Photochemical Doping and Tuning of the Work Function and Dirac Point in Graphene Using Photoacid and Photobase Generators

Abstract

This work demonstrates that photochemical doping of CVD-grown graphene can be easily achieved using photoacid (PAG) and photobase (PBG) generators such as triphenylsulfonium perfl uoro-1-butanesufonate (TPS-Nf ) and 2-nitrobenzyl N -cyclohexylcarbamate (NBC). The TPS-Nf ionic onium salt photoacid generator does not noticeably dope or alter the electrical properties of graphene when coated onto the graphene surface, but is very effective at inducing p-doping of graphene upon exposure of the PAG-coated graphene sample. Likewise, the neutral NBC photobase generator does not signifi cantly affect the electrical properties of graphene when coated, but upon exposure to ultraviolet light produces a free amine, which induces n-doping of the graphene. Electrical measurements show that the doping concentration can be modulated by controlling the deep ultraviolet (DUV) light exposure dose delivered to the sample. The interaction between both dopants and graphene is also investigated. The photochemical doping process is able to tune the work function of the single-layer graphene samples used in this work from 3.4 eV to 5.3 eV. Finally, a p-n junction is fabricated and analyzed, showing that it is possible to control the position of the two current minima (two Dirac points) in the ambipolar p-n junction.

Recent Advances and Challenges in the Design of Organic Photoacid and Photobase Generators for Polymerizations

“…The most common ionic PAGs are onium salt derivatives. Although onium salts have been known for a century, their application in photopolymerization has only been recently developed . When onium salts are exposed to light, photolysis occurs, which gives rise to the simultaneous formation of Brønsted acids and cations.…”

Multifunctional oxides for integrated manufacturing of efficient graphene electrodes for organic electronics

“…[23][24][25][26] Further, lithography typically involves the use of solvents and chemicals that might affect or degrade the properties of doped graphene. [8][9][10][11]21,[27][28][29][30][31] Here, we show that all of these challenges for efficient graphene-based TCEs can be effectively addressed at once via a thin (>10 nm) metal oxide (MoO 3 or WO 3 ) coating of the graphene. The metal oxide can be deposited by various means, 9,18,19 but we focus here on thermal evaporation.…”

Graphene chemiresistors modified with functionalized triphenylene for highly sensitive and selective detection of dimethyl methylphosphonate

“…Manipulating the properties of graphene without degrading its electrical properties is highly desired to realize a wide range of applications of graphene. Previous studies have reported various dopants for graphene; [32][33][34][35][36] however, there still remain a few challenges on developing dopants that can be processed and patterned easily. Our solution-processable p-type dopant has the potential to manipulate the electrical properties of graphene, which we demonstrate for gas sensing applications.…”