OLED Emission Layers with Condensed Cyclic Compounds for Low-Stokes Shift
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Solution Overview
Problem
Existing organic light-emitting devices face challenges in achieving high light efficiency and stability, particularly in maintaining structural integrity and reducing Stokes shift to enhance light extraction efficiency.
Innovation Solution
Incorporation of a condensed cyclic compound represented by Formula 1 in the emission layer and interlayer of the light-emitting device, which includes a hole transport region and a second capping layer with a refractive index greater than 1.6, along with a thin-film transistor for improved electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional organic light-emitting materials are used in the emission layer, then device structure can be maintained, but light efficiency is insufficient and stability is poor
Solution Approach 1:
The patent changes the chemical structure parameters of the emission layer materials by introducing condensed cyclic compounds with specific molecular formulas (Formula 1) containing fused aromatic rings and heterocyclic groups. This structural parameter change enables simultaneous improvement of light efficiency and device stability, resolving the contradiction between energy loss and reliability.
Solution Approach 2:
The patent employs composite material design by combining condensed cyclic compounds (Formula 1) with hole transport materials (Formula 201 or 202) in the emission layer. This composite approach creates synergistic effects where the condensed cyclic compound provides high light efficiency and stability while the hole transport material ensures proper charge carrier management, together resolving the contradiction.
2Productivity
If conventional emission layer materials are used, then device structure is maintained, but Stokes shift is large resulting in poor light extraction efficiency
Solution Approach 1:
The patent changes the optical parameters of the emission layer by using condensed cyclic compounds with specific molecular structures (Formula 1) that have reduced Stokes shifts. The fused ring structures and heterocyclic groups in these compounds enable better overlap between absorption and emission spectra, reducing energy loss and improving light extraction efficiency.
3Loss of energy
If high light efficiency materials are used, then light extraction is improved, but structural integrity and device lifespan are compromised
Solution Approach 1:
The patent uses composite material design combining condensed cyclic compounds (Formula 1) with hole transport materials (Formula 201 or 202) to achieve both high light efficiency and structural integrity. The condensed cyclic compound provides the optical properties needed for efficiency while the composite structure maintains stability and device lifespan.
Solution Approach 2:
The patent changes the chemical composition parameters by introducing condensed cyclic compounds with specific molecular formulas that inherently possess both high light efficiency and structural stability. The fused aromatic ring systems and heterocyclic groups provide both optical performance and structural integrity, eliminating the trade-off between efficiency and stability.
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 enhances light efficiency, maintains structural stability, and extends the lifespan of the device by reducing the Stokes shift and increasing the f-value, resulting in a low driving voltage and improved light extraction.
Implementation Method 1
Carriers, such as holes and electrons, recombine in the emission layer to produce excitons. These excitons transition from an excited state to a ground state to thereby generate light.
Implementation Method 2
a second capping layer outside the second electrode and having a refractive index of equal to or greater than 1.6
Data Source
AI summary
A light-emitting device including a condensed cyclic compound and an electronic apparatus including the light-emitting device are provided. The light-emitting device includes a first electrode, a second electrode facing the first electrode, and an interlayer between the first electrode and the second electrode, wherein the interlayer further includes a hole transport region between the first electrode and the emission layer, the hole transport region includes a compound represented by Formula 201, a compound represented by Formula 202, or any combination thereof, and the emission layer includes at least one condensed cyclic compound represented by Formula 1:The substituents are as defined in the detailed description.