White OLED Functional Layers Block Energy Transfer
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Solution Overview
Problem
Conventional white organic light emitting devices (OLEDs) face challenges in achieving high luminous efficiency and uniform color spectrum due to energy transfer issues between light emitting layers, leading to reduced efficiency and power consumption.
Innovation Solution
A white OLED structure with functional layers between red, blue, and green light emitting layers to block energy transfer and control electron mobility, utilizing specific materials with defined energy band gaps and molecular orbital levels to prevent exciton dispersion and enhance electron/hole balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single light emitting layer with multiple dopants is used, then the device structure is simple, but energy transfer between dopants occurs reducing luminous efficiency
Solution Approach 1:
The light emitting layer is segmented into multiple separate light emitting layers, each containing a different dopant (red, green, blue). This segmentation prevents energy transfer between dopants while maintaining a relatively simple overall device structure.
Solution Approach 2:
Carrier blocking layers are introduced as intermediary elements between the different light emitting layers. These layers have specific energy band gaps and carrier mobility characteristics that prevent energy transfer between layers while allowing the device to maintain good electron-hole balance.
2Loss of energy
If multiple light emitting layers are stacked, then energy transfer between layers is reduced, but exciton dispersion becomes difficult and manufacturing complexity increases
Solution Approach 1:
The patent optimizes specific parameters including the thickness of carrier blocking layers (50-100 Å), energy band gap values, and carrier mobility ratios to control exciton distribution and prevent excessive energy transfer while maintaining manufacturability.
Solution Approach 2:
Carrier blocking layers serve as mediators that control the interaction between adjacent light emitting layers, enabling exciton confinement in each layer while maintaining overall device performance and manufacturability.
3Illumination intensity
If dopant concentration is increased to improve color saturation, then energy transfer between dopants increases reducing luminous efficiency
Solution Approach 1:
By segmenting the light emitting layer into multiple separate layers, each with its own dopant, the patent achieves high color saturation through concentrated dopant placement while preventing energy transfer that would otherwise occur in a single-layer system.
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 results in a white OLED with improved luminous efficiency, suitable color coordinates for display, and reduced power consumption by maximizing quantum efficiency and controlling electron/hole balance.
Implementation Method 1
The functional layer formed between the blue light emitting layer and the red light emitting layer has a hole transport characteristic, has an energy band gap greater than that of the blue light emitting layer
Implementation Method 2
The functional layer controls electron mobility in the light emitting layer and maximizes electron-hole balance
Implementation Method 3
Organic light emitting devices (OLEDs) are emissive display devices that use light generated from combinations of electrons and holes, which are supplied to a fluorescent or phosphorus organic compound thin film
Data Source
AI summary
Provided is a white organic light emitting device and a display apparatus and a lighting apparatus that include the white organic light emitting device. The white organic light emitting device comprises an anode, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode. The light emitting layer includes a red light emitting layer, a blue light emitting layer, and a green light emitting layer sequentially formed from the anode. A functional layer, which blocks an energy transfer and controls electron mobility between the light emitting layers, is formed between the red light emitting layer and the blue light emitting layer or between the blue light emitting layer and the green light emitting layer. The functional layer formed between the red light emitting layer and the blue light emitting layer has a thickness of 50 to 100 Å.