A New Class of Lasing Materials: Intrinsic Stimulated Emission from Nonlinear Optically Active Metal-Organic Frameworks

Two new anionic blue phosphor 3D interpenetrated metal organic framework (MOFs) with rare tfi and dmd connectivity were synthesized.. These materials showed unique intrinsic stimulated emission with low fluence thresholds of 36 and 27 mJ cm^-2 for In- and Zn-MOFs, without any dye loading or doping and in the absence of external cavity. This intrinsic STE property depends on the packing density and on the arrangement of the TCPE linker molecules. To further confirm the STE, time-resolved photoluminescence (TRPL) measurements were performed on these single crystals with laser powers below and above the STE threshold, which showed a decrease in fluorescence lifetime from 900 to 500 ns, suggesting a faster recombination of exciton driven STE, which is consistent with the signature of stimulated emission. The lower threshold powers of the Zn-MOF are assigned to the denser packing of linkers in the material. Exceptionally high nonlinear absorption with 2PEF action cross-section values up to 3072 GM were found for In-MOF, the highest for any hybrid solid state material so far.