Efficient Long-Range Triplet Exciton Transport by Metal-Metal Interaction at Room Temperature

Efficient and long-range exciton transport is critical for photosynthesis and opto-electronic devices, and for triplet-harvesting materials, triplet exciton diffusion length (LD ) and coefficient (D ) are key parameters in determining their performances. Herein, we observed that Pt-II and Pd-II organometallic nanowires exhibit long-range anisotropic triplet exciton L-D of 5-7 mu m along the M-M direction using direct photoluminescence (PL) imaging technique by low-power continuous wave (CW) laser excitation. At room temperature, via a combined triplet-triplet annihilation (TTA) analysis and spatial PL imaging, an efficient triplet exciton diffusion was observed for the Pt-II and Pd-II nanowires with extended close M-M contact, while is absent in nanowires without close M-M contact. Two-dimensional electronic spectroscopy (2DES) and calculations revealed a significant contribution of the delocalized (1/3)[d sigma*(M-M)->pi*] excited state during the exciton diffusion modulated by the M-M distance.