Organic Transistor Dopant Layer for Low Voltage Operation

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Solution Overview

Problem

Organic transistors face challenges with high operating voltages due to suboptimal charge carrier injection and mobility, particularly at interfaces between metal electrodes and organic materials, which limits their efficiency and scalability in applications like RFID and screen control.

Innovation Solution

An organic electronic component is designed with a channel layer comprising an organic semiconducting material and a dopant material with a specific formula (AB), where the dopant material is used to modify the Fermi level and enhance charge carrier mobility, reducing the threshold voltage and operating voltage through quasi-doping mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal electrodes are used in direct contact with organic semiconductor material, then charge carrier injection is improved, but high off-currents occur due to high conductivity at the interface

Engineering Contradiction:
Improvecharge carrier injectionVSAvoidhigh off-currents
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a dopant material layer as an intermediary between the metal electrode and the organic semiconductor channel layer. This dopant layer has intermediate conductivity properties that enable effective charge carrier injection while preventing the high off-currents that would result from direct metal-to-organic contact. The dopant material acts as a buffer that mediates the electrical interaction between the highly conductive metal electrode and the semiconductor channel.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If high gate voltage is applied to fill localized states and achieve high carrier mobility, then field effect mobility is improved, but operating voltage becomes unacceptably high

Engineering Contradiction:
Improvefield effect mobilityVSAvoidoperating voltage
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The dopant material layer is applied in advance to the organic semiconductor material before the transistor operation begins. This preliminary doping action pre-fills the localized states and creates a higher baseline carrier density in the channel, eliminating the need for high gate voltages to achieve adequate mobility. The dopant layer prepares the semiconductor in an optimized state before device operation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the physical-chemical parameters of the organic semiconductor channel by introducing dopant materials with specific electronic properties. The dopant materials have different HOMO and LUMO energy levels than the pure semiconductor, which modifies the carrier density and mobility characteristics. This parameter change allows the device to operate at lower voltages while maintaining high performance.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If encapsulation layers are added to improve device functionality, then device performance is enhanced, but device complexity and manufacturing steps increase

Engineering Contradiction:
Improvedevice functionalityVSAvoidlayer structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The dopant material layer serves multiple functions simultaneously: it acts as a charge carrier source, modifies the Fermi level of the semiconductor, improves charge carrier injection from the electrode, and stabilizes the interface. By combining these functions into a single layer, the patent avoids the need for multiple separate encapsulation and functional layers, thereby reducing overall device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 proposed solution significantly improves field effect mobility and reduces the operating voltage, enhancing the performance and efficiency of organic transistors by increasing charge carrier density and reducing defects, while maintaining stability and air resistance.

Implementation Method 1

a first dopant material is in direct contact with the organic semiconducting material of the channel layer and acts as an electrical n-dopant for the organic semiconducting material

Methodology Applied
Scientific EffectCharge transfer: Electron Beam

Implementation Method 2

acts as an electrical n-dopant for the organic semiconducting material in the channel layer

Methodology Applied
Scientific EffectElectrical doping: Dopants

Implementation Method 3

Charge carrier transport in thin organic films is generally described by temperature-activated charge carrier hopping, resulting in relatively low mobility and a strong influence of disorder

Methodology Applied
Scientific EffectCharge carrier hopping: Phononic Crystal

Implementation Method 4

The field effect mobility in OTFTs generally depends on the carrier density. Therefore, a relatively high gate voltage is usually necessary to fill the localized states and achieve high carrier mobility in the organic layers

Methodology Applied
Scientific EffectField effect: Electric Field

Data Source

PatentEP2724389B1Organic electronic device
Publication Date: 2018.05.16 NOVALED GMBH
  • EP2724389B1 patent drawingFigure 1~2
  • EP2724389B1 patent drawingFigure 3a~3b
  • EP2724389B1 patent drawingFigure 4~6

AI summary

The invention relates to an organic electronic component, comprising a first electrode (11), a second electrode (12), a channel layer (14) comprising an organic semiconducting material, and a dopant material.