Review-Mn4+ vs Cr3+: A Comparative Study as Activator Ions in Red and Deep Red-Emitting Phosphors

The Mn4+ and Cr3+-activated phosphor properties are examined in detail from an aspect of spectroscopic point of view. The phosphor materials discussed here are fluorides and oxides. Such Mn4+ and Cr3+-activated fluoride and oxide phosphors are classified from a different kind of host materials together with the different spectroscopic properties of photoluminescence (PL) and PL excitation (PLE) spectra into five groups: types F-Mn (F = fluoride), F-Cr, O-Mn (O = oxide), O-Cr-A, and O-Cr-B. The spectroscopic properties of the Mn4+ and Cr3+-activated phosphors are examined by analyzing PL and PLE spectra based on the Franck-Condon analysis model. The results show that an energy inequality relation of the zero-phonon line (ZPL) energies for types F-Mn, O-Mn, and O-Cr-A phosphors is given by E(E-2(g))(ZPL) < E(T-4(2g))(ZPL), whereas that for types F-Cr and O-Cr-B phosphors is given by E(E-2(g))(ZPL) >= E(T-4(2g))(ZPL). As a result, the former phosphors promise to emit light caused by the E-2(g) -> (4)A(2g) transitions and the latter ones by the T-4(2g) -> (4)A(2g) transitions. Difference in the temperature-dependent PL intensity between the Mn4+ and Cr3+ red and deep red emissions are also discussed in detail. (C) 2020 The Electrochemical Society (ECS). Published on behalf of ECS by IOP Publishing Limited.