Research Team Creates Inkjet Printed Light Detectors

A team of researchers at Karlsruhe Institute of Technology has found a way to create and produce wavelength-sensitive light detectors. They successfully printed devices using common inkjet printing with semiconducting inks.

When Gutenberg invented the printing press over 500 years ago, he probably couldn’t even dream of all the advancements that have been made in the world of print ever since. Recently, a team at the Karlsruhe Institute of Technology (KIT) has found a way to adopt a familiar technology to now print wavelength-sensitive light detectors by using the team’s own semiconductor ink.

In High Demand

Light detection might sound rather odd at first, but it is actually a technology everyone is in contact with every day, in one form or another. Gerado Hernandez-Sosa, a researcher on the project, says:

“When we take pictures with our camera, when we hold the door of an elevator or when we measure our heartrate with a smart watch. Often the detectors are hidden, but they are crucial elements.”

Since future technologies will have an increased demand for optical sensors, his team set out to provide an easier way to manufacture the high-tech optoelectronic devices. Their technique could be simplifying printing processes for the fabrication of photodetectors significantly and change the devices’ conductivity when exposed to light.

Let’s Shed Some Light

“In our case we use organic semiconductors in the ink that will be printed to form the light sensitive layer of the photodetector. Depending on the material that is used the detector will react in different magnitude to the color of the light. However, when changing the organic material composition one would also change the fabrication process which is many times complicated,”

he explained.

Image source: Noah Strobel, KIT

Their printed light detectors can scale from small to large form factors. But the team plans to continue their research to further improve on the variety of colors, to close in on smaller color differences by finding more material that can react to more precise wavelengths of light. The team aims to create light detectors that can work at higher speeds and therefore enable optical communication in the future.

“When exchanging this material we managed to keep the properties of the ink constant. This enabled us to print photodetectors that react to different colors using the same printing ‘recipe’.”

Upcoming Technologies

One of those upcoming technologies Hernandez-Sosa is keen on supporting is visible light communication (VLC), a technology that uses indoor lightning in buildings for optical communication and could even be the future of how data is transmitted.

“It offers a number of advantages compared to current technologies like Wi-Fi or Bluetooth in terms of security, speed, and accessibility. Our research contributes to this technology by exploiting the advantages of a special kind of materials (organic semiconductors) and their fabrication with printing techniques.”

Hernandez-Sosa told Design News.

Another field they are hoping to improve is solar energy. The team believes their research can be useful for the development of the next generation of solar cells.

Read the team’s paper published on Advanced Materials or continue through our library of everything related to print, packaging or innovation. What other future technologies using light do you know?

Image source light sensor: Noah Strobel, KIT

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