Ru-based donor–acceptor photosensitizer that retards charge recombination in a p-type dye-sensitized solar cell

Abstract

We report on the synthesis and characterization of a donor-acceptor ruthenium polypyridyl complex as a photosensitizer for p-type dye-sensitized solar cells (DSSCs). The electrochemical, photophysical, and photovoltaic performance of two ruthenium-based photosensitizers were tested in NiO-based DSSCs; bis-(2,2'-bipyridine-4,4'-dicarboxylic acid)(2)N-(1,10-phenanthroline)-4-nitronaphthalene-1,8-dicarboximide ruthenium(II), ([Ru(dcb)(2)(NMI-phen)](PF(6))(2)) and tris-(2,2'-bipyridine-4,4'-dicarboxylic acid)(3) ruthenium(ii), [(Ru(dcb)(3))Cl(2)]. The presence of an electron-accepting group, 4-nitronaphthalene-1,8-dicarboximide (NMI), attached to the phenanthroline of [Ru(dcb)(2)(NMI-phen)](2+) resulted in long-lived charge separation between reduced [Ru(dcb)(2)(NMI-phen)](2+) and NiO valence band holes; 10-50 μs. In the reduced state for [Ru(dcb)(2)(NMI-phen)](2+), the electron localized on the distal NMI group. In tests with I(3)(-)/I(-) and Co(4,4'-di-tert-butyl-bipyridine)(3)(2+/3+) electrolytes, [Ru(dcb)(2)(NMI-phen)](2+) outperformed [Ru(dcb)(3)](2+) in solar cell efficiency in devices. A record APCE (25%) was achieved for a ruthenium photosensitizer in a p-type DSSC. Insights on photosensitizer regeneration kinetics are included.

Can aliphatic anchoring groups be utilised with dyes for p-type dye sensitized solar cells?

“…8 Recently, significant improvements to NiO-based p-DSCs have been made by designing dyes which promote charge separation and limit the recombination between the sensitizer and/or electrolyte and the semiconductor. [9][10][11][12][13][14] Currents obtained in these devices have reached over 8 mA cm -2 at 1 sun illumination. 4,15 Earlier, we reported a high performance dye based on a triphenyl amine electron donor and a cationic indolium acceptor unit that absorbed in this region.…”

Visible Light-Driven Electron Transfer from a Dye-Sensitizedp-Type NiO Photocathode to a Molecular Catalyst in Solution: Toward NiO-Based Photoelectrochemical Devices for Solar Hydrogen Production

“…5,6,9,44−46 In addition, we and others have previously demonstrated that such complexes were suitable photosensitizers to inject holes into NiO films for solar cells. 47,48 One bipyridine ligand of the ruthenium complex ([Ru((PO 3 H 2 CH 2 ) 2 bpy)(bpy) 2 ](PF 6 ) 2 ) was substituted with two methyl phosphonic acid groups in the 4,4′ positions to establish a strong and stable linkage with the NiO surface (see Scheme 1).…”

Ruthenium Imidazophenanthrolinium Complexes with Prolonged Excited‐State Lifetimes

“…[11][12][13][14] Owing to their remarkably stable photoredox chemistry, many ruthenium polypyridyl complexes are potent chromophores for lightdriven catalysis, [15,16] dye-sensitized solar cells, [17][18][19] and photocatalytic water splitting. [20,21] Crucial factors for their application herein are (1) high chemical stability, (2) intense absorption of visible light, (3) efficient population of a reactive charge-transfer (CT) excited state, and (4) long excitedstate lifetimes (up to the μs range).…”