Imec, a research and innovation hub in nano­electronics and digital techno­logies in Leuven, Belgium, presents a perovskite LED stack (PeLED), emitting light a thousand times brighter than state-of-the-art OLEDs. This result is a pivotal step towards a perovskite injection laser, promising exciting appli­cations in image projection, environmental sensing, medical diagnostics, and beyond. 

From appli­cations in our homes to industry, LEDs are used for all lighting applications, from indoor lighting over TV screens to biomedicine. Widely used organic LEDs (OLEDs) today, for example in smartphone screens, employ organic thin-film materials as a semiconductor. However, their maximum brightness remains limited; just think of trying to read your smartphone screen on a very sunny day. Meanwhile, perovskites – a class of materials with a specific crystal structure – are proving their worth beyond solar cells. With excellent opto­electrical properties, low-cost processa­bility and efficient charge transport, these materials have emerged in the last ten years as interesting candidates for light emission appli­cations, such as LEDs.

However, while perovskites can withstand very high current densities, laser operation with the emission of high-intensity coherent light has not been reached yet. “In the ULTRA-LUX project, imec showed for the first time a PeLED archi­tecture with low optical losses and pumped these PeLEDs to current densities that support the stimulated emission of light”, explained Paul Heremans, the principal inves­tigator of the project. “This novel architecture of transport layers, transparent electrodes and perovskite as the semi­conductor active material, can operate at electrical current densities tens of thousands of times higher than conventional OLEDs can.”

“With this architecture, imec enhanced amplified spon­taneous emission, with an electrical assist of the conventional optical pumping. By doing so, imec demonstrated that electrical injection contributes 13 percent to the total amount of stimulated emission and thus approaches the threshold to achieve a thin-film injection laser”, stated Robert Gehlhaar, imec project manager. “Reaching this landmark milestone towards high-power thin-film laser diodes is paving the way to exciting new appli­cations of thin-film perovskite lasers.” (Source: imec)

Reference: K. Elkhouly et al.: Electrically assisted amplified spontaneous emission in perovskite light-emitting diodes, Nat. Phot., online 3 January 2024; DOI: 10.1038/s41566-023-01341-7

Link: Large Area Electronics, IMEC, Leuven, Belgium