Universal p-Type Doping via Lewis Acid for 2D Transition-Metal Dichalcogenides.

Developing spatially controlled and universal p-type doping of transition-metal dichalcogenides (TMDs) is critical for optoelectronics. Here, a facile and universal p-doping strategy via Sn 4+ ions exchanging is proposed and the p-doping of PdSe 2 is demonstrated systematically as the example. The polarity of PdSe 2 can be modulated from n-type to bipolar and p-type precisely by changing the concentration of SnCl 4 solution. The modulation effectively reduces the electron concentration and improves the work function by ∼72 meV. In addition, the solution-processable route makes the spatially controlled doping possible, which is demonstrated by constructing the lateral PdSe 2 p-n homojunction with rectification behavior and photovoltaic effect. This p-doping method has been further proved in modulating various TMDs including WSe 2 , WS 2 , ReSe 2 , MoSe 2 , MoTe 2 , and PtSe 2 . This spatially controlled and universal method based on Sn atoms substitution realizes p-type doping of TMDs.