Optical Characterization of Highly Conductive Single-Wall Carbon-Nanotube Transparent Electrodes

We report on a complete characterization of the optical dispersion properties of conducting thin films of single-wall carbon nanotubes (SWCNTs). The films studied exhibit sheet resistances between 50 and 1000 Ω sq and optical transparencies between 65% and 95% on glass and quartz substrates. These films have the potential to replace transparent conducting oxides in applications such as photovoltaics and flat-panel displays; however, their optical properties are not sufficiently well understood. The SWCNT films are shown to be hole conductors, potentially enabling their use as hole-selective contacts and allowing alternative device designs. The fundamental optical, morphological, and electrical characteristics of the films are presented here, and a phenomenological optical model that accurately describes the optical behavior of the films is introduced. Particular attention is paid to ellipsometry measurements and thorough evaluation of the reflection and absorption spectra of the films.