Vectorial Electron Relay at ITO Electrodes Modified with Self‐Assembled Monolayers of Ferrocene–Porphyrin–Fullerene Triads and Porphyrin–Fullerene Dyads for Molecular Photovoltaic Devices

Abstract

Systematic series of indium tin oxide (ITO) electrodes modified covalently with self-assembled monolayers (SAMs) of ferrocene-porphyrin-fullerene triads and porphyrin-fullerene dyads were designed to gain valuable insight into the development of molecular photovoltaic devices. The structures of SAMs on ITO have been investigated by UV/Vis absorption spectroscopy, atomic force microscopy, and cyclic voltammetry. The photoelectrochemical and photophysical (fluorescence lifetime and time-resolved transient absorption) properties were also determined. The highest quantum yield of photocurrent generation (11 %) among donor-acceptor linked systems which are covalently attached to the surface of ITO electrodes was achieved with SAMs of ferrocene-zinc porphyrin-fullerene linked triad on ITO electrodes. The quantum yields of photocurrent generation correlate well with the charge-separation efficiency and the lifetime of the charge-separated state of the porphyrin-fullerene linked systems in solution. These results provide valuable information for the construction of photonic molecular devices and artificial photosynthetic systems on ITO electrodes.

Photoinduced Processes within Compact Dyads Based on Triphenylpyridinium‐Functionalized Bipyridyl Complexes of Ruthenium(II)

“…In previous studies, [10] we have reported on the properties of such "compact dyads" (e.g. 1-tpy; Figure 1) based on the ruthenium(ii)-bis-terpyridyl complex ([Ru(tpy) 2 ] 2 + ; 0-tpy) as a P unit. It has been shown that the strong intramolecular electronic coupling dramatically affects the photophysical behavior of the photosensitizer, up to make it a so weak primary electron donor in the excited state that an intramolecular PET was precluded.…”

“…[10a] In that case, A can be considered as a substituent of P rather than a true component of a P-A acceptor dyad. To circumvent this drawback, we reasoned that the adverse contribution of electronic coupling could be counterbalanced by using a primary light-triggered electron-donor (*P) stronger than *[Ru(tpy) 2 ] 2 + , namely the archetypal ruthenium(ii)-tris-bipyridyl complex. [11,15] It is thus expected that, despite the noticeable intramolecular interaction, the excited-state reducing strength of P will remain strong enough to initiate the transient reduction of A.…”

“…[1][2][3] One of the major goals, within the latter framework of research, is to Abstract: As an alternative to conventional charge-separation functional molecular models based on long-range ET within redox cascades, a "compact approach" has been examined. To this end, spacer elements usually inserted between main redox-active units within polyad systems have been removed, allowing extended rigidity but at the expense of enhanced intercomponent electronic communication.…”

“…[2][3][4][5] Multicomponent systems built from a photosensitizer (P) covalently linked-normally via spacers [6] -to suitably arranged electron-withdrawing (A) and/or electron-releasing (D) units, are well adapted for that purpose. [1][2][3][4][5][6][7][8] In our effort to further compact these molecular devices [9] and exert a more acute control over their intramolecular geometry, [10] we have designed putative acceptor-dyads models (P-A), made of A group(s) directly attached to P (e.g. 1-tpy and 1-bpy; Figure 1).…”

Creation of Fullerene-Based Artificial Photosynthetic Systems

“…52,56,59,61,67,77,78,86,92 In particular, alkanethiol has been tethered at the end of Fc-porphyrin (P)-C 60 triads 13 (M ¼ Zn) and 14 (M ¼ H 2 ), because they can exhibit efficient formation of a final charge-separated state with a moderate lifetime via photoinduced multistep ET in solutions (Fig. 8).…”