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

Angew Chem Int Ed Engl. 2022 Mar 1;61(10):e202114323. doi: 10.1002/anie.202114323. Epub 2022 Jan 17.

Abstract

Efficient and long-range exciton transport is critical for photosynthesis and opto-electronic devices, and for triplet-harvesting materials, triplet exciton diffusion length ( L D ) and coefficient ( D ) are key parameters in determining their performances. Herein, we observed that PtII and PdII organometallic nanowires exhibit long-range anisotropic triplet exciton LD of 5-7 μm 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 PtII and PdII 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 [dσ*(M-M)→π*] excited state during the exciton diffusion modulated by the M-M distance.

Keywords: Delocalized Excited State; Energy Transfer; Metal-Metal Interactions; Supramolecular Polymer; Triplet Exciton.