Work

Uncovering the Origin of the Emitting States in Bi3+-Activated CaMO3 (M = Zr, Sn, Ti) Perovskites: Metal-To-Metal Charge Transfer Versus s–p Transitions

Year: 2019

Type: article

Abstract: After more than a century of studies on the optical properties of Bi 3+ ions, the assignment of the nature of the emissions and the bands of the absorption spectra remain ambiguous. Here, we report an insight into the spectroscopy of Bi 3+ -activated CaMO 3 perovskites (M = Zr, Sn, and Ti), discussing the factors driving the metal-to-metal charge transfer and sp → s 2 transitions. With the aim to figure out the whole scenario, a combined experimental and theoretical approach is employed. The comparison between the temperature dependence of the photoluminescence emissions with the temperature dependence of the exciton energy of the systems has led to an unprecedented evidence of the charge-transfer character of the emitting states in Bi 3+ -activated phosphors. Low-temperature vacuum ultraviolet spectroscopy together with the design of the vacuum-referred binding energy diagram of the luminescent center is exploited to shed light on the origin of the absorption bands. In addition, the X-ray absorption near the edge structure unambiguously confirmed the stabilization of Bi 3+ in the Ca 2+ site in both CaSnO 3 and CaZrO 3 perovskites. This breakthrough into the understanding of the excited-state origin of Bi 3+ could pave the way toward the design of a new generation of effective Bi 3+ -activated phosphors.

Source: The Journal of Physical Chemistry C

DOI: 10.1021/acs.jpcc.9b03940