Facile Doping and Work‐Function Modification of Few‐Layer Graphene Using Molecular Oxidants and Reductants

Abstract

Doping of graphene is a viable route towards enhancing its electrical conductivity and modulating its work function for a wide range of technological applications. In this work, we demonstrate facile, solution-based, non-covalent surface doping of few-layer graphene (FLG) using a series of molecular metal-organic and organic species of varying n-and p-type doping strengths. In doing so we tune the electronic, optical and transport properties of FLG. We modulate the work function of graphene over a range of 2.4 eV (from 2.9 to 5.3 eV) -unprecedented for solution-based doping -via surface electron transfer. A substantial improvement of the conductivity of FLG is attributed to increasing carrier density, slightly offset by a minor reduction of mobility via Coulomb scattering. The mobility of single layer graphene has been reported to decrease significantly more via similar surface doping than FLG, which has the ability to screen buried layers. The dopant dosage influences the properties of FLG and reveals an optimal window of dopant coverage for the best transport 2 properties, wherein dopant molecules aggregate into small and isolated clusters on the surface of FLG. This study shows how soluble molecular dopants can easily and effectively tune the work function and improve the optoelectronic properties of graphene.

Formation of environmentally stable hole-doped graphene films with instantaneous and high-density carrier doping via a boron-based oxidant

“…Moreover, the decrease in R/R 0 was saturated within a short time (~4 s), which is substantially faster than previously reported hole-doping times (60 min). 24 It should be noted that we performed the same experiments using a lower density ODCB solution of Mes 2 B + [(C 6 F 5 ) 4 B] − (0.3 mg/mL), and the necessary doping time is very similar (see supplementary S2), also revealing efficient carrier doping by Mes 2 B + [(C 6 F 5 ) 4 B] − . However, the achieved R/R 0 by the lower density ODCB solution (35.0%) is slightly higher than that of saturated ODCB solution (see supplementary S2).…”

“…To date, numerous accounts of the chemical doping of graphene have been reported. 3,[18][19][20][21][22][23][24][25][26][27][28][29] However, none of them fulfills all four of the aforementioned requirements.…”

A Computational Approach toward the Enhanced Performance of Graphene–Perovskite Schottky Solar Cells

“…For graphene–perovskite Schottky solar cell, graphene not only served as a conductive electrode for carrier collection but also as an optical window. The Schottky barrier height is a crucial factor that determines the solar cell performance, which is directly related to the graphene WFWF, and its value can be tuned in a wide range . To investigate the effects of Schottky barrier height on device performance, the graphene WF is varied from 4.6 to 5.6 eV, whereas the back contact WF is kept as 4.1 eV.…”

2D Materials for Large‐Area Flexible Thermoelectric Devices

“…However, there are various requirements in these solution‐based doping methods: i) tuning of the wide‐range carrier density to exceed the optimum carrier density, ii) improving the long‐term air and moisture stability of the doped 2D materials, and iii) ensuring compatibility with other solution‐based processes at room temperature. Since these problems are also important to realize the optoelectronic application of 2D materials, such as large‐area graphene transparent electrodes, many chemical dopant molecules have been investigated in an attempt to satisfy the above requirements in this field as well . Although the search for the best dopants is still ongoing, the developed doping techniques will be applied to the 2D thermoelectric research field.…”