OLED Conductive Layer for Brightness Uniformity and Top-Emission

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Solution Overview

Problem

Conventional OLEDs face issues with non-uniform brightness due to TFT driving instability and manufacturing variability, which affects the threshold voltage of the TFTs, leading to inconsistent pixel brightness.

Innovation Solution

Incorporating a conductive layer with a thickness of 10 nm to 100 nm within the light emitting layer or directly contacting it, allowing for external voltage adjustment to balance current and brightness, while preventing damage to the light emitting layer, thus enabling top-emission OLED components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a conventional OLED structure with ITO anode is used, then top-emission is achieved, but the organic material is damaged by evaporated ITO

Engineering Contradiction:

Improvemanufacturing processVSAvoiddamage to light emitting layer

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an organic conductive layer as an intermediary between the ITO anode and the light emitting layer. This conductive layer serves as a protective barrier that prevents direct contact between the evaporated ITO and the organic material, thereby avoiding damage to the light emitting layer while maintaining the top-emission structure

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The organic conductive layer is formed by evaporating the same organic material that constitutes the light emitting layer onto the ITO anode first. This self-service approach allows the structure to protect itself during manufacturing, as the conductive layer is created from the material itself before the main functional layer is deposited

Inventive Principle:

Principle #25Self-service

2Ease of operation

If TFTs are used to drive OLED pixels, then the OLED can be controlled, but the brightness becomes non-uniform due to TFT threshold voltage shifts and manufacturing variability

Engineering Contradiction:

Improvebrightness controlVSAvoidbrightness uniformity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent modifies the electrical parameters of the OLED by introducing the organic conductive layer with specific thickness (10-100 nm) and conductivity characteristics. This changes the current-voltage relationship of the device, making the brightness less sensitive to TFT threshold voltage variations and improving uniformity across pixels

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The conductive layer is placed specifically at the interface between the anode and the light emitting layer, creating a localized modification of the electrical field distribution. This local quality change optimizes the current injection characteristics without affecting the overall device structure

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS9780324B2Orangic light emitting diodes (OLED)

Publication Date: 2017.10.03 TCL CHINA STAR OPTOELECTRONICS TECHNOLOGY CO LTD

AI summary

An OLED includes a first electrode, a second electrode arranged on the first electrode, a light emitting layer arranged between the first electrode and the second electrode, and a conductive layer arranged within the light emitting layer or being directly contacted with the light emitting layer. In view of the above, by configuring a conductive layer within the OLED, the OLED may be adjusted and balanced by an external voltage such that the OLED may not be limited to the circuit input between two electrodes. In this way, the lighting brightness of the OLED may be adjusted. In addition, the evaporated conductive layer may not damage the light emitting layer, and thus the OLED component of top-emission may be adopted.