Cool White OLED Deep Light Blue Emitter Energy Transfer
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Solution Overview
Problem
Current organic light emitting devices (OLEDs) for cool white lighting applications face inefficiencies and short lifetimes due to the use of deep blue emitters, which are less efficient and have shorter lifetimes compared to light blue emitters, and struggle with color stability during aging.
Innovation Solution
Incorporating both deep blue and light blue emitters in a single device structure, with the deep blue emitter positioned next to the red-green emissive layer and light blue emitter, allowing for energy transfer that enhances efficiency and lifetime, and maintains color stability during the aging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If deep blue emitter is used in OLED, then cool white lighting is achieved, but efficiency and lifetime are reduced
Solution Approach 1:
The patent combines deep blue emitter and light blue emitter in a single OLED device structure. The deep blue emitter (with peak wavelength 400-470 nm) and light blue emitter (with peak wavelength 460-500 nm) are positioned adjacent to each other in the emissive layer, allowing energy transfer from deep blue to light blue while achieving cool white lighting with improved efficiency and lifetime compared to using deep blue emitter alone.
2Temperature
If deep blue emitter is used in OLED, then cool white lighting is achieved, but efficiency is reduced
Solution Approach 1:
The light blue emitter acts as an intermediary in the energy transfer process. Energy from the deep blue emitter is transferred to the light blue emitter, which then emits light. This intermediary approach allows the device to achieve cool white lighting while improving overall efficiency, as the light blue emitter has better efficiency characteristics than the deep blue emitter alone.
3Device complexity
If single blue emitter is used, then device structure is simple, but color stability during aging is poor
Solution Approach 1:
The patent merges deep blue emitter and light blue emitter in a single device, creating a more complex but color-stable structure. The energy transfer between the two emitters compensates for aging effects, maintaining color stability over time. The deep blue emitter (400-470 nm) and light blue emitter (460-500 nm) work together to provide stable cool white output during the aging process.
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 combination of deep blue and light blue emitters in a single device structure improves the efficiency and lifetime of cool white OLEDs, maintaining minimal color change and meeting Energy Star specifications for cool white lighting applications.
Implementation Method 1
the deep blue emitter is positioned next to the red-green emissive layer and light blue emitter, allowing energy transfer and enhancing the efficiency and lifetime of cool white OLEDs
Data Source
AI summary
A light emitting system is provided including a first organic light emitting device. The first organic light emitting device includes an anode, a cathode, a first organic emitting layer disposed between the anode and the cathode, and a second organic emitting layer disposed between the anode and the cathode. The first organic emitting layer and the second organic emitting layer each include an emissive dopant having a peak wavelength of between 400 to 500 nanometers, but one of the peak wavelength of one of the dopants is at least 4 nm less than the peak wavelength of the other dopant. The first organic emitting layer and the second organic emitting layer may overlap each other, such as being disposed one over the other. The device may be used in white light or multi-color systems.