Multicolor tunable emission induced by Cu ion doping of perovskite zirconate

We report on a multicolor tunable emission induced by Cu ion doping of perovskite zirconate SrZrO3 with a fairly large bandgap (5.6 eV). X-ray photoelectron spectroscopy of our samples revealed the existence of two mixed valence states of the doped Cu ions, +1 and +2, with a ratio of 3:1. In photoluminescence excitation spectroscopy the absorption structures of the 3d states in monovalent Cu+ and divalent Cu2+ were identified near 5 eV and 3.5 eV, respectively. Interestingly, in relation to the valence states of the Cu ions, the emission spectra depended strongly on the photo-excitation energy (Eex). For Eex<3.8 eV (UVA) two orange and green emissions were observed with the involvement of the Cu2+ state. For Eex>3.8 eV (UVB/UVC), however, the Cu+ state, instead of the Cu2+ state, was dominant in the emission process, causing the visible emission to be turned into violet. Our results were indicative of the complementary role of the different Cu-ion valence states in a wide range of visible emission with respect to Eex.