highly efficient single-stack hybrid cool white oled utilizing blue thermally activated delayed fluorescent and yellow phosphorescent emitters

by:LCD Mall     2020-08-10
Efficient single
Stacked mixed White Organic Light
LEDs (OLEDs)having blue-yellow-
Blue multi-layer emission layer (EMLs)
Delayed fluorescence activation using Blue Heat (TADF)
Yellow LEDs. The out-
By adjusting the thickness of ITO and total devices, the coupling efficiency of yellow and blue emission is maximized, which satisfies the two anti-node positions of yellow and blue emission with a limited number of EML thicknesses
To get a cool white launch, blue-yellow-
The blue multi-EML system is controlled by manipulating the composite region through the charge conductivity change of the host medium in the blue tadf eml.
The resulting device has a very high cold white emission with a maximum external quantum efficiency of 23.
1% and CIE color coordinates (0. 324, 0. 337).
We expect that the methodology studied will improve
Stacked hybrid cool white oled for high performance display applications.
White Organic LightLEDs (WOLED)
Is the core technology of large enterprises.
Area active matrix OLED (AMOLED)
Promising candidates for display and next-generation lighting applications.
Recently, WOLED has become more and more important for large-size oled TV monitors.
Oled TV has been successfully commercialized by adopting an OLED panel consisting of fluorescent blue and fluorescent yellow green units
Series configuration and red, green, blue color filters.
In fact, in the cool forestCWOLEDs)
, Since a highly stable blue-ray transmitter has not been developed so far, a hybrid system of fluorescent blue and fluorescent green and red or yellow transmitters is used to ensure sufficient device life.
Usually, the hybrid CWOLED structure is particularly divided into single
Stack and tandem configuration.
Only three of them.
The stack tandem structure is used for display applications due to its high efficiency and long equipment life.
In this series structure, two blue emission layers (EML)
It is used to compensate for low-intensity blue fluorescence for efficient cold white emission and long device life.
However, this complex structure not only increases the cost of manufacturing and drive voltage, but also reduces the perspective properties.
On the other hand, single
The stacked hybrid WOLED has a simpler structure than the series structure.
Therefore, it is possible to reduce the cost of equipment manufacturing and provide better Perspective features.
However, inefficiency is the most challenging problem in a single mode.
Stack hybrid WOLEDs. In the single-
Stacked hybrid CWOLED with 100% internal quantum efficiency (IQE)
If all blue tri-state excitation is converted into yellow Tri-State excitation by Dexter energy transfer, it can be realized as shown in the figure.
In this case, however, yellow emissions are three times higher than blue emissions;
Therefore, the resulting emission will be warm white.
Therefore, in order to achieve a cold and white launch,
It should be through the non-loss of the triple state of the blue triple state excitation
Radiation attenuation as shown in the figure
This is the reason for the low efficiency and the single-
A stacked hybrid system using a traditional blue fluorescent transmitter.
The most effective way to solve this problem is to introduce a blue TADF transmitter instead of a traditional blue fluorescent transmitter.
As shown in the figure.
, All the blue triple-state stimuli generated by electricity can cross through the reverse system (RISC)
Energy Transfer from Dexter in blue EML and yellow EML.
Therefore, 100% IQE and cool white emission can be achieved at the same time.
However, there are very few papers on singles
So far, stacked cool white oled with blue TADF transmitter has been reported.
In this work, we have studied a single-
Stack hybrid CWOLED. The blue-yellow-
Use the Blue multiple EML structure to harvest all the excitation produced by electricity and balance the intensity of the blue and yellow emission.
Maximize output
Considering the coupling efficiency of the yellow and blue emission, the ITO and total device thickness of the antinode position that satisfies the yellow and blue emission at a limited number of EML thicknesses.
Also, in blue-yellow-
The Blue multiple EML system regulates the composite area by controlling the change in charge conductivity of the main material in the blue tadf eml.
Very high external quantum efficiency by utilizing the optimal device thickness and multiple EML systems (EQE)of 23.
CIE color coordinates are (1%) and cool white emission0. 324, 0. 337)
Is in the single
Stack hybrid CWOLED.
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