Pressure-Induced Effects in Cs2Na0.6Ag0.4InCl6:Bi3+ Microcrystals − An Experimental and Theoretical Study

Cs 2 AgInCl 6 -based double perovskites have recently attracted attention due to their direct electronic band gap and have been identified as promising candidates for a wide range of device applications. Various doping methods applied to this material, including doping with Bi along with precise adjustments of its composition, have resulted in enhanced luminescence. In this work, results of high-pressure studies of structural, vibrational, and luminescent properties of Cs 2 Na 0.6 Ag 0.4 InCl 6 :Bi 3+ are reported. High-pressure X-ray diffraction and Raman spectra consistently reveal a reversible structural phase transition from a cubic to a tetragonal structure at a pressure of about 11.5 GPa. High-pressure photoluminescence results (PL) are consistent with recombination of a defect-bound exciton. It is suggested that the defect is related to bismuth. This luminescence is strongly quenched above 3.5 GPa. A possible mechanism based on level crossing of the exciton ground state and the valence band maximum is discussed, which is qualitatively consistent with the observed pressure-dependent PL quenching and the calculated host-band evolution.