OLED Substrate Auxiliary Electrode Voltage Drop
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Solution Overview
Problem
Large organic light-emitting display devices face issues with voltage drop and luminance non-uniformity due to increased wiring resistance, and the process of forming auxiliary electrodes can damage the organic layer or electrode, while also leading to reduced transmittance.
Innovation Solution
A display substrate with a conductive layer, such as an auxiliary electrode, is formed using a deposition assistant layer and a transmittance measurement pattern unit, which includes materials like 8-quinolinolato lithium and N,N-diphenyl-N,N-bis(9-phenyl-9H-carbazol-3-yl)biphenyl-4,4′-diamine, to prevent voltage drop and damage, and a method to detect transmittance defects during manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an auxiliary electrode is formed to prevent voltage drop, then voltage uniformity is improved, but the organic layer or electrode may be damaged
Solution Approach 1:
A buffer layer is introduced as an intermediary between the auxiliary electrode and the organic light-emitting layer. This buffer layer prevents direct contact and potential damage to the organic layer while still allowing the auxiliary electrode to function in preventing voltage drop and ensuring voltage uniformity across the display device.
2Reliability
If a conductive layer is formed to reduce wiring resistance, then voltage drop is reduced, but transmittance decreases
Solution Approach 1:
The conductive layer is selectively formed only in the inactive area of the substrate where transmittance requirements are not critical. This local placement allows the conductive layer to reduce wiring resistance and prevent voltage drop in areas where it is needed, while maintaining high transmittance in the active display areas.
Solution Approach 2:
The conductive layer is positioned in the inactive area dimension, separating its function from the active display area. This spatial separation in another dimension (inactive vs. active area) allows the conductive layer to perform its electrical function without interfering with the optical transmittance properties of the display region.
3Area of stationary object
If the display device size is increased, then display area is improved, but wiring resistance increases causing voltage drop
Solution Approach 1:
Multiple auxiliary electrodes are distributed across the large display area, segmenting the electrical path into smaller sections. This segmentation reduces the overall wiring resistance by providing multiple parallel conduction paths, ensuring voltage uniformity across the expanded display area.
Solution Approach 2:
Auxiliary electrodes are added in the vertical dimension (stacked layers) rather than only expanding in the horizontal plane. This dimensional addition provides multiple conduction layers that work together to maintain voltage uniformity across the large display area without increasing the horizontal wiring path length.
Data Source
AI summary
A display substrate and a method of manufacturing the same. The display substrate includes a substrate including an active area and an inactive area, an organic light-emitting diode (OLED) unit disposed on the active area of the substrate, and a transmittance measurement pattern unit disposed on the inactive area of the substrate. The transmittance measurement pattern unit includes a deposition assistant layer pattern disposed on the substrate.