P-type Semiconductor Polymers for Stable Ambient TFTs
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Solution Overview
Problem
Conventional semiconductor materials for thin film transistors (TFTs) face issues such as oxidative doping by ambient oxygen, leading to low current on/off ratios and rapid degradation, especially when used in flexible and large-area devices, which increases manufacturing costs and limits their durability and performance.
Innovation Solution
The development of p-type semiconductor polymers with specific monomeric units containing tertiary amines and thieno groups, which are solution-processable and exhibit enhanced stability and conjugation, allowing for the fabrication of TFTs with improved mechanical durability and structural flexibility, enabling stable operation in ambient conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional semiconductor materials are used in TFTs, then device fabrication is simplified, but the materials undergo rapid photo oxidative degradation under ambient conditions resulting in low field effect mobilities and large off-currents
Solution Approach 1:
The patent employs composite semiconductor materials combining polythiophene backbones with triarylamine units and thieno groups. This composite structure integrates the oxidative stability of triarylamines with the high mobility characteristics of conjugated thiophene systems, resolving the contradiction between stability and mobility
Solution Approach 2:
The patent modifies molecular parameters including introducing alkyl side chains to enhance solubility and processability, and optimizing the conjugation length through thieno groups to achieve high field effect mobility while maintaining ambient stability
2Ease of manufacture
If regioregular polyhexylthiophenes are used, then solution processability is improved, but they undergo rapid photo oxidative degradation under ambient conditions
Solution Approach 1:
The patent creates composite structures by incorporating triarylamine units into the polythiophene chain, maintaining the solution processability of polythiophenes while adding oxidative stability through the triarylamine moieties
Solution Approach 2:
The patent applies local chemical modification by placing triarylamine units at specific positions along the polythiophene backbone, providing oxidative protection at critical locations while preserving the overall solution processability and conjugation of the polymer
3Productivity
If acenes are used for high field effect mobility, then mobility is improved, but they are rapidly oxidized by atmospheric oxygen under light and are not processable at ambient conditions
Solution Approach 1:
The patent modifies the molecular structure by extending conjugation through thieno groups and incorporating electron-donating triarylamine units, which raises the HOMO level and reduces susceptibility to oxidation, enabling ambient processability while maintaining high mobility
Solution Approach 2:
The triarylamine units act as intermediary electron-donating groups that protect the conjugated backbone from oxidation by atmospheric oxygen, mediating between the high mobility requirement and ambient stability constraint
4Reliability
If materials stable under ambient conditions are used, then oxidative doping is reduced, but manufacturing costs increase due to rigorous precautions required during processing
Solution Approach 1:
The semiconductor material is designed to be self-protecting against oxidation through its intrinsic molecular structure (triarylamine units and extended conjugation), eliminating the need for complex protective measures during manufacturing and enabling simple ambient processing
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
These p-type semiconductor polymers provide TFTs with high current on/off ratios and stable performance over time, even in ambient conditions, reducing the need for rigorous oxygen exclusion and lowering manufacturing costs, while maintaining mechanical durability and structural flexibility.
Implementation Method 1
A number of semiconductor materials are not, it is believed, stable when exposed to air as they become oxidatively doped by ambient oxygen resulting in increased conductivity
Implementation Method 2
two thieno end or termination groups of the monomeric unit of the polymer structure for extended conjugation for integrated circuit logic elements
Data Source
Figure 1~2
Figure 3~4
AI summary
An electronic device containing a polymer of Formula (I), Formula (II), or mixtures, or isomers thereof wherein each R1 through R10 is independently hydrogen, alkyl, aryl, alkoxy, halogen, arylalkyl, cyano, or nitro providing that R1 and R2 exclude halogen, nitro and cyano; a and b represent the number of rings; and n represents the number of repeating groups or moieties.