The Search for Panchromatic Light-Harvesting Systems: Ternary and Binary Antennae Based on Self-Organised Materials

Abstract This study presents a series of light-harvesting materials, where multiple chromophores are organised into host-guest silica-micelle structures at specific locations by means of self-assembly strategies. Binary and ternary mesoscopic antennae were realized, using organometallic complexes and organic dyes as energy transfer units and varying their content and localization to manipulate transfer rate and efficiency inside the materials. Steady-state and time-resolved UV-visible spectroscopy revealed that the three-dye systems show excitation energy cascade from intramicellar dyes to a silica-grafted acceptor, with transfer efficiencies of 20-24% per step and overall light emission spanning the whole visible range. The two-dye system reaches analogous panchromatic response, featuring almost-white light emission and 47% efficient transfer, by exploiting the blue-green dual emission of a metallosurfactant as energy donor inside the micellar template and the red emission of a rhodamine acceptor on the silica framework. Both systems show that control over the donor-acceptor distances can be achieved to a certain extent in complex mesoscopic materials and that a vast potential is available for transfer and colour tuning, and specific use of the materials as solid-state sensitisers.