Aerosol Jet Printed Encapsulation for Optoelectronics: A Study of Line Morphology

Hermetic encapsulation is essential for organic electronic devices such as organic light-emitting diodes (OLEDs) and organic photovoltaic (OPV) devices, which are highly sensitive to degradation caused by water and oxygen. Building on our previous work [1], this study investigates a potentially cost-effective encapsulation method using the aerosol jet printing (AJP) process with Perhydropolysilazane (PHPS) as the encapsulating material. A key focus is understanding how line morphology evolves under varying printing conditions to optimize the final encapsulation layer. Specifically, we examine the influence of different process gas flow rates, printing speed and substrate temperature on the morphology of printed PHPS lines, with particular attention to the coffee-ring effect (CRE). The CRE is characterized by the ratio of the highest line edges to the minimum line thickness, referred to as the CRE index this work. Our findings demonstrate that a CRE index of less than 2 can be achieved through careful adjustment of gas flow parameters and printing speed at room temperature. However, the AJ-printed PHPS layer still exhibits a surface roughness approximately 10 times greater than that of a blade-coated sample, primarily due to CRE and line overlapping.