Insulated Balance Electrode for OLED Charge Control
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Solution Overview
Problem
In organic light emitting display devices, the difference in mobility between holes and electrons leads to a loss of charge balance in the organic light emitting layer, resulting in reduced light emitting efficiency due to unrecycled electric charges.
Innovation Solution
An organic light emitting display device is designed with a balance electrode that maintains hole-electron charge balance by varying the electric potential applied to it, adjusting the number of holes and electrons injected into the organic light emitting layer, using materials like indium tin oxide or metal alloys, and is insulated from the light emitting diode to optimize charge injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional light emitting diode structure is used without a balance electrode, then the device structure is simple, but the hole-electron charge balance is lost in the organic light emitting layer, reducing light emitting efficiency
Solution Approach 1:
The electrode structure is segmented into three distinct components: a first electrode, a second electrode, and a balance electrode. The balance electrode is positioned to face the organic light emitting layer and is electrically insulated from both the first and second electrodes. This segmentation allows independent control of charge injection, enabling separate optimization of hole and electron injection to achieve charge balance in the organic light emitting layer, thereby resolving the contradiction between structural simplicity and light emitting efficiency.
Solution Approach 2:
The balance electrode acts as an intermediary component between the first and second electrodes. It mediates the charge balance by providing an additional pathway for charge injection and recombination control. The balance electrode's insulating structure allows it to influence the electric field distribution and charge carrier density in the organic light emitting layer without directly contacting the main electrodes, thus improving light emitting efficiency while maintaining relative structural simplicity.
2Ease of operation
If the balance electrode is electrically connected to the light emitting diode, then charge control is simplified, but insulation between the balance electrode and light emitting diode is compromised, affecting charge balance maintenance
Solution Approach 1:
The balance electrode is designed with dynamic electrical isolation from the light emitting diode through an insulating structure. This dynamic isolation allows the balance electrode to independently control charge injection into the organic light emitting layer without being constrained by the electrical connections of the main electrodes. The insulating structure can be optimized for different operating conditions, enabling flexible charge balance maintenance while preserving ease of operation through independent voltage control.
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 ensures that holes and electrons recombine proportionally to the total electric charges injected, enhancing the light emitting efficiency of the device by maintaining charge balance within the organic light emitting layer.
Implementation Method 1
The first electrode may have a first electric potential, the second electrode has a second electric potential different from the first electric potential, and the balance electrode has a third electric potential different from either of the first and second electric potentials
Implementation Method 2
a hole and an electron are injected into an organic light emitting layer through an anode and a cathode, and are recombined in the organic light emitting layer to generate an exciton. The exciton emits energy when an excited state returns to a ground state as light
Data Source
AI summary
An organic light emitting display device includes a substrate, a light emitting diode disposed on the substrate, and a balance electrode insulated from the light emitting diode and from each of the first and second electrodes. The light emitting diode includes a first electrode, a second electrode facing the first electrode, and an organic light emitting layer disposed between the first electrode and the second electrode. The balance electrode maintains a hole-electron charge balance within the organic light emitting layer by varying the amount of electrons and holes that are injected into the organic light emitting layer from the first and second electrodes by varying an electric potential applied to the balance electrode.