OLED Emissive Layer Sensitizer-Acceptor-Host Segmentation
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Solution Overview
Problem
Current organic light emitting diode (OLED) technologies face challenges in achieving saturated colors and efficient energy transfer for phosphorescent emission, particularly in devices with complex layer structures and materials that require precise tuning of emission wavelengths.
Innovation Solution
The use of a specific organic light emitting device configuration comprising an anode, a cathode, and an emissive region with a first compound capable of phosphorescent emission as a sensitizer, a second compound as an acceptor emitter, and a third compound as a host, where at least one of the compounds is doped, and the host may contain a boron atom or a metal complex with a specific ligand structure, facilitating energy transfer and improved emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional OLED materials and configurations are used, then device structure is simpler, but emission color saturation and energy transfer efficiency are insufficient
Solution Approach 1:
The emissive region is segmented into multiple functional components: a sensitizer compound (first compound) for phosphorescent emission, an acceptor emitter (second compound), and a host compound (third compound). This segmentation allows each component to perform its specific function optimally, achieving saturated emission colors through the coordinated action of these segmented elements rather than relying on a single complex material.
Solution Approach 2:
The patent employs composite material systems where the sensitizer and acceptor are doped into the host compound to form a composite emissive layer. This composite structure combines the phosphorescent properties of the sensitizer with the emission characteristics of the acceptor, enabled by the host matrix, achieving high color saturation and efficient energy transfer that cannot be obtained with single materials.
2Use of energy by moving object
If phosphorescent emission is implemented, then emission efficiency is improved, but triplet formation on fluorescent acceptors increases
Solution Approach 1:
The host compound acts as an intermediary between the phosphorescent sensitizer and the fluorescent acceptor emitter. The sensitizer transfers energy to the host, which then mediates the energy transfer to the acceptor, preventing direct triplet formation on the fluorescent acceptor. This intermediary mechanism allows efficient energy transfer while avoiding the harmful triplet state accumulation.
Solution Approach 2:
The patent converts the potential harmful effect of triplet formation into a beneficial energy transfer pathway. By designing the energy levels such that the sensitizer transfers energy through the host to the acceptor, the system utilizes what would otherwise be lossful triplet states on the fluorescent acceptor and transforms them into productive energy transfer that enhances overall emission efficiency without damaging triplet accumulation.
3Productivity
If multiple compounds are doped in the emissive region, then energy transfer efficiency is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the doping parameters by selecting specific concentration ranges for the sensitizer and acceptor in the host matrix. By establishing optimal parameter windows for doping concentrations, the system achieves high energy transfer efficiency while maintaining compatibility with conventional manufacturing processes. The parameter optimization ensures that even with normal manufacturing variations, the device maintains high performance.
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 enhances the efficiency of energy transfer and emission, allowing for the production of saturated colors and improved luminance, particularly in OLEDs with a boron-containing host, which aids in boosting recombination efficiency and reducing triplet formation on fluorescent acceptors.
Implementation Method 1
the first compound S1 is capable of phosphorescent emission at room temperature and is a sensitizer that transfers energy to the second compound A1
Implementation Method 2
the first compound S1 is a sensitizer that transfers energy to the second compound A1; wherein the second compound A1 is an acceptor that is an emitter
Data Source
AI summary
Provided is an OLED that includes an anode; a cathode; and an emissive region disposed between the anode and the cathode. The emissive region includes a first compound S1; a second compound A1; and a third compound H1. The first compound S1 is capable of phosphorescent emission at room temperature and is a sensitizer that transfers energy to the second compound A1; the second compound A1 is an acceptor that is an emitter; and the third compound H1 is a first host, and at least one of the first compound S1 and the second compound A1 is doped in the third compound H1. Consumer products including the OLED are also provided, as are formulations containing the first, second, and third compounds.