Person:
López Duarte, Ismael

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First Name
Ismael
Last Name
López Duarte
URI
https://hdl.handle.net/20.500.14352/86447
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Farmacia
Department
Química en Ciencias Farmacéuticas
Area
Química Física
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2009 - 20102
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    Ru(II)-phthalocyanine sensitized solar cells: the influence of co-adsorbents upon interfacial electron transfer kinetics
    (Journal of Materials Chemistry, 2009) Morandeira Ramírez, Ana ; López Duarte, Ismael; O'Regan, Brian ; Martínez Díaz, María Victoria; Forneli Rubio, María Amparo; Palomares Gil, Emilio; Torres Cebada, Tomás ; Durrant, James Robert
    The development of efficient red sensitizer dyes is essential for the optimization of dye-sensitized photoelectrochemical solar cells. Ru-phthalocyanines are good candidates because they show high absorbance in the red while their axial ligands hinder the formation of aggregates, a recurrent problem among phthalocyanine dyes. In this paper, we present the photophysics and photovoltaic device performance for a series of novel Ru-phthalocyanines. We focus in particular upon the origin of the enhancement in device performance observed in the presence of two additives, Li+ and chenodeoxycholic acid. The addition of Li+ lowers the conduction band edge of the TiO2 semiconductor leading to a higher electron injection yield and a higher photocurrent in the device. The increases in injection yield and photocurrent are large for these sensitizers, compared to the widely studied ruthenium bipyridyl dye N719, due to the relatively slow injection dynamics, emphasizing the importance of injection yield in limiting device performance for this Ru-phthalocyanine dye series. Of particular interest is the effect of chenodeoxycholic acid. This coadsorbent dramatically enhances the photocurrent of the studied devices without lowering the photovoltage. Unlike previous studies, in this case the photocurrent rise can not be attributed to an increment in the electron injection yield due to the effect of the coadsorbent hindering the formation of dye aggregates. Photophysical measurements instead show that the slower recombination of dye cations with the TiO2 electrons and faster regeneration of the dye cations by the electrolyte are the reasons for the enhanced photocurrent.
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    Zn(ii) versus Ru(ii) phthalocyanine-sensitised solar cells. A comparison between singlet and triplet electron injectors
    (Energy & Environmental Science, 2010) Listorti, Andrea; López Duarte, Ismael; Martínez Díaz, María Victoria; Torres Cebada, Tomás; Dos Santos Gómez, Tracy Alba; Barnes, Piers R. F.; Durrant, James Robert
    In this study, the injection efficiencies and photovoltaic device performances for two different phthalocyanine sensitisers—a Zn(II)Pc (TT-1) and a Ru(II)Pc (TT-35) in dye sensitized photoelectrochemical solar cells were compared. These dyes have similar structures and energetics, but differ significantly in their photophysics, with TT-1 exhibiting a reasonably long lived singlet state, whilst TT-35 exhibits rapid intersystem crossing to a long lived triplet state. Time correlated single photon counting (TCSPC) approach and incident photon conversion efficiency (IPCE) measurements were applied to study the injection efficiency of these two Pc dyes. A comparison of the injection efficiency determined by the two independent techniques, TCSPC and IPCE analysis, shows a good agreement. TT-35 shows higher injection efficiency in comparison to TT-1. This result is consistent with the relative energy and lifetime of the TT-35 triplet state compared to the TT-1 singlet excited state. The high injection efficiency and the long electron diffusion length shown by TT-35 make this dye an interesting red absorbing sensitizer for dye solar cells.