Tailored Near-Infrared Photoemission in Fluoride Perovskites through Activator Aggregation and Super-Exchange between Divalent Manganese Ions.

ABSTRACT: Biomedical imaging and labeling through luminescence microscopy requires materials that are active in the near-infrared spectral range, i.e., within the transparency window of biological tissue. For this purpose, tailoring of Mn²⁺-Mn²⁺ activator aggregation is demonstrated within the ABF₃ fluoride perovskites. Such tailoring promotes distinct near-infrared photoluminescence through antiferromagnetic super-exchange across effective dimers. The crossover dopant concentrations for the occurrence of Mn²⁺ interaction within the first and second coordination shells comply well with experimental observations of concentration quenching of photoluminescence from isolated Mn²⁺ and from Mn²⁺-Mn²⁺ effective dimers, respectively. Tailoring of this procedure is achieved via adjusting the Mn-F-Mn angle and the Mn-F distance through substitution of the A⁺ and/or the B²⁺ species in the ABF₃ compound. Computational simulation and X-ray absorption spectroscopy are employed to confirm this. The principle is applied to produce pure anti-Stokes near-infrared emission within the spectral range of ?760-830 nm from codoped ABF₃:Yb³⁺,Mn²⁺ upon excitation with a 976 nm laser diode, challenging the classical viewpoint where Mn²⁺ is used only for visible photoluminescence: in the present case, intense and tunable near-infrared emission is generated. This approach is highly promising for future applications in biomedical imaging and labeling.

SUBMITTER: Song E 

PROVIDER: S-EPMC5115432 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature