The 85th Meeting of the Israel Chemical Society

Influence of ethylene amine doping on the work function and junction resistance in transparent carbon nanotubes networks

Rotem Dover 1 Chen Klein 2 Avigail Stern 1 Dvir Rotem 1 Gabby Sarusi 2 Danny Porath 1
1Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
2Electro-Optics and Photonics Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel

Transparency, flexibility and conductivity are desirable qualities for electrodes in applications such as electronic displays and solar cells. Single-walled carbon nanotube (SWCNT) networks are promising candidates for such electrodes. In order to integrate them efficiently in functional devices, the work function and the interwire resistivity must be adjusted. Specifically, SWCNTs possess high work function. Therefore, they can serve as a good transparent anode but poor transparent cathode. In addition, the interwire (junction) resistivity is known as the limiting factor for networks conductivity.1 One approach to enhance both factors is by doping. Short ethylene amines have been reported as stable n-type dopants for graphene by forming non-covalent bonds.2 Here, we show the influence of Triethylenetetramine (TETA) doping on the interwire resistance and work function of SWCNT networks.

We used a special conductive atomic force microscopy (cAFM) setup to determine the resistance of individual junctions before and after exposure to heat and TETA fumes. This setup involves a stationary gold electrode that is evaporated over the nano-wires of interest and a cAFM tip serving as a second mobile electrode that contacts single nano-wires protruding beneath the gold electrode. The setup allowed measurement of specific locations before and after the TETA treatment. Undesirable increase in junction resistance from 106.5±0.2Ω to 107.0±0.2Ω observed. However, additional heating reduced the resistance to 106.0±0.3Ω. Kelvin-Probe measurements showed a stable decrease of the network work function by nearly 0.5ev as a result of the TETA doping. Understanding the factors which governs the doping properties is important for controlling the physical properties of SWCNT. Thus, allowing the tailoring of materials for designated devices and applications.

1. A.Stern, S.Azoubel, E.Sachyani, G.I.Livshits, D.Rotem, S.Magdassi and D.Porath, Journal of Physical Chemistry C, 2018, 122, 14872-14876.
2. I.Jo, Y.Kim, J.Moon, S.Park, J.S.Moon, W.B.Park, J.S.Lee and B.H.Hong, Physical Chemistry Chemical Physics, 2015, 17, 29492-29495.









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