Resolving electron injection from singlet fission-borne triplets into mesoporous transparent conducting oxides.

Autor:	Gish MK; National Renewable Energy Laboratory 15013 Denver West Pkwy CO 80401 USA justin.johnson@nrel.gov., Raulerson EK; National Renewable Energy Laboratory 15013 Denver West Pkwy CO 80401 USA justin.johnson@nrel.gov., Pekarek RT; National Renewable Energy Laboratory 15013 Denver West Pkwy CO 80401 USA justin.johnson@nrel.gov., Greenaway AL; National Renewable Energy Laboratory 15013 Denver West Pkwy CO 80401 USA justin.johnson@nrel.gov., Thorley KJ; Department of Chemistry, University of Kentucky Lexington Kentucky 40506 USA., Neale NR; National Renewable Energy Laboratory 15013 Denver West Pkwy CO 80401 USA justin.johnson@nrel.gov., Anthony JE; Department of Chemistry, University of Kentucky Lexington Kentucky 40506 USA., Johnson JC; National Renewable Energy Laboratory 15013 Denver West Pkwy CO 80401 USA justin.johnson@nrel.gov.
Jazyk:	angličtina
Zdroj:	Chemical science [Chem Sci] 2021 Jul 19; Vol. 12 (33), pp. 11146-11156. Date of Electronic Publication: 2021 Jul 19 (Print Publication: 2021).
DOI:	10.1039/d1sc03253d
Abstrakt:	Photoinduced electron transfer into mesoporous oxide substrates is well-known to occur efficiently for both singlet and triplet excited states in conventional metal-to-ligand charge transfer (MLCT) dyes. However, in all-organic dyes that have the potential for producing two triplet states from one absorbed photon, called singlet fission dyes, the dynamics of electron injection from singlet vs. triplet excited states has not been elucidated. Using applied bias transient absorption spectroscopy with an anthradithiophene-based chromophore ( ADT-COOH ) adsorbed to mesoporous indium tin oxide ( nanoITO ), we modulate the driving force and observe changes in electron injection dynamics. ADT-COOH is known to undergo fast triplet pair formation in solid-state films. We find that the electronic coupling at the interface is roughly one order of magnitude weaker for triplet vs. singlet electron injection, which is potentially related to the highly localized nature of triplets without significant charge-transfer character. Through the use of applied bias on nanoITO : ADT-COOH films, we map the electron injection rate constant dependence on driving force, finding negligible injection from triplets at zero bias due to competing recombination channels. However, at driving forces greater than -0.6 eV, electron injection from the triplet accelerates and clearly produces a trend with increased applied bias that matches predictions from Marcus theory with a metallic acceptor. Competing Interests: There are no conflicts to declare. (This journal is © The Royal Society of Chemistry.)
Databáze:	MEDLINE
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