Publication Date:
2014-12-20
Description:
We report photoluminescence measurements performed on monolayer- and two-layer-MoS 2 placed on two types of mixed self-assembled monolayers (mSAMs) of photoswitchable azobenzene molecules. The two mSAMs differ via the electronegative character of the azobenzene derivatives. Thin layers of a transition metal dichalcogenide—MoS 2 —were mechanically exfoliated on mSAM to allow for direct interaction between the molecules and the MoS 2 layers. When the MoS 2 nanosheet is in contact with the electropositive azobenzene molecules in trans configuration, an emission side band at lower energies and at low excitation powers suggest n-type doping. The photoisomerization of the molecules from trans to cis configuration lowers the doping, quenching the side band and enhancing the overall PL efficiency by a factor of ∼3. Opposite results were observed with the chlorinated, more electronegative molecules, exhibiting a reversed trend in the PL efficiency between trans and cis , but with an overall larger intensity. The type of doping induced by the two types of mSAMs was determined by Kelvin probe force microscopy technique.
Print ISSN:
0003-6951
Electronic ISSN:
1077-3118
Topics:
Physics
Permalink