Semiconducting Carbon Nanotube Networks for Flexible and Stretchable High-Frequency Circuits
Final Report Abstract
The selective dispersion of semiconducting single-walled carbon nanotubes by wrapping with conjugated polymers in organic solvents enables subsequent solution-processing into random networks that can act as the semiconducting layer in field-effect transistors with high carrier mobilities. Thus, they become suitable for high-frequency electronics on flexible substrates. A range of the polyfluorene-based conjugated co-polymers were designed and synthesized that not only enabled selective dispersion but also had cleavable groups within the polymer backbone that should allow for their complete removal after network deposition. While some of the polymers showed good selectivity toward semiconducting carbon nanotubes, they could not be cleaved without also damaging the nanotubes. Hence, random networks of nanotubes with different diameters were deposited with as little as possible of non-cleavable conjugated polymer and characterized. Field-effect transistors with ultrathin hybrid gate dielectrics were fabricated on flexible polyimide substrates. They showed good ambipolar charge transport with high hole and electron mobilities (5 - 15 cm²/(Vs)). The transistors operated reproducibly at very low voltages (< 2 V) even under repeated bending and could be tuned to be only ptype or only n-type by treatment with various molecular dopants (ttmgb, F4TCNQ and HATCN). The obtained complementary transistors were integrated in simple inverter circuits that showed good rail-to-rail operation with high gain and low static power consumption. Overall, we could show that transistors with doped, polymer-sorted nanotube networks exhibit promising properties for high-frequency circuits on flexible polymer substrates.
Publications
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Molecular n-Doping of Large- and Small-Diameter Carbon Nanotube Field-Effect Transistors with Tetrakis(tetramethylguanidino)benzene. ACS Applied Electronic Materials, 3(2), 804-812.
Gotthardt, Jan M.; Schneider, Severin; Brohmann, Maximilian; Leingang, Simone; Sauter, Eric; Zharnikov, Michael; Himmel, Hans-Jörg & Zaumseil, Jana
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Poster at NT22 Conference 2022 in Suwon, Republic of Korea (Best Poster Award) “Molecular Doping of Bottom-Gate Top-Contact Semiconducting Carbon Nanotube Network Field-Effect Transistors for Flexible Electronics”
J.M. Gotthardt
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Talk at MRS Fall Meeting 2022, Symposium NM02 “Molecular Doping of Bottom-Gate/Top-Contact Nanotube Network Field-Effect Transistors for Flexible Electronics”
J.M. Gotthardt
