Transparent Oxynitride Pixel Electrodes for Organic TFT Substrates
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Solution Overview
Problem
Existing display substrates for liquid crystal displays (LCDs) face surface damage issues during the formation of pixel electrodes, leading to defects in the organic semiconductor layer and reduced transmittance due to the use of conventional transparent conductors like amorphous indium tin oxide (a-ITO) or amorphous indium zinc oxide (a-IZO), which damage the gate insulating layer.
Innovation Solution
The use of transparent oxynitride as the conductive material for pixel electrodes and the formation of organic thin film transistors, which reduces surface defects on the gate insulating layer and improves light transmittance by minimizing protrusions and enhancing the structural integrity of the organic semiconductor layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transparent conductors (a-ITO or a-IZO) are used to form pixel electrodes, then electrical conductivity is achieved, but surface damage occurs on the gate insulating layer causing defects in the organic semiconductor layer and reduced transmittance
Solution Approach 1:
The patent changes the material composition parameters of the transparent conductor from conventional a-ITO or a-IZO to an oxynitride system with specific atomic ratios (In:Sn:Nitrogen = 4:1:0.1 to 1:4:0.1 to 1:4:4). This compositional parameter change fundamentally alters the deposition characteristics and surface interaction properties, eliminating surface damage while maintaining electrical conductivity and enhancing organic semiconductor layer integrity.
Solution Approach 2:
The patent employs a composite transparent conductor material comprising multiple elements (Indium, Tin, Nitrogen, and optionally Zinc or Gallium) in specific ratios. This composite oxynitride material combines the beneficial properties of different elements to achieve low surface damage, high conductivity, and improved organic layer formation, resolving the contradiction between reliability and manufacturing precision.
2Illumination intensity
If conventional transparent conductors are used, then the pixel electrode structure is formed, but light transmittance is reduced due to surface defects and protrusions
Solution Approach 1:
By changing the material parameters to oxynitride with controlled atomic ratios, the deposition process produces a smoother surface with fewer protrusions. This parameter change directly improves light transmittance by reducing scattering centers while maintaining the electrical function of the pixel electrode.
3Temperature
If organic thin film transistors are formed on the gate insulating layer, then low temperature processing is enabled, but surface damage during pixel electrode formation compromises the organic semiconductor layer
Solution Approach 1:
The patent changes the transparent conductor material parameters to oxynitride, which enables low-temperature processing while simultaneously improving the quality of the organic semiconductor layer. The specific compositional parameters (In:Sn:Nitrogen ratios) ensure that the deposition process does not damage the organic layer, thus maintaining reliability at low temperatures.
Solution Approach 2:
The oxynitride transparent conductor acts as an intermediary material between the pixel electrode function and the organic semiconductor layer. Its unique compositional properties mediate the interaction, providing electrical conductivity while protecting the organic layer from surface damage during formation, thus enabling reliable low-temperature processing.
Data Source
AI summary
An improved display substrate is provided to reduce surface defects on insulating layers of organic thin film transistors. Related methods of manufacture are also provided. In one example, a display substrate includes a base, a plurality of data lines, a plurality of gate lines, a pixel defined by the data lines and the gate lines, an organic thin film transistor, and a pixel electrode. The data lines are on the base and are oriented in a first direction. The gate lines are oriented in a second direction that crosses the first direction. The organic thin film transistor includes a source electrode electrically connected to one of the data lines, a gate electrode electrically connected to one of the gate lines, and an organic semiconductor layer. The pixel electrode is disposed in the pixel and electrically connected to the organic thin film transistor. The pixel electrode comprises a transparent oxynitride.