Viable Alternative to N719 for Dye-Sensitized Solar Cells

Abstract

A new synthetically facile heteroleptic ruthenium(II) sensitizer (NBu(4))[Ru(4,7-dpp)(dcbpyH)(NCS)(2)], coded as YS5, where NBu(4) is tetrabutylammonium, 4,7-dpp is 4,7-diphenyl-1,10-phenanthroline, and dcbpyH is the singly deprotonated surface anchoring derivative of 4,4'-dicarboxy-2,2'-bipyridine (dcbpyH(2)), was designed, synthesized, and incorporated into regenerative mesoscopic titania-based dye-sensitized solar cells. The sensitizer has characteristic broad, high extinction coefficient MLCT bands spanning the visible spectrum. The compound was fully characterized by 1D and 2D (1)H NMR, MALDI-TOF-MS, UV-vis, photoluminescence, Raman, IR, and electrochemistry. YS5 exhibits strong visible absorption properties with a molar extinction coefficient of 1.71 x 10(4) M(-1) cm(-1) at its 522 nm maximum. In operational liquid junction-based DSSCs under simulated AM 1.5G one-sun excitation (100 mW/cm(2)), the photovoltaic performance of YS5 compares almost equally against the current benchmark sensitizer N719 in side-by-side comparisons, producing a power conversion efficiency of 6.05% with a maximum IPCE of 65% at 540 nm. The data presented in this manuscript strongly suggest that YS5 is indeed a viable sensitizer for nanocrystalline TiO(2)-based DSSCs, seemingly poised for widespread adaptation.

Interrelationship between the Ancillary Ligand Structure, Acid–Base Properties, and TiO2 Surface Coverage of RuII Dyes

“…The values determined for deprotonated 1a and 4a were similar to those reported in deaerated DMF. [6a], Compound 4a exhibited the higher τ and τ′ values in the series due to the presence of the phenyl groups. [9e]…”

Spectroscopy and Photophysics in Cyclometalated RuII–Bis(bipyridyl) Complexes

“…The widespread investigation of Ru II -polypyridyl complexes over the past 30 years largely has roots in their impressive photophysical and redox properties, which make them amenable for adaptation to a myriad of technologies including dye-sensitized solar cells (DSSCs), [1][2][3][4][5][6][7] solar fuels photochemistry, [8] light-emitting electrochemical cells, [9] photoluminescence sensors, [10] biophotonics, [11,12] photochromics, [13][14][15][16][17][18] water-oxidation catalysis, [19] low-power photon upconversion, [20][21][22][23] as well as fundamental studies in photoinduced electron and energy transfer. [24][25][26][27][28][29] Interestingly, the related class of Ru II molecules that incorporate one or more cyclometalating ligands into their structure were only sparingly investigated over the same time frame.…”

Ruthenium(II) Sensitizers with Heteroleptic Tridentate Chelates for Dye‐Sensitized Solar Cells

“…Key examples of Ru II sensitizers for DSSCs include the wellestablished N3 and N719 dyes and their functionalized derivatives. [5,6] These dyes are commonly assembled by incorporation of at least one 4,4'-dicarboxy-2,2'-bipyridine chelate (Scheme 1), on which the carboxy anchors allow efficient electron injection into the TiO 2 nanoparticles. The accompanying thiocyanate ancillary ligands are pointed away from the TiO 2 surface, thus providing intimate contact to the I À /I 3 À redox couple in the electrolyte and subsequently triggering rapid regeneration of the oxidized sensitizer.…”

“…Key examples of Ru II sensitizers for DSSCs include the wellestablished N3 and N719 dyes and their functionalized derivatives. [5,6] These dyes are commonly assembled by incorporation of at least one 4,4'-dicarboxy-2,2'-bipyridine chelate (Scheme 1), on which the carboxy anchors allow Scheme 1. Ru II sensitizers N3, N719, N749, and PRT4.…”