Printable laser-emitting droplets offer new display technology

Researchers at the University of Tsukuba have developed an innovative method to quickly create large quantities of laser light sources using an inkjet printer that ejects laser-emitting droplets.

By applying an electric field to these droplets, the researchers demonstrated that it was possible to turn the light emission on and off. In addition, they managed to create a compact laser display by arranging these droplets on a printed circuit.

The study is published in Advanced materials.

Screens for TVs, PCs and smartphones are continually improving image qualityclarity and energy efficiency. Laser screens are expected to represent the next generation model. Particularly with respect to brightness and color reproducibility, laser displays have the potential to overcome the intrinsic limitations of conventional light-emitting devices, such as OLEDs and liquid crystals.

However, to be used effectively as displays, components must be miniaturized beyond current levels and arranged in high density and large quantities.

In this study, researchers discovered that droplets of a specific organic liquid, ejected by a inkjet printeremit laser light. The laser light can be turned on and off by applying an electric field to the droplets. These droplets are extremely small (30 µm in diameter) and can be densely arranged in large quantities over areas of up to several centimeters.

When an electric field is applied to the droplet by placing it between electrodes, the spherical droplet deforms into an ellipsoidal shape, causing the laser light emission to stop.

This demonstrated that the droplet functions as an electrically switchable “laser pixel.” Additionally, the researchers discovered that the laser emission from each pixel can be controlled individually in a 2 × 3 array of these pixels. droplets.

Further improvements in electrical device configuration and laser performance are expected to contribute significantly to the future development of commercial laser displays.