Up and down-conversion photoluminescence energy demonstration of Ho3+/Yb3+ co-doped double perovskites microcrystals

Recently, lanthanide-doped fluorescence materials with perovskite structures have attracted great attention due to their abundant 4f energy levels, of which up- and down-conversion photoluminescence (PL) usually can be achieved by energy-level transition of single or multiple rare-earth ions (REI). Here, we synthesized for the first time a series of holmium (Ho) and ytterbium (Yb) co-doped Cs2Ag0.4Na0.6In0.9Bi0.1Cl6 (CANIBC) microcrystals (MCs) by hydrothermal method and realized the synergistic effect of efficient dual-mode PL of host and REI. The CANIBC MCs show yellow-white light emission stimulated by a 405 nm laser, of which the down-conversion (DC) PL is superimposed by the self-trapped excitons (STEs) emission of [AgCl6]5- octahedral and the energy level leap emission of REI. While the green emission of Ho3+ can be observed on the up-conversion (UC) PL stimulated by a 980 nm laser. We systematically analyzed the effect of CANIBC MCs in the dual-mode PL by time-resolved spectroscopy and found the existence of energy transfer between the STEs to REI in the DC PL process. Whereas in UC PL there is only energy transfer between REI. The variable-temperature dual-mode PL, reflects good temperature measurement performance. Simultaneously, it is effectively processed into a powder and mixed with 415 nm chips to create warm white light-emitting diodes with a CIE of (0.34, 0.36).