title: Enhanced photovoltaic performance of nanowire dye-sensitized solar cells based on coaxial TiO2@TiO heterostructures with a cobalt(II/III) redox electrolyte.
abstract: The growth of a TiO shell at the surface of TiO2 nanowires (NWs) allowed us to improve the power conversion efficiency of NW-based dye-sensitized solar cells (DSCs) by a factor 2.5. TiO2@TiO core-shell NWs were obtained by a two-step process: First, rutile-phase TiO2 NWs were hydrothermally grown. Second, a hongquiite-phase TiO shell was electrochemically deposited at the surface of the TiO2 NWs. Bare TiO2 and heterojunction TiO2@TiO NW-based DSCs were obtained using a cobalt(II/III) redox electrolyte and LEG4 as the dye. With this electrolyte/dye combination, DSCs with outstanding Voc values above 900 mV were systematically obtained. While TiO2@TiO NW-based DSCs had slightly lower Voc values than bare TiO2 NW-based DSCs, they provided 3-fold higher photocurrents, overall reaching 2.5-fold higher power conversion efficiencies. The higher photocurrents were associated with the larger surface roughness and an enhanced charge-carrier separation/transfer at the NW/dye interface.
authors.affiliation: Catalonia Institute for Energy Research (IREC) , Sant Adrià de Besòs 08930, Spain.
authors.forename: Jiandong
authors.initials: J
authors.lastname: Fan
authors.forename: Cristian
authors.initials: C
authors.lastname: Fàbrega
authors.forename: Reza R
authors.initials: RR
authors.lastname: Zamani
authors.forename: Yan
authors.initials: Y
authors.lastname: Hao
authors.forename: Andres
authors.initials: A
authors.lastname: Parra
authors.forename: Teresa
authors.initials: T
authors.lastname: Andreu
authors.forename: Jordi
authors.initials: J
authors.lastname: Arbiol
authors.forename: Gerrit
authors.initials: G
authors.lastname: Boschloo
authors.forename: Anders
authors.initials: A
authors.lastname: Hagfeldt
authors.forename: Joan Ramon
authors.initials: JR
authors.lastname: Morante
authors.forename: Andreu
authors.initials: A
authors.lastname: Cabot
mesh_terms: D003035:Cobalt / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry; D011211:Electric Power Supplies; D004573:Electrolytes / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D053770:Nanowires / Q000737:chemistry*; D010084:Oxidation-Reduction; D012993:Solar Energy; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D004396:Coloring Agents; D004573:Electrolytes; D007477:Ions; C009495:titanium dioxide; D003035:Cobalt; D014025:Titanium