Photoluminescence of TlInS 2 at Low Temperatures

The photoluminescence bands are observed at 2.36 eV (A), 2.5 eV (B), 2.545 eV (D), 2.55 eV (E), 2.554 eV (F) and 2.559 eV (G) at 20 K, and 2.54 eV (C) at 10 K, and they show strange temperature dependences. These temperature dependences are interpreted by the variation in crystal structure and coexistence of some polytypes. The band D, E, F and G are interpreted as the excitons and the band A and B are interpreted as the non-local lattice defects. The origin of the band C is supposed to be also by the lattice defect but can not be made clear.