Promoting NIR‐Driven Luminescence Activity of Calcium zinc galliumate via Energy Transfer from Mn4+ to Ho3+ for Second Biological Window

Abstract NIR luminescent materials are widely available for biological applications, and the NIR emitting of Ho 3+ ions has received widespread attention in the second biological window. In this work, Ca 14 Zn 6 Ga 10 O 35 : Mn 4+ ,Ho 3+ luminescent materials were synthesized using a high temperature solid state method. Optical properties and energy transfer mechanisms have studied in detail. Upon UV‐vis light excitation, the Mn single doped Ca 14 Zn 6 Ga 10 O 35 phosphors exhibit deep red and NIR emission centered at 712 and 1151 nm assigned to Mn 4+ and Mn 5+ , respectively. Another stronger NIR emitting peaked at 1195 nm occurs when the Ho 3+ ion is co‐doped into Ca 14 Zn 6 Ga 10 O 35 : Mn 4+ . The energy transfer from Mn 4+ to Ho 3+ ion is performed through a resonant type by a dipole‐dipole interaction mechanism. In addition, the thermal stability of Ca 14 Zn 6 Ga 10 O 35 : Mn 4+ ,Ho 3+ phosphor has been investigated, and the NIR emission of Ho 3+ ion maintains more than half the strength at 423 K. The findings indicate that the as‐prepared Ca 14 Zn 6 Ga 10 O 35 : Mn 4+ ,Ho 3+ luminescent materials hold promise for potential applications in the second biological window.