Organic Light Emitting Device Hole Accumulation
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Solution Overview
Problem
Organic light emitting devices face durability issues due to luminescence degradation over time, with existing combinations of hole-transporting and electron-transporting materials being ineffective in addressing stability and emitter deterioration.
Innovation Solution
An organic light emitting device structure featuring a pair of electrodes with a plurality of organic layers, including an emission layer composed of a host material, a light emitting material, and another material with a smaller ionization potential and similar or greater hole mobility, which helps prevent hole accumulation and enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional stacked structure with mixed layer is used, then charge leakage is blocked and efficiency increases, but hole accumulation in the emitting material still occurs leading to degradation
Solution Approach 1:
The invention changes key parameters of the hole-transporting material: selecting materials with ionization potential within 0.1-2.0 eV of the emitter and hole mobility at least 0.1 cm²/Vs. These parameter changes create an energy landscape that promotes uniform hole distribution and prevents accumulation at the emitter
Solution Approach 2:
The hole-transporting material acts as an intermediary between the anode and the emitter, mediating hole transport to prevent direct hole accumulation at the emitter. This intermediary layer with optimized properties facilitates smooth hole transfer while protecting the emitter from degradation
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 proposed structure significantly improves the stability and longevity of organic light emitting devices by moderating hole accumulation, leading to enhanced durability and luminance efficiency.
Implementation Method 1
generates an exciton from the fluorescent organic compound by injection of an electron and a hole from each electrode, and utilizes light to be radiated when the exciton returns to the ground state
Data Source
AI summary
It is an object of the present invention to provide an organic light emitting device having a long-life optical output. The organic light emitting device according to the present invention is provided with an emission layer including at least a host material, a light emitting material, and another material, wherein the another material has a smaller ionization potential than and almost the same hole mobility as or a greater hole mobility than an ionization potential and a hole mobility of a compound which forms an emission layer-side-interface.