexible substrate including a display area; and a plurality of pixels disposed in the display area, each of the plurality of pixels having a first transistor that includes a polycrystalline semiconductor, a first source electrode, a drain electrode, and a first gate electrode, and a second transistor that includes an oxide semiconductor, a second source electrode, a second drain electrode, and a second gate electrode; a light-emitting diode on the first transistor and the second transistor; and an encapsulation layer on the light-emitting diode, wherein the second gate electrode is composed of at least two metal layers including a first metal layer and a second metal layer on the first metal layer, and the second metal layer has a greater width than that of the first metal layer.
15 . The display device according to claim 14 , wherein the flexible substrate further includes a non-display area outside the display area, the display device further comprises a gate driver and one or more dams, and the encapsulation layer is disposed to extend on the gate driver and the one or more dams.
16 . The display device according to claim 14 , wherein the second transistor is disposed on the first gate electrode.
17 . The display device according to claim 14 , further comprising: metal layers located below the polycrystalline semiconductor and the oxide semiconductor, respectively.
18 . The display device according to claim 14 , wherein the first gate electrode is a single layer made of any one of silver (Ag), molybdenum (Mo), copper (Cu), titanium (Ti), aluminum (Al), chromium (Cr), nickel (Ni), neodymium (Nd), tungsten (W), and gold (Au) or an alloy thereof.
19 . The display device according to claim 14 , further comprising: a third metal layer between the first metal layer and the second metal layer.

Description

BACKGROUND Technical Field The present disclosure relates to a display device, and more particularly, to a display device including a plurality of thin film transistors by which reliability of elements of the display device can be improved. Description of the Related Art Recent display devices which can display various information and interact with a user who views the corresponding information have various sizes, various shapes, and various functions. The display devices include a liquid crystal display device (LCD), an electrophoretic display device (FPD), and a light-emitting diode display device (LED). Since the LED as a self-luminous display device does not require an additional light source unlike the LCD, the LED can be manufactured to be light and thin. Further, the LED is driven with low voltage to be advantageous in terms of power consumption and excellent even in color expression, response speed, viewing angle, and contrast ratio (CR). Thus, the LED has been under research as a next-generation display. If the LED is an organic light-emitting diode display device (OLED), a light-emitting diode layer may be an organic light-emitting diode layer including an anode, an emission layer, and a cathode. Also, as the light-emitting diode layer, a quantum dot light-emitting diode (QLED) including quantum dots (QD) may be used. Hereinafter, even though the description will be made under the assumption that the LED is the OLED, the type of the light-emitting diode layer is not limited thereto. The OLED displays information on a screen by allowing a plurality of pixels to emit light. The plurality of pixels includes the light-emitting diode layer having the emission layer. The OLED may be classified into an active matrix type organic light-emitting diode display (AMOLED) or a passive matrix type organic light-emitting diode display (PMOLED) according to a scheme to drive the pixels. The AMOLED displays an image by controlling a current which flows on an organic light-emitting diode by using a thin film transistor (or “TFT”). The AMOLED may include various TFTs including a switching TFT, a driving TFT connected to the switching TFT, and an organic light-emitting diode (OLED) connected to the driving TFT. A plurality of driving circuits for controlling an operation of the light-emitting diode layer may be disposed in a display area of a substrate. The light-emitting diode layer may be electrically connected to the driving circuits. The driving circuits may supply the light-emitting diode layer with a driving current corresponding to a data signal in response to a scan signal. For example, the plurality of driving circuits may include a plurality of TFTs and a plurality of storage capacitors. In the plurality of TFTs, different types of semiconductor patterns or hybrid TFTs may be disposed. The different types of semiconductor patters may include, for example, a polycrystalline semiconductor pattern made of low temperature poly-silicon (LTPS) and an oxide semiconductor pattern made of an oxide material. BRIEF SUMMARY The inventors have realized that a channel region of the oxide semiconductor may be made conductive at undesired times due to hydrogen permeating from the outside. Therefore, characteristics of elements may be degraded. The present disclosure provides a display device which includes different types of semiconductor patterns and stably secures characteristics of elements of a transistor including an oxide semiconductor. According to an aspect of the present disclosure, the display device includes a first flexible substrate and a second flexible substrate including a first area, a second area, and a third area. Also, the display device includes an intermediate layer disposed between the first flexible substrate and the second flexible substrate. A plurality of pixels is disposed in the first area. The plurality of pixels includes a first transistor including a polycrystalline semiconductor and a first gate electrode. Also, the plurality of pixels includes a second transistor including an oxide semiconductor and a second gate electrode composed of a first metal layer, a second metal layer, and a third metal layer. A third transistor including a polycrystalline semiconductor is disposed in the second area. A plurality of dams, a first line, a second line, and a cathode are disposed in the third area, and the cathode extends to the first area and the second area. Other detailed matters of the example embodiments are included in the detailed description and the drawings. According to the present disclosure, a display device includes different types of thin film transistors and secures stability of a transistor including an oxide semiconductor and thus improves display quality. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS The above and other aspects, features and other advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction