Wearable OLED NIR Generation via Down-Conversion Layer
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Solution Overview
Problem
Current organic light emitting diode (OLED) technologies face challenges in efficiently generating near-infrared (NIR) emission, as direct electroluminescence methods result in low device efficiency and complex fabrication processes, making it difficult to integrate NIR emitters within the OLED stack.
Innovation Solution
Incorporating a down-conversion layer that absorbs a portion of the display electroluminescence and re-emits light at a longer NIR wavelength, utilizing materials like quantum dots, organic molecular emitters, or lanthanide down-conversion layers to generate NIR emission while maintaining transparency in the visible spectrum and minimizing optical density in the visible range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If direct electroluminescence methods are used to generate NIR emission in OLEDs, then NIR light output is achieved, but device efficiency is low and fabrication process becomes complex
Solution Approach 1:
The patent introduces a down-conversion layer as an intermediary component between the visible light emitting layer and the NIR output. This layer absorbs visible photons and re-emits NIR photons, enabling efficient NIR generation without requiring direct electroluminescence from NIR emitters, thus avoiding the efficiency losses and fabrication complexities associated with direct NIR electroluminescence
2Adaptability or versatility
If down-conversion layer is added to generate NIR emission, then NIR output capability is improved, but device structure becomes more complex
Solution Approach 1:
The down-conversion layer serves multiple functions simultaneously: it converts visible light to NIR light, acts as a wavelength transformation medium, and enables the OLED to output multiple wavelengths (visible and NIR) from a single emissive layer. This multi-functionality approach adds NIR capability without requiring separate NIR emitting structures, thereby limiting the increase in device complexity
3Loss of energy
If down-conversion layer is used for NIR generation, then heat output is reduced, but visible light transmission must be maintained
Solution Approach 1:
The down-conversion layer exhibits wavelength-selective properties: it strongly absorbs visible photons to convert them to NIR photons, while being transparent or minimally absorbing to NIR photons. This local quality differentiation in absorption characteristics allows the layer to reduce heat output by converting high-energy visible photons while maintaining NIR transmission for the final output
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 allows for efficient generation of NIR emission with reduced heat output and increased efficiency, enabling the production of wearable devices that can output multiple wavelengths of light, including red, blue, and NIR, while maintaining visible light operation without disrupting the OLED stack's performance.
Implementation Method 1
a down-conversion layer that absorbs a portion of the display electroluminescence and re-emits light at a longer NIR wavelength
Implementation Method 2
OLEDs make use of thin organic films that emit light when voltage is applied across the device
Data Source
AI summary
Embodiments of the disclosed subject matter provide a wearable device that includes an organic light emitting diode (OLED) light source to output light having one peak wavelength from a single OLED emissive layer, and a first barrier layer that is disposed over or between the single OLED emissive layer and one or more down-conversion layers. One or more regions of the single OLED emissive layer are independently switchable and controllable so that the wearable device is configurable to output a plurality of wavelengths of light. One of the plurality of wavelengths of light that is output is near infrared light.