OLED Green Emission Layer Phosphor Host Exciplex Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Organic light emitting devices face limitations in luminescence efficiency and lifetime, particularly in green emission layers, leading to increased power consumption and reduced reliability, especially when using traditional green fluorescent host materials.
Innovation Solution
Incorporating a phosphor host material with a second phosphor host material and a dopant in the green emission layer, along with a wide band gap material for exciplex generation, which enhances luminescence efficiency and reduces power consumption by forming an exciplex state through thermal evaporation methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional green fluorescent host material is used in the green emission layer, then the device structure is simple and manufacturing is easy, but luminescence efficiency is low and lifetime is short
Solution Approach 1:
The green emission layer uses a composite material system comprising a phosphor host material (e.g., Alq3 or BCP) combined with a second phosphor host material and a dopant material. This composite structure enables exciplex formation between the host and guest materials, significantly improving luminescence efficiency and device lifetime while maintaining manageable complexity through systematic material selection.
Solution Approach 2:
The invention changes the fundamental material parameters of the emission layer by transitioning from conventional fluorescent materials to phosphor-based exciplex materials. This parameter change involves selecting materials with specific energy levels, molecular weights, and chemical structures that enable exciplex formation, thereby achieving enhanced luminescence efficiency and stability.
2Illumination intensity
If high current is applied to increase luminance, then luminance output is improved, but power consumption increases and reliability deteriorates
Solution Approach 1:
The invention changes the luminescence mechanism parameter from conventional electroluminescence to exciplex-based luminescence. The exciplex materials exhibit higher luminescence efficiency, enabling the device to achieve high luminance output with lower current density, thereby reducing power consumption while maintaining or improving reliability.
3Reliability
If phosphor host material with exciplex generation is used, then luminescence efficiency is improved, but manufacturing process complexity increases
Solution Approach 1:
The invention employs organic phosphor materials that can be deposited using conventional vacuum evaporation techniques, making the manufacturing process accessible with standard equipment. The materials are designed to be processable at reasonable costs, and while the emission layer requires precise composition control, the overall fabrication remains compatible with existing OLED manufacturing workflows.
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 solution improves luminescence efficiency by 10.7 cd/A and reduces driving voltage by approximately 0.6V, while extending the device's lifetime by 67% compared to conventional methods, thus enhancing both performance and energy efficiency.
Implementation Method 1
a first phosphor host material and a second phosphor host material, and a dopant material which are pre-mixed in a specific ratio are deposited on a substrate by a thermal evaporation method
Implementation Method 2
at least one of the red emission layer, the green emission layer, and the blue emission layer emits a baseline mount of light, and further includes a plurality of organic materials generating an exciplex state of energy in an exciplex state, the plurality of organic materials emitting additional amount of light above the baseline amount of light in the exciplex state
Data Source
AI summary
A light emitting device is discussed, and includes a first electrode; a hole transporting layer (HTL) on the first electrode; an organic light-emission layer (EML) having a red emission layer (EML) formed in a red sub pixel area Rp, a green emission layer formed in a green sub pixel area Gp, and a blue emission layer formed in a blue sub pixel area Bp; an electron transporting layer (ETL) on the red, green and blue emission layers; and a second electrode on the electron transporting layer, wherein the green emission layer includes a phosphor host material, a second phosphor host material, and a dopant material.