OLED Blue Sub-Pixel Pulsing for Longer Display Lifetime
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Solution Overview
Problem
Existing OLED displays face challenges in achieving low power consumption and long operational lifetimes, particularly in blue sub-pixels, which are crucial for full-color displays.
Innovation Solution
The solution involves reducing the current density to drive blue sub-pixels by pulsing the drive current with a duty cycle less than 100% and using a tandem structure with multiple emissive layers, along with a plasmonic PHOLED design and a non-reflective anode, to enhance efficiency and longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high current density is used to drive blue sub-pixels to achieve high luminance, then brightness is improved, but operational lifetime deteriorates
Solution Approach 1:
The patent applies periodic action by pulsing the drive current to blue sub-pixels with a duty cycle less than 100%, allowing the OLED to operate at high luminance during active periods while reducing overall stress and heat generation, thereby extending operational lifetime
Solution Approach 2:
The patent segments the blue sub-pixel emission into multiple emissive layers (tandem structure), where each layer contributes to the overall luminance output. This distribution reduces the current burden on individual layers, maintaining high brightness while improving durability
2Adaptability or versatility
If high current density is applied to blue sub-pixels to maintain color saturation, then color gamut is improved, but power consumption increases
Solution Approach 1:
By using pulsed current with duty cycle <100%, the patent maintains saturated blue color output during active periods while reducing average power consumption compared to continuous high current operation
Solution Approach 2:
The patent transitions from a single emissive layer to a tandem structure with multiple emissive layers, adding a vertical dimension to light emission. This enables maintained color gamut with reduced current density per layer, lowering overall power consumption
3Device complexity
If conventional single emissive layer structure is used, then device simplicity is maintained, but efficiency and lifetime are insufficient
Solution Approach 1:
The patent divides the blue emissive layer into multiple tandem layers, each optimized for specific performance characteristics. This segmentation improves overall efficiency and lifetime while maintaining manageable device complexity through systematic design
Solution Approach 2:
The patent employs composite material strategies by combining multiple emissive layers with different organic compounds (e.g., BCP, Alq3, Bpy-OXD) to achieve synergistic effects that enhance both efficiency and operational lifetime
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 approach results in an OLED display with low power consumption, high luminance, and extended operational lifetime, capable of operating at 1,000 cd/m2 with a drive current as low as 0.5 mA/cm2, while maintaining high color gamut and resolution.
Implementation Method 1
OLEDs make use of thin organic films that emit light when voltage is applied across the device
Implementation Method 2
using not more than a 0.5 mA/cm2 drive current for a blue sub-pixel... along with a plasmonic PHOLED design
Data Source
AI summary
Embodiments of the disclosed subject matter provide a device having a full-color organic light emitting device (OLED) display having a plurality of pixels, with each pixel having a plurality of sub-pixels and where no individual sub-pixel of the plurality of sub-pixels emits white light. The OLED display may be configured to operate with a luminance of at least 1,000 cd/m2 at the D65 or higher white point, and using not more than a 0.5 mA/cm2 drive current for a blue sub-pixel of the plurality of sub-pixels based on an overall active area of the full-color OLED display.