Organic thin film transistor providing smoother movement of holes between electrodes and semiconductor layer and flat panel display device including the same

1. An organic thin film transistor comprising:

a substrate;

a gate electrode disposed on the substrate;

a p-type organic semiconductor layer insulated from the gate electrode;

a source electrode and a drain electrode separated from each other and insulated from the gate electrode; and

a hole injection layer interposed between the source and drain electrodes and the p-type organic semiconductor layer;

wherein the p-type organic semiconductor layer is disposed over the source electrode and the drain electrode, the gate electrode is disposed over the p-type organic semiconductor layer, and a gate insulation film is further disposed between the p-type organic semiconductor layer and the gate electrode; and

wherein the hole injection layer is disposed on the entire surface of the substrate to cover the source and drain electrodes;

wherein the hole injection layer consists of the same material throughout the entire surface of the substrate.

2. The organic thin film transistor of claim 1 , wherein the p-type organic semiconductor layer is a hole transport layer.

3. The organic thin film transistor of claim 1 , wherein a highest occupied molecular orbit level of the hole injection layer exists in between a Fermi level of the source electrode or drain electrode and a highest occupied molecular orbit level of the p-type organic semiconductor layer.

4. The organic thin film transistor of claim 1 , wherein a hole mobility of the p-type organic semiconductor layer is greater than a hole mobility of the hole injection layer.

5. The organic thin film transistor of claim 1 , wherein the thickness of the hole injection layer is from about 10 nm to about 100 nm.

6. The organic thin film transistor of claim 1 , wherein the hole injection layer is formed of at least one compound selected from the group consisting of a triarylamine-based compound, a diarylamine-based compound, an arylamine-based compound, and a phthalocyan-based compound containing metal.

7. The organic thin film transistor of claim 1 , wherein the p-type organic semiconductor layer is formed of at least one material selected from the group consisting of pentacene, polythienylenevinylene, poly-3-hexylthiophene, α-hexathienylene, tetracene, antharacene, naphthalene, α-6-thiophene, α-4-thiophene, perylene, rubrene, coronene, polythiophene, polyparaphenylenevinylene, polyparaphenylene, polyfluorene, polythiophenevinylene, polythiophene-heterocyclic aromatic copolymer, and derivatives of these materials.

8. The organic thin film transistor of claim 1 , further comprising a channel region wherein the thickness of the channel region to be formed in the p-type organic semiconductor layer is from about 50 nm to about 200 nm.

9. A flat panel display device comprising one or more organic thin film transistors, each comprising:

a substrate;

a gate electrode disposed on the substrate;

a p-type organic semiconductor layer insulated from the gate electrode;

a source electrode and a drain electrode separated from each other and insulated from the gate electrode; and

a hole injection layer interposed between the source and drain electrodes and the p-type organic semiconductor layer;

wherein the p-type organic semiconductor layer is disposed over the source electrode and the drain electrode, the gate electrode is disposed over the p-type organic semiconductor layer, and a gate insulation film is further disposed between the p-type organic semiconductor layer and the gate electrode; and

wherein the hole injection layer is disposed on the entire surface of the substrate to cover the source and drain electrodes;

wherein the hole injection layer consists of the same material throughout the entire surface of the substrate.

10. The flat panel display device of claim 9 wherein the p-type organic semiconductor layer is a hole transport layer.

11. The flat panel display device of claim 9 , wherein a highest occupied molecular orbit level of the hole injection layer exists in between a Fermi level of the source electrode or drain electrode and a highest occupied molecular orbit level of the p-type organic semiconductor layer.

12. The flat panel display device of claim 9 , wherein a hole mobility of the p-type organic semiconductor layer is greater than a hole mobility of the hole injection layer.

13. The flat panel display device of claim 9 wherein the thickness of the hole injection layer is from about 10 nm to about 100 nm.

14. The flat panel display device of claim 9 , wherein the hole injection layer is formed of at least one compound selected from the group consisting of a triarylamine-based compound, a diarylamine-based compound, an arylamine-based compound, and a phthalocyan-based compound containing metal.

15. The flat panel display device of claim 9 , wherein the p-type organic semiconductor layer is formed of at least one material selected from the group consisting of pentacene, polythienylenevinylene, poly-3-hexylthiophene, α-hexathienylene, tetracene, antharacene, naphthalene, α-6-thiophene, α-4-thiophene, perylene, rubrene, coronene, polythiophene, polyparaphenylenevinylene, polyparaphenylene, polyfluorene, polythiophenevinylene, polythiophene-heterocyclic aromatic copolymer, and derivatives of these materials.

16. The flat panel display device of claim 9 , further comprising a channel region wherein the thickness of the channel region to be formed in the p-type organic semiconductor layer is from about 50 nm to about 200 nm.