Electron Adjust Layer Suppresses Black Floating in Light-Emitting Devices
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Solution Overview
Problem
The black floating phenomenon in light-emitting devices, where a minute voltage applied between the cathode and anode results in unintended light emission, disrupts the contrast ratio and color balance, particularly in display devices using white light-emitting elements and color filters, leading to undesirable color emission.
Innovation Solution
Incorporating an electron adjust layer with insulating properties between the cathode terminal and cathode, which also functions as an electron injection layer, to control the electron supply and prevent unwanted light emission by overlapping with the light-emitting layers, and using an auxiliary cathode with higher conductivity to reduce the drive voltage and assist electron transportation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a minute voltage is applied between the cathode and anode to enable light emission, then the light-emitting element can emit light, but the black floating phenomenon occurs causing unintended light emission and degraded contrast ratio
Solution Approach 1:
An electron adjust layer is introduced as an intermediary component between the cathode terminal and the cathode. This layer includes a material with insulating properties that adjusts the amount of electrons supplied from the cathode terminal to the cathode, preventing the black floating phenomenon while maintaining proper light emission function.
Solution Approach 2:
The electron adjust layer changes the electrical parameters (electron supply amount) in the circuit. By controlling the electron flow through its insulating properties, it adjusts the voltage and current characteristics to eliminate unintended light emission during the off-state while preserving normal operation during the on-state.
2Power
If the drive transistor electrically connects between the anode and power source to apply drive voltage, then light emission is enabled, but a minute voltage remains applied causing black floating phenomenon
Solution Approach 1:
The electron adjust layer serves as a mediator in the electron supply path between the cathode terminal and cathode. It adjusts the electron flow to completely suppress the black floating phenomenon, eliminating the harmful effect of minute voltage application while allowing proper drive voltage application for light emission.
3Device complexity
If light emission balance between individual light-emitting layers is changed due to black floating phenomenon, then the device structure remains simple, but color accuracy deteriorates and wrong colors are emitted
Solution Approach 1:
The electron adjust layer acts as a mediator that precisely controls electron supply to maintain proper light emission balance across all light-emitting layers. This prevents color accuracy deterioration and eliminates wrong color emission while keeping the overall device structure relatively simple.
Solution Approach 2:
By adjusting the electron supply parameters through the electron adjust layer, the light emission balance between different colored layers is maintained. This ensures accurate color reproduction and prevents the black floating phenomenon from causing color distortion.
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
Effectively suppresses the black floating phenomenon, maintaining high contrast ratios and accurate color balance by ensuring precise electron supply and reduced drive voltage, enabling high-quality image display in light-emitting devices.
Implementation Method 1
an electron adjust layer which includes a material having insulating properties and which adjusts the amount of electrons supplied from the cathode terminal to the cathode
Implementation Method 2
when an electric field is applied between the anode and the cathode, electrons and holes are simultaneously injected from a cathode side and an anode side, respectively, into the light-emitting layer, and since the electrons and the holes are recombined in the light-emitting layer, excitons are generated. When the excitons thus generated are returned to the ground state, the energy generated thereby is released in the form of light
Data Source
AI summary
A light-emitting device is provided which includes: a cathode; an anode; at least one light-emitting layer which is provided between the cathode and the anode and which emits light when a voltage is applied between the cathode and the anode; a cathode terminal which is provided at a portion not in contact with the anode and the light-emitting layer and which supplies electrons to the cathode; and an electron adjust layer which includes a material having insulating properties and which adjusts the amount of electrons supplied from the cathode terminal to the cathode, and in the light-emitting device described above, the cathode is connected to the cathode terminal with the electron adjust layer interposed therebetween.