Organic EL Electron Transport Layer Doping for Crack Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In organic electroluminescence (EL) elements, foreign matter can cause cracks in the sealing layer, leading to reduced light emittance efficiency due to reaction with n-type dopants, resulting in defective light-emitting regions with decreased luminance or no light emission, which affects commercial value.
Innovation Solution
An organic EL element with an electron transport layer doped at a higher concentration than the optimal for maximum light emittance efficiency, ensuring increased efficiency and luminance adjacent to defective regions, thereby minimizing their conspicuousness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electron transport layer is doped with n-type dopant at optimal concentration for maximum light emittance efficiency, then light emittance efficiency is maximized, but when cracks occur in the sealing layer, the defective regions become conspicuous and harm commercial value
Solution Approach 1:
The patent changes the doping concentration parameter from the optimal value (which maximizes light emittance efficiency) to a higher value. This parameter change creates a buffer that compensates for dopant loss due to cracks, ensuring that even when water or oxygen enters through sealing layer cracks and reacts with the n-type dopant, sufficient dopant remains to maintain light emittance efficiency and prevent conspicuous defective regions
Solution Approach 2:
The patent applies beforehand cushioning by pre-doping the electron transport layer with a higher concentration of n-type dopant than normally required. This excess dopant serves as a cushion or reserve that compensates for future dopant loss when cracks occur in the sealing layer during use, preventing the formation of conspicuous defective light-emitting regions
2Illumination intensity
If the doping concentration of n-type dopant is increased above optimal level, then light emittance efficiency and luminance increase in regions adjacent to defective areas, but the overall doping concentration is higher than necessary for optimal efficiency
Solution Approach 1:
The patent applies preliminary anti-action by preemptively increasing the doping concentration to counteract the future harmful effect of dopant loss. The excess dopant is introduced in advance to compensate for the anticipated reaction with water or oxygen that will occur when sealing layer cracks develop during use, thereby maintaining luminance and preventing defective regions
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 higher doping concentration in the electron transport layer enhances light emittance efficiency and luminance near defective regions, reducing their apparent size and making them less noticeable, thus maintaining the element's commercial value.
Implementation Method 1
an n-type dopant that includes an electron-donating substance
Implementation Method 2
electroluminescence in the organic light-emitting layer occurring due to recombination of carriers (holes, electrons)
Data Source
AI summary
An organic electroluminescence (EL) element that has an anode; a cathode; an organic light-emitting layer between the anode and the cathode that emits light according to recombination of holes injected from the anode and electrons injected from the cathode; and an electron transport layer between the cathode and the organic light-emitting layer that transports electrons from the cathode to the organic light-emitting layer. The electron transport layer includes an n-type dopant that includes an electron-donating substance, the electron transport layer being doped with the n-type dopant at a doping concentration that is higher than a doping concentration at which light emittance efficiency of the organic light-emitting layer is greatest.