Organic Light-Emitting Display Panel Auxiliary Pattern Current Leakage
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Solution Overview
Problem
Conventional organic light-emitting display panels experience lateral current leakage due to high hole mobility in common layers, leading to color mixing and poor low-gradation displays, especially when adjacent sub-pixels are not intended to be illuminated.
Innovation Solution
An auxiliary pattern with higher electron mobility than the common layer is introduced, positioned between sub-pixels to prevent lateral current flow, utilizing an electron transport material with a lower HOMO energy level than the common layer, and a second common layer with hole transport properties is used to manage hole transport and electron blocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a common layer with high hole mobility is used to continuously form other organic layers in sub-pixels without shadow mask, then manufacturing efficiency is improved, but lateral current leakage occurs between adjacent sub-pixels
Solution Approach 1:
The patent divides the continuous common layer into separate regions by introducing an auxiliary pattern layer between adjacent sub-pixels. This segmentation prevents holes from laterally migrating across sub-pixel boundaries while maintaining the continuous formation benefit of the common layer structure.
Solution Approach 2:
The auxiliary pattern layer acts as an intermediary barrier between adjacent sub-pixels. This layer has different charge transport properties (electron transport with lower HOMO energy level) compared to the common layer, thereby blocking lateral hole current while allowing the common layer to maintain its hole transport function within each sub-pixel.
2Speed
If hole mobility of the common organic layer is increased to improve charge transport, then charge transport efficiency is improved, but lateral current leakage to adjacent sub-pixels increases
Solution Approach 1:
The patent applies different material properties to different regions: the common layer maintains high hole mobility for efficient charge transport within sub-pixels, while the auxiliary pattern layer introduces electron transport properties with lower HOMO energy level specifically at sub-pixel boundaries to block lateral hole leakage.
Solution Approach 2:
The patent creates a composite structure combining the common layer (with high hole mobility) and the auxiliary pattern layer (with electron transport properties). This composite approach allows simultaneous achievement of efficient charge transport and lateral current blocking by leveraging the complementary properties of different materials in different spatial locations.
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 effectively prevents current leakage between sub-pixels, enhancing color purity and extending the lifespan and luminous efficacy of the display by ensuring accurate color representation and reduced unintended light emission during low-gradation displays.
Implementation Method 1
utilizing an electron transport material with a lower HOMO energy level than the common layer
Implementation Method 2
The organic light-emitting layer substantially functions to emit light as the energy of excitons, produced via the combination of holes and electrons, falls down to the ground state
Data Source
Figure 1
Figure 2
Figure 3~4A
AI summary
Disclosed is an organic light-emitting display panel, which prevents current leakage to an adjacent sub-pixel (SP) through a common layer having high hole mobility, via the arrangement of an auxiliary pattern (132). The organic light-emitting display panel includes a bank (120) provided in a non-emission portion so as to overlap an edge of a first electrode (110), a first common layer (131) located on the first electrode (110) in an emission portion and the bank (120) in the non-emission portion, and an auxiliary pattern (132) in contact with the first common layer (131) on the bank (120).