Abnormal temperature-dependent photoluminescence characteristics of ReS₂nanowalls

Two samples with [001] orientated rhenium disulfide (ReS₂) nanowalls (NWs) grown above and in front of precursor (NH₄ReO₄) by chemical vapor deposition were investigated. The temperature-dependent photoluminescence (PL) indicated that the PL peak exhibited linear blue-shift at a rate of ∼0.24 meV K^-1with increasing the temperature from 10 to 300 K, while the linewidth monotonically increased due to the exciton-phonon interaction. This abnormal blue-shift of PL emission energy, which is explained by a competition between the band gap shrinkage and the energy level degeneracy with respect to the increase of temperature and lattice constant, enables ReS₂NWs to possess great potential for development of thermal sensors. In addition, exciton localization effect in the ReS₂NWs from abundant edges and weak interlayer interaction was also observed to be related to the height and density of ReS₂NWs. These results not only enrich the understanding for exciton dynamics in ReS₂NWs, but also help to exploit ReS₂NWs for device applications.