Highly Efficient One-Dimensional Triplet Exciton Transport in a Palladium-Porphyrin-Based Surface-Anchored Metal-Organic Framework
Item Type:Journal Article
Citation:Adams, M., Kozlowska, M., Baroni, N., Oldenburg, M., Ma, R., Busko, D., Turshatov, A., Emandi, G., Senge, M.O., Haldar, R., Wöll, C., Nienhaus, G.U., Richards, B.S. & Howard, I.A., Highly Efficient One-Dimensional Triplet Exciton Transport in a Palladium-Porphyrin-Based Surface-Anchored Metal-Organic Framework', 2019, ACS Applied Materials and Interfaces, 11, 17
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Efficient photon harvesting materials require easy-to-deposit materials exhibiting good absorption and excited-state transport properties. We demonstrate an organic thin-film material system, a palladium-porphyrin based surface-anchored metal-organic framework (SURMOF) thin film, that meets these requirements. Systematic investigations using transient absorption spectroscopy confirm that triplets are very mobile within single crystalline domains; a detailed analysis reveals a triplet transfer rate on the order of 1010 s-1. The crystalline nature of the SURMOFs also allows a thorough theoretical analysis using density functional theory (DFT). The theoretical results reveal that the intermolecular exciton transfer can be described by a Dexter electron exchange mechanism that is considerably enhanced by virtual charge-transfer exciton intermediates. Based on the photophysical results, we predict exciton diffusion lengths on the order of several micrometers in perfectly ordered, single-crystalline SURMOFs. In the presently available samples, strong interactions of excitons with domain boundaries present in these metal-organic thin films limit the diffusion length to the diameter of these two-dimensional grains, which amount to about 100 nm. These results demonstrate potential of SURMOFs for energy harvesting applications.
Science Foundation Ireland
Author: Senge, Mathias; Adams, Michael; Kozlowska, Mariana; Baroni, Nicolò; Oldenburg, Michael; Ma, Rui; Busko, Dmitry; Turshatov, Andrey; Emandi, Ganapathi; Haldar, Ritesh; Wöll, Christof; Nienhaus, G. Ulrich; Richards, Bryce S.; Howard, Ian A.
Type of material:Journal Article
Series/Report no:ACS Applied Materials and Interfaces;
Availability:Full text available
Keywords:Exciton transport, Metal-organic frameworks, Porphyrin, Thin films, Transient absorption, Electronic coupling, DFT