title: Evidence for photo-induced charge separation between dye molecules adsorbed to aluminium oxide surfaces.
abstract: Excited state dynamics and photo-induced charge transfer of dye molecules have been widely studied due to their relevance for organic and dye-sensitised solar cells. Herein, we present a femtosecond transient absorption spectroscopy study of the indolene dye D131 when adsorbed to inert Al2O3 substrates for different surface concentration of the dye. Surprisingly, we find that at high surface concentrations, the first singlet excited state of the dye is converted into a new state with an efficiency of about 80%. We assign the absorption features of this state to the oxidised dye and discuss the possibility of photo-induced charge separation between neighboring dye molecules. Our study is the first to show that this process can be highly efficient without the use of donor and acceptor molecules of different chemical structures.
authors.affiliation: Department of Chemistry, Imperial College London, SW7 2AZ, UK.
authors.forename: Ute B
authors.initials: UB
authors.lastname: Cappel
authors.affiliation: Department of Physics, Imperial College London, SW7 2AZ, UK.
authors.forename: Davide
authors.initials: D
authors.lastname: Moia
authors.affiliation: Department of Chemistry, Imperial College London, SW7 2AZ, UK.|Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Portici (Naples), Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Bruno
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts avenue, Cambridge, MA 02139, USA.
authors.forename: Valerie
authors.initials: V
authors.lastname: Vaissier
authors.affiliation: Department of Chemistry, Imperial College London, SW7 2AZ, UK.
authors.forename: Saif A
authors.initials: SA
authors.lastname: Haque
authors.affiliation: Department of Physics, Imperial College London, SW7 2AZ, UK.
authors.forename: Piers R F
authors.initials: PR
authors.lastname: Barnes