Organic light emitting diode display device having first and second capacitors disposed on a substrate wherein the first capacitor comprises an undoped semiconductor layer electrode.
View Patent ↗An organic light emitting diode (OLED) display device and a method of fabricating the same capable of minimizing the number of process operations and a decrease in aperture ratio. The OLED display device includes a compensation circuit to compensate for a threshold voltage of a driving transistor. A pixel circuit of the OLED display device can be stably driven, can minimize a threshold voltage of a driving transistor using a minimized structure, and can increase an aperture ratio of the display device.
1. An organic light emitting diode (OLED) display device comprising:
a substrate having a first capacitor region, a second capacitor region, and a thin film transistor (TFT) region;
a first capacitor disposed on the first capacitor region of the substrate, the first capacitor including a first semiconductor layer having an impurity doped first region extending from an undoped region, a first electrode, and a first insulating layer disposed between the first semiconductor layer and the first electrode;
a second capacitor disposed on the second capacitor region of the substrate, the second capacitor including a second semiconductor layer, a second electrode, and a second insulating layer disposed between the second semiconductor layer and the second electrode;
a thin film transistor (TFT) disposed on the TFT region of the substrate, the TFT including a third semiconductor layer having a source region, a drain region and a channel region, a gate electrode, a gate insulating layer disposed between the gate electrode and the channel region, a source electrode connected to the source region, and a drain electrode connected to the drain region;
a power supply voltage line disposed on the first capacitor and electrically connected to the first region of the first semiconductor layer; and
an organic light emitting diode disposed on the TFT and including at least one organic emission layer.
2. The OLED display device according to claim 1 , wherein the TFT comprises;
a first switching transistor electrically connected between a data line and a first node;
a second switching transistor electrically connected between the power supply voltage line and a second node; and
a driving transistor disposed between the second node and the organic light emitting diode to supply a driving current to the organic light emitting diode according to a voltage of the first node.
3. The OLED display device according to claim 2 , wherein the first capacitor is electrically connected between the first node and the power supply voltage line, and the second capacitor is electrically connected between the first node and the second node.
4. The OLED display device according to claim 1 , wherein the first semiconductor layer, the second semiconductor layer, and the third semiconductor layer have a same crystal structure.
5. The OLED display device according to claim 1 , wherein the first insulating layer and the second insulating layer are formed of a same material.
6. The OLED display device according to claim 5 , wherein the first insulating layer, the second insulating layer, and the gate insulating layer are formed of the same material.
7. The OLED display device according to claim 1 , wherein the area of the first electrode is smaller than the area of the first semiconductor layer by the area of the first region.
8. The OLED display device according to claim 1 , wherein the first electrode and the second electrode are formed of a same material.
9. The OLED display device according to claim 8 , wherein the first electrode, the second electrode, and the gate electrode are formed of the same material.
10. The OLED display device according to claim 1 , wherein the first electrode is electrically connected to the second electrode.
11. The OLED display device according to claim 1 , wherein the first region of the first semiconductor layer and the source and drain regions of the third semiconductor layer are doped with a same impurity.
12. The OLED display device according to claim 11 , wherein the first region of the first semiconductor layer and the source and drain regions of the third semiconductor layer are doped with a P-type impurity.