OLED Charge Injection Materials With Deep LUMO and Stable Films
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Solution Overview
Problem
Existing organic light-emitting diode (OLED) technologies face challenges in achieving high efficiency, long device lifetime, and low operating voltage, particularly due to limitations in hole injection layers (HILs) with deep LUMO levels, high stability, and good film-forming ability.
Innovation Solution
Development of novel compounds with dehydrobenzodiimidazole or dehydrobenzodipyrrole structures, which serve as charge-transporting materials and charge injection materials in OLEDs, possessing deep LUMO energy levels and improved application prospects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional hole injection layers with deep LUMO levels are used, then charge injection efficiency is improved, but device lifetime and stability deteriorate
Solution Approach 1:
The patent modifies the molecular structure of hole injection layer materials by incorporating electron-withdrawing groups (such as fluorine atoms, cyano groups, or trifluoromethyl groups) to adjust the LUMO energy level parameter. This structural modification enables achieving deep LUMO levels (below -6.0 eV) while maintaining high stability and long device lifetime, resolving the contradiction between charge injection efficiency and device reliability
Solution Approach 2:
The patent develops composite hole injection layer materials that combine electron-withdrawing groups with stable molecular backbones (such as triarylamine or carbazole structures). This composite approach allows the material to simultaneously achieve deep LUMO levels for efficient charge injection and high structural stability for extended device lifetime
2Productivity
If materials with deep LUMO levels are used to improve charge injection, then charge mobility is improved, but film-forming ability deteriorates
Solution Approach 1:
The patent carefully balances the strength and position of electron-withdrawing groups in the molecular structure to achieve deep LUMO levels while maintaining appropriate HOMO levels and molecular packing characteristics. This parameter optimization ensures both high charge mobility and good film-forming ability, allowing the material to be processed into uniform films without defects
3Use of energy by moving object
If phosphorescent emitters are used to achieve high efficiency, then internal quantum efficiency is improved, but device lifetime and color saturation deteriorate
Solution Approach 1:
The patent introduces a carefully designed hole injection layer as an intermediary between the anode and the phosphorescent emissive layer. This intermediary layer with deep LUMO level and high stability protects the phosphorescent emitters from degradation while maintaining efficient charge injection, thereby extending device lifetime without sacrificing the high internal quantum efficiency provided by phosphorescent emission
Solution Approach 2:
The patent modifies the energy level parameters of the hole injection layer to create an optimal energy cascade that enhances charge injection efficiency while reducing energy back-transfer to the phosphorescent emitters. This parameter optimization minimizes degradation pathways and extends device lifetime while maintaining high efficiency
Data Source
AI summary
Organic electroluminescent materials and devices are disclosed. The organic electroluminescent materials are novel dehydrobenzodiimidazole or dehydrobenzodipyrrole or its analogous structure compounds, which can be used as charge transporting materials or charge injection materials or the like in an electroluminescent device. These novel compounds have deep LUMO energy level, and have better potential and excellent application prospecty in the field of charge-transporting materials, charge injection materials or the like. An organic electroluminescent device and a compound formulation are also disclosed.