Optical properties and birefringence of ZnIn2S4 layered crystals

Defect-Mediated Slow Carrier Recombination and Broad Photoluminescence in Non-Metal-Doped ZnIn2S4 Nanosheets for Enhanced Photocatalytic Activity

“…This means that the optical band edge must be lying in the 460–490 nm region of the electromagnetic spectra. Hence the 400 nm hump must be originating from higher energy excitonics transitions triumphing over the lower energy transitions, which has already been discussed in the case of ZIS nanosheets . Following O doping, the absorption of ZIS is greatly enhanced, which indicates the presence of a larger number of defect states (active sites) in the system.…”

“…These three peaks correspond to the intrinsic photoluminescence of ZIS along with two defect-state-mediated transitions. These bands correspond to the different transitions in the ZIS electronic band structure . The presence of a broad PL spectrum in the red region indicates closely spaced defect states in the inter-band-gap region of ZIS.…”

“…Hence the 400 nm hump must be originating from higher energy excitonics transitions triumphing over the lower energy transitions, which has already been discussed in the case of ZIS nanosheets. 29 Following O doping, the absorption of ZIS is greatly enhanced, which indicates the presence of a larger number of defect states (active sites) in the system. This is also observable for the N-doping case, although the intensity is not that high.…”

“…These bands correspond to the different transitions in the ZIS electronic band structure. 29 The presence of a broad PL spectrum in the red region indicates closely spaced defect states in the inter-band-gap region of ZIS. With O doping, the PL spectrum undergoes an almost two-fold increment in the intensity, which is possibly the resultant of the enhancement of charge carriers in the system.…”

“…Previously, Stamov et al reported several optical signatures in ZIS polytypes for direct transitions in the Γ space of the ZIS band structure. 29 They found that the band-edge transition originating from VBM and CBM is not observable at room temperature. Rather, the first peak in the absorption spectra corresponds to the transitions occurring within the higher energy valence band and CBM (Figure 1b).…”