Interfacial Charge Transfer Induced Electronic Property Tuning of MoS2 by Molecular Functionalization

The modulation of electrical properties of MoS2 has attracted extensive research interest because of its potential applications in electronic and optoelectronic devices. Herein, interfacial charge transfer induced electronic property tuning of MoS2 are investigated by in situ ultraviolet photoelectron spectroscopy and x-ray photoelectron spectroscopy measurements. A downward band-bending of MoS2-related electronic states along with the decreasing work function, which are induced by the electron transfer from Cs overlayers to MoS2, is observed after the functionalization of MoS2 with Cs, leading to n-type doping. Meanwhile, when MoS2 is modified with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F (4)-TCNQ), an upward band-bending of MoS2-related electronic states along with the increasing work function is observed at the interfaces. This is attributed to the electron depletion within MoS2 due to the strong electron withdrawing property of F (4)-TCNQ, indicating p-type doping of MoS2. Our findings reveal that surface transfer doping is an effective approach for electronic property tuning of MoS2 and paves the way to optimize its performance in electronic and optoelectronic devices.