Abstract
Hole carrier doping into single-crystalline transition metal dichalcogenide (TMDC) films can be achieved with various chemical reagents. However, large-area polycrystalline TMDC monolayers produced by a chemical vapor deposition (CVD) growth method have yet to be chemically doped. Here, we report that a salt of a two-coordinate boron cation, Mes 2 B + (Mes: 2,4,6-trimethylphenyl group), with a chemically stable tetrakis(pentafluorophenyl)borate anion, [(C 6 F 5 ) 4 B] - , can serve as an efficient hole-doping reagent for large-area CVD-grown tungsten diselenide (WSe 2 ) films. Upon doping, the sheet resistance of large-area polycrystalline WSe 2 monolayers decreased from 90 GΩ/sq to 3.2 kΩ/sq.