Design Criteria for Transparent Single-Wall Carbon Nanotube Thin-Film Transistors

Abstract

A study based on two-dimensional percolation theory yielding quantitative parameters for optimum connectivity of transparent single-wall carbon nanotube (SWNT) thin films is reported. Optimum SWNT concentration in the filtrated solution was found to be 0.1 mg/L with a volume of 30 mL. Such parameters lead to SWNT fractions in the films of approximately Φ = 1.8 × 10^-3, much below the metallic percolation threshold, which is found to be ∼Φ_C = 5.5 × 10^-3. Therefore, the performance of transparent carbon nanotube thin-film transistors is limited by the metallic SWNTs, even below their percolation threshold. We show how this effect is related to hopping or tunneling between neighboring metallic tubes.