Tunable n-type and p-type doping of two-dimensional layered PdSevia organic molecular adsorption.

Palladium diselenide (PdSe) is a two-dimensional (2D) transition metal dichalcogenide (TMD) semiconductor with desirable properties for nanoelectronics. Here, we demonstrate that 2D layered PdSe adsorbed with two kinds of organic molecules, an electrophilic molecule tetracyano-p-quinodimethane (TCNQ) as an electron acceptor and a nucleophilic molecule tetrathiafulvalene (TTF) as an electron donor, can realize tunable p-type and n-type doping of 2D PdSe by using first-principles density functional theory (DFT) calculations. We find that TCNQ attracts electrons from PdSe and introduces shallow acceptor states close to the valence band edge, resulting in p-type doping of PdSe, while TTF donates electrons into PdSe and introduces shallow donor states close to the conduction band edge, resulting in n-type doping of PdSe. Furthermore, such p-type and n-type doping of PdSe can be efficiently controlled with an external electric field, interlayer distance and substrate thickness. Such effective bipolar doping of PdSevia molecular adsorption would broaden its applications in nanoelectronics.