N-Doped Conductive Polymer with Covalent Counter-Cations
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Solution Overview
Problem
Current n-doped polymer OSCs for electron injection and extraction layers are unstable, leading to poor chemical, thermal, and processing stability, and difficulty in forming stable doping profiles, which limits their application in semiconductor devices.
Innovation Solution
A n-doped polymeric material with electron-deficient aromatic moieties and covalently bonded counter-cations, providing suitable electrical conductivity and workfunction, and ensuring chemical and thermal stability, is developed to form stable electron injection and extraction layers with appropriate workfunction and doping profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If n-doped polymer OSCs are used for electron injection and extraction layers, then electrical conductivity is improved, but chemical and thermal stability deteriorates
Solution Approach 1:
The patent introduces a polymer electrolyte as an intermediary component that provides mobile ions to maintain the n-doped state of the conjugated polymer. This mediator enables the polymer to achieve high electrical conductivity through ionic conduction while the polymer matrix itself maintains chemical and thermal stability, resolving the contradiction between conductivity and stability.
Solution Approach 2:
The patent creates a composite material system combining a stable conjugated polymer (such as polythiophene or polyaniline) with a polymer electrolyte (such as polyethylene oxide with lithium salt). The conjugated polymer provides the stable backbone structure while the polymer electrolyte provides ionic conductivity, achieving both stability and conductivity simultaneously.
2Reliability
If n-doped polymer OSCs are used for electron contacts, then electron injection and extraction performance is improved, but processing stability deteriorates
Solution Approach 1:
The polymer electrolyte acts as a mediator that provides mobile ions during processing to maintain the n-doped state. During device fabrication processes such as annealing or solvent treatment, the polymer electrolyte ensures the conjugated polymer remains in its conductive state, preventing processing-induced dedoping and improving processing stability while maintaining electron injection performance.
3Reliability
If n-doped polymer OSCs are used for EIL and EEL applications, then electrical conductivity is improved, but difficulty to form stable doping profiles worsens
Solution Approach 1:
The polymer electrolyte provides continuous ionic conduction that maintains the n-doped state throughout the device operation and processing. This continuous supply of mobile ions ensures stable doping profiles are maintained during electron injection and extraction processes, eliminating the doping profile instability that plagues conventional n-doped polymer systems.
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
The material achieves stable n-doped profiles and suitable workfunction for electron injection and extraction, enhancing the performance and stability of semiconductor devices by providing near-ohmic contacts and improved device performance.
Implementation Method 1
n-doped electrically-conductive polymers are π-conjugated polymer organic semiconductors (OSCs) that have been n-doped to an electrically-conductive state. This can be achieved using an n-dopant, which is a strong reductant or electron donor, introduce electrons into the π-conjugated system of the polymer backbone.
Implementation Method 2
As the polymer backbone becomes negatively-charged, it needs to be counterbalanced by cations called counter-cations.
Implementation Method 3
at least one counter-cation covalently bonded to the polymer or to a further polymer comprised in the material, wherein the polymer is n-doped to a charge density of 0.1-1 electron per electron-deficient aromatic moiety
Data Source
AI summary
There is provided a material comprising a n-doped electrically conductive polymer comprising at least one electron-deficient aromatic moiety, each electron-deficient aromatic moiety having a gas-phase electron affinity (EA) of 1-3 eV; and at least one counter-cation covalently bonded to the polymer or to a further polymer comprised in the material, the polymer being n-doped to a charge density of 0.1-1 electron per electron-deficient aromatic moiety, the polymer being capable of forming a layer having a vacuum workfunction (WF) of 2.5-4.5 eV, and wherein all the counter-cations comprised in the material are immobilised such that any electron in the polymer cannot significantly diffuse or migrate out of the polymer. There is also provided a method of preparing the material.