Application of highly-ordered TiO{sub 2} nanotube-arrays in heterojunction dye-sensitized solar cells Paulose, Maggie; Shankar, Karthik; Varghese, Oomman K; Mor, Gopal K; Grimes, Craig A [Department of Electrical Engineering, Department of Material Science and Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)] 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ACETONITRILE; ANODIZATION; CARBOXYLIC ACIDS; CRYSTALLIZATION; CURRENT DENSITY; DOPED MATERIALS; ELECTRIC POTENTIAL; ELECTRICAL FAULTS; ELECTROLYTES; FILL FACTORS; FLUORINE; HETEROJUNCTIONS; NANOTUBES; RUTHENIUM; SOLAR CELLS; THIN FILMS; TIN OXIDES; TITANIUM; TITANIUM CHLORIDES; TITANIUM OXIDES Highly-ordered TiO{sub 2} nanotube arrays are made by potentiostatic anodization of a titanium film in a fluoride containing electrolyte. Here we describe the application of this unique material architecture in both front-side and back-side illuminated dye-sensitized solar cells (DSSCs). The back-side illuminated solar cells are based on the use of 6.2 {mu}m long (110 nm pore diameter, 20 nm wall thickness) highly-ordered nanotube-array films made by anodization of a 250 {mu}m thick Ti foil in a KF electrolyte. Front-side illuminated solar cells use a negative electrode composed of optically transparent nanotube arrays, approximately 3600 nm in length (46 nm pore diameter, 17 nm wall thickness), grown on a fluorine doped tin oxide coated glass substrate by anodic oxidation of a previously deposited RF-sputtered titanium thin film in a HF electrolyte. After crystallization by oxygen annealling the nanotube-arrays are treated with TiCl{sub 4} to enhance photocurrent amplitudes. The arrays are then sensitized by a self-assembled monolayer of bis(tetrabutylammonium)-cis-(dithiocyanato)-N, N'- bis(4-carboxylato-4'-carboxylic acid-2, 2'-bipyridine)ruthenium(II) (commonly called 'N719'). Superior photoresponse is obtained using acetonitrile as the dye solvent. Voltage decay measurements indicate that the highly-ordered TiO{sub 2} nanotube-arrays, in comparison with nanoparticulate systems, provide excellent pathways for electron percolation with superior electron lifetimes. The front-side illuminated DSSCs, show a typical AM 1.5 photocurrent of 10.3 mA cm{sup -2}, open circuit voltage of 0.84 V, 0.54 fill factor, and 4.7% efficiency although the transparent nanotube-array negative electrode is only 360 nm thick. The back-side illuminated DSSCs show an AM 1.5 short-circuit current density of 10.6 mA cm{sup -2}, 0.82 V open circuit potential and a 0.51 fill factor yielding a solar conversion efficiency of 4.4%. Available online at http://stacks.iop.org/0022-3727/39/2498/d6_12_005.pdf or at the Web site for the Journal of Physics. D, Applied Physics (ISSN 1361-6463) http://www.iop.org/;INIS United Kingdom 2006-06-21 English Journal Article Journal Name: Journal of Physics. D, Applied Physics; Journal Volume: 39; Journal Issue: 12; Other Information: PII: S0022-3727(06)15255-9; DOI: 10.1088/0022-3727/39/12/005; Country of input: International Atomic Energy Agency (IAEA) Medium: X; Size: page(s) 2498-2503 https://doi.org/10.1088/0022-3727/39/12/005; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA) [] 12 39 Journal ID: ISSN 0022-3727; JPAPBE; TRN: GB06Q0645001249 GBN 2010-12-31 20825841