OLED Electrode Layout for Shielding Hybrid TFTs From Light
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Solution Overview
Problem
Organic EL display devices with hybrid TFT structures, comprising polysilicon and oxide semiconductor TFTs, are susceptible to light, particularly affecting the oxide semiconductor TFTs, which need improvement to reduce light incidence.
Innovation Solution
The display device incorporates a base substrate layer with a light-emitting element layer featuring first electrodes that surround and protrude towards thin-film transistors, including a common edge cover and a common second electrode, to shield TFTs from light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a hybrid structure with oxide semiconductor TFT is used, then low leakage current is achieved, but light susceptibility increases
Solution Approach 1:
A light blocking film is introduced as an intermediary component between the light source and the oxide semiconductor TFT. This film specifically blocks light from reaching the TFT while allowing the device to maintain its low leakage current characteristics. The light blocking film acts as a mediator that protects the light-sensitive oxide semiconductor without affecting its electrical performance.
2Object-affected harmful factors
If polysilicon TFT is used, then light resistance is improved, but mobility decreases
Solution Approach 1:
The device is segmented into different functional regions: oxide semiconductor TFTs are used in regions requiring low leakage current (such as switch TFTs), while polysilicon TFTs are used in regions requiring high mobility (such as drive TFTs). This segmentation allows each TFT type to be optimized for its specific function, overcoming the limitations of using a single material throughout the device.
3Object-affected harmful factors
If light blocking structures are added, then light incidence on TFT is reduced, but device complexity increases
Solution Approach 1:
The light blocking film serves multiple functions simultaneously: it blocks light from reaching the TFT, provides planarization for subsequent layers, and can be integrated with existing manufacturing processes. By making the light blocking structure multi-functional, the patent reduces the need for additional separate components, thereby limiting the increase in device complexity.
Data Source
AI summary
A display device, includes: a base substrate layer; a thin-film transistor layer provided on the base substrate layer, and including a plurality of subpixels forming a display region, each of the subpixels being provided with a thin-film transistor on which a planarization film is stacked; and a light-emitting element layer provided on the thin-film transistor layer, and including a plurality of first electrodes, a common edge cover, a plurality of light-emitting functional layers, and a common second electrode, all of which are sequentially stacked on top of another in association with the plurality of subpixels, wherein each of the first electrodes has a peripheral edge portion provided to: surround, in plan view, the thin-film transistor corresponding to the first electrode; and protrude toward the base substrate layer.