Layer-dependent exciton-photon interaction in two-dimensional CrCl₃ layers

Hien Gap¹, Ranjit A. Patil^1*, Yuan-Ron Ma¹

¹Department of Physics, National Dong Hwa University, Hualien, Taiwan

* Presenter:Ranjit A. Patil, email:rapatil@gms.ndhu.edu.tw

The layer-dependent photoluminescence (PL) studies of the two-dimensional (2D) layered materials has attracted immense interest for the applications in modern on-chip optoelectronic nanodevices due to the characteristic electronic structure, strong exciton-phonon interaction, and exciton generation-recombination. The 2D single crystals of CrCl₃ flakes were synthesized using the chemical vapor transport technique and mechanically exfoliated to bilayers. The anomalous PL spectrum of layered CrCl₃ flakes is observed at varying temperatures for the first time. The temperature-dependent PL spectroscopy of flakes to the bilayer CrCl₃ shows a broadening of linewidth proportionally with increasing temperature in the range of 80–300 K. The microscale and nanoscale investigations confirm that the broadening of PL spectra of CrCl₃ with varying temperatures emphasizes the effect of the exciton–phonon interactions. The temperature-induced linewidth broadening is extensive for the bilayers compared to the 72 layers upon the cooling and heating of 2D CrCl₃ layers. In addition, the exciton-phonon coupling strength drastically decreases for the bilayer to the 72 layers, suggesting the exciton-phonon coupling-induced homogeneous broadening is significant in the bilayer compared to the multilayer.

Keywords: 2D nanomaterials, CrCl3, photoluminescence, exciton-phonon interaction, bilayer