Polyethylene glycol (PEG) assembled on the surface of two-dimensional tungsten disulfide (WS2) into a limited number of nanoislands (NIs), nanoshell (NS), and granular nanoparticulates (GNPs) depending on its chain length. NIs assemblies showed a non-measurable shift of photoluminescence (PL) and the A and B absorption peaks of WS2. This confirmed that the electronic doping by thiol is not effective. PEG NS assembly displayed a smaller red-shift of the PL and a slight decrease of the energy difference between the A and B absorption peaks of WS2. However, increasing the dielectric function on the surface of WS2 has a small influence on their optical properties. The PEG NPs assembly on WS2 exhibited a significant red-shift of the PL spectrum and a large decrease of the energy difference between A and B absorption peaks. Deforming the WS2 sheet by PEG NPs assembly decreased the orbital coupling and lowered the electronic direct band gap significantly. Raman bands of WS2 are shifted to a higher frequency due to improving its mechanical strength after PEG assembly.

Tuning the band gap of semiconducting two-dimensional materials by changing the structure of polymer assembled on their surface

2019 Fall National Meeting

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