Display device
A display device includes a touch panel; a display panel under the touch panel and displaying an image; a piezoelectric element under the touch panel and including an upper electrode, a lower electrode and a piezoelectric layer; and a rectifying circuit connected to the piezoelectric element.
1. A display device, comprising:
a thin film transistor over a substrate;
an overcoat layer on the thin film transistor;
a first electrode on the overcoat layer;
a light-emitting layer on the first electrode;
a second electrode on the light-emitting layer;
an encapsulation layer on the second electrode;
a piezoelectric element over the encapsulation layer;
a touch panel over the piezoelectric element; and
a polarizing plate over the encapsulation layer,
wherein the piezoelectric element includes an upper electrode, a lower electrode, and a piezoelectric layer,
wherein a display area displaying an image and a non-display area surrounding the display area are defined on the substrate, and
wherein each of the lower electrode and the upper electrode has a larger area than a total area of electrodes of the touch panel formed in the display area.
2. The display device of claim 1 , wherein the polarizing plate is disposed over the touch panel or disposed between the piezoelectric element and the encapsulation layer.
3. The display device of claim 1 , wherein the piezoelectric layer includes a piezoelectric polymer.
4. The display device of claim 3 , wherein the piezoelectric polymer includes polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-trifluoroethylene (P(VDF-TrFE)), poly(vinylidene fluoride-co-triluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)), poly(vinylidene fluoride-co-triluoroethylene-chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)), PVDF doped with carbon nanotubes, or a phosphazene-based polymer.
5. The display device of claim 1 , wherein the piezoelectric element further includes a first buffer layer under the lower electrode and a second buffer layer on the upper electrode.
6. The display device of claim 5 , wherein the second buffer layer has a larger area than each of the lower electrode and the upper electrode.
7. The display device of claim 5 , wherein the second buffer layer is in contact with the first buffer layer in the non-display area.
8. The display device of claim 1 , wherein the piezoelectric layer is interposed between the lower electrode and the upper electrode, and one of the lower electrode and the upper electrode is disposed between the piezoelectric layer and the touch panel.
9. The display device of claim 1 , wherein each of the lower electrode and the upper electrode is partially disposed in the non-display area.
10. The display device of claim 1 , further comprising a rectifying circuit connected to the piezoelectric element and formed in the non-display area on the substrate.
11. The display device of claim 10 , wherein each of the lower electrode and the upper electrode is configured as one or more patterns with respect to an entire surface of the substrate.
12. The display device of claim 11 , wherein a number of the rectifying circuit corresponds to the number of the patterns of each of the lower electrode and the upper electrode.
13. The display device of claim 10 , wherein the rectifying circuit includes a diode having an anode, a cathode, a P-type semiconductor, and an N-type semiconductor, the anode and the cathode are formed of a same material in a same layer as a gate electrode or source and drain electrodes of the thin film transistor, and one of the P-type semiconductor and the N-type semiconductor is formed of a same material in a same layer as a semiconductor layer of the thin film transistor.
14. The display device of claim 10 , wherein each of the upper electrode and the lower electrode has a protrusion in the non-display area, and the protrusion of the lower electrode and the protrusion of the upper electrode are spaced apart from each other and are electrically connected to the rectifying circuit formed in the non-display area.
15. The display device of claim 10 , wherein the lower electrode is connected to the rectifying circuit through a contact hole formed in the encapsulation layer and the overcoat layer.
16. The display device of claim 1 , wherein the piezoelectric layer includes a piezoelectric polymer, a piezoelectric ceramic, or an organic-inorganic complex including a piezoelectric ceramic and a polymer.