Bidirectional energy transfer in Er3+/Sm3+ co-doped BaFCl nanoparticles

Elucidating the energy transfer (ET) process and further controlling the up/down luminescence in lanthanide ion-doped luminescent materials is significant in various related fields such as color display, biomedical imaging, and quantum computing. In this work, studies were performed on the ET process in erbium (Er[Formula: see text]) and samarium (Sm[Formula: see text]) ions co-doped BaFCl nanoparticles by measuring luminescence from spectral and time dimensions. Efficient ET was realized via the usual Er[Formula: see text] to Sm[Formula: see text] pathway by varying Sm[Formula: see text] doping concentration, achieving a high efficiency of 47%. Further analysis reveals that the ET is caused by dipole–dipole interactions. Another ET process from Sm[Formula: see text] to Er[Formula: see text] was also simultaneously observed under excitation with high laser powers. Further, the dynamic luminescence decay lifetimes of Er[Formula: see text] were verified and their mechanism was analyzed in detail. The revealed ET channel provided valuable insights and different perspectives for future research on Er[Formula: see text]/Sm[Formula: see text] co-doped nanomaterials.