Tailoring of bound exciton photoluminescence emission in WS${}_2$ monolayers

Temperature‐ and laser power‐dependent photoluminescence (PL) properties of the asymmetric defect‐bound exciton band 𝑋${}_D$ in defective WS${}_2$ monolayers, grown by chemical vapor deposition, are studied. Based on PL mapping, a monolayer region with an intensive 𝑋D band emission at about 1.9 eV is chosen for further studies. The 𝑋D band is thermally quenched above 180 K, and the thermal activation energy is found to be 𝐸${}_a$ = 33 ± 4 meV. At 𝑇= 15 K, the 𝑋${}_D$ band intensity reveals a sublinear dependence with increasing excitation power and the peak position shows a blueshift of about 15 meV per decade of laser power. It is shown that the 𝑋${}_D$ band is related to the deep defect states within the band gap of WS${}_2$. (© 2019 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)