Organic Light-Emitting Device Host Material ΔST Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing organic light-emitting devices face challenges with compound durability due to high ΔST values in compounds like 1-A and 1-C, and low sublimability in compound 1-B, leading to reduced device lifetime and performance.
Innovation Solution
An organic compound with a phenanthrene molecule attached to a benzene ring at the 2-position, reducing ΔST and enhancing sublimability, is used as a host material in the light-emitting layer, improving hole and electron injection properties and device stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If compound 1-A or 1-C is used, then the device can emit light, but the device lifetime is reduced due to large ΔST
Solution Approach 1:
The patent modifies the molecular structure parameters by attaching phenanthrene groups at specific positions (2, 7, or 9) on the benzene ring, and by selecting specific substituents (Ar groups) to optimize the energy levels. This structural parameter change achieves a balance where ΔST is sufficiently large for efficient phosphorescent emission but not excessively large to cause device degradation, thereby improving device lifetime while maintaining emission efficiency
Solution Approach 2:
The patent creates a composite molecular structure combining benzene ring core with phenanthrene groups and various Ar substituents (carbazolyl, aryl, heterocyclic groups). This composite structure integrates the benefits of rigid phenanthrene for stability with the electronic properties of Ar groups, achieving both high device lifetime and efficient light emission through synergistic molecular design
2Reliability
If compound 1-B is used, then the device can emit light, but the device lifetime is reduced due to low sublimability
Solution Approach 1:
The patent optimizes the molecular weight and structural parameters by selecting specific Ar groups (carbazolyl, aryl, heterocyclic groups with chalcogen elements) attached to the phenanthrene-benzene core. These parameter adjustments enhance intermolecular interactions and crystallinity, significantly improving sublimability while maintaining the compound's light-emitting properties and device lifetime
Solution Approach 2:
The patent introduces specific Ar groups as intermediary structures that mediate between the phenanthrene core and the device environment. These Ar groups (particularly carbazolyl and heterocyclic groups with chalcogen elements) act as intermediaries that enhance sublimability through improved molecular packing and intermolecular forces, while also contributing to charge transport and device 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 organic compound with reduced ΔST and improved sublimability results in an organic light-emitting device with enhanced luminous efficiency, reduced device voltage, and extended lifetime by optimizing charge transport and reducing unnecessary charge accumulation.
Implementation Method 1
Compound 1-B has low sublimability. For this reason, when compound 1-B is used in an organic light-emitting device, compound 1-B is disadvantageous in terms of device lifetime.
Data Source
AI summary
An organic compound represented by the following formula (1):where in formula (1), Ar is a carbazolyl group, an aryl group, or a heterocyclic group containing a chalcogen element, provided that when Ar is a phenanthrenyl group, the phenanthrenyl group contains a substituent, and R1 to R21 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a halogen atom, an alkyl group, an alkoxy group, a silyl group, an amino group, an aryl group, and a heterocyclic group.