OLED Panel Lifetime Prediction via Small Device Segmentation
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Solution Overview
Problem
Existing methods for determining the lifetime of large area organic emissive panels are unreliable due to heat generation and dissipation issues, making it difficult to accurately extrapolate lifetimes from high to low current densities.
Innovation Solution
A method involving accelerated lifetesting of small area individual organic emissive devices at various ambient temperatures and current densities, followed by determining the junction temperature of a large area panel, allows for the estimation of the panel's lifetime without applying high current densities, using the relationship between device lifetime and ambient temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high current densities are applied to large area organic emissive panels for accelerated lifetesting, then the testing time is reduced, but heat generation causes unreliable results and catastrophic failure
Solution Approach 1:
The patent segments the testing approach by separating small area devices (used for accelerated lifetesting at high current densities) from large area panels (used for operational deployment). Small devices can withstand high current densities without catastrophic thermal failure, allowing accelerated testing to determine lifetime parameters that are then applied to predict large panel lifetimes at lower operational current densities.
Solution Approach 2:
The patent introduces small area organic emissive devices as intermediary test subjects. These small devices serve as a bridge between accelerated testing conditions and actual large panel operational conditions. By testing small devices at high current densities and using the determined lifetime parameters to model large panel behavior at lower current densities, the patent avoids direct high-current testing of large panels while still obtaining accelerated lifetime data.
2Loss of time
If high current densities are applied to determine panel lifetime, then the testing duration is shortened, but the risk of catastrophic failure increases
Solution Approach 1:
The patent divides the testing function into small area devices that承受 (withstand) high current densities during accelerated lifetesting. These segmented small devices act as sacrificial test subjects that can fail without compromising the entire large panel system, thereby enabling time-accelerated testing while containing the catastrophic failure risk to isolated small device units.
Solution Approach 2:
The patent employs small area devices as a cushioning layer against catastrophic failure. By performing accelerated lifetesting on these small devices before deploying large panels, the system obtains lifetime parameter data that allows prediction of large panel lifetimes under operational conditions, thereby cushioning against the risk of unexpected large panel failures and enabling informed deployment decisions.
3Device complexity
If conventional lifetime extrapolation methods are used from high to low current densities, then the process is simplified, but accuracy deteriorates due to heat generation and dissipation issues
Solution Approach 1:
The patent applies local quality by using small area devices with different thermal characteristics than large panels. The small devices have superior heat dissipation relative to their size, allowing them to withstand high current densities without the heat accumulation problems that plague large panels. This local difference in thermal management enables accurate lifetime parameter extraction from small devices that can then be applied to predict large panel behavior.
Solution Approach 2:
The patent changes the size parameter of the test device from large panel dimensions to small device dimensions. This parameter change fundamentally alters the thermal behavior and current density tolerance, enabling accelerated lifetesting at high current densities. The lifetime parameters obtained from these small devices are then used to model and predict large panel lifetimes at lower operational current densities, improving accuracy over direct extrapolation methods.
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 provides a more accurate and cost-effective method for determining the lifetime of large area organic emissive panels by correlating small area device data with panel junction temperature, reducing the risk of catastrophic failure and optimizing thermal management.
Implementation Method 1
OLEDs make use of thin organic films that emit light when voltage is applied across the device
Implementation Method 2
One application for phosphorescent emissive molecules is a full color display
Data Source
AI summary
A method for accelerated life testing of organic devices is provided. The lifetime of each of one or more individual organic emissive devices is measured at a non-heating current density. Based upon the measured lifetimes of the one or more devices, the device lifetime is determined for a selected luminance. An organic emissive panel is also obtained having a second organic stack that consists essentially of the one or more organic layers of the first organic stack. The junction temperature of the organic emissive panel is then determined at a heating current density. Based upon the junction temperature and the device lifetime of the one or more individual organic emissive devices, the expected lifetime of the organic emissive panel is then determined at the heating current density.