Organic EL Gel Layer for Brightness Uniformity
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Solution Overview
Problem
Organic EL light-emitting devices experience brightness unevenness due to heat generation from transparent electrodes, leading to central dark spots and bright areas near power-feeding parts, which can cause element destruction.
Innovation Solution
A method for manufacturing organic EL light-emitting devices using a sealing substrate with a gel layer containing organosiloxane or fluorinated polyether, along with moisture absorbents and heat-transfer agents, to enhance thermal conductivity and moisture protection, thereby dissipating heat uniformly and preventing brightness unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transparent electrode with high electrical resistivity (such as ITO) is used in the organic EL element, then the electrode can provide adequate transparency for light emission, but the current distribution becomes uneven causing brightness non-uniformity and heat generation
Solution Approach 1:
An auxiliary electrode is introduced as an intermediary component between the transparent electrode and the organic light-emitting layer. This auxiliary electrode serves as a current distribution mediator that redirects current flow to regions with lower current density, thereby equalizing the overall current distribution across the device area and reducing brightness non-uniformity while maintaining the transparency of the original transparent electrode
Solution Approach 2:
The auxiliary electrode is designed with spatially varying properties - it has different conductivity characteristics in different regions of the device. By making the auxiliary electrode's conductivity higher in regions where current density is low and lower in regions where current density is already high, the system achieves local current redistribution that results in uniform overall current distribution and uniform brightness across the entire device area
2Illumination intensity
If high current is applied to increase light emission brightness, then the brightness increases, but heat generation increases causing potential element destruction
Solution Approach 1:
The auxiliary electrode acts as a thermal management intermediary by providing an additional current pathway that reduces the current burden on any single region. This distributed current flow reduces localized Joule heating (I²R losses) while maintaining the required total brightness output, thereby managing heat generation at higher current levels
Solution Approach 2:
The auxiliary electrode converts the potentially harmful effect of high current density concentration into a beneficial distributed current flow pattern. By intentionally designing the auxiliary electrode to redirect current away from high-density regions, the system transforms what would be hotspots into uniformly distributed current paths, reducing peak temperatures while maintaining overall brightness
3Illumination intensity
If the current density is increased in certain regions to compensate for brightness unevenness, then the local brightness improves, but the heat generation in those regions increases causing runaway heating and element destruction
Solution Approach 1:
The auxiliary electrode serves as a preventive intermediary that anticipates and counteracts current density imbalances before they cause runaway heating. By continuously redistributing current at the electrode level, it prevents the formation of hotspots that would lead to thermal runaway, thereby maintaining element stability even under high overall current conditions
Solution Approach 2:
The auxiliary electrode creates a passive feedback mechanism where regions with higher current density automatically receive less current due to the conductivity distribution design, while regions with lower current density receive more current. This self-regulating feedback prevents runaway heating by inherently limiting current concentration in any single region, maintaining both brightness uniformity and element reliability
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
The solution effectively prevents brightness unevenness and maintains uniform operational temperature, reducing the risk of element destruction and simplifying the manufacturing process while enhancing moisture protection.
Implementation Method 1
A method for manufacturing organic EL light-emitting devices using a sealing substrate with a gel layer containing organosiloxane or fluorinated polyether, along with moisture absorbents and heat-transfer agents, to enhance thermal conductivity and moisture protection, thereby dissipating heat uniformly
Implementation Method 2
A method for manufacturing organic EL light-emitting devices using a sealing substrate with a gel layer containing organosiloxane or fluorinated polyether, along with moisture absorbents and heat-transfer agents
Data Source
Figure 1~2
Figure 3A(A)~3A(D)
Figure 3B(E)~3B(G)
AI summary
This invention provides an organic EL light-emitting device, which can prevent the occurrence of brightness unevenness due to resistance of a transparent electrode, in a large surface light-emitting panel of an organic EL element. The organic EL light-emitting device includes an element formation substrate 1, on which an organic EL element 2 including an organic light-emitting layer is stacked, and a sealing substrate 3 for sealing the organic EL element so as to accommodate the organic EL element between the element formation substrate and the sealing substrate. A sealing portion 4 formed of an adhesive is formed in the peripheral edge portion between the element formation substrate 1 and the sealing substrate 3, and a grease layer 5 or a gel layer 5 is accommodated in between the element formation substrate, on which the organic EL element surrounded by the sealing portion is formed, and the plate-shaped sealing substrate so as to adhere to the element formation substrate and the sealing substrate. The grease layer 5 or the gel layer 5 contains an oligomer or a polymer having organosiloxane bond(-R2SiO-) or fluorinated polyether (-CF2CFYO-) as a skeleton.