Photophysical and photochemical aspects of coupled semiconductors. Charge-transfer processes in colloidal CdS-TiO sub 2 and CdS-AgI systems

Journal Article · Thu Aug 09 04:00:00 EDT 1990 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100379a051· OSTI ID:6329510

Gopidas, K R; Bohorquez, M; Kamat, P V ^[1]

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1. Univ. of Notre Dame, IN (USA)

The mechanistic and kinetic details of the charge injection from excited CdS into a large bandgap semiconductor such as AgI and TiO{sub 2} have been investigated by coupling the two semiconductor systems in the colloidal form. The interaction between the two colloids led to the quenching of CdS emission. The rate constants for the charge injection from excited CdS into the conduction band of AgI and TiO{sub 2} colloids were determined to be 2.2 {times} 10{sup 7} and >5 {times} 10{sup 10} s{sup {minus}1}, respectively. Transmission electron microscopic analysis indicated the possibility of several CdS colloidal particles interacting with a single particle of TiO{sub 2} and participating in the charge injection process. Primary photochemical events in the CdS-TiO{sub 2} system were investigated by picosecond laser flash photolysis. The charge injected into the TiO{sub 2} colloid and trapped at the Ti{sup 4+} site was characterized from its broad absorption in the region of 500-760 nm. The extended lifetime of these trapped charge carriers indicated an improved charge separation in the coupled semiconductor system.

• OSTI ID: 6329510
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 94:16; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
CADMIUM COMPOUNDS
CADMIUM SULFIDES
CHALCOGENIDES
CHARGE TRANSPORT
CHEMICAL REACTIONS
COLLOIDS
DATA
DISPERSIONS
EXPERIMENTAL DATA
INFORMATION
INORGANIC PHOSPHORS
MATERIALS
MEASURING METHODS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHOSPHORS
PHOTOCHEMICAL REACTIONS
SEMICONDUCTOR MATERIALS
SULFIDES
SULFUR COMPOUNDS
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS