skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Multiple-exponential electron injection in Ru(dcbpy){sub 2}(SCN){sub 2} sensitized ZnO nanocrystalline thin films

Abstract

The authors have studied the electron injection dynamics of Ru(dcbpy){sub 2}(SCN){sub 2} sensitized ZnO nanocrystalline thin films by femtosecond mid-IR absorption spectroscopy. Upon 400 nm excitation of the sensitizer, nonexponential electron injection kinetics from the sensitizer MLCT excited state to ZnO were observed by probing the absorption of injected electrons in the 2,000 to 1,900 cm{sup {minus}1} region on the < 1 ns time scale. A three-exponential fit to the data yields the following rise time constants and amplitudes (in parentheses): < 1 ps (18%), 42 ps (46%), and 450 ps (36%). For films with increasing coverage of sensitizer molecules (optical density at 500 nm of 0.7, 2.3, 2.6), similar electron injection times were observed, while the injection yield decreases. This result suggests that aggregation or multilayer formation of sensitizer molecules reduces the quantum yield of electron injection to ZnO on the < 1 ns time scale, and the observed multiexponential injection kinetics are attributed to the distribution of injection rates from the first monolayer of sensitizers. Possible reasons for the nonexponential injection are discussed. The injection dynamics are also compared with the very different injection dynamics observed for the same sensitizer on TiO{sub 2}.

Authors:
; ;  [1]
  1. Emory Univ., Atlanta, GA (United States). Dept. of Chemistry
Publication Date:
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
691308
DOE Contract Number:  
FG02-98ER14918
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical
Additional Journal Information:
Journal Volume: 103; Journal Issue: 32; Other Information: PBD: 12 Aug 1999
Country of Publication:
United States
Language:
English
Subject:
40 CHEMISTRY; 14 SOLAR ENERGY; ELECTRONS; DYNAMICS; THIN FILMS; ZINC OXIDES; RUTHENIUM COMPLEXES; INFRARED SPECTRA; SENSITIZERS

Citation Formats

Asbury, J.B., Wang, Y.Q., and Lian, T. Multiple-exponential electron injection in Ru(dcbpy){sub 2}(SCN){sub 2} sensitized ZnO nanocrystalline thin films. United States: N. p., 1999. Web.
Asbury, J.B., Wang, Y.Q., & Lian, T. Multiple-exponential electron injection in Ru(dcbpy){sub 2}(SCN){sub 2} sensitized ZnO nanocrystalline thin films. United States.
Asbury, J.B., Wang, Y.Q., and Lian, T. Thu . "Multiple-exponential electron injection in Ru(dcbpy){sub 2}(SCN){sub 2} sensitized ZnO nanocrystalline thin films". United States.
@article{osti_691308,
title = {Multiple-exponential electron injection in Ru(dcbpy){sub 2}(SCN){sub 2} sensitized ZnO nanocrystalline thin films},
author = {Asbury, J.B. and Wang, Y.Q. and Lian, T.},
abstractNote = {The authors have studied the electron injection dynamics of Ru(dcbpy){sub 2}(SCN){sub 2} sensitized ZnO nanocrystalline thin films by femtosecond mid-IR absorption spectroscopy. Upon 400 nm excitation of the sensitizer, nonexponential electron injection kinetics from the sensitizer MLCT excited state to ZnO were observed by probing the absorption of injected electrons in the 2,000 to 1,900 cm{sup {minus}1} region on the < 1 ns time scale. A three-exponential fit to the data yields the following rise time constants and amplitudes (in parentheses): < 1 ps (18%), 42 ps (46%), and 450 ps (36%). For films with increasing coverage of sensitizer molecules (optical density at 500 nm of 0.7, 2.3, 2.6), similar electron injection times were observed, while the injection yield decreases. This result suggests that aggregation or multilayer formation of sensitizer molecules reduces the quantum yield of electron injection to ZnO on the < 1 ns time scale, and the observed multiexponential injection kinetics are attributed to the distribution of injection rates from the first monolayer of sensitizers. Possible reasons for the nonexponential injection are discussed. The injection dynamics are also compared with the very different injection dynamics observed for the same sensitizer on TiO{sub 2}.},
doi = {},
journal = {Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical},
number = 32,
volume = 103,
place = {United States},
year = {1999},
month = {8}
}