Spiro Compound Hole Transport Material for OLED Stability

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Solution Overview

Problem

Current organic electroluminescent devices face challenges in achieving high luminous efficiency, long service life, and balanced hole and electron transport, particularly for blue light-emitting devices, due to limitations in the thermal, photochemical, and electrochemical stability of existing materials.

Innovation Solution

A spiro compound with a specific structure is introduced, offering high optical and electrical stability, low sublimation temperature, and low lateral mobility of carriers, which can be used as a hole injection or transport material in organic electroluminescent devices, enhancing their performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional hole transport materials are used, then device structure is simple, but service life and luminous efficiency are insufficient

Engineering Contradiction:

Improveservice lifeVSAvoidmaterial structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs composite spirofluorene aromatic amine materials that combine the spirofluorene core structure with aromatic amine functional groups. This composite structure integrates the thermal stability and morphological control of spirofluorene with the hole transport capability of aromatic amines, achieving both extended service life and improved luminous efficiency without excessive structural complexity

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent systematically varies key structural parameters including substituent types (alkyl, aryl, heteroaryl groups), substituent positions, and molecular weight through controlled polymerization degrees. These parameter changes optimize the balance between service life (through enhanced thermal stability) and luminous efficiency (through adjusted HOMO levels and charge transport properties)

Inventive Principle:

Principle #35Parameter changes

2Reliability

If materials with high thermal stability are selected, then service life improves, but lateral hole mobility decreases

Engineering Contradiction:

Improveservice lifeVSAvoidlateral hole mobility

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The patent introduces localized flexible alkyl chain substituents (such as tert-butyl, isopropyl groups) at specific positions on the rigid spirofluorene aromatic amine backbone. These local flexible segments enhance lateral hole mobility by improving molecular packing and intermolecular interactions, while the overall rigid spirofluorene core maintains high thermal stability for extended service life

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The composite structure combines rigid spirofluorene core (providing thermal stability) with flexible aromatic amine side chains (providing charge transport pathways). This duality resolves the contradiction between thermal stability and charge mobility by assigning different functional roles to different parts of the molecular structure

Inventive Principle:

Principle #40Composite materials

3Illumination intensity

If blue light-emitting materials are used, then color saturation is achieved, but service life deteriorates

Engineering Contradiction:

Improvecolor saturationVSAvoidservice life

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The patent uses composite spirofluorene aromatic amine materials where the spirofluorene core provides rigid structural framework for high color saturation in blue emission, while the aromatic amine functional groups and stable molecular structure confer high thermal and photochemical stability, thereby extending service life despite the inherent instability of blue light-emitting materials

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent addresses the short lifetime of blue light-emitting materials by incorporating them into a stable host matrix system where the spirofluorene aromatic amine provides protective structural environment, effectively extending the operational lifetime of the blue emitter through matrix stabilization

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Loss of energy

If drive current is reduced, then device efficiency improves, but carrier transport balance deteriorates

Engineering Contradiction:

Improvedrive currentVSAvoidcarrier transport balance

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent optimizes the HOMO energy level parameter of the spirofluorene aromatic amine material to achieve better energy level alignment with adjacent layers, facilitating balanced hole injection and transport. This parameter optimization enables reduced drive current while maintaining charge transport balance through improved energetic matching rather than relying on high current

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20230329090A1Spiro compound and application thereof

Publication Date: 2023.10.12 SICHUAN AG RAY NEW MATERIALS CO LTD

AI summary

The present disclosure relates to a spiro compound and application thereof. The spiro compound has a structure as shown in a formula (1). The material provided in the present disclosure has advantages such as high optical and electrical stability, low sublimation temperature, low drive current, low lateral mobility of carriers, high luminous efficiency, and long service life of a device, and can be used in an organic electroluminescent device. In particular, the compound has the possibility of being applied in the AMOLED industry as a hole injection or transport material.