Self-Trapped Exciton Photoluminescence from Polycrystalline K₂AgI₃ Obtained by Solid-State Reaction Method

Polycrystalline K₂AgI₃ is synthesized by solid-state reaction at 403 K using AgI and KI as starting materials. X-ray diffraction, photoluminescence (PL) spectra, photoluminescence excitation (PLE) spectra, electron paramagnetic resonance (EPR) and absorption spectra are employed to investigate the structure and photo-physical properties of such material. A broad luminescence band centered at about 608 nm at 180 K with large Stokes shift is found. When the temperature rises to about 300 K, an obvious PL blue-shift, PL intensity weakening, and an emission band broadening are observed. It is suggested that the emission at about 608 nm may originate from the recombination of self-trapped excitons.