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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2008 - 20102
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Author: Durrant, James Robert × Subject: 615:54 ×

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    Catalysis of Recombination and Its Limitation on Open Circuit Voltage for Dye Sensitized Photovoltaic Cells Using Phthalocyanine Dyes
    (Journal of the American Chemical Society, 2008) O'Regan, Brian C.; López Duarte, Ismael; Martínez Díaz, María Victoria; Forneli Rubio, María Ámparo; Albero Sancho, Josep; Morandeira Ramírez, Ana; Palomares Gil, Emilio; Torres Cebada, Tomás; Durrant, James Robert
    In order to increase the energy efficiency of dye-sensitized solar cells beyond 10%, an improved dye needs to be developed with greater light absorption in the red and near-infrared. Many dyes have been tested for this purpose; however, no dye with significant absorption beyond 750 nm has functioned properly. We have examined a series of ruthenium phthalocyanines, a dye class with large and tunable absorption in the red. For these dyes we observe a large reduction in the output voltage of the cells relative to the benchmark dye (N719). By examination of photovoltage transients and charge density measurements, we demonstrate that this reduction in voltage is caused by a 100-fold increase in the rate constant for recombination (iodine reduction) at the TiO2/electrolyte interface. N719, however, does not seem to catalyze this reaction. By examination of the literature, we propose that catalysis of the recombination reaction may be occurring for many other classes of potentially useful dyes including porphyrins, coumarins, perylenes, cyanines, merocyanines, and azulene. This widespread ability of the dye to catalyze recombination has not been appreciated before. This finding has important implications for future work to improve the red response of dye sensitized photovoltaics.
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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.