Light Blocking Portion in Oxide TFT Organic Displays
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Solution Overview
Problem
The use of oxide semiconductors in thin-film transistors (TFTs) for organic light-emitting display apparatuses is hindered by light penetration, which affects the threshold voltage and stability, particularly due to blue light emission from organic layers, leading to reduced DC stability and manufacturing challenges on large substrates.
Innovation Solution
A light blocking portion is integrated into the TFT structure, specifically formed in the pixel defining layers with openings around the active layer, where the second electrode is positioned to reflect and block light emitted from the organic layer, preventing direct incidence on the TFT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide semiconductors are used in TFTs for organic light-emitting display apparatuses, then the display performance is improved, but light penetration from organic layers causes threshold voltage variation and reduced DC stability
Solution Approach 1:
A light blocking portion is introduced as an intermediary element between the organic light-emitting layer and the oxide semiconductor TFT. This light blocking portion, formed by extending the pixel defining layer or adding a separate layer, selectively blocks light from reaching the TFT while allowing the oxide semiconductor to maintain its electrical functions. The intermediary structure resolves the contradiction by preventing harmful light interaction without compromising the display performance benefits of oxide semiconductors.
Solution Approach 2:
The pixel defining layer is segmented or extended to create a light blocking portion that specifically targets the area above the TFT. This segmentation allows the structure to simultaneously define the pixel boundary and block light from reaching the oxide semiconductor TFT, thereby maintaining both display performance and DC stability without requiring complete structural redesign.
2Reliability
If a light blocking portion is added to block light from reaching the TFT, then DC stability is improved, but device complexity increases
Solution Approach 1:
The light blocking portion is merged with the existing pixel defining layer structure. By extending the pixel defining layer to overlap with the TFT, the invention combines the pixel boundary definition function with the light blocking function into a single integrated structure. This merging approach improves DC stability without significantly increasing device complexity, as it utilizes and extends existing structural elements rather than adding completely separate components.
3Object-affected harmful factors
If the pixel defining layer is extended to block light, then light blocking effectiveness is improved, but manufacturing precision requirements increase
Solution Approach 1:
The pixel defining layer is extended during the manufacturing process to preemptively block light paths before they can reach the TFT. By incorporating the light blocking function into the pixel defining layer formation step, the invention establishes the protective structure in advance, ensuring light blocking effectiveness while maintaining compatibility with existing manufacturing sequences and precision capabilities.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively blocks light from the organic layer, enhancing the stability and reliability of the oxide semiconductor TFTs, improving DC stability and enabling mass production on larger substrates by preventing light-induced variations in threshold voltage.
Implementation Method 1
A portion of the light emitted from the organic layer may be reflected by the second electrode that is formed in the holes of the PDLs
Data Source
AI summary
An organic light-emitting display apparatus including a thin-film transistor (TFT) is disclosed. In one embodiment, the organic light-emitting display apparatus includes a thin-film transistor (TFT) and an organic light-emitting device electrically connected to the TFT. The apparatus further includes a light blocking portion formed directly above at least a portion of the TFT and configured to prevent light, emitted from the organic light-emitting device, from entering the portion of the TFT.