Organic EL Carrier Trapping Layer for Short Wavelength Lifespan
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Solution Overview
Problem
Organic electroluminescent devices with shorter wavelength light emitting layers have shorter lifespans due to carrier imbalance and degradation, complicating the configuration when trying to emit only shorter wavelengths, as longer wavelengths are also emitted, requiring additional filtering steps.
Innovation Solution
Incorporating a carrier trapping layer with a thiazole-based compound between the anode and cathode, which traps carriers and emits near-infrared light, preventing degradation and allowing for a longer lifespan without changing the chromaticity, and using host materials like amine, anthracene, or naphthacene for enhanced transportability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light emitting layer emitting shorter wavelength luminescent color is used, then the luminance life span becomes shorter, but the desired short wavelength emission is achieved
Solution Approach 1:
A carrier trapping layer containing a thiazole-based compound is introduced as an intermediary between the light emitting layer and the electron transporting layer. This intermediate layer selectively traps electrons that have passed through the light emitting layer, preventing them from being re-injected into the light emitting layer, thereby reducing carrier imbalance and extending the luminance life span of short wavelength emitting devices
Solution Approach 2:
The energy levels of the carrier trapping layer are specifically designed to match the electron transport characteristics of adjacent layers. The thiazole-based compound provides appropriate LUMO and HOMO levels that enable selective electron trapping while maintaining hole transport, creating optimal carrier balance parameters for extended device lifespan
2Illumination intensity
If a color filter is added to absorb long wavelength luminescent color, then only short wavelength luminescent color is emitted, but the element configuration becomes complicated and manufacturing processes increase
Solution Approach 1:
Instead of adding a color filter to remove long wavelength emission, the invention extracts and suppresses the root cause of the problem at the carrier transport level. By preventing excessive electron injection into the light emitting layer through the carrier trapping layer, the device naturally emits only the desired short wavelength light without requiring additional filtering components
Solution Approach 2:
The carrier trapping layer acts as an intermediary that controls carrier flow to achieve pure short wavelength emission. This intermediate functional layer replaces the need for optical filtering components, simplifying the overall device configuration while maintaining emission purity
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 solution extends the lifespan of light emitting layers emitting shorter wavelengths like blue or yellow without the need for color filters, simplifying the device configuration and manufacturing process by maintaining chromaticity and preventing material degradation.
Implementation Method 1
a carrier trapping layer containing a thiazole based compound... which traps carriers and emits near-infrared light
Data Source
AI summary
The light emitting element of the embodiment includes an anode; a cathode; a visible light emitting layer provided between the anode and the cathode and emitting visible light; and a carrier trapping layer containing a thiadiazole based compound represented by the following formula (1).[In formula (1), A indicates a hydrogen atom, an alkyl group, an aryl group which may have a substituent, an arylamino group, or a triaryl amine, and B indicates a hydrogen atom, an alkyl group, an aryl group which may have a substituent, an arylamino group, or a triaryl amine, or may form a ring.]