Optical Scientist Creates Inkjet Printed Light-Emitting Devices

Inkjet printing is a versatile printing process that can be applied to almost any size surface -- from postage stamps to building wraps. Images are formed by the precise placement of extremely small droplets of ink fired at high speeds from the nozzles of computer-controlled print heads.

Optical sciences Professor Ghassan E. Jabbour and his student Yuka Yoshioka inkjet print an organic solution onto electrically conductive surface producing a self-illuminated photo.

"We came up with a new process using inkjet to vary conductivity of conductors. We can do some chemistry with the inkjet printer that allows us to control where we want to allow a lot of electrons and where we don't want to allow a lot of electrons," Jabbour said.

"There's a lot of science and technology involved, but basically, we take a picture, or design an electronic circuit, scan it to computer, then send it to the printer. We already have programmed the printer to interpret colors and convert them to a chemical reaction, so the printer prints images just like it was printing on paper," he said.

This writer sent her photo to Jabbour and Yoshioka, who printed it on plastic so it glowed LED green.

But using different materials, they could have printed the photo to emit in other visible colors or in the infrared, wavelengths which are invisible to the naked eye. Printed in the infrared on plastic, silicon or glass, light-emitting images have interesting security applications, for starters.

The ability to continuously vary electrical conductivity in materials could be useful in such hot-topic areas as microfluidics and other microtechnologies, Jabbour added. "We might build very tiny heaters that can vary heat from one place to another, or micro filters that can filter ions from a solution, which is not easily done otherwise," he said.

Inkjet printing is only one project in Jabbour's broad research program, which focuses on fundamental understanding, as well as practical applications, of photonic and electronic materials and devices. (Photonic materials are materials that interact strongly with light. What electrons are to electronics, photons are to photonics.)

His program involves making and testing materials, devices and systems from the "nano" scale to the mega-scale. With colleagues at the University of Arizona and collaborators at other universities, national laboratories and industry, Jabbour and his group also work on:

* Printed organic and hybrid photonics and electronics

* Plastic and roll-to-roll photonics and electronics for displays, solar cells and lighting applications

* Hybrid organic-inorganic sol-gel micro-optical passive and active elements for information technology applications

* Organic based transistors and lasers

* Nano-data storage

* Combinatorial electronic and optical materials and device discovery

* Optical coatings

* Electronic and optical properties of thin films

* Computational modeling