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dc.contributorWichita State University. Department of Chemistryen_US
dc.contributor.authorSubbaiyan, Navaneetha K.en_US
dc.contributor.authorMaligaspe, Erandaen_US
dc.contributor.authorD'Souza, Francisen_US
dc.identifier.citationACS applied materials & interfaces. 2011 Jul; 3(7): 2368-76.en_US
dc.descriptionClick on the DOI link below to access the article (may not be free).en_US
dc.description.abstractThin transparent SnO(2) films have been surface modified with cationic water-soluble porphyrins for photoelectrochemical investigations. Free-base and zinc(II) derivatives of three types of cationic water-soluble porphyrins, (P)M, viz., tetrakis(N-methylpyridyl)porphyrin chloride, (TMPyP)M, tetrakis(trimethylanilinium)porphyrin chloride, (TAP)M, and tetrakis(4'-N-methylimidazolyl-phenyl)porphyrin iodide, (TMIP)M, (M = 2H or Zn) are employed. The negative surface charge and the porous structure of SnO(2) facilitated binding of positively charged porphyrins via electrostatic interactions, in addition to strong electronic interactions in the case of (TMPyP)M binding to nanocrystalline SnO(2). The SnO(2)-porphyrin binding in solution was probed by absorption spectroscopy which yielded apparent binding constants in the range of 1.5-2.6 × 10(4) M(-1). Both steady-state and time-resolved fluorescence studies revealed quenching of porphyrin emission upon binding to SnO(2) in water suggesting electron injection from singlet excited porphyrin to SnO(2) conduction band. Addition of LiClO(4) weakened the ion-paired porphyrin-SnO(2) binding as revealed by reversible emission changes. Over 80% of the quenched fluorescence was recovered in the case of (TMPyP)M and (TAP)M compounds but not for (TMIP)M suggesting stronger binding of the latter to SnO(2) surface. Photoelectrochemical studies performed on FTO/SnO(2)/(P)M electrodes revealed incident photon-to-current conversion efficiencies (IPCE) up to 91% at the peak maxima for the SnO(2)-dye modified electrodes, with very good on-off switchability. The high IPCE values have been attributed to the strong electrostatic and electronic interactions between the dye, (TMPyP)M and SnO(2) nanoparticles that would facilitate better charge injection from the excited porphyrin to the conduction band of the semiconductor. Electrochemical impedance spectral measurements of electron recombination resistance calculations were supportive of this assignment.en_US
dc.publisherAmerican Chemical Societyen_US
dc.relation.ispartofseriesACS applied materials & interfacesen_US
dc.relation.ispartofseriesACS Appl Mater Interfacesen_US
dc.subjectResearch Support, Non-U.S. Gov'ten_US
dc.titleNear unity photon-to-electron conversion efficiency of photoelectrochemical cells built on cationic water-soluble porphyrins electrostatically decorated onto thin-film nanocrystalline SnO2 surfaceen_US
dc.coverage.spacialUnited Statesen_US
dc.description.versionPeer reviewed
dc.rights.holderCopyright © 2011 American Chemical Societyen_US

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