Tunable Tandem OLED with Segmented Light Units
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Solution Overview
Problem
Conventional tandem OLEDs face challenges in achieving tunable luminance and color temperature due to increased driving voltage requirements and inability to individually drive multiple light emission units, leading to limitations in practical applications.
Innovation Solution
A luminance and color temperature tunable tandem OLED design comprising a transparent conductive substrate, multiple light units with specific emission capabilities, and a controlling unit to electrically drive these units individually or simultaneously, allowing for user-desirable color temperature and illuminance adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If multiple light emission units are stacked vertically to increase brightness and extend lifetime, then luminance and lifetime are improved, but driving voltage increases and individual unit control becomes difficult
Solution Approach 1:
The tandem OLED is divided into multiple independently controllable light emission units (first, second, and third units), each with its own hole transport layer, emission layer, and electron transport layer. This segmentation allows individual units to be driven separately through distinct electrical pathways, enabling color temperature tuning while distributing the overall voltage requirement across separate controllable segments.
Solution Approach 2:
The patent implements dynamic control capability where the brightness and activation state of each light emission unit can be adjusted independently in real-time. This dynamic control allows the system to optimize performance by activating only necessary units, thereby managing driving voltage requirements while maintaining extended lifetime benefits from the multi-unit structure.
2Illumination intensity
If multiple light emission units are stacked vertically to increase brightness, then luminance is improved, but the ability to individually drive units for color temperature tuning is lost
Solution Approach 1:
The tandem OLED is divided into multiple independently controllable light emission units (first, second, and third units), each with its own hole transport layer, emission layer, and electron transport layer. This segmentation allows individual units to be driven separately through distinct electrical pathways, enabling color temperature tuning while maintaining high luminance output from the combined structure.
Solution Approach 2:
Each light emission unit is designed with specific local characteristics - different emission layers (blue, green, red) that emit distinct wavelengths. This local quality differentiation enables color temperature tuning by selectively activating units with specific emission characteristics, while the overall stacked structure maintains high luminance through cumulative light output.
3Illumination intensity
If high current density is used to drive white light OLED for illuminance devices, then luminance output is improved, but thermal degradation occurs and lifetime is shortened
Solution Approach 1:
The tandem OLED structure divides the high luminance output requirement across multiple light emission units operated at lower individual current densities. Each unit contributes to the total luminance output, allowing the system to achieve high overall illumination intensity while each unit operates within safer current density limits, reducing thermal degradation and extending lifetime.
Solution Approach 2:
Multiple light emission units are combined in a stacked configuration where each unit operates at moderate current density but collectively they produce high luminance output. This merging approach distributes the thermal load across multiple units rather than concentrating it in a single unit driven at high current density, thereby improving reliability while maintaining high illumination intensity.
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
Enables flexible control over luminance and color temperature, extending the OLED's functionality in illuminance devices by allowing for the emission of various white light types, thereby enhancing user experience and device performance.
Implementation Method 1
organic light emitting diode (OLED) was initially invented and proposed by Eastman Kodak Company through a vacuum evaporation method. Tang and VanSlyke working for Kodak Company deposited an electron transport material (ETL) such as Alq3 on a transparent indium tin oxide (abbreviated as ITO) glass, thereby forming with an organic layer of aromatic diamine on the ITO glass. Consequently, Tang and VanSlyke further completed the fabrication of an organic electroluminescent (EL) device
Data Source
AI summary
Disclosures of the present invention describe a luminance and color temperature tunable (LCTT) tandem OLED, which mainly consists of a transparent conductive substrate, a HTL, a first lighting unit, a first carrier generation unit, a second lighting unit, a second carrier generation unit, a third lighting unit, an ETL, and a cathode electrode. The first lighting unit is designed to emit a cold-white light, a pure-white light or an orange-white light, the second lighting unit is designed to emit a warm-white light, and third lighting unit is designed to emit an orange-white light, a pure-white light or a cold-white light corresponding to the first lighting unit. By such arrangement, it is easy for a user to make the LCTT tandem OLED provide an illumination with user-desirable color temperature and illuminance by using a control interface to electrically drive the three lighting units, either individually or simultaneously.