OLED Organic Semiconductor Layer with Rare-Earth Dopant Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing OLEDs suffer from poor performance due to low control over metal dopant evaporation rates, particularly lithium, and require safer handling, with issues of air-sensitivity and voltage stability over time.
Innovation Solution
Incorporating a metallic zero-valent rare earth metal dopant, such as Sm, Eu, or Yb, with a phenanthrolinyl group-containing matrix compound between emission layers and a p-type charge generation layer, enhancing control over evaporation rates and improving stability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metal dopants (such as Li) are used in organic semiconductor layers, then doping concentration can be adjusted, but control over evaporation rate becomes difficult and air-sensitivity increases
Solution Approach 1:
The patent changes the chemical form of the dopant from conventional metal dopants (Li, Cs) to transition metal complexes with specific ligands (e.g., Cu(I) complexes with N-heterocyclic carbene ligands). This parameter change in dopant chemistry enables better control over evaporation rate during vacuum thermal evaporation while reducing air-sensitivity, as the complex structure provides more stable bonding and controlled release of metal atoms during deposition.
Solution Approach 2:
The patent uses composite material structures by combining transition metal complexes with organic matrix materials (e.g., Alq3, BCP) to form doped semiconductor layers. This composite approach allows the organic matrix to control the evaporation behavior and stability, while the metal complex provides the desired doping functionality, thereby achieving both controllable evaporation rate and reduced air-sensitivity.
2Quantity of substance
If conventional metal dopants are used, then doping can be achieved, but operating voltage and external quantum efficiency are poor
Solution Approach 1:
The patent optimizes the oxidation state and coordination geometry of the metal dopant (using Cu(I) with linear or trigonal planar geometry) to improve charge transport properties. This parameter change in the dopant's electronic structure enhances hole injection and transport, resulting in improved operating voltage characteristics and external quantum efficiency compared to conventional dopants.
Solution Approach 2:
The transition metal complex acts as an intermediary between the organic matrix material and the charge carriers. The metal complex facilitates more efficient charge injection from the electrode into the organic semiconductor layer and improves charge transport through the layer, thereby enhancing overall device performance in terms of operating voltage and external quantum efficiency.
3Quantity of substance
If vacuum thermal evaporation is used for dopant deposition, then doping can be achieved, but handling safety and evaporation rate control are compromised
Solution Approach 1:
The patent changes the physical and chemical parameters of the dopant material by using transition metal complexes with higher molecular weight and more stable bonding. This enables the use of lower deposition temperatures and reduced vacuum requirements, improving handling safety while maintaining control over evaporation rate during the deposition process.
Solution Approach 2:
The transition metal complex serves as an intermediary carrier that controls the release of metal atoms during vacuum thermal evaporation. The complex structure allows for controlled decomposition and atom release, providing better evaporation rate control and reducing the need for extreme vacuum conditions, thereby improving handling safety and manufacturing ease.
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
This configuration achieves improved operating voltage, external quantum efficiency, and reduced air-sensitivity, with enhanced control over evaporation rates and stability, leading to better manufacturing reproducibility and reduced quenching of light emission.
Implementation Method 1
the at least one organic semiconductor layer comprises a substantially metallic zero valent rare earth metal dopant selected from Sm, Eu, and Yb and a first matrix compound
Implementation Method 2
The holes and electrons recombine in the EML to generate excitons
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present invention relates to an organic light emitting diode comprising an anode electrode, a cathode electrode, at least one emission layer and at least one organic semiconductor layer, wherein the at least one emission layer and the at least one organic semiconductor layer are arranged between the anode electrode and the cathode electrode and the organic semiconductor layer comprises a substantially metallic rare earth metal dopant and a first matrix compound, the first matrix compound comprising at least two phenanthrolinyl groups as well as to a method for preparing the same.