Polycyclic Compound Dopant for Deep Blue OLED Efficiency

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Solution Overview

Problem

Current organic electroluminescence devices face challenges in achieving high efficiency and deep blue emission with minimal roll-off phenomenon due to limitations in triplet excitation state transitions and thermal energy requirements.

Innovation Solution

A polycyclic compound represented by specific formulas is used as a dopant in the emission layer, featuring a high triplet excitation state that undergoes reverse intersystem crossing to a singlet state, allowing for efficient deep blue emission with reduced thermal energy requirements and minimized roll-off.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional organic electroluminescence devices use traditional emission materials, then device structure is simple, but emission efficiency is low and roll-off phenomenon occurs

Engineering Contradiction:

Improveemission efficiencyVSAvoiddevice structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent changes the energy level parameters of the emission material by introducing a polycyclic compound with specific triplet and singlet energy levels. The compound has a triplet energy level (T1) of 2.7-3.2 eV and singlet energy level (S1) of 2.5-3.0 eV, creating an inverted energy level structure that enables efficient emission while reducing roll-off phenomenon.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite emission layer comprising a host material and the polycyclic dopant material. The host material provides the base structure while the polycyclic compound (0.1-10 wt%) introduces specific energy level characteristics, combining advantages of both materials to achieve high efficiency and reduced roll-off.

Inventive Principle:

Principle #40Composite materials

2Productivity

If high triplet excitation state transitions are utilized, then external quantum efficiency increases, but thermal energy requirements increase

Engineering Contradiction:

Improveexternal quantum efficiencyVSAvoidthermal energy requirements

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent optimizes the energy gap between triplet and singlet states to minimize thermal energy requirements. The polycyclic compound is designed with T1-S1 energy difference optimized for efficient reverse intersystem crossing at reduced thermal energy, achieving high external quantum efficiency without excessive thermal energy input.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces thermal energy-driven transitions with a quantum mechanical reverse intersystem crossing mechanism. The polycyclic compound's specific molecular structure enables spin-orbit coupling that facilitates triplet-to-singlet transition without relying solely on thermal energy, reducing the thermal energy barrier.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If deep blue emission is achieved, then emission efficiency improves, but roll-off phenomenon increases

Engineering Contradiction:

Improveemission efficiencyVSAvoidroll-off resistance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the energy level parameters to achieve deep blue emission wavelength (450-480 nm) while maintaining high efficiency. The polycyclic compound's S1 energy level is tuned to correspond to deep blue emission, and the inverted T1-S1 energy relationship reduces non-radiative transitions that cause roll-off, maintaining reliability at high current densities.

Inventive Principle:

Principle #35Parameter changes

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 polycyclic compound enhances emission efficiency and reduces the likelihood of roll-off in organic electroluminescence devices by facilitating transitions from high triplet to singlet states, achieving higher external quantum efficiency and deeper blue emission.

Implementation Method 1

Methodology Applied

Scientific EffectReverse intersystem crossing:

Implementation Method 2

The polycyclic compound enhances emission efficiency and reduces the likelihood of roll-off in organic electroluminescence devices by facilitating transitions from high triplet to singlet states

Methodology Applied

Scientific EffectTriplet to singlet state transition:

Implementation Method 3

holes and electrons injected from a first electrode and a second electrode recombine in an emission layer, and a light-emitting material which is an organic compound included in the emission layer emits light

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 4

The holes and electrons injected into the emission layer recombine to produce excitons in the emission layer. The organic electroluminescence device emits light using light generated by the transition of the excitons to a ground state

Methodology Applied

Scientific EffectExciton transition:

Data Source

PatentUS11655211B2Polycyclic compound and organic electroluminescence device including the same

Publication Date: 2023.05.23 SAMSUNG DISPLAY CO LTD

AI summary

A polycyclic compound is represented by Formula 1:where X1, R1 to R11, L1, L2, and n1 to n4 are further defined. An organic electroluminescence device includes the polycyclic compound.