OLED Emitter Layer Energy Transfer for Efficiency
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Solution Overview
Problem
Current organic light emitting diodes (OLEDs) face limitations in luminous efficiency, color purity, driving voltage, and luminous lifespan, with existing materials exhibiting poor performance in commercial display devices due to issues with energy level bandgaps and exciton interactions.
Innovation Solution
The use of an OLED structure comprising a first compound as a host and second and third compounds with specific energy level relationships, including a delayed fluorescent material and a fluorescent material, to optimize energy transfer and reduce exciton quenching, thereby enhancing luminous efficiency, color purity, and extending lifespan while lowering driving voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional emitting materials are used in OLED, then device structure can be kept simple, but luminous efficiency and color purity are poor
Solution Approach 1:
The patent uses a composite emitting material system consisting of a host compound and a guest compound with specific energy level relationships. The host compound (first compound) has higher HOMO and LUMO energy levels than the guest compound (second compound), enabling efficient energy transfer from host to guest. This composite material approach achieves high luminous efficiency and color purity while maintaining reasonable device structure complexity.
2Power
If existing emitting materials are used, then driving voltage can be maintained at current levels, but power consumption remains high and luminous lifespan is short
Solution Approach 1:
The patent optimizes the energy level parameters of the emitting materials, specifically designing the host compound with HOMO energy level higher than the guest compound by at least 0.1 eV and LUMO energy level higher than the guest compound by at least 0.8 eV. This parameter optimization enables more efficient exciton management, reducing non-radiative recombination and improving device efficiency, which leads to lower power consumption and extended luminous lifespan.
3Ease of manufacture
If simple emitting material layers are used, then manufacturing process is easy, but exciton quenching occurs and reduces luminous efficiency
Solution Approach 1:
The patent introduces a localized energy level gradient within the emitting material layer by selecting host and guest compounds with specific energy level differences. The host compound's higher energy levels create a favorable energy landscape that confines excitons locally and prevents quenching at interfaces or defect sites. This local quality optimization achieves high luminous efficiency without complicating the overall manufacturing process.
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 improves luminous efficiency, maintains high color purity, extends the OLED's lifespan, and reduces power consumption by efficiently managing energy levels and exciton interactions within the emitting material layer.
Implementation Method 1
the emitting material layer includes a first compound, a second compound and a third compound... an excited state singlet energy level (S1H) of the first compound is higher than an excited state singlet energy level (S1TD) of the second compound, and wherein an excited state singlet energy level (S1TD) of the second compound is higher than an excited state singlet energy level (S1FD) of the third compound
Implementation Method 2
In the OLED, when electrical charges are injected into an emitting material layer between an electron injection electrode (i.e., cathode) and a hole injection electrode (i.e., anode), electrical charges are combined to be paired, and then emit light as the combined electrical charges are canceled
Data Source
AI summary
Disclosed is an organic light emitting diode (OLED) comprising at least one emitting unit that includes a first compound, which may have a bipolar property, a second compound, which may have a delayed fluorescent property, and a third compound, which may have narrow FWHM (full width at half maximum) and a fluorescent property, and an organic light emitting device including the OLED. Further the compounds have defined relative LUMO and HOMO energies. The OLED and the organic light emitting device has enhanced luminous efficiency, color purity and luminous life span as well as low driving voltage.