Light emitting element, display device including the same, and charge transport material for the light emitting element
A light-emitting element includes a first electrode, a second electrode disposed on the first electrode, and at least one functional layer disposed between the first electrode and the second electrode. The at least one functional layer includes a charge transport material derived from an azide compound represented by Formula 1 and a polymer compound including an aromatic ring group. The light-emitting element may be formed by a wet process and may exhibit improved flexibility.
1 . A light-emitting element comprising:
a first electrode, a second electrode, and at least one functional layer disposed between the first electrode and the second electrode,
the at least one functional layer including a charge transport material that is derived from a mixture of an azide compound represented by Formula 1 and a polymer compound including an aromatic ring group:
wherein, in Formula 1,
n1 is an integer of 1 to 9,
R 1 and R 2 are each independently a hydrogen atom or an optionally substituted alkyl group having 1 to 10 carbon atoms,
R 3 and R 4 are each independently a hydrogen atom or an optionally substituted alkyl group having 1 to 9 carbon atoms,
wherein a mole ratio of moles of the azide compound of Formula 1 to moles of the polymer compound is about 1:1.85 to about 1:3.0, and the azide compound includes only one azide group.
2 . The light-emitting element of claim 1 , wherein the charge transport material is formed by crosslinking the polymer compound with the azide compound.
3 . The light-emitting element of claim 1 , wherein the polymer compound comprises poly(triphenylamine), poly(9,9-dioctylfluorene-alt-N-(4-sec-butylphenyl)-diphenylamine), poly(p-phenylenevinylene), polythiophenes, poly(p-phenylene), polyfluorenes, or cyano-poly(p-phenylene vinylene), or the polymer compound is a polyvinylcarbazole represented by Formula 4:
wherein, in Formula 4, n2 is an integer of 100 to 300.
4 . The light-emitting element of claim 1 , wherein the at least one functional layer comprises: a light-emitting layer; a hole transport region disposed between the first electrode and the light-emitting layer; and an electron transport region disposed between the light-emitting layer and the second electrode, and
the hole transport region includes the charge transport material.
5 . The light-emitting element of claim 4 , wherein the hole transport region includes a hole injection layer disposed on the first electrode and a hole transport layer disposed on the hole injection layer, and
at least one of the hole injection layer or the hole transport layer includes the charge transport material.
6 . The light-emitting element of claim 1 , wherein the at least one functional layer comprises: a light-emitting layer; a hole transport region disposed between the first electrode and the light-emitting layer; and an electron transport region disposed between the light-emitting layer and the second electrode, and
the electron transport region comprises the charge transport material.
7 . The light-emitting element of claim 1 , wherein the at least one functional layer comprises: a light-emitting layer; a hole transport region disposed between the first electrode and the light-emitting layer; and an electron transport region disposed between the light-emitting layer and the second electrode, and
the light-emitting layer includes the charge transport material.
8 . The light-emitting element of claim 1 , wherein the azide compound is represented by a compound of Compound Group 1:
9 . A display device comprising:
a base layer, and a light-emitting element disposed on the base layer,
wherein the light-emitting element comprises:
a first electrode, a second electrode, and at least one functional layer disposed between the first electrode and the second electrode,
the at least one functional layer including a charge transport material derived from a mixture of an azide compound represented by Formula 1 and a polymer compound including an aromatic ring group:
wherein, in Formula 1,
n1 is an integer of 1 to 9,
R 1 and R 2 are each independently a hydrogen atom or an optionally substituted alkyl group having 1 to 10 carbon atoms,
R 3 and R 4 are each independently a hydrogen atom or an optionally substituted alkyl group having 1 to 9 carbon atoms,
wherein a mole ratio of moles of the azide compound of Formula 1 to moles of the polymer compound is about 1:1.85 to about 1:3.0, and the azide compound includes only one azide group.
10 . The display device of claim 9 , wherein the display device has a first state in which the display device has a first area on a plane; and a second state in which the display device has a second area on the plane that is larger than the first area.
11 . The display device of claim 9 , wherein the display device has a folded state and a non-folded state, and
the display device comprises a folding region that is folded with respect to a folding axis which is a virtual line extending in a first direction in the folding state, and a first non-folding region and a second non-folding region which are spaced apart from each other in a second direction perpendicular to the first direction.
12 . The display device of claim 9 , wherein the at least one functional layer comprises a light-emitting layer, a hole transport region disposed between the first electrode and the light-emitting layer, and an electron transport region disposed between the light-emitting layer and the second electrode, and
the hole transport region includes a hole injection layer disposed on the first electrode and a hole transport layer disposed on the hole injection layer, and
at least one of the hole injection layer or the hole transport layer includes the charge transport material.
13 . The display device of claim 10 , wherein the at least one functional layer comprises a light-emitting layer, a hole transport region disposed between the first electrode and the light-emitting layer, and an electron transport region disposed between the light-emitting layer and the second electrode, and
the electron transport region comprises an electron injection layer and an electron transport layer disposed between the light emitting layer and the electron injection layer, and
at least one of the light-emitting layer, the electron injection layer, or the electron transport layer includes the charge transport material.
14 . The display device of claim 9 , wherein the at least one functional layer is formed by applying the charge transport material by a wet process.
15 . The display device of claim 9 , wherein the display device is a personal digital terminal, a tablet, a car navigation unit, a game machine, or a wearable device.
16 . A charge transport material derived from a mixture of an azide compound represented by Formula 1 and a polymer compound including an aromatic ring group:
wherein, in Formula 1,
n1 is an integer of 1 to 9,
R 1 and R 2 are each independently a hydrogen atom or an optionally substituted alkyl group having 1 to 10 carbon atoms,
R 3 and R 4 are each independently a hydrogen atom or an optionally substituted alkyl group having 1 to 9 carbon atoms,
wherein with respect to the total number of moles of the azide compound and the polymer compound in the charge transport material, the mole percent of the azide compound is about 25 mol % to about 35 mol %, and the azide compound includes only one azide group.
17 . The charge transport material of claim 16 , wherein the polymer compound comprises poly(triphenylamine), poly(9,9-dioctylfluorene-alt-N-(4-sec-butylphenyl)-diphenylamine), poly(p-phenylenevinylene), polythiophenes, poly(p-phenylene), polyfluorenes, or cyano-poly(p-phenylene vinylene) or the polymer compound is a polyvinylcarbazole represented by Formula 4:
wherein, in Formula 4, n2 is an integer of 100 to 300.
18 . The charge transport material of claim 16 , wherein Formula 1 is represented by any one of the compounds of Compound Group 1: