Photosensitization of nanocrystalline semiconductor films. Modulation of electron transfer between excited ruthenium complex and SnO{sub 2} nanocrystallites with an externally applied bias

Journal Article · Thu Mar 21 00:00:00 EST 1996 · Journal of Physical Chemistry

DOI:https://doi.org/10.1021/jp951269l· OSTI ID:232514

Kamat, P V; Bedja, I; Hotchandani, S; Patterson, L K ^[1]

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1. Univ. of Notre Dame, IN (United States)

In situ spectroelectrochemical measurements have been carried out to probe the charge injection from excited Ru(bpy){sub 2}(dcbpy){sup 2+}, Ru(II), into the SnO{sub 2} nanocrystallites. The dependence of luminescence yield and lifetime at various applied potentials suggests that the heterogeneous electron transfer from excited sensitizer into the semiconductor can be controlled by the externally applied electrochemical bias. The maximum quenching is seen at positive potentials while an increase in the luminescence yield and lifetime is seen at negative potentials. Laser flash photolysis of Ru(II)-modified SnO{sub 2} nanocrystalline film has been carried out to record the transient absorption spectra at different applied potentials. The yield of electron transfer product, Ru(III), decreases as the applied bias is switched to negative potentials. At an applied bias of -0.7 V the only observable transient is the excited Ru(II) complex (Ru(II){sup *}). The maximum apparent electron transfer rate constant, k{sub et} (nearly equals 4 x 10{sup 8} s{sup -1}), observed at positive bias agrees with the previously determined electron transfer rate constants from emission lifetime and microwave conductivity experiments. The apparent rate constant for heterogeneous electron transfer is dependent on the applied bias, and it decreases as the difference between the pseudo-Fermi level of SnO{sub 2} and oxidation potential of Ru(II){sup *} decreases. 71 refs., 13 figs., 1 tab.

• OSTI ID: 232514
• Journal Information: Journal of Physical Chemistry, Vol. 100, Issue 12; Other Information: PBD: 21 Mar 1996
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
36 MATERIALS SCIENCE
66 PHYSICS
RUTHENIUM COMPLEXES
ELECTRON TRANSFER
ABSORPTION SPECTRA
TIN OXIDES
SEMICONDUCTOR MATERIALS
SENSITIZERS
SURFACE TREATMENTS
PHOTOLYSIS
FILMS
CHEMICAL REACTION KINETICS
LUMINESCENCE
LIFETIME
ELECTRIC POTENTIAL
PHOTOELECTROCHEMICAL CELLS
EMISSION SPECTRA
CRYSTALS