A new roll-to-roll compatible process can produce organic light-emitting electrochemical cells (LECs) under ambient conditions, which could lead to large-area light-emitting devices used in informative displays, and, later, in lighting applications. Umeå University physics professor Ludvig Edman and his colleagues are developing LECs that use innovative organic materials such as graphene and light-conducting and -emitting polymers. The researchers have enhanced the operating life and energy efficiency of the devices, and demonstrated the unique physics and chemistry behind their operation. A roll-to-roll compatible process produces organic light-emitting electrochemical cells that could lead to large-area light-emitting devices used in informative displays, and even lighting. (Image: Umeå University) Once they had improved the performance to a level suitable for signage applications, they needed to ensure that the manufacturing costs could be low enough for commercial applications. The team used air-stable materials in a roll-coater apparatus to deposit a PEDOT:PSS anode and a light-emitting layer over a flexible cathode-coated substrate mounted on a roll via a slot-die head. The resulting layers were highly uneven, and the thickness of both the anode and the active layer was approximately 1 µm. However, because of its unique self-doping operation, the LEC emitted light uniformly, a feature suitable for roll-to-roll processes. The LEC technology can be used to fabricate large-area light-emitting devices at a lower cost under ambient conditions because all of the steps involved, including ink preparation, the subsequent constituent layer coating and the final device operation, can be carried out under ambient air. Henrik Dam and professor Frederik Krebs of the Technical University of Denmark contributed to the work. Edman has founded LunaLEC to develop LECs for commercial applications. The technology was described in Nature Communications. For more information, visit: www.physics.umu.se/english/research/photonics/organic-electronics