[3]-Radialene P-Dopant Thermal Stability in OLED Evaporation

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Solution Overview

Problem

The existing radialene p-dopants used in organic light emitting diodes (OLEDs) have insufficient long-term thermal stability, limiting the duration of production campaigns in industrial manufacturing processes, as they often degrade at evaporation temperatures used in vacuum thermal evaporation processes.

Innovation Solution

Development of [3]-radialene compounds with specific aryl or heteroaryl substitutions, allowing for extended thermal stability and adjustable doping strength, which are evaporated at reduced pressures and elevated temperatures, enabling longer processing times and improved robustness in OLED manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional radialene p-dopants are used in vacuum thermal evaporation processes, then the doping function is achieved, but the thermal stability is insufficient causing degradation at evaporation temperatures

Engineering Contradiction:

Improvethermal stabilityVSAvoidevaporation temperature

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent modifies the chemical structure of radialene p-dopants by introducing specific aryl and heteroaryl substituents (fluorinated phenyl, pyridine, triazine groups) to change the thermal and electronic parameters of the molecule, enabling stability at higher evaporation temperatures while maintaining doping functionality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates composite molecular structures combining the radialene core with multiple electron-withdrawing aryl and heteroaryl groups, forming a composite material that achieves both thermal stability and appropriate redox potential for p-doping in OLEDs

Inventive Principle:

Principle #40Composite materials

2Productivity

If evaporation temperature is increased to improve deposition rate, then productivity increases, but dopant degradation occurs reducing reliability

Engineering Contradiction:

Improvedeposition rateVSAvoiddopant stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the thermal parameters of the dopant molecules through structural modification, raising the decomposition temperature above the evaporation temperature range (100-300°C), thereby enabling higher deposition rates without dopant degradation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent designs dopant molecules with inherent thermal stability buffers by incorporating robust aryl and heteroaryl substituents that resist degradation, providing a cushion against thermal stress during the evaporation process

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Loss of time

If evaporation source is loaded once for long-term production, then loss of time is reduced, but thermal stability of dopant is insufficient limiting campaign duration

Engineering Contradiction:

Improveproduction campaign durationVSAvoidlong-term thermal stability

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The patent modifies the thermal parameters of dopant molecules to withstand prolonged exposure to evaporation temperatures (100-300°C) over extended periods, enabling production campaigns to last through complete evaporation source utilization without dopant degradation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent ensures continuous dopant functionality throughout the entire evaporation process by designing molecules that maintain structural integrity and doping activity from initial to final stages of the production campaign

Inventive Principle:

Principle #20Continuity of useful action

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 new radialene compounds provide enhanced thermal stability and adjustable doping strength, enabling longer production campaigns and improved performance in OLED devices, with the ability to adjust volatility and doping strength to match chosen matrix materials, offering a broader range of options for device design.

Implementation Method 1

evaporating the [3]-radialene p-dopant at an elevated temperature and at a reduced pressure

Methodology Applied

Scientific EffectVacuum thermal evaporation: Evaporation

Implementation Method 2

The vaporized compound (I) is, subsequently, either deposited in form of a neat layer, or co-deposited with an appropriate matrix material

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Data Source

PatentUS10128442B2Substituted 1,2,3-triylidenetris(cyanomethanylylidene) cyclopropanes for VTE, electronic devices and semiconducting materials using them

Publication Date: 2018.11.13 NOVALED GMBH

AI summary

Provided are processes for preparing an electrically doped semiconducting material that includes a [3]-radialene p-dopant. Also provided are processes for preparing an electronic device containing a layer that includes a [3]-radialene p-dopant. The processes may include (i) loading an evaporation source with a [3]-radialene p-dopant and (ii) evaporating the [3]-radialene p-dopant at an elevated temperature and at a reduced pressure. The [3]-radialene p-dopant may be selected from compounds having a structure according to formula (I) herein.