OLED Cathode Overlapping Subcathodes Reduce Sheet Resistance
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Solution Overview
Problem
Existing organic light-emitting devices face challenges with high cathode sheet resistance, which affects charge injection efficiency and emission performance, particularly as device size increases.
Innovation Solution
The design incorporates overlapping subcathodes in non-emission regions of subpixels, allowing for a reduced sheet resistance and improved charge injection, using materials like silver (Ag), magnesium-silver (Mg—Ag), and transparent conductive metal oxides, with thicknesses ranging from 60 Å to 200 Å in emission regions and up to 400 Å in non-emission regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the cathode is designed as separate subcathodes for each subpixel, then the device complexity is reduced and manufacturing is simplified, but the cathode sheet resistance increases
Solution Approach 1:
Adjacent subcathodes are merged through overlapping in the non-emission regions, creating continuous conductive paths that reduce sheet resistance while maintaining the simplified subcathode structure for each subpixel
Solution Approach 2:
The subcathodes extend into the non-emission regions (vertical/dimensional extension beyond the emission area), creating overlapping regions that provide additional conductive pathways and reduce resistance without affecting the emission quality
2Reliability
If the cathode thickness is increased to reduce sheet resistance, then charge injection efficiency improves, but light transmission in emission regions is reduced
Solution Approach 1:
The cathode structure has different thicknesses in different regions: thinner in emission regions (60-200 Å) to maintain light transmission and thicker in non-emission regions (up to 400 Å) to reduce sheet resistance, optimizing both functions locally
Solution Approach 2:
The cathode is segmented into emission regions and non-emission regions with different thickness characteristics, allowing independent optimization of optical and electrical properties in each segment
Data Source
AI summary
An organic light-emitting device with a plurality of subpixels, each subpixel including an emission region and a non-emission region, the organic light-emitting device including a substrate; an anode on the substrate, the anode including patterns that separately correspond to respective ones of the plurality of subpixels; an organic layer on the anode, the organic layer being common to the plurality of subpixels; and a cathode on the organic layer, the cathode including a plurality of subcathodes that each correspond to at least one of the subpixels and that allow light to pass through in emission regions, wherein adjacent two of the subcathodes overlap with each other in non-emission regions.