Vertical Transistor and OLET Overlap for Display Substrate Resolution
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Solution Overview
Problem
OLED display substrates have lower display accuracy and resolution due to staggered arrangements of switching TFTs, driving TFTs, and OLEDs, resulting in larger pixel unit areas and fewer pixel units per unit area.
Innovation Solution
A display substrate design where the plurality of functional layers form both a vertical thin film transistor (VTFT) and an organic light-emitting transistor (OLET) with overlapping orthographic projection regions, reducing the total projection area and increasing the number of pixel units per area, comprising specific layers such as gate, insulating, electrode, semiconductor, and electroluminescent layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If switching TFTs, driving TFTs, and OLEDs are arranged in a staggered configuration, then device functionality is achieved, but pixel unit area increases and display resolution decreases
Solution Approach 1:
The patent combines switching TFT and driving TFT into a single integrated pixel unit structure, where the TFT shares common electrodes and insulating layers with the OLED. This merging reduces the total pixel unit area by eliminating redundant structures and enabling overlapping orthographic projections of different functional layers.
Solution Approach 2:
The patent transitions from a planar staggered arrangement to a vertically stacked three-dimensional configuration. Multiple functional layers (gate layer, insulating layers, electrode layers, semiconductor layers) are arranged in the vertical direction, allowing orthographic projections to overlap on the substrate plane, thereby reducing pixel unit area.
2Manufacturing precision
If pixel unit area is reduced to increase pixel density, then display resolution improves, but device complexity increases
Solution Approach 1:
The patent implements multi-functionality where the same structural layers serve multiple purposes. For example, the gate electrode layer functions as both the gate for the TFT and an electrode for the OLED, and insulating layers provide both electrical isolation and structural support. This reduces overall device complexity despite the vertically integrated design.
Solution Approach 2:
The patent segments the pixel unit into distinct functional layers (gate layer, first insulating layer, first electrode layer, bottom semiconductor material layer, second electrode layer, second insulating layer, top semiconductor material layer, electroluminescent layer, capping layer) that can be independently designed and optimized, making the complex structure manageable and manufacturable.
Data Source
AI summary
Provided are a display substrate and a preparation method thereof, a display panel, and a display device. The display substrate includes a substrate and a plurality of pixel units on the substrate. The pixel unit comprises a plurality of functional layers that are sequentially arranged in a direction away from the substrate. At least one of the plurality of functional layers, which is close to the substrate, constitutes a vertical thin film transistor (VTFT). At least one of the plurality of functional layers, which is away from the substrate, constitutes an organic light-emitting transistor (OLET). An orthographic projection region of the OLET on the substrate and an orthographic projection region of the VTFT on the substrate at least partially overlap.