Molecularly Smooth Self-Assembled Monolayer for High-Mobility Organic Field-Effect Transistors.

Das, Saurabh; Lee, Byoung Hoon; Linstadt, Roscoe T H; Cunha, Keila; Li, Youli; Kaufman, Yair; Levine, Zachary A; Lipshutz, Bruce H et al. · Nano Lett · 2016

basic_science · Level V

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Abstract

Despite the need for molecularly smooth self-assembled monolayers (SAMs) on silicon dioxide surfaces (the most common dielectric surface), current techniques are limited to nonideal silane grafting. Here, we show unique bioinspired zwitterionic molecules forming a molecularly smooth and uniformly thin SAM in "water" in <1 min on various dielectric surfaces, which enables a dip-coating process that is essential for organic electronics to become reality. This monomolecular layer leads to high mobility of organic field-effect transistors (OFETs) based on various organic semiconductors and source/drain electrodes. A combination of experimental and computational techniques confirms strong adsorption (W<sub>ad</sub> > 20 mJ m<sup>-2</sup>), uniform thickness (∼0.5 or ∼1 nm) and orientation (all catechol head groups facing the oxide surface) of the "monomolecular" layers. This robust (strong adsorption), rapid, and green SAM represents a promising advancement toward the next generation of nanofabrication compared to the current nonuniform and inconsistent polysiloxane-based SAM involving toxic chemicals, long processing time (>10 h), or heat (>80 °C).