Organic light-emitting device and organic light-emitting display device using the same

• US 10,373,559 B2
• Filed: 12/12/2017
• Issued: 08/06/2019
• Est. Priority Date: 12/30/2016
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Kim, Seok-Hyun, Park, Eun-Jung, Kim, Ho-Sung
• Primary Examiner(s): Arora, Ajay
• Application Number:
  US15/838,887
• Publication Number:
  US 20180190193A1
• Time in Patent Office: 602 Days
• Field of Search: 257 40
• CPC Class Codes: G09G 3/3216 using a passive matrix
• CPC Class Codes: G09G 3/3225 using an active matrix
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements
• CPC Class Codes: H10K 50/131 with spacer layers between the electroluminescent layers
• CPC Class Codes: H10K 50/19 Tandem OLEDs
• CPC Class Codes: H10K 50/818 Reflective anodes, e.g. ITO combined with thick metallic layers
• CPC Class Codes: H10K 50/852 comprising a resonant cavity structure, e.g. Bragg reflector pair
• CPC Class Codes: H10K 50/865 comprising light absorbing layers, e.g. light-blocking layers
• CPC Class Codes: H10K 59/1216 the pixel elements being capacitors
• CPC Class Codes: H10K 59/17 Passive-matrix OLED displays
• CPC Class Codes: H10K 59/32 Stacked devices having two or more layers, each emitting at different wavelengths
• CPC Class Codes: H10K 59/35 comprising red-green-blue [RGB] subpixels

Abstract

An organic light-emitting device and an organic light-emitting display device using the same are discussed. In a structure in which emission layers that emit light having the same color are provided in a plurality of stacks, the emission layers have different properties such that the light emission efficiencies of the stacks are made uniform, whereby the lifespan of the organic light-emitting device is increased through charge balance.

Claims

1. An organic light-emitting device comprising:

a first electrode and a second electrode provided opposite each other;

a charge generation layer provided between the first electrode and the second electrode;

a first stack provided between the first electrode and the charge generation layer, the first stack comprising a first hole transport layer, a first emission layer, and a first electron transport layer; and

a second stack provided between the charge generation layer and the second electrode, the second stack comprising a second hole transport layer, a second emission layer, which emits a same color as the first emission layer, and a second electron transport layer,

wherein a hole transport rate of the second emission layer is higher than a hole transport rate of the first emission layer so that an emission zone of the second emission layer is maintained without movement towards the charge generation layer over time.

2. The organic light-emitting device according to claim 1, wherein:

the first emission layer and the second emission layer have a first bipolar host and a second bipolar host, respectively, and

hole mobility of the second host is higher than hole mobility of the first host, or a highest occupied molecular orbital (HOMO) energy level of the second host is lower than a HOMO energy level of the first host.

3. The organic light-emitting device according to claim 2, wherein an electron mobility of the second host is higher than an electron mobility of the first host.

4. The organic light-emitting device according to claim 1, wherein:

the first emission layer has a first hole transport host and a first electron transport host, and

the second emission layer has a second hole transport host and a second electron transport host.

5. The organic light-emitting device according to claim 4, wherein:

an electron transport rate of the first emission layer is higher than an electron transport rate of the second emission layer, and

a hole transport rate of the second emission layer is higher than a hole transport rate of the first emission layer.

6. The organic light-emitting device according to claim 5, wherein:

an amount of the second hole transport host in the second emission layer is greater than an amount of the first hole transport host in the first emission layer, and

an amount of the first electron transport host in the first emission layer is greater than an amount of the second electron transport host in the second emission layer.

7. The organic light-emitting device according to claim 4, wherein:

a hole mobility of the first hole transport host is at least 10 times higher than a hole mobility of the first electron transport host, and

an electron mobility of the first electron transport host is at least 10 times higher than an electron mobility of the first hole transport host.

8. The organic light-emitting device according to claim 7, wherein:

a hole mobility of the second hole transport host is at least 10 times higher than hole mobility of the second electron transport host, and

an electron mobility of the second electron transport host is at least 10 times higher than electron mobility of the second hole transport host.

9. The organic light-emitting device according to claim 4, wherein:

a hole mobility of the second hole transport host is higher than a hole mobility of the first hole transport host, and

an electron mobility of the first electron transport host is higher than an electron mobility of the second electron transport host.

10. An organic light-emitting display device comprising:

a substrate having a plurality of sub-pixels;

a thin film transistor provided at at least one of the sub-pixels on the substrate; and

an organic light-emitting device connected to the thin film transistor,

wherein the organic light-emitting device comprises;

a first electrode and a second electrode opposite each other;

a charge generation layer provided between the first electrode and the second electrode;

a first stack provided between the first electrode and the charge generation layer, the first stack comprising a first hole transport layer, a first emission layer, and a first electron transport layer; and

a second stack provided between the charge generation layer and the second electrode, the second stack comprising a second hole transport layer, a second emission layer, which emits a same color as the first emission layer, and a second electron transport layer, and

wherein a hole transport rate of the second emission layer is higher than a hole transport rate of the first emission layer so that an emission zone of the second emission layer is maintained without movement towards the charge generation layer over time.

11. The organic light-emitting device according to claim 10, wherein a highest occupied molecular orbital (HOMO) energy level of a second host in the second emission layer is lower than a HOMO energy level of a first host of the first emission layer.

12. The organic light-emitting device according to claim 11, wherein an electron mobility of the second host is higher than an electron mobility of the first host.

13. An organic light-emitting device comprising:

a first electrode and a second electrode provided opposite each other;

a charge generation layer provided between the first electrode and the second electrode;

a first stack provided between the first electrode and the charge generation layer, the first stack comprising a first hole transport layer, a first emission layer, and a first electron transport layer; and

a second stack provided between the charge generation layer and the second electrode, the second stack comprising a second hole transport layer, a second emission layer, which emits a same color as the first emission layer, and a second electron transport layer,

wherein a hole transport rate of the second emission layer is higher than a hole transport rate of the first emission layer, and

wherein an electron transport rate of the first emission layer is higher than an electron transport rate of the second emission layer.