Interfacial structure and dynamics in molecular solar cells

A novel approach to studying interfacial processes in dye-sensitized solar cells is presented. In order to reduce the complexities of heterogeneity at the heterojunction in such cells, charge transfer is investigated from single fluorescent molecules (alkyl-perylene bisimide) to a highly defined single-crystalline wide-bandgap semiconductor (GaN) using confocal fluorescence microscopy under ultrahigh vacuum conditions. We report detailed studies on the energy level alignment between the perylene bisimide and GaN, characterize the nature of the surfaces involved and demonstrate confocal fluorescence microscopy in an ultrahigh vacuum set-up. The results reported here indicate that the excited state in the chromophore lies at 0 ± 100 meV with respect to the bulk conduction band minimum of GaN.

[1]  K. Müllen,et al.  Exponential and Power-Law Kinetics in Single-Molecule Fluorescence Intermittency , 2004 .

[2]  B. Parkinson,et al.  Dye sensitization of the anatase (101) crystal surface by a series of dicarboxylated thiacyanine dyes. , 2005, Journal of the American Chemical Society.

[3]  X. Xie,et al.  Optical studies of single molecules at room temperature. , 1998, Annual review of physical chemistry.

[4]  L. Kronik,et al.  Yellow luminescence and related deep levels in unintentionally doped GaN films , 1999 .

[5]  Ladislav Kavan,et al.  ELECTROCHEMICAL AND PHOTOELECTROCHEMICAL INVESTIGATION OF SINGLE-CRYSTAL ANATASE , 1996 .

[6]  Ashraful Islam,et al.  Highly efficient quasi-solid state dye-sensitized solar cell with ion conducting polymer electrolyte , 2004 .

[7]  Metal Contacts to Silicon Carbide and Gallium Nitride Studied with Ballistic Electron Emission Microscopy , 2001 .

[8]  U. Bach,et al.  Comment on \"Measurement of Ultrafast Photoinduced Electron Transfer from Chemically Anchored Ru-Dye Molecules into Empty Electronic States in a Colloidal Anatase TiO2 Film\" , 1998 .

[9]  N. Armstrong,et al.  Ultrathin Films of Perylenedianhydride and Perylenebis(dicarboximide) Dyes on (001) Alkali Halide Surfaces , 1998 .

[10]  X. Xie,et al.  Single-Molecule Kinetics of Interfacial Electron Transfer , 1997 .

[11]  B. Parkinson,et al.  Adsorption morphology, light absorption, and sensitization yields for squaraine dyes on SnS2 surfaces. , 2003, Journal of the American Chemical Society.

[12]  H. P. Lu,et al.  Intermittent single-molecule interfacial electron transfer dynamics. , 2004, Journal of the American Chemical Society.

[13]  Toby D M Bell,et al.  Characterizing the fluorescence intermittency and photobleaching kinetics of dye molecules immobilized on a glass surface. , 2006, The journal of physical chemistry. A.

[14]  H. Morkoç,et al.  Luminescence properties of defects in GaN , 2005 .

[15]  Ulrike Diebold,et al.  The surface science of titanium dioxide , 2003 .

[16]  B. Parkinson,et al.  Adsorption, Desorption, and Sensitization of Low-Index Anatase and Rutile Surfaces by the Ruthenium Complex Dye N3 , 2006 .

[17]  Frank Würthner,et al.  Perylene bisimide dyes as versatile building blocks for functional supramolecular architectures. , 2004, Chemical communications.

[18]  J. Kim,et al.  Magnesium oxide gate dielectrics grown on GaN using an electron cyclotron resonance plasma , 2003 .

[19]  T. Kampen.  Electronic structure of organic interfaces – a case study on perylene derivatives , 2006 .

[20]  Saif A. Haque,et al.  Charge Recombination Kinetics in Dye-Sensitized Nanocrystalline Titanium Dioxide Films under Externally Applied Bias , 1998 .

[21]  D. Schlettwein,et al.  Investigations of n/p-junction photovoltaic cells of perylenetetracarboxylic acid diimides and phthalocyanines , 1995 .

[22]  Josef Salbeck,et al.  Solid-state dye-sensitized mesoporous TiO2 solar cells with high photon-to-electron conversion efficiencies , 1998, Nature.

[23]  T. Kato,et al.  Quasi-solid dye sensitized solar cells solidified with chemically cross-linked gelators: Control of TiO2/gel electrolytes and counter Pt/gel electrolytes interfaces , 2004 .

[24]  Valery Shklover,et al.  Nanocrystalline titanium oxide electrodes for photovoltaic applications , 2005 .

[25]  Thomas Hannappel,et al.  Measurement of Temperature-Independent Femtosecond Interfacial Electron Transfer from an Anchored Molecular Electron Donor to a Semiconductor as Acceptor , 1996 .

[26]  F. Ren,et al.  Band offsets in the Sc2O3∕GaN heterojunction system , 2006 .