OLED Emissive Layer Host-Dopant Architecture for Lifetime and Efficiency
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Solution Overview
Problem
Existing OLED devices face challenges in achieving high efficiency and long device lifetime while maintaining saturated color emission, particularly with deep HOMO host materials.
Innovation Solution
The use of an OLED device architecture that includes an anode, a cathode, and an emissive layer with a phosphorescent dopant, a hole transporting host, and an electron transporting host, where the hole transporting host has a HOMO energy ≤ −5.45 eV and/or a specific structural formula, and the phosphorescent dopant has a specific formula Ir(LA)x(LB)y(LC)z.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If deep HOMO host materials are used in OLED emissive layers, then device lifetime is improved, but manufacturing complexity increases due to the need for precise HOMO energy level control (≤−5.45 eV) and specific structural formulas
Solution Approach 1:
The patent applies parameter changes by establishing specific HOMO energy level ranges (≤−5.45 eV) and structural formula requirements for the hole transporting host material. This allows the emission layer to achieve both long device lifetime and controlled manufacturing through defined material parameters rather than complex process control
Solution Approach 2:
The patent uses an intermediary approach by introducing a host material with specific HOMO energy levels that mediates between the phosphorescent dopant and the electrodes. This host material (with HOMO ≤−5.45 eV) serves as a bridge that enables both long lifetime operation and manufacturable energy level alignment
2Illumination intensity
If phosphorescent dopants with specific Ir(LA)x(LB)y(LC)z formulas are used, then saturated color emission is achieved, but device complexity increases due to multiple ligand combinations and structural requirements
Solution Approach 1:
The patent applies composite materials by combining phosphorescent dopants with specific Ir(LA)x(LB)y(LC)z formulas and hole transporting host materials with HOMO ≤−5.45 eV in a single emission layer. This composite approach achieves saturated color emission while managing complexity through defined material classes rather than requiring entirely new material designs
Solution Approach 2:
The patent uses local quality by assigning specific functional requirements to different components: the phosphorescent dopant provides saturated color emission while the host material with HOMO ≤−5.45 eV provides hole transport and lifetime enhancement. This division of functional qualities allows each component to be optimized independently
3Productivity
If dual host system (hole transporting host and electron transporting host) is implemented, then high efficiency is maintained, but device complexity increases due to requiring two different host materials with specific functions
Solution Approach 1:
The patent applies universality by designing host materials that can perform multiple functions: the hole transporting host with HOMO ≤−5.45 eV provides both hole transport and contributes to long lifetime operation, while the electron transporting host provides electron transport. This multi-functional approach maintains high efficiency without requiring entirely separate specialized materials for each function
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
This configuration enhances device lifetime and maintains high efficiency while achieving saturated color emission, particularly with deep HOMO host materials.
Implementation Method 1
OLEDs make use of thin organic films that emit light when voltage is applied across the device
Implementation Method 2
the organic materials may have performance advantages over conventional materials... OLEDs make use of thin organic films that emit light when voltage is applied
Data Source
AI summary
An organic electroluminescent device (OLED) comprising an anode; a cathode; and an emissive layer, disposed between the anode and the cathode is provided. The emissive layer comprises a phosphorescent dopant, a first host, and a second host, where the first host is a hole transporting host, the second host is an electron transporting host, the first host has a HOMO energy≤−5.45 eV and/or the first host comprises a structure of Formula V:and the phosphorescent dopant has a formula Ir(LA)x(LB)y(LC)z. In formula Ir(LA)x(LB)y(LC)z, ligand LA has a structure of Formula I,where: moiety A is a ring; moiety B is a fused ring structure comprising at least three rings; K is a direct bond or a linker; Z1 and Z2 are C or N; each RA and RB is hydrogen or a General Substituent defined herein. Consumer products containing the OLED are also provided.