OLED Turn-On Voltage Homogenization via Energy Level Engineering
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Solution Overview
Problem
Conventional OLED display technologies suffer from color shift issues under low gray scales due to differences in turn-on voltages of red, green, and blue sub-pixels, leading to inaccurate color representation.
Innovation Solution
An organic light emitting element is designed with a light emitting layer comprising multiple portions emitting different colors, where the energy level differences between the hole layer, light emitting portions, and electron layer are optimized to reduce turn-on voltage disparities, using specific materials like 4,7-diphenyl-1,10-phenanthroline and 4,4′,4″-tris(carbazol-9-yl)-triphenylamine to achieve closer turn-on voltages and improved electron mobility control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional OLED materials with different band gaps are used for RGB sub-pixels, then each sub-pixel can emit its characteristic color, but the turn-on voltages become inconsistent causing color shift at low gray scales
Solution Approach 1:
The patent changes the energy level parameters of the hole layer and electron layer to achieve consistent turn-on voltages across RGB sub-pixels. Specifically, the hole layer's energy level is set to 5.0-6.0 eV and the electron layer's energy level is set to 2.0-3.0 eV, which homogenizes the turn-on characteristics of different colored sub-pixels and eliminates color shift at low gray scales
Solution Approach 2:
The patent creates equipotential conditions for the turn-on voltages of red, green, and blue sub-pixels by carefully selecting materials with appropriate energy levels. This ensures that all sub-pixels start emitting at the same voltage threshold, achieving uniform color representation across the display
2Reliability
If the hole layer has good conductivity to distribute voltage, then voltage can be applied uniformly to all sub-pixels, but the red sub-pixel turns on first due to its low turn-on voltage causing red color shift
Solution Approach 1:
The patent raises the turn-on voltage of the red sub-pixel by adjusting the energy level difference between the hole layer and the red light emitting material. By setting the hole layer energy level to 5.0-6.0 eV, the energy barrier for red sub-pixel activation is increased, preventing it from turning on prematurely and causing red color shift
3Manufacturing precision
If different energy level materials are used for RGB light emitting layers, then each sub-pixel emits correct color, but the turn-on voltage differences cause brightness inconsistency at low gray scales
Solution Approach 1:
The patent changes the energy level parameters of the charge transport layers to compensate for the inherent turn-on voltage differences of different colored OLED materials. By optimizing the hole layer energy level (5.0-6.0 eV) and electron layer energy level (2.0-3.0 eV), the patent achieves uniform turn-on characteristics across all sub-pixels, ensuring brightness consistency at low gray scales while maintaining correct color emission
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 reduces color shift under low gray scales by homogenizing turn-on voltages across sub-pixels, enhancing the display's color accuracy and brightness consistency.
Implementation Method 1
a hole layer disposed on the first electrode; a light emitting layer disposed on the hole layer... an electron layer disposed on the light emitting layer
Implementation Method 2
a light emitting layer disposed on the hole layer and comprising a first light emitting portion, a second light emitting portion and a third light emitting portion
Data Source
AI summary
The present disclosure relates to an organic element, a display panel and a display device. The organic light emitting element includes: a first electrode; a hole layer disposed on the first electrode; a light emitting layer including a first light emitting portion, a second light emitting portion and a third light emitting portion; an electron layer on the light emitting layer; and a second electrode disposed on the electron layer. An energy level difference between the hole layer and the first light emitting portion and/or an energy level difference between the first light emitting portion and the electron layer is greater than or equal to a first threshold, so that a turn-on voltage difference between the first light emitting portion and the second light emitting portion is smaller than a second threshold.