Organic Vapor‐Jet Printing with Reduced Heat Transfer for Fabrication of Flexible Organic Devices

Abstract

Abstract Organic vapor‐jet printing (OVJP) is an ink‐free printing method for organic thin films wherein a thermally generated vapor of organic small molecules is jetted through a nozzle by inert carrier gas. OVJP holds a great promise because it uses a field‐proven small‐molecular technology as it yet keeps the benefits of jet printing methods such as being mask‐free, easily scalable, and frugal in material usage. However, fabrication on plastic substrates with OVJPs is challenging due to the excessive heat from the nozzle, preventing its use for flexible electronics. Thermal damage issues in the OVJP are particularly of problem because its nozzle should be close to a substrate for high‐resolution patterning. Here, a simple yet highly effective method is proposed to reduce the radiant heat transfer from the nozzle and thereby enable fabrication of flexible organic devices. Upon application of an electroplated gold layer on the nozzle as a low‐emissivity coating, the temperature of a substrate underneath the nozzle gets significantly reduced below its glass‐transition temperature. A flexible organic light‐emitting diode signage device and an active‐matrix tactile sensor patch are demonstrated on plastic substrates with the proposed approach, demonstrating its feasibility in unlocking the full potential of OVJP methods.