Excitonic photoluminescence in CuAlS2 powders

Abstract

Copper aluminum disulfide (CuAlS 2 ) powders were synthesized in the evacuated ampoule. The luminescence properties of obtained powders were evaluated by photoluminescence (PL) at various temperatures. The visible emission peaks at 2.16 and 1.90 eV, and weak ultraviolet emission peak at 3.47 eV were obtained in the room temperature PL. The temperature dependence of the PL revealed that the ultraviolet emission at room temperature was considered to be free-exciton. Several emission peaks related to free-exciton, bound-exciton and phonons were observed in the high-resolution PL at 12 K, reflecting that the obtained powders had high crystallinity. Emission peaks at 3.459 and 3.300 eV for CuAlS 2 were observed for the first time. The former emission might be originated from the bound exciton and the latter from the donoracceptor pair recombination.

Exciton-Phonon Interaction in CuAlS₂ Powders

“…The origin of the emission peaks at 3.534 and 3.514 eV has not been clarified yet. In our previous report [6], the emission peak at 3.459 eV was related to bound exciton (I 8 ) in the viewpoint of these spectral position and small half-width. In the range between 3.470 to 3.320 eV, several weak emissions were observed.…”

“…However, it is not easy to induce the excitonic emission. Only a few basic research of CuAlS 2 exhibiting excitonic emission were reported [2,[4][5][6].…”