Particularly regarding 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 effectively used as displays, the components must be miniaturized beyond current levels and laid out in high density and large quantities. Researchers at the University of Tsukuba have developed a method for rapidly creating laser light sources in large quantities using an inkjet printer that ejects laser-emitting droplets. By applying an electric field to these droplets, the researchers demonstrated that switching the emission of light on and off is possible. Furthermore, they successfully created a compact laser display by arranging these droplets on a circuit board. A rendering of the compact laser display created by the researchers. An inkjet printer ejects laser-emitting droplets onto a circuit board and an electric field is applied to them to toggle the light emission of the droplets. Courtesy of Hiroshi Yamagishi. The researchers found that droplets of a specific organic liquid, ejected by an inkjet printer, emit laser light. These droplets are extremely small (30 µm in diameter) and can be densely arranged in large quantities over areas as large as several centimeters. When an electric field is applied to the droplet by positioning it between electrodes, the spherical droplet deforms into an ellipsoidal shape, causing the laser light emission to cease. This demonstrates that the droplet functions as an electrically switchable "laser pixel." Additionally, the researchers discovered that the laser emission of each pixel can be individually controlled in a 2×3 array of these droplets. Ultimately, the researchers were able to deposit the inkjet printed droplets with high precision, scalability, and the ability to switch electric fields using the electrodes, though they did identify some areas where the method and design would need to improve. These areas included the laser dyes’ pumping energy and lifetime as well as the laser display’s relative bulk and thickness due to the photoexcitation setup, the latter of which they believe will be solved by future advancements in waveguiding technologies that hold the promise for miniaturizing and flattening the light source and optical path. Once these have all been remedied, the researchers said that the device’s novel configuration should contribute to future advancements in laser displays and that its liquid droplets offer potential for next-generation optoelectronic devices since the droplets can be integrated into existing organic electronics that are characterized by flexibility, adaptability, and biocompatibility. The research was published in Advanced Materials (www.doi.org/10.1002/adma.202413793).