Highly in-plane anisotropic optical properties of fullerene monolayers

Both the intrinsic anisotropic optical materials and fullerene-assembled 2D materials have attracted much interest in fundamental science and potential applications. The synthesis of a monolayer (ML) fullerene makes the combination of these two features plausible. In this work, using first-principles calculations, we systematically study the electronic structure and optical properties of quasi-hexagonal phase (qHP) ML and quasi-tetragonal phase (qTP) ML fullerenes. The calculations of qHP ML show that it is a semiconductor with small anisotropic optical absorption, which agrees with the recent experimental measurements. However, the results for qTP ML reveal that it is a semimetal with highly in-plane anisotropic absorption. The dichroic ratio, namely the absorption ratio of x- and y-polarized light alpha(xx)/alpha(yy), is around 12 at photon energy of 0.29 eV. This anisotropy is much more pronounced when the photon energy is between 0.7 and 1.4 eV, where alpha(xx) becomes nearly zero while alpha(yy) is more than two orders of magnitude larger. This indicates qTP ML as a candidate for long-pursuit lossless metal and a potential material for atomically thin polarizer. We hope this will stimulate further experimental efforts in the study of qTP ML and other fullerene-assembled 2D materials.

Automated summary

This study investigates the electronic structure and optical properties of quasi-hexagonal phase (qHP) and quasi-tetragonal phase (qTP) monolayer fullerenes. It is found that qHP is a semiconductor whereas qTP is a semimetal with highly in-plane anisotropic absorption. The anisotropy of qTP suggests its potential as a long-pursuit lossless metal and atomically thin polarizer.