Negative differential resistive switching in poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) thin film through electrohydrodynamic atomization
Muhammad Naeem Awais1, Jeong-Dai Jo2and Kyung Hyun Choi1*
1Department of Mechatronics Engineering, Jeju National University, Jeju, Korea
2Korea Institute of Machinery and Materials, Daejon, Korea
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*Phone: +82-64-754-3713
*Fax: +82-64-752-3174
Journal of Applied Physics A: Materials Science & Processing
Details about the deposition of PEDOT:PSS
PEDOT:PDD ink was filled in the syringe that was connected to the syringe pump. Polymeric ink was pumped to the metallic nozzle through Teflon tube by the syringe pump.Under the absence of electric field from nozzle to the substrate only dripping of the conjugated polymer came into happened due to the gravity. When the metallic nozzle was forced with the positive potential through high voltage source and the substrate was grounded, the meniscus appearing at the apex of the nozzle deformed into dripping, micro-dripping, unstable cone-jet and finally into a conical shape according to the voltage level supplied by the high power source. The conical shape (Taylor cone) appeared because of the electric stress overcome the surface tension of the liquid (PEDOT:PSS ink) and thin liquid jet came out of the Taylor cone. The jet emerging at the apex of the Taylor cone was given a sufficient flight time by adjusting the distance from nozzle to substrate so that it disintegrated into uniform small droplets and collected over the ITO coated PET substrate. During the flight time of the droplets most of solvent evaporated. Further increase in voltage resulted into a multi cone-jet mode of the EHDA process of the PEDOT:PSS ink. All the EHDA modes appeared in the deposition of the PEDOT:PSS ink are shown in figure ESM_1. PEDOT:PSS operating envelope was also investigated with different voltages and flow rates of the polymeric ink as shown in figure ESM_2. The shaped area in the graph indicates the cone-jet mode of the EHDA of PEDOT:PSS ink that is needed to deploy a uniform nano-layer of PEDOT:PSS polymeric ink.
List of Figures
FigureESM_1.EHDA modes of PEDOT:PSS Ink: (a) Dripping (b) Unstable Cone-Jet (c) Cone-Jet (d) Multi Cone-Jet
FigureESM_2.Operating envelope of the EHDA of PEDOT:PSS ink