Capacitor Work Function Modifiers Reduce Charging Time
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Solution Overview
Problem
Solid electrolytic capacitors exhibit anomalous charging behavior due to high work function of conductive polymer layers, leading to prolonged charging times, which is not effectively addressed by previous methods focusing on PSS mobility or delamination.
Innovation Solution
Incorporating work function modifiers between conductive polymer layers and adjacent layers to reduce the work function, specifically through materials that interact with surface PSS, forming bonds or mixed layers to decrease surface charge density and electron blocking effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive polymer layers with high work function are used, then good conductivity and film forming properties are achieved, but charging time is prolonged
Solution Approach 1:
The patent introduces work function modifier layers as intermediary layers between the dielectric and conductive polymer layers. These modifier layers have lower work functions than the conductive polymers and facilitate electron transport, thereby reducing charging time while maintaining the conductivity benefits of the high work function conductive polymers.
Solution Approach 2:
The patent changes the work function parameter of the interface by applying modifier layers with specifically selected lower work function materials. This parameter change at the interface level enables faster electron emission and reduces the anomalous charging behavior without compromising the overall conductivity of the capacitor structure.
2Reliability
If PEDT:PSSA based polymer dispersions are used, then excellent performance in high voltage applications is achieved, but anomalous transient current and prolonged charging time occur
Solution Approach 1:
The work function modifier layers act as intermediary layers that mediate between the dielectric and the PEDT:PSSA conductive polymer layers. These modifiers reduce the work function at the interface, which suppresses the generation of anomalous transient currents while preserving the excellent high voltage performance characteristics of the PEDT:PSSA material.
Solution Approach 2:
The patent converts the harmful high work function property of the conductive polymer interface into a benefit by applying modifier layers. The modifiers create a favorable electron emission environment that eliminates the anomalous transient current problem while maintaining the structural and electrical benefits of the PEDT:PSSA system.
3Ease of manufacture
If surface PSS concentration is high, then good film forming properties are achieved, but work function increases leading to slower charging
Solution Approach 1:
The patent applies local quality modification by introducing work function modifier layers specifically at the critical interface regions between the dielectric and conductive polymer layers. This localized modification addresses the high work function problem at the interface without changing the bulk composition and film forming properties of the PEDT:PSSA material.
Solution Approach 2:
The work function modifier layers serve as intermediary layers that decouple the relationship between surface PSS concentration and work function. The modifiers provide a low work function interface even when the underlying conductive polymer layer has high PSS concentration, thus maintaining both film forming properties and fast charging characteristics.
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 use of work function modifiers significantly reduces charging time, achieving times no more than 1.5 times the theoretical limit, with some embodiments reaching or approaching theoretical charging times, thereby improving capacitor performance.
Implementation Method 1
Incorporating work function modifiers between conductive polymer layers and adjacent layers to reduce the work function, specifically through materials that interact with surface PSS, forming bonds or mixed layers to decrease surface charge density and electron blocking effects
Data Source
AI summary
A capacitor, and method for making the capacitor, is provided with improved charging characteristics. The capacitor has an anode, a cathode comprising a conductive polymer layer and a work function modifier layer adjacent the conductive polymer layer and a dielectric layer between the anode and the cathode.