Fully Printed Electrolyte‐Gated Transistor Formed in a 3D Polymer Reservoir with Laser Printed Drain/Source Electrodes

Abstract In solution processed electronic devices it is crucial that the deposited inks are properly aligned and that all post‐processing steps are compliant with each other. Moreover, shorter channel lengths are highly beneficial to increase the device performance. Herein, laser printing of metals and polymer reservoirs allows to print sub‐micrometer sized channel lengths while confining functional inks into these small gaps. Therefore, a manufacturing concept and optimized material stack, suitable for combined inkjet and laser printing are proposed. A nanoparticulate indium oxide (In₂O₃) semiconductor is inkjet printed into and constrained by a 3D laser written polymer (pentaerythritol triacrylate, PETA) reservoir. Inside the 3D printed polymer reservoir, platinum (Pt) electrodes, that are further routed over the reservoir walls, are laser printed by a metal reduction process. The transistor fabrication is completed by a second inkjet printed layer of composite solid polymer electrolyte and an organic top‐gate layer (PEDOT:PSS). This concept does not exceed annealing temperatures higher than 100 °C, and is compatible with a range of substrates. The characterized electrolyte‐gated field‐effect transistor show a reasonable on/off‐ratio in the range of 10⁴ with negligible leakage currents. This materials and hybrid device manufacturing scheme has believed great potential for bioelectronics, lab‐on‐a‐chip applications and others.