THIN-FILM TRANSISTOR ELEMENT AND METHOD FOR PRODUCING SAME, ORGANIC EL DISPLAY ELEMENT, AND ORGANIC EL DISPLAY DEVICE

• US 20140042419A1
• Filed: 10/23/2013
• Published: 02/13/2014
• Est. Priority Date: 06/21/2011
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: OKUMOTO, Yuko, MIYAMOTO, Akihito, UKEDA, Takaaki
• Granted Patent: US 8,994,186 B2
• Time in Patent Office: Days
• US Class Current: 257/40
• CPC Class Codes: H01L 27/1292 using liquid deposition, e.g. printing
• CPC Class Codes: H10K 10/46 Field-effect transistors, e.g. organic thin-film transistors [OTFT] H10K10/43 takes precedence
• CPC Class Codes: H10K 10/484 characterised by the channel regions
• CPC Class Codes: H10K 59/123 Connection of the pixel electrodes to the thin film transistors [TFT]
• CPC Class Codes: H10K 59/125 including organic TFTs [OTFT]

Abstract

A thin film transistor element includes: a gate electrode; a source electrode and a drain electrode; an insulating layer; partition walls; and an organic semiconductor layer. The partition walls define a first aperture. Within the first aperture, at least a part of the source electrode and at least a part of the drain electrode are in contact with the semiconductor layer. In plan view of the bottom of the first aperture, the center of the total of the areas of the source electrode and the drain electrode is offset from the center of the area of the bottom in a given direction.

Claims

1. A thin film transistor element comprising:

a gate electrode;

an insulating layer disposed on the gate electrode;

a source electrode and a drain electrode disposed on the insulating layer with a gap therebetween;

partition walls surrounding at least a part of the source electrode and at least a part of the drain electrode, the partition walls having liquid-repellant surfaces and defining a first aperture; and

an organic semiconductor layer disposed on the source electrode and the drain electrode within the first aperture so as to cover the source electrode and the drain electrode and fill the gap between the source electrode and the drain electrode, the organic semiconductor layer being in contact with the source electrode and the drain electrode, wherein

in plan view of a bottom of the first aperture, a center of a total of areas of the source electrode and the drain electrode is offset from a center of an area of the bottom in a given direction.

2. The thin film transistor element of claim 1, wherein

the bottom of the first aperture includes a portion where the insulating layer is in direct contact with the organic semiconductor layer, the portion being located in an opposite direction from the given direction with respect to the center of the area of the bottom.

3. The thin film transistor element of claim 2, wherein

the bottom of the first aperture includes another portion where the insulating layer is in direct contact with the organic semiconductor layer, said another portion being located in the given direction with respect to the center of the area of the bottom, and

in plan view of the bottom of the first aperture, an area of the portion located in the opposite direction is greater than an area of said another portion located in the given direction.

4. The thin film transistor element of claim 1, wherein

the partition walls further define a second aperture, with a gap between the first aperture and the second aperture,

the first aperture includes a portion of the organic semiconductor layer, and functions as a channel portion,

the second aperture does not include any portion of the organic semiconductor layer and does not function as a channel portion, and

the given direction is an opposite direction of the second aperture.

5. The thin film transistor element of claim 1, wherein

in plan view of the bottom of the first aperture, a center of an area of one of the source electrode and the drain electrode is offset from the center of the area of the bottom in the given direction, and a center of an area of the other one of the source electrode and the drain electrode is located at the center of the area of the bottom.

6. The thin film transistor element of claim 1, wherein

at the bottom of the first aperture, at least one of the source electrode and the drain electrode is located apart from a side surface portion of the partition walls that faces the first aperture, and the at least one of the source electrode and the drain electrode is in contact with another side surface portion of the partition walls that faces the first aperture, the side surface portion being located in an opposite direction from the given direction with respect to the center of the area of the bottom, and said another side surface portion being located in the given direction with respect to the center of the area of the bottom.

7. The thin film transistor element of claim 1, wherein

a liquid repellency of the surfaces of the partition walls is greater than a liquid repellency of a surface of the insulating layer that is in contact with the organic semiconductor layer, and

the liquid repellency of the surface of the insulating layer that is in contact with the semiconductor layer is greater than a liquid repellency of a surface of each of the source electrode and the drain electrode.

8. The thin film transistor element of claim 4, wherein

one of the source electrode and the drain electrode extends to a bottom of the second aperture, or a wiring line electrically connecting with the source electrode or the drain electrode is formed on the bottom of the second aperture.

9. An organic EL display element comprising:

the thin film transistor element of claim 1;

a planarizing film formed above the thin film transistor element and having a contact hole formed therein;

a lower electrode formed on the planarizing film so as to cover the planarizing film and a side surface of the planarizing film defining the contact hole, and electrically connected with one of the source electrode and the drain electrode;

an upper electrode formed above the lower electrode; and

an organic light-emitting layer interposed between the lower electrode and the upper electrode.

10. An organic EL display element comprising:

the thin film transistor element of claim 4;

a planarizing film formed above the thin film transistor element and having a contact hole formed therein;

a lower electrode formed on the planarizing film so as to cover the planarizing film and a side surface of the planarizing film defining the contact hole, and electrically connected with one of the source electrode and the drain electrode;

an upper electrode formed above the lower electrode; and

an organic light-emitting layer interposed between the lower electrode and the upper electrode, wherein

the contact hole is in communication with the second aperture.

11. An organic EL display device comprising the organic EL display element of claim 9.

12. An organic EL display device comprising the organic EL display element of claim 10.

13. A method of manufacturing a thin film transistor element comprising:

a first step of forming a gate electrode on a substrate;

a second step of forming an insulating layer above the gate electrode;

a third step of forming a source electrode and a drain electrode on the insulating layer so as to be adjacent to each other with a gap therebetween;

a fourth step of depositing a layer of photosensitive resist material such that, above the insulating layer, the layer of photosensitive resist material covers the source electrode and the drain electrode as well as areas therearound;

a fifth step of forming partition walls on the insulating layer by performing mask exposure and patterning of the layer of photosensitive resist material, the partition walls having liquid-repellant surfaces and defining a first aperture, the first aperture surrounding at least a part of the source electrode and at least a part of the drain electrode; and

a sixth step of forming an organic semiconductor layer so as to be in contact with the source electrode and the drain electrode by applying organic semiconductor material within the first aperture and drying the organic semiconductor material so applied, wherein

in the fifth step, the partition walls are formed such that in plan view of a bottom of the first aperture, a center of a total of areas of the source electrode and the drain electrode is offset from a center of an area of the bottom in a given direction.

14. The method of claim 13, wherein

in the fifth step,

the partition walls are formed such that the bottom of the first aperture includes a portion where the insulating layer is in direct contact with the organic semiconductor layer, the portion being located in an opposite direction from the given direction with respect to the center of the area of the bottom.

15. The method of claim 13, wherein

in the second step through the sixth step,

a liquid repellency of the surfaces of the partition walls is made greater than a liquid repellency of a surface of the insulating layer that is in contact with the organic semiconductor layer, and

the liquid repellency of the surface of the insulating layer that is in contact with the semiconductor layer is made greater than a liquid repellency of a surface of each of the source electrode and the drain electrode.