Electron–Phonon Interaction in Organic/2D-Transition Metal Dichalcogenide Heterojunctions: A Temperature-Dependent Raman Spectroscopic Study

[Image: see text] The heterojunctions of organic/two-dimensional transition metal dichalcogenides (TMDs) have the potential to be used in the next-generation optoelectronic and photonic devices. Herein, we have systemically investigated the temperature-dependent Raman spectroscopy to elucidate the phonon shift and thermal properties of the semiconducting TMD nanosheets grafted by a conjugated polymer (PG-MoS(2) and PG-MoSe(2)) forming heterojunctions. Our results reveal that softening of Raman modes of PG-TMDs as temperature increases from 77 to 300 K is due to the negative temperature coefficient (TC) and anharmonicity. The TCs of E(1)(2g) and A(1g) modes of PG-MoS(2) nanosheets and A(1g) mode of PG-MoSe(2) were found to be −0.015, −0.010, and −0.010 cm(–1) K(–1), respectively. The origin of negative TCs is explained on the basis of a double resonance process, which is more active in single- and few-layer MoS(2) and MoSe(2). Interestingly, the temperature-dependent behavior of the phonon modes of PG-MoS(2) and PG-MoSe(2) is similar to that of pristine nanosheets. Grafting by conjugated polymer does not affect the electron–phonon (e–p) interaction in the semiconducting (2H-phase) TMDs, hinting the application potential of such materials in field-effect electronic devices.