OLED Panel Pixel Structure Voltage Uniformity
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Solution Overview
Problem
In OLED display panels, the common hole blocking layer with lower mobility results in higher operating voltage for the blue pixel compared to red and green pixels, causing pixel crosstalk at low gray levels due to the inclusion of a hole-type material as a host in at least one of the red, green, and blue light-emitting layers.
Innovation Solution
The OLED display panel design eliminates the common hole blocking layer for the red and green light-emitting sub-layers, and optionally includes a hole blocking layer made of electronic blue light host material between the blue light-emitting sub-layer and the electron transport layer, using organic small molecule materials like ruthenium, biguanide, naphthalene, or anthracene as a core, to reduce operating voltage and improve current efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a common hole blocking layer with lower mobility is disposed on the light-emitting layer, then holes or excitons in the light-emitting layer are prevented from diffusing into the electron transport layer, but the operating voltage of blue pixel becomes relatively higher causing pixel crosstalk
Solution Approach 1:
The patent divides the device into three independent pixel regions (red, green, blue) with different host material configurations. The blue pixel uses an electron-type host material while red and green pixels use hole-type host materials, allowing each pixel to be optimized independently without requiring a common hole blocking layer across all pixels.
Solution Approach 2:
The patent applies different host material types to different pixel regions based on their specific requirements. The blue light-emitting layer uses an electron-type host material to facilitate electron transport and reduce operating voltage, while red and green pixels use hole-type host materials, creating local optimization rather than a uniform structure.
2Device complexity
If a common hole blocking layer is used across all pixels, then the structure is simplified, but the operating voltage of blue pixel is relatively higher causing pixel crosstalk at low gray levels
Solution Approach 1:
The patent segments the device structure into pixel-specific regions with different host material configurations. By dividing the light-emitting layer into distinct red, green, and blue sub-layers with different host material types, the patent eliminates the need for a common hole blocking layer while maintaining structural organization through localized material selection.
3Reliability
If hole-type material is used as host material in light-emitting layers, then the light-emitting function is achieved, but a hole blocking layer is required which increases operating voltage and causes pixel crosstalk
Solution Approach 1:
The patent inverts the conventional approach by using an electron-type host material for the blue light-emitting layer instead of a hole-type host material. This inversion allows the blue pixel to transport electrons as the primary charge carriers, eliminating the need for a hole blocking layer and reducing operating voltage while maintaining light-emitting function.
Data Source
AI summary
The present invention provides an organic light-emitting diode (OLED) display panel, including: an array substrate; an anode disposed on the array substrate; a light-emitting layer disposed on the anode, the light-emitting layer including a red light-emitting sub-layer, a green light-emitting sub-layer, and a blue light-emitting sub-layer in a pixel region; and a cathode disposed on the light-emitting layer, wherein the pixel region at least corresponding to the red light-emitting sub-layer and the green light-emitting sub-layer is not provided with a hole blocking layer.