MXene-induced nonradiative energy transfer

Since their discovery in 2011, MXenes have risen to prominence for energy storage, electromagnetic shielding, and optoelectronics. Yet, the nonradiative energy transfer properties of this family of 2D materials remain elusive, which may have implications in optoelectronics, photovoltaics and biosensing. Here, we use single-molecule fluorescence confocal microscopy and DNA origami nanopositioners to investigate, for the first time, the distance-dependent energy transfer of an organic emitter (ATTO 542) placed on transparent thin films made of spincast Ti3C2Tx flakes. We propose a specific immobilization chemistry for DNA origami nanostructures based on glycine-MXene interaction, allowing us to precisely control their orientation on the surface. Each DNA origami structure is designed to carry a single dye molecule at predetermined heights. Our findings reveal that when the dye is located at distances of 1 nm < d < 8 nm from the surface, the fluorescence is quenched following a distance dependence of d-3. This is in agreement with the Förster-type mechanism of energy transfer in transparent conductors at the bulk level. 50% of energy transfer efficiency is reached at 2.7 nm (d0). MXenes could therefore be used as short-distance spectroscopic nanorulers, sensitive at a distance regime that common energy transfer tools cannot access.