title: Ultrafast photodynamics of the indoline dye D149 adsorbed to porous ZnO in dye-sensitized solar cells.
abstract: We investigate the ultrafast dynamics of the photoinduced electron transfer between surface-adsorbed indoline D149 dye and porous ZnO as used in the working electrodes of dye-sensitized solar cells. Transient absorption spectroscopy was conducted on the dye in solution, on solid state samples and for the latter in contact to a I(-)/I(3)(-) redox electrolyte typical for dye-sensitized solar cells to elucidate the effect of each component in the observed dynamics. D149 in a solution of 1:1 acetonitrile and tert-butyl alcohol shows excited-state lifetimes of 300±50 ps. This signature is severely quenched when D149 is adsorbed to ZnO, with the fastest component of the decay trace measured at 150±20 fs due to the charge-transfer mechanism. Absorption bands of the oxidized dye molecule were investigated to determine regeneration times which are in excess of 1 ns. The addition of the redox electrolyte to the system results in faster regeneration times, of the order of 1 ns.
authors.affiliation: Laser Research Institute, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.
authors.forename: Egmont
authors.initials: E
authors.lastname: Rohwer
authors.forename: Christoph
authors.initials: C
authors.lastname: Richter
authors.forename: Nadine
authors.initials: N
authors.lastname: Heming
authors.forename: Kerstin
authors.initials: K
authors.lastname: Strauch
authors.forename: Christian
authors.initials: C
authors.lastname: Litwinski
authors.forename: Tebello
authors.initials: T
authors.lastname: Nyokong
authors.forename: Derck
authors.initials: D
authors.lastname: Schlettwein
authors.forename: Heinrich
authors.initials: H
authors.lastname: Schwoerer