Dye-sensitized nanocrystalline TiO2 solar cells based on ruthenium(II) phenanthroline complex photosensitizers

Citation
K. Hara et al., Dye-sensitized nanocrystalline TiO2 solar cells based on ruthenium(II) phenanthroline complex photosensitizers, LANGMUIR, 17(19), 2001, pp. 5992-5999
Citations number
41
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
LANGMUIR
ISSN journal
0743-7463 → ACNP
Volume
17
Issue
19
Year of publication
2001
Pages
5992 - 5999
Database
ISI
SICI code
0743-7463(20010918)17:19<5992:DNTSCB>2.0.ZU;2-2
Abstract
We have synthesized four carboxylated Ru(II) phenanthroline complexes with different numbers of carboxyl groups, cis-bis(4,7-dicarboxy-1,10-phenanthro line)dithiocyanato ruthenium(II) (Ru(dcphen)(2)-(NCS)(2)), cis-bis(4-monoca rboxy-1,10-phenanthroline)dithiocyanato ruthenium(II) (Ru(mcphen)(2)(NCS)(2 )), cis-(4,7-dicarboxy-1,10-phenanthroline)(1,10-phenanthroline)dithiocyana to ruthenium(II) (Ru(dcphen)(phen)(NCS)(2)), and cis-(4-monocarboxy-1,10-ph enanthroline)(1,10-phenanthroline)dithiocyanato ruthenium(II) (Ru(mcphen)(p hen)(NCS)(2)), as photosensitizers for oxide semiconductor solar cells. We have studied photovoltaic properties of dye-sensitized nanocrystalline semi conductor solar cells based on Ru phenanthroline complexes and an iodine re dox electrolyte. The photovoltaic performance of the TiO2 solar cell sensit ized by Ru(dcphen)(2)(NCS)(2)(TBA)(2) exceeded that of ZnO, SnO2, and In2O3 solar cells. A solar energy to electricity conversion efficiency (eta) of 6.6% was obtained under the standard AM 1.5 irradiation (100 MW cm(-2), JIS A class) with a short-circuit photocurrent density (J(sc)) of 12.5 mA cm(- 2), an open-circuit photovoltage (V-oc) of 0.74 V, and a fill factor (ff) o f 0.71. Monochromatic incident photon to current conversion efficiency was 78% at 526 nm. Deoxycholic acid as a coadsorbate and decreasing film thickn ess improved V-oc especially due to suppression of the dark current reactio n corresponding to the reduction of triiodide ions with injected electrons. The improved photovoltaic property due to the added coadsorbate suggests t hat some aggregates of the Ru complex suppress efficient electron injection to the semiconductor. The position and number of carboxyl groups attached to the phenanthroline ligand as an anchor affect photosensitizer performanc e significantly, suggesting that the anchoring configuration of Ru phenanth roline complexes on the semiconductor surface is important to efficient pho tovoltaic cell performance. Two carboxyl groups attached to phenanthroline ligands are necessary for effective electron injection.