Polysilicon TFT Display Structure with Offset Light-Shielding Film
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Solution Overview
Problem
In flexible organic EL display devices, the provision of a light-shielding film towards the resin substrate can create a level difference that risks breaking the semiconductor layer, particularly when the semiconductor layer is electrically connected through a conductor region of a polysilicon film.
Innovation Solution
The display device incorporates a light-shielding film positioned such that its peripheral end is outside the peripheral end of the semiconductor layer, ensuring the semiconductor layer is not provided on a level difference, and the light-shielding film is formed as a single piece, separate pieces, or coupled together, to prevent cracking and stabilize TFT characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light-shielding film is provided to the semiconductor layer toward the resin substrate, then polarization of the resin substrate does not affect characteristics of the TFTs, but a level difference of the light-shielding film might break the semiconductor layer
Solution Approach 1:
An insulating film is introduced as an intermediary layer between the light-shielding film and the semiconductor layer. This mediator eliminates direct contact between the two layers, preventing the light-shielding film's peripheral end from creating level differences that would break the semiconductor layer, while still allowing the light-shielding film to perform its function of blocking polarized light from affecting TFT characteristics
Solution Approach 2:
The problem is solved by transitioning from a two-dimensional planar arrangement to a three-dimensional stacked structure. The light-shielding film is positioned in a different spatial dimension (below the semiconductor layer, separated by insulating films), allowing both layers to coexist without interfering with each other's structural integrity while maintaining the light-shielding function
Data Source
AI summary
A display device includes: a resin substrate; and a TFT layer provided on the resin substrate, and including a plurality of TFTs arranged for each of subpixels forming a display region. Each of the TFTs has a semiconductor layer formed of a polysilicon film. The plurality of TFTs are electrically connected to one another through a conductor region of the semiconductor layer. The TFT layer includes a light-shielding film provided to the semiconductor layer toward the resin substrate. The light-shielding film has a peripheral end disposed outside a peripheral end of the semiconductor layer.