Flexible Blade‐Coated Multicolor Polymer Light‐Emitting Diodes for Optoelectronic Sensors

A method to print two materials of different functionality during the same printing step is presented. In printed electronics, devices are built layer by layer and conventionally only one type of material is deposited in one pass. Here, the challenges involving printing of two emissive materials to...

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Bibliographic Details
Published in:Advanced materials (Weinheim) 2017-06, Vol.29 (22), p.n/a
Main Authors: Han, Donggeon, Khan, Yasser, Ting, Jonathan, King, Simon M., Yaacobi‐Gross, Nir, Humphries, Martin J., Newsome, Christopher J., Arias, Ana C.
Format: Article
Language:English
Subjects:
Accessories
Blade coating
Electronic devices
Emissivity
flexible electronics
Light emitting diodes
Materials science
Near infrared radiation
Optoelectronic devices
Organic light emitting diodes
organic light‐emitting diodes (OLEDs)
Oxygenation
polymer light‐emitting diodes (PLEDs)
printed sensors
Printing
pulse oximetry
Reproducibility
Sensors
wearable sensors
Wrist
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Summary:A method to print two materials of different functionality during the same printing step is presented. In printed electronics, devices are built layer by layer and conventionally only one type of material is deposited in one pass. Here, the challenges involving printing of two emissive materials to form polymer light‐emitting diodes (PLEDs) that emit light of different wavelengths without any significant changes in the device characteristics are described. The surface‐energy‐patterning technique is utilized to print materials in regions of interest. This technique proves beneficial in reducing the amount of ink used during blade coating and improving the reproducibility of printed films. A variety of colors (green, red, and near‐infrared) are demonstrated and characterized. This is the first known attempt to print multiple materials by blade coating. These devices are further used in conjunction with a commercially available photodiode to perform blood oxygenation measurements on the wrist, where common accessories are worn. Prior to actual application, the threshold conditions for each color are discussed, in order to acquire a stable and reproducible photoplethysmogram (PPG) signal. Finally, based on the conditions, PPG and oxygenation measurements are successfully performed on the wrist with green and red PLEDs. Blade‐coated polymer light‐emitting diodes (PLEDs) with different colors are successfully demonstrated on one substrate using surface energy patterning (SEP). SEP is further utilized to fabricate two PLEDs with different colors on one substrate. The PLEDs are used to perform photoplethysmogram measurements with a silicon photodiode. With the multicolor PLEDs, pulse and oxygenation measurements are successfully demonstrated.
ISSN:0935-9648
1521-4095
DOI:10.1002/adma.201606206