Organic Light-Emitting Diode Pixel Layout for Residual Image Suppression
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Solution Overview
Problem
Residual image phenomenon occurs in organic electroluminescence (EL) display devices due to insufficient absorption of thermal energy by thermally activated materials in the light-emitting layer.
Innovation Solution
The display device incorporates a configuration where a first organic light-emitting diode with a thermally activated delayed fluorescence material is positioned overlapping a drive TFT, while a second organic light-emitting diode without thermally activated material is positioned not overlapping the drive TFT, and an insulating film is used to prevent heat energy transfer to the second light-emitting layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a thermally activated material is used in the light-emitting layer, then the display device can achieve efficient light emission, but residual image phenomenon occurs due to insufficient absorption of thermal energy
Solution Approach 1:
An insulating film is introduced as an intermediary between the drive TFT and the light-emitting layer. This insulating film acts as a thermal mediator that directs heat flow preferentially to the thermally activated material while preventing excessive heat accumulation that causes residual images. The insulating film has specific thermal conductivity properties that enable selective heat management.
Solution Approach 2:
The thermal conductivity parameter of the insulating film is specifically controlled to optimize heat transfer. By adjusting the thermal conductivity of the insulating film, the patent achieves balanced heat distribution - sufficient to activate the thermally activated material for efficient light emission, but limited to prevent residual image formation.
2Temperature
If the drive TFT is arranged overlapping the light-emitting layer, then thermal energy can be effectively transferred to the thermally activated material, but heat may be insufficiently absorbed leading to residual images
Solution Approach 1:
The insulating film serves as a thermal intermediary layer between the drive TFT and the light-emitting layer. It mediates the heat transfer process by providing a controlled thermal pathway that ensures sufficient heat reaches the thermally activated material while preventing uncontrolled heat accumulation that leads to residual images.
Solution Approach 2:
The insulating film is positioned specifically at the boundary between the pixel and the light-emitting area, creating localized thermal management. This local quality approach allows different regions to have different thermal properties - the insulating film provides thermal isolation in specific areas while allowing heat transfer in other regions.
3Reliability
If an insulating film is added to prevent heat transfer, then residual image phenomenon is suppressed, but device complexity increases
Solution Approach 1:
The insulating film is applied selectively only at the pixel boundary regions where thermal management is most critical, rather than uniformly across the entire device. This local application minimizes the added structural complexity while maximizing the residual image suppression effect in the most problematic areas.
Solution Approach 2:
The insulating film is integrated as part of the existing pixel structure, serving as a multifunctional intermediary element that provides both electrical insulation and thermal management. This integration approach avoids significant increases in device complexity by combining multiple functions in a single component.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively suppresses the residual image phenomenon by enhancing the absorption of heat energy by the thermally activated material and preventing energy transfer to non-thermally activated layers, thereby improving the display device's performance.
Implementation Method 1
enhancing the absorption of heat energy by the thermally activated material
Implementation Method 2
an insulating film is used to prevent heat energy transfer to the second light-emitting layer
Data Source
AI summary
A display device according to an embodiment of the present invention includes: a substrate; a first organic light-emitting diode including a first lower electrode provided above the substrate and for each pixel, a first organic layer provided above the first lower electrode, a first light-emitting layer provided within the first organic layer and for each pixel and including a thermally activated material, and an upper electrode provided above the first organic layer; and a first drive TFT provided between the substrate and the first organic light-emitting diode, connected to the first lower electrode, and arranged overlapping the first light-emitting layer as viewed in a plan view.