Organic Light Emitting Element Host Material Design
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Solution Overview
Problem
Organic light emitting elements face challenges with efficiency and lifespan due to imbalanced hole and electron mobility in the light emitting layer, leading to reduced light emission and stability issues.
Innovation Solution
An organic light emitting element is designed with a compound represented by chemical formula 1, which forms the organic material layer, enhancing the efficiency and lifespan by optimizing the host material's triplet level and stability, and includes a light emitting layer with a host compound and dopant configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phosphorescent organic light emitting element uses conventional host material, then triplet level is insufficient, but using host material with high triplet level improves efficiency, however material stability deteriorates
Solution Approach 1:
The patent employs a composite host material system comprising a first host compound and a second host compound in specific weight ratios (5:95 to 95:5). The first host compound provides high triplet level (2.5 eV or higher) for efficient phosphorescent emission, while the second host compound contributes superior thermal and chemical stability. This composite approach allows the material to simultaneously achieve high light emitting efficiency through the first host's triplet level and enhanced stability through the second host's protective matrix, resolving the contradiction between efficiency and stability.
Solution Approach 2:
The patent optimizes the weight ratio parameter of the two host compounds to achieve the desired balance between efficiency and stability. By adjusting the composition ratio within the specified range (5:95 to 95:5), the material properties can be fine-tuned to achieve both high triplet level for efficiency and sufficient thermal/chemical stability for reliability, demonstrating parameter optimization to resolve the contradiction.
2Duration of action of moving object
If light emitting layer has long triplet state lifespan, then excitons are distributed over wide area, but light emission is reduced
Solution Approach 1:
The patent introduces a charge generation layer with specific local properties between the light emitting layers. This charge generation layer has optimized charge transport characteristics that create localized charge accumulation zones, which in turn create localized electric fields that confine excitons to specific regions rather than allowing them to distribute uniformly over the entire light emitting layer. This local confinement mechanism maintains the beneficial long triplet state lifespan while preventing excessive spatial distribution that would reduce light emission intensity.
Solution Approach 2:
The charge generation layer acts as an intermediary component that mediates between the long-lived triplet states and the light emission process. By introducing this intermediate layer with specific charge transport properties, the system can maintain extended triplet state lifespans for efficient exciton generation while the intermediary layer's electric field effects confine the exciton distribution spatially, thereby preserving high light emission intensity despite the long triplet lifespan.
3Productivity
If efficiency is increased, then driving voltage is decreased, but Joule heating increases causing crystallization and reduced lifespan
Solution Approach 1:
The composite host material system addresses the Joule heating issue by combining two materials with complementary properties. The first host compound with high triplet level enables high efficiency operation at lower driving voltages, reducing overall power consumption and Joule heating. The second host compound provides superior thermal stability and higher glass transition temperature, which prevents crystallization even when localized heating occurs. This composite structure allows the element to operate efficiently while resisting thermal degradation.
Solution Approach 2:
The patent employs materials with inherently high thermal stability as a form of beforehand cushioning against Joule heating effects. By selecting host compounds with high glass transition temperatures and excellent thermal stability from the outset, the system is pre-equipped to withstand the thermal stress generated during high-efficiency operation, preventing crystallization and extending lifespan before thermal degradation can occur.
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 achieves improved efficiency and extended lifespan of the organic light emitting element by effectively distributing excitons and reducing Joule heating, thereby enhancing light emission properties.
Implementation Method 1
organic light emission refers to a phenomenon in which electric energy is converted into light energy by an organic material
Implementation Method 2
the crystallization of the organic material by the Joule heating during driving is reduced
Data Source
AI summary
Embodiments of the disclosure relate to an organic light emitting element. Specifically, there may be provided an organic light emitting element having high efficiency or long lifespan by including a first electrode, a second electrode, and an organic material layer positioned therebetween wherein the organic material layer includes a specific compound.