2, Sungkyunkwan University, Suwon, , Korea (the Republic of)
3, Pohang Accelerator Laboratory, Pohang, , Korea (the Republic of)
Multilayer transition metal dichalcogenides (TMDs) potentially provide opportunities for large-area electronics, including flexible displays and wearable sensors. However, most TMDs suffer from a Schottky barrier (SB) and non-uniform defects, which severely limit their electrical performances. We present a new chemical doping scheme to significantly enhance electrical characteristics of multilayer MoSe2 devices, including on-current (~2,000-fold higher) and photoresponsivity (~10-fold larger) over the baseline device. By simply coating a planar conjugated polymer (PDPP3T) on as-synthesized multilayer MoSe2, the coated PDPP3T induces strong n-doping phenomena. Based on comprehensive analysis using X-ray photoelectron spectroscopy (XPS), 2D-grazing incidence wide-angle X-ray diffraction (2D-GIWAXD), near edge X-ray absorption fine structure (NEXAFS), and other supporting spectroscopy techniques, we show that two mechanisms (dipole-induced and charge-transfer doping effects) account for such enhancements in the multilayer MoSe2 device. We further demonstrate the methodical generality of the strong n-doping behaviour of multilayer MoSe2 by applying thiophene instead of PDPP3T.