OLED Subpixel Bank Structure Reducing Photolithography Damage
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Solution Overview
Problem
OLED display devices face damage and efficiency issues during the photolithography process, leading to decreased lifespan and performance of the light emitting layer.
Innovation Solution
The display device incorporates a substrate with first and second banks, where the light emitting layer is separated on the second bank from the light emitting layer on the first bank, reducing exposure and damage during photolithography processes by forming subpixels such that one subpixel surrounds another, thereby minimizing damage to the light emitting layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography process is used to form light emitting layer in patterns, then subpixel patterns are formed, but light emitting layer is damaged and lifespan decreases
Solution Approach 1:
The light emitting layer is divided into multiple separate regions corresponding to different subpixels (red, green, blue subpixels). Each subpixel region is formed through separate photolithography processes with different photoresist materials, preventing damage to the entire light emitting layer in a single process and reducing cumulative damage.
Solution Approach 2:
A bank structure is formed in advance before the light emitting layer is deposited. This bank serves as a protective barrier and pattern definition structure that prevents direct exposure of the light emitting layer to harsh photolithography conditions, reducing damage during the patterning process.
2Manufacturing precision
If multiple photolithography processes are performed to form light emitting layer, then subpixel patterns are created, but light emitting layer is exposed multiple times causing damage
Solution Approach 1:
The patent combines multiple photolithography processes into a single integrated process by using different photoresist materials (positive and negative type) that can be simultaneously processed. This allows formation of multiple subpixel patterns in one exposure step, reducing the number of times the light emitting layer is exposed to damage.
Solution Approach 2:
The bank structure is prepared in advance with specific geometric features that enable multiple subpixel patterns to be defined in a single photolithography step. This preliminary structuring reduces the need for multiple sequential exposure processes.
Data Source
AI summary
A display device includes: a substrate having thereon a first subpixel, a second subpixel, and a third subpixel; a first electrode in each of the first to third subpixels on the substrate; a first bank between the first electrodes; a second bank on the first bank and having a width less than that of the first bank; a light emitting layer on the first electrodes, the first bank, and the second bank; and a second electrode on the light emitting layer. The light emitting layer provided on the second bank and the light emitting layer provided on the first bank are spaced apart from each other.