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Titolo:
Electron transfer dynamics in nanocrystalline titanium dioxide solar cellssensitized with ruthenium or osmium polypyridyl complexes
Autore:
Kuciauskas, D; Freund, MS; Gray, HB; Winkler, JR; Lewis, NS;
Indirizzi:
CALTECH, Div Chem & Chem Engn, Pasadena, CA 91125 USA CALTECH Pasadena CAUSA 91125 iv Chem & Chem Engn, Pasadena, CA 91125 USA CALTECH, Beckman Inst, Pasadena, CA 91125 USA CALTECH Pasadena CA USA 91125 LTECH, Beckman Inst, Pasadena, CA 91125 USA
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 2, volume: 105, anno: 2001,
pagine: 392 - 403
SICI:
1520-6106(20010118)105:2<392:ETDINT>2.0.ZU;2-G
Fonte:
ISI
Lingua:
ENG
Soggetto:
POLYCRYSTALLINE TIO2 ELECTRODES; EXCITED-STATE EVOLUTION; EXTERNALLY APPLIED BIAS; MARCUS INVERTED REGION; FLAT-BAND POTENTIALS; RU-DYE MOLECULES; CHARGE-TRANSFER; SEMICONDUCTOR-FILMS; SPECTROSCOPIC DETERMINATION; PHOTOELECTROCHEMICAL CELLS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
50
Recensione:
Indirizzi per estratti:
Indirizzo: Lewis, NS CALTECH, Div Chem & Chem Engn, Pasadena, CA 91125 USA CALTECH Pasadena CA USA 91125 Chem Engn, Pasadena, CA 91125 USA
Citazione:
D. Kuciauskas et al., "Electron transfer dynamics in nanocrystalline titanium dioxide solar cellssensitized with ruthenium or osmium polypyridyl complexes", J PHYS CH B, 105(2), 2001, pp. 392-403

Abstract

The electron transfer dynamics in solar cells that utilize sensitized nanocrystalline titanium dioxide photoelectrodes and the iodide/triiodide redoxcouple have been studied on a nanosecond time scale. The ruthenium and osmium bipyridyl complexes Ru(H2L')(2)(CN)(2), Os(H2L)(2)(CN)(2), Ru(H2L')(2)(NCS)(2), and Os(H2L')(2)(NCS)(2), when H2L' is 4,4'-dicarboxylic acid 2,2'-bipyridine, inject electrons into the semiconductor with a rate constant > 10(8) s(-1). The effects of excitation intensity, temperature, and applied potential on the recombination reaction were analyzed using a second-order kinetics model. The rates of charge recombination decrease with increasing driving force to the oxidized sensitizer, indicating that charge recombination occurs in the Marcus inverted region. The electronic coupling factors between the oxidized sensitizer and the injected electrons in TiO2 and the reorganization energies for the recombination reaction vary significantly for the different metal complexes. The charge recombination rates are well described by semiclassical electron transfer theory with reorganization energies of 0.55-1.18 eV. Solar cells sensitized with Ru(H2L')(2)(CN)(2), Os(H2L')(2)-(CN)(2), and Ru(H2L')(2)(NCS)(2) have favorable photoelectrochemical characteristics, and iodide is oxidized efficiently. in contrast, iodide oxidation limits the efficiency of cells based on sensitization of TiO2 with Os(H2L')(2)(NCS)(2). The observation that charge recombination occurs in the Marcus inverted region has important implications for the design of molecular sensitizers in nanocrystalline solar cells operated under our experimental conditions.

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Documento generato il 01/04/20 alle ore 00:54:36