Enhanced excitonic features in an anisotropic ReS 2 /WSe 2 heterostructure.

Two-dimensional (2D) semiconductors have opened new horizons for future optoelectronic applications through efficient light-matter and many-body interactions at quantum level. Anisotropic 2D materials like rhenium disulphide (ReS 2 ) present a new class of materials with polarized excitonic resonances. Here, we demonstrate a WSe 2 /ReS 2 heterostructure which exhibits a significant photoluminescence quenching at room temperature as well as at low temperatures. This indicates an efficient charge transfer due to the electron-hole exchange interaction. The band alignment of two materials suggests that electrons optically injected into WSe 2 are transferred to ReS 2 . Polarization resolved luminescence measurements reveal two additional polarization-sensitive exciton peaks in ReS 2 in addition to the two conventional exciton resonances X 1 and X 2 . Furthermore, for ReS 2 we observe two charged excitons (trions) with binding energies of 18 meV and 15 meV, respectively. The bi-excitons of WSe 2 become polarization sensitive and inherit polarizing properties from the underlying ReS 2 layers, which act as patterned substrates for top layer. Overall, our findings provide a better understanding of optical signatures in 2D anisotropic materials.