Light emitting device and transparent display device using the same

1. A transparent display device comprising:

a substrate including a light emission area that emits light and a light transmission area that transmits light; and

a light emitting device on the substrate, the light emitting device including:

an anode;

a light emitting layer on the anode at the light emission area;

an electron transport layer at the light emission area and the transmission area, the electron transport layer comprises a first component comprising a heterocyclic compound having atoms with lone-pair electrons and a second component comprising at least one of an electron-injecting metal or an electron-injecting metal compound, a volume of the second component being less than a volume of the first component in the electron transport layer;

a cathode on the electron transport layer and disposed at both of the light emitting area and the light transmission area, the cathode comprising a metal component; and

a first organic layer comprising a third component as a same material as the first component and a transition metal, the first organic layer over a first surface of the cathode,

wherein the first surface of the cathode is opposite to a second surface of the cathode and the electron transport layer is directly in contact with the second surface of the cathode, and

wherein at least one of the atoms with the lone-pair electrons of the first component is bonded to the metal component constituting the cathode,

wherein the cathode is in contact with the first organic layer including the first component and the transition metal at the transmission area and the light emission area.

2. The transparent display device according to claim 1 , further comprising a second organic layer provided between the anode and the light emitting layer,

wherein the second organic layer is provided throughout the light emission area and the light transmission area.

3. The transparent display device according to claim 2 , wherein the first organic layer is in contact with the first surface of the cathode.

4. The transparent display device according to claim 3 , wherein an upper surface of the electron transport layer includes further bonds between the second component in the electron transport layer and the metal component constituting the cathode.

5. The transparent display device according to claim 3 , wherein the first surface of the cathode, between the first organic layer and the cathode, includes bonds between the atoms with lone-pair electrons in the first organic layer and the metal component constituting the cathode.

6. The transparent display device according to claim 1 , wherein the metal component of the cathode comprises one of a transflective metal or a transflective metal alloy.

7. The transparent display device according to claim 6 , wherein the metal component of the cathode further comprises a transition metal.

8. The transparent display device according to claim 1 , wherein the electron-injecting metal is one selected from a transition metal, an alkali metal, and an alkali earth metal.

9. The transparent display device according to claim 1 , wherein the electron transport layer further comprises lithium quinoline.

10. The transparent display device according to claim 1 , wherein the first organic layer further comprises lithium quinoline.

11. The transparent display device according to claim 6 , wherein the cathode has a thickness of 100 Å or less.

12. The transparent display device according to claim 1 , wherein an interface between the cathode and the electron transport layer includes a bonding unit having horizontally continuous arrangement of bonds between the atoms with lone-pair electrons and the metal component constituting the cathode, and particles of the metal component constituting the cathode are arranged on the bonding unit, wherein the particles of the metal component constituting the cathode are arranged without aggregation in the cathode.

13. The transparent display device according to claim 1 , wherein the first component of the electron transport layer comprises at least one selected from a Chemical formula 1, a Chemical formula 2 and a Chemical formula 3,