Generation of singlet oxygen due to energy transfer from photoexcited silicon nanocrystals in D2O is demonstrated. It is shown that the singlet oxygen generation efficiency, i.e., the intensity of near-infrared emission from singlet oxygen gradually decreases when Si nanocrystals are continuously irradiated in O2-saturated D2O. The mechanism of the photodegradation of the photosensitizing efficiency is studied using photoluminescence and infrared absorption techniques. Experimental results suggest that the interaction of photogenerated singlet oxygen with the hydrogen-terminated surface of silicon nanocrystals results in photo-oxidation of silicon nanocrystals, and the surface oxides reduce the photosensitizing efficiency. It is also demonstrated that photo-oxidation of porous silicon in O2-saturated water results in a strong enhancement of the photoluminescence quantum yield of porous Si.

1.
D.
Kovalev
, and
M.
Fujii
,
Adv. Mater. (Weinheim, Ger.)
17
,
2531
(
2005
).
2.
N. J.
Turro
,
Modern Molecular Photochemistry
(
University Science Books
,
Sausalito, CA
,
1991
).
3.
L.
Packer
and
H.
Sies
,
Singlet Oxygen, UV-A, and Ozone
(
Academic
,
London
,
2000
).
4.
C.
Schweitzer
and
R.
Schmidt
,
Chem. Rev. (Washington, D.C.)
103
,
1685
(
2003
).
5.
J. G.
Moser
,
Photodynamic Tumor Therapy: 2nd and 3rd Generation Photosensitizers
(
G and B Science
,
New York
,
1998
).
6.
D.
Kovalev
,
E.
Gross
,
N.
Künzner
,
F.
Koch
,
V.
Yu. Timoshenko
, and
M.
Fujii
,
Phys. Rev. Lett.
89
,
137401
(
2002
).
7.
E.
Gross
,
D.
Kovalev
,
N.
Künzner
,
J.
Diener
,
F.
Koch
,
V.
Yu. Timoshenko
, and
M.
Fujii
,
Phys. Rev. B
68
,
115405
(
2003
).
8.
M.
Fujii
,
S.
Minobe
,
M.
Usui
,
S.
Hayashi
,
E.
Gross
,
J.
Diener
, and
D.
Kovalev
,
Phys. Rev. B
70
,
085311
(
2004
).
9.
M.
Fujii
,
D.
Kovalev
,
B.
Goller
,
S.
Minobe
,
S.
Hayashi
, and
V.
Yu. Timoshenko
,
Phys. Rev. B
72
,
165321
(
2005
).
10.
A. G.
Cullis
,
L. T.
Canham
, and
P. D. J.
Calcott
,
J. Appl. Phys.
82
,
909
(
1997
).
11.
B. A.
Cosgrove
and
J.
Walkley
,
J. Chromatogr.
216
,
161
(
1981
).
12.
D.
Kovalev
,
E.
Gross
,
V.
Yu. Timoshenko
, and
M.
Fujii
,
Appl. Phys. Lett.
85
,
3590
(
2004
).
13.
W.
Theiss
,
Surf. Sci. Rep.
29
,
91
(
1997
).
14.
V.
Petrova-Koch
,
T.
Muschik
,
A.
Kux
,
B. K.
Meyer
, and
F.
Koch
,
Appl. Phys. Lett.
61
,
943
(
1992
).
You do not currently have access to this content.