The record low thermal conductivity of monolayer Cuprous Iodide (CuI) with direct wide bandgap

TL;DR

This study predicts that monolayer CuI has an exceptionally low thermal conductivity and a wide direct bandgap, making it promising for nano-electronics and optoelectronic applications.

Contribution

The paper reports the first prediction of ultralow thermal conductivity and a wide direct bandgap in monolayer CuI using first-principles calculations.

Findings

Thermal conductivity of 0.116 W/mK in monolayer CuI

Wide direct bandgap of 3.57 eV in monolayer CuI

Significant improvement over bulk CuI properties

Abstract

Two-dimensional materials have attracted lots of research interests due to the fantastic properties that are unique to the bulk counterparts. In this paper, from the state-of-the-art first-principles, we predicted the stable structure of monolayer counterpart of the {\gamma}-CuI (Cuprous Iodide), which is a p-type wide bandgap semiconductor. The monolayer CuI presents multifunctional superiority in terms of electronic, optical, and thermal transport properties. Specifically, the ultralow thermal conductivity of 0.116 Wm-1K-1 is predicted for monolayer CuI, which is much lower than {\gamma}-CuI (0.997 Wm-1K-1) and other typical semiconductors. Moreover, an ultrawide direct bandgap of 3.57 eV is found in monolayer CuI, which is larger than {\gamma}-CuI (2.95-3.1 eV), promoting the applications in nano-/optoelectronics with better optical performance. The ultralow thermal conductivity and direct wide bandgap of monolayer CuI as reported in this study would promise its potential applications in transparent and wearable electronics.