Bi3+‐Er3+ and Bi3+‐Yb3+ Codoped Cs2AgInCl6 Double Perovskite Near‐Infrared Emitters

Abstract Bi 3+ and lanthanide ions have been codoped in metal oxides as optical sensitizers and emitters. But such codoping is not known in typical semiconductors such as Si, GaAs, and CdSe. Metal halide perovskite with coordination number 6 provides an opportunity to codope Bi 3+ and lanthanide ions. Codoping of Bi 3+ and Ln 3+ (Ln=Er and Yb) in Cs 2 AgInCl 6 double perovskite is presented. Bi 3+ ‐Er 3+ codoped Cs 2 AgInCl 6 shows Er 3+ f‐electron emission at 1540 nm (suitable for low‐loss optical communication). Bi 3+ codoping decreases the excitation (absorption) energy, such that the samples can be excited with ca. 370 nm light. At that excitation, Bi 3+ ‐Er 3+ codoped Cs 2 AgInCl 6 shows ca. 45 times higher emission intensity compared to the Er 3+ doped Cs 2 AgInCl 6 . Similar results are also observed in Bi 3+ ‐Yb 3+ codoped sample emitting at 994 nm. A combination of temperature‐dependent (5.7 K to 423 K) photoluminescence and calculations is used to understand the optical sensitization and emission processes.