Direct Printing of Asymmetric Electrodes for Improving Charge Injection/Extraction in Organic Electronics

Abstract

Engineering the energy levels of organic conducting materials can be useful for developing high-performance organic field-effect transistors (OFETs), whose electrodes must be well controlled to facilitate easy charge carrier transport from the source to drain through an active channel. However, symmetric source and drain electrodes that have the same energy levels are inevitably unfavorable for either charge injection or charge extraction. In this study, asymmetric source and drain electrodes are simply prepared using the electrohydrodynamic (EHD)-jet printing technique after the careful work function engineering of organic conducting material composites. Two types of additives effectively tune the energy levels of poly­(3,4-ethylenedioxythiophene) polystyrene sulfonate-based composites. These solutions are alternately patterned using the EHD-jet printing process, where the use of an electric field makes fine jet control that enables to directly print asymmetric electrodes. The asymmetric combination of EHD-printed electrodes helps in obtaining advanced charge transport properties in p-type and n-type OFETs, as well as their organic complementary inverters. This strategy is believed to provide useful guidelines for the facile patterning of asymmetric electrodes, enabling the desirable properties of charge injection and extraction to be achieved in organic electronic devices.

Directly Patterning Conductive Polymer Electrodes on Organic Semiconductor via In Situ Polymerization in Microchannels for High-Performance Organic Transistors

“…Remarkably, as shown in Figures c,d and S14, the PPy top-contacted DNTT transistor obtained a width-normalized contact resistance as small as 1.01 kΩ·cm under a −60 V gate voltage, which is much smaller than most of the conductive polymer contacted transistors with well-defined field-effect characteristics (Table ). ,,− Although the contact resistance in this work is less than that of the reported device with conductive polymer electrodes, it should be noted that the lower contact resistance (tens and hundreds of Ω·cm) has been achieved with other combinations of organic semiconductor/ metal electrodes. , For the OFETs with top-contacted PPy electrodes, some reasons for the excellent contact performance can be understood as follows. (1) The PPy electrode film grown in situ is conformally adsorbed on the semiconductor, which effectively improves the quality of the interface between electrode and semiconductor.…”

Current developments of eco-friendly organic field-effect transistors: from molecular engineering of organic semiconductors to greener device processing

“…19,115 PEDOT:PSS, the most commonly used conductive polymer, is a water-soluble material that has been widely used as an electrode for OFETs by improving conductivity using eco-friendly solvents such as ethylene glycol and dimethyl sulfoxide. 116,117 Watersoluble and alcohol-based silver inks have also been widely utilized as electrode materials for OFETs. 118 Besides, Tang et al reported the MXene ink dissolved in ethanol, and applied the MXene source/drain electrodes for OFETs.…”

Fabrication of Electronics by Electrohydrodynamic Jet Printing

“…[10] The high resolution is very important for the fabrication of the electronics with high density or precision as electrode, transistor, sensor, and heater. [11][12][13][14] Researchers have summarized the ink properties, the printer system, and the substrates for the e-jet printing. The mechanism of electrohydrodynamic-induced fluid movement, interface controlling, or e-jet printing as an additive manufacture method for flexible electronics has been reviewed.…”