Spectroscopic Studies of the Physical Origin of Environmental Aging Effects on Doped Graphene

TL;DR

This study investigates how environmental factors like humidity and defects cause aging in doped graphene, revealing that water reactions with dopants lead to degradation, which can be mitigated by additional graphene layers.

Contribution

It provides a detailed spectroscopic analysis of the physical mechanisms behind environmental aging in doped graphene and shows how layered structures can reduce degradation.

Findings

Higher humidity accelerates graphene degradation.

Water reacts with dopants causing chemical and structural damage.

Additional graphene layers mitigate aging effects.

Abstract

The environmental aging effect of doped graphene is investigated as a function of the organic doping species, humidity, and the number of graphene layers adjacent to the dopant by studies of the Raman spectroscopy, x-ray and ultraviolet photoelectron spectroscopy, scanning electron microscopy, infrared spectroscopy, and electrical transport measurements. It is found that higher humidity and structural defects induce faster degradation in doped graphene. Detailed analysis of the spectroscopic data suggest that the physical origin of the aging effect is associated with the continuing reaction of H2O molecules with the hygroscopic organic dopants, which leads to formation of excess chemical bonds, reduction in the doped graphene carrier density, and proliferation of damages from the graphene grain boundaries. These environmental aging effects are further shown to be significantly mitigated by added graphene layers.