Dynamics of a Covalently Conjoined FRET Dye Ensemble for Electron Injection into ZnO Nanorods

Abstract

A low molecular weight purely organic Forster resonance energy transfer (FRET) sensitizer system combining multiple chromophores into a single molecule via covalent attachment is designed to adjust the ratio and relative position of the fluorol donor and coumarin acceptor units. A phenyl based scaffold accommodates both FRET partners and is connected to a carboxylic anchor group for adsorption on a semiconductor surface. The functionality of the complete ensemble is demonstrated by UV−vis and luminescence lifetime measurements. The energy and charge transfer dynamics of the FRET assemblies in solution and adsorbed on ZnO nanorods are measured by femtosecond transient absorption spectroscopy. Optical pump THz probe (OPTP) spectroscopy is applied to detect the injected electrons in the ZnO electrode, confirming the full electronic pathway from FRET light harvesting to subsequent charge carrier injection.

Sequential “click” functionalization of mesoporous titania for energy-relay dye enhanced dye-sensitized solar cells

“…Name., 2012, 00, [1][2][3] This journal is © The Royal Society of Chemistry 2012 explored the copper(I)-catalyzed 1,3 dipolar azide-alkyne cycloaddition, referred to as a "click" reaction, for the purpose of covalently linking molecular fragments to each other. 15,16 However, this is the first demonstration that this reaction can be used to covalently link molecular fragments directly on and inside the confined space of a mesoporous TiO 2 electrode. 25,26 Within the context of DSCs this reaction has been employed in the synthesis of dyes [27][28][29] and dyadic energy-transfer compounds.…”

“…25,26 Within the context of DSCs this reaction has been employed in the synthesis of dyes [27][28][29] and dyadic energy-transfer compounds. 15,16 However, this is the first demonstration that this reaction can be used to covalently link molecular fragments directly on and inside the confined space of a mesoporous TiO 2 electrode. Noncovalently linked compounds have been demonstrated by association reactions such as ion pairing.…”

“…8 The ETE between the ERD and ID depends on the Förster radius and distance. [15][16][17][18][19] In quasi solid-state dye sensitized solar cells, physisorption of ERDs on dye-sensitized mesoporous TiO 2 films prior to the deposition of the quasi solid hole transporting medium proved beneficial for high ETEs. [15][16][17][18][19] In quasi solid-state dye sensitized solar cells, physisorption of ERDs on dye-sensitized mesoporous TiO 2 films prior to the deposition of the quasi solid hole transporting medium proved beneficial for high ETEs.…”

“…5,14 Supramolecular sensitizers with light harvesting antennas can be considered as examples where the ERD is linked covalently to a surface-bonded sensitizer. [15][16][17][18][19] In quasi solid-state dye sensitized solar cells, physisorption of ERDs on dye-sensitized mesoporous TiO 2 films prior to the deposition of the quasi solid hole transporting medium proved beneficial for high ETEs. 12,13 Herein we demonstrate a sequential functionalization approach assembling complex molecules from molecular fragments directly on the mesoporous TiO 2 surface.…”

Suppressing Förster Resonance Energy Transfer between Organic Dyes on a Cosensitized Metal Oxide Surface

“…17,18 Alternatively, FRET can be embraced in schemes where only the acceptor dye is attached to the electrode, with the donor dye either doped in the electrolyte or tethered to the acceptor dye using a molecular chain. [19][20][21][22][23][24][25] In this study, we use time-resolved fluorescence spectroscopy to investigate whether FRET between two different organic dyes on co-sensitized metal-oxide nanoparticles (NPs) can be suppressed by deliberately misaligning the transition dipole moments of the donor and acceptor dyes. This is achieved by selecting dyes possessing different surfacebinding groups, which govern the relative orientation of the two dyes on the surface.…”