PEDOT:PSS deposition in OECTs: Inkjet printing, aerosol jet printing and spin coating

As the world moves towards integrating new functionalities into everyday objects, the demand for diverse substrates grows, making additive manufacturing an invaluable tool. Organic electronic materials have played a major role in this transition thanks to their excellent electronic and mechanical properties, adaptability and solution processability. The aim of this study is to compare spin coating, inkjet printing (IJP), and aerosol jet printing (AJP) for applying poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as the channel material in organic electrochemical transistors (OECTs). This work investigates the often-overlooked impact of deposition techniques on the electrical performance of OECTs. Spin coating has been analysed as a reference technique, while AJP and IJP are addressed as promising pathways towards fully printed OECTs. The normalized transconductance and Ion/Ioff ratio have been analysed as figures of merit for this study. AJP devices have shown the best performance, displaying a normalized transconductance of 885 S∙nm and an Ion/Ioff ratio around 10^3. The spin coated OECTs showed a slightly lower normalized transconductance (740 S∙nm) and much lower Ion/Ioff ratio in the order of 10^1. Last, IJP exhibited a transconductance of 433 S∙nm and a Ion/Ioff ratio in the order of 10^2. This work could be beneficial for a wide range of applications, adding an additional degree of freedom to the tunability of the OECT channel properties. It also opens the discussion for more comprehensive studies on the films from a materials perspective.