OLEDs and inorganic quantum dots hybrid approach through inkjet-printing
These "hybrid" OLEDs, also called quantum dot LEDs (QD-LEDs), increase the efficiency of the light-emitting devices and also increase the range of colours that can be produced.
To make OLEDs more cheaply and easily, researchers from the University of Louisville in Kentucky are developing new materials and production methods using modified quantum dots and inkjet printing.
According to Delaina Amos, professor at the University of Louisville and principal investigator of the team’s efforts, expense of materials and manufacturing processes has been a major barrier to using OLEDs in everyday lighting devices.
To inexpensively apply the quantum dots to their hybrid devices, the Louisville researchers use inkjet printing, popular in recent years as a way to spray quantum dots and OLED materials onto a surface with great precision. But unlike other groups experimenting with this method, Amos’ team has focused on adapting the inkjet printing technique for use in a commercial setting, in which mass production minimizes expense and translates to affordable off-the-shelf products. "We are currently working at small scale, typically 1 inch by 1 inch for the OLEDs," Amos says. "The process can be scaled up from here, probably to 6 inches by 6 inches and larger."
To bring their QD-LEDs closer to becoming market-ready as household lighting appliances, Amos and her team have been synthesizing new, less expensive and more environmentally friendly quantum dots. The team has also modified the interfaces between the quantum dots and other layers of the OLED to improve the efficiency with which electrons are transferred, allowing them to produce more efficient light in the visible spectrum.
What’s more, Amos’ QD-LEDs also use low-toxicity materials, making them potentially better for the environment. "Ultimately we want to have low cost, low toxicity, and the ability to make flexible devices," Amos says. The team has recently demonstrated small working devices, and Amos hopes to have larger devices within the next several months.
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