Polyethylene glycol (PEG) assembled on the surface of two-dimensional tungsten disulfide (WS 2 ) into a limited number of nanoislands (NIs), nanoshells (NSs), and granular nanoparticulates (GNPs) depending on its chain length. NI assemblies showed a nonmeasurable shift of photoluminescence (PL) and the A and B absorption peaks of WS 2 . This confirmed that the electronic doping by thiol is not effective. The 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 WS 2 . However, increasing the dielectric function on the surface of WS 2 has a small influence on their optical properties. The PEG NP assembly on WS 2 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 WS 2 sheet by the PEG NP assembly decreased the orbital coupling and lowered the electronic direct band gap significantly. Raman bands of WS 2 are shifted to a higher frequency on improving its mechanical strength after the PEG assembly.

Ultra-high-resolution optical microscopic techniques are used to measure the reflectance and photoluminescence (PL) spectrum of individual monolayered MoS 2 of dimensions below 200 × 200 nm, while placed on top of a thin film conjugated polymer (CP). p-type and n-type CPs such as poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM), respectively, modified the optical band gap of the MoS 2 sheet differently. However, the optical band gap is decreased after integration with P3HT, while it is increased after being combined with PCBM. The acceptable reason for the modification of the band gap of MoS 2 by CPs is the generation of interlayer excitons (ILE) at their interface. The optical band gap of MoS 2 is further changed by introducing an inert polymer spacer of different thickness to separate MoS 2 from the CP. This is attributed to the reduction of the efficiency of excitonic interactions and lowering the exciton binding energy, which is induced by the increase of the dielectric function at the CP−MoS 2 interface. No sign of electron injection to the conduction band of MoS 2 after integration with P3HT or PCBM, as no significant shift of the A 1 ′ Raman band of MoS 2 was measured on top of CPs, which is sensitive to the electron injection.