Highly efficient DCL, UCL, and TPEF in hybridized Ln-complexes from Ir-metalloligand

Abstract

In molecular level lanthanide complexes, it is still challenging to achieve near-infrared (NIR) down-conversion luminescence (DCL) and visible up-conversion luminescence (UCL) efficiently under ambient conditions. By delicate design of hybridized iridium−europium−ytterbium (Ir–Eu–Yb) trimetallic complexes from an Ir-metalloligand, DCL and UCL emissions with opposite photon conversion pathways were achieved simultaneously in one integrated system. In detail, three different types of energy transfer (ET) and photoluminescence (PL) were detected, as follows: (1) Highly sensitized NIR-DCL from Yb(III) center via ETIr→Eu→Yb, which gave the longest decay lifetime (553 μs) at room temperature ever reported in solid-state Yb-complexes. (2) Unprecedented UCL red emission from Eu(III) center via ETYb→Eu using 980 nm continuous wavelength (CW) laser excitation, which required ultralow energy threshold (0.616 W/cm2). (3) Two-photon excited fluorescence (TPEF) via ETIr→Eu using femtosecond pulsed laser excitation. This exquisite module of “one stone, three birds” provides a new stimulus in the design and application of multifunctional UCL/DCL/ TPEF optical materials under ambient conditions.