Fig. 2: UC luminescence characterization of MLnS2:Er3+.
From: Towards highly efficient NIR II response up-conversion phosphor enabled by long lifetimes of Er3+
a, b Normalized visible UC luminescence spectra of MYS2:Er3+ (M = Li, Na, K) and NaLnS2:Er3+ (Ln = La, Y, Lu, Gd) under 1532 nm excitation. c, d Integral luminescence intensity and green to red emission ratio (Ig/Ir) of MYS2:Er3+ (M = Li, Na, K) and NaLnS2:Er3+ (Ln = La, Y, Lu, Gd). e UC luminescence spectrum of NaYS2:Er3+ in visible and NIR regions. f UC luminescence populating mechanism of NaYS2:Er3+ under 1532 nm excitation, the 1-5 present the excited state absorption (ESA) process, 6-8 present the cross-relaxation process. g UC luminescence spectra of NaYS2 doped with 2, 5, 10, 15 mol% Er3+ (inset: integral intensity varies with concentration of Er3+). h-i, Lifetimes of 4I9/2→4I15/2 and 4I13/2→4I15/2 transitions of Er3+ in MLnS2:Er3+. Source data is provided in this paper.
