Fluoranthene Host Material for Phosphorescent OLED Efficiency
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Solution Overview
Problem
Existing organic electroluminescence devices face challenges with short lifetime due to molecular degradation and high driving voltage, especially when using CBP as a host material, and require improvements in luminous efficiency and stability.
Innovation Solution
The use of an organic EL device material with a specific structure, represented by formulae (1), (2), and (3), which includes a 3-fluoranthenyl, 5-benzo[c]phenanthrenyl, or 6-benzo[c]phenanthrenyl group as a host for a phosphorescent dopant, providing a phosphorescent organic EL device with reduced driving voltage and enhanced efficiency and lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CBP is used as the host material, then luminous efficiency is improved, but device lifetime deteriorates due to molecular degradation
Solution Approach 1:
The patent changes the chemical structure parameters of the host material from CBP to fluoranthene derivatives, specifically modifying the molecular skeleton to achieve both high triplet energy and oxidation stability. This structural parameter change resolves the contradiction by providing a host material that maintains efficient energy transfer while resisting degradation.
Solution Approach 2:
The patent employs fluoranthene derivative compounds as composite host materials that integrate multiple functional characteristics: high triplet energy for efficient phosphorescent energy transfer and aromatic hydrocarbon structure for oxidation stability. This composite approach allows simultaneous achievement of high luminous efficiency and long device lifetime.
2Use of energy by moving object
If anthracene derivative is used as the host material, then triplet energy is reduced, but energy transfer to phosphorescent dopant deteriorates
Solution Approach 1:
The patent adjusts the triplet energy parameter by selecting fluoranthene derivatives with specifically designed molecular structures. These compounds achieve optimal triplet energy levels (higher than anthracene derivatives but suitable for red phosphorescent emission) while maintaining structural stability, thus resolving the energy parameter contradiction.
3Use of energy by stationary object
If driving voltage is reduced, then power consumption is improved, but luminous efficiency may deteriorate
Solution Approach 1:
The patent optimizes the energy level parameters of the host material to achieve efficient charge injection and transport at lower voltages. The fluoranthene derivative structure provides appropriate HOMO-LUMO levels that facilitate charge injection from electrodes while maintaining efficient exciton generation and energy transfer to phosphorescent dopants, thus reducing power consumption without sacrificing luminous efficiency.
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 proposed material structure significantly reduces driving voltage while maintaining high luminous efficiency and extending the device's lifetime by effectively transferring triplet energy to phosphorescent dopants, enabling efficient light emission within the visible spectrum.
Implementation Method 1
the organic-EL-device material has a fused aromatic ring (Ar) with 10 to 30 carbon atoms and with triplet energy of 2.10 eV or more, and the aromatic hydrocarbon ring adjoined and coupled to the polycyclic fused ring is a divalent benzene ring having a meta bonding
Implementation Method 2
an organic EL device including: a cathode; an anode; and an organic thin-film layer including at least one layer and provided between the cathode and the anode. At least one layer of the organic thin-film layer includes: an organic-EL-device material... and at least one phosphorescent material
Implementation Method 3
An organic EL device, which includes an organic thin-film layer (in which an emitting layer is included) between an anode and a cathode, has been known to emit light using exciton energy generated by a recombination of holes and electrons that have been injected into the emitting layer
Data Source
Figure 1
AI summary
An organic electroluminescence device includes: a cathode; an anode; and an organic thin-film layer including at least one layer and provided between the cathode and the anode. At least one layer of the organic thin-film layer includes: an organic-electroluminescence-device material represented by any one of the following formulae (1), (2) and (3); and at least one phosphorescent material, in which the organic-electroluminescence-device material may have a substituent. A or Ar may be substituted by a phenyl group or a naphthyl group.