Construction of Porphyrin-Sensitized Solar Cells Containing Toray™/TGP-H-060 Carbon - Based Cathodes

Abstract

In this work, we present the construction and photovoltaic response of porphyrin-sensitized solar cells containing TorayTM/TGP-H-060 carbon – modified indium-doped tin oxide (ITO) cathodes (ITO/C), as a viable alternative for substituting platinum oxides – modified ITO cathodes (ITO/PtOx), which are traditionally employed for designing dye-sensitized solar cells. In this case, a binary mixture (75:25) of propylene carbonate (PC) : 3-methoxypropionitrile (MPN), containing 0.015M I2 plus 0.285M LiI was employed as electrolyte for filling the photo-cells. On one hand, our experimental results demonstrated that both cathodic systems, ITO/C and ITO/PtOx, had a very comparable electron transfer kinetics when studied the cathodic semi-reaction I3 - + 2e­ - --> 3I- at these electrode surfaces. Table 1. Electron transfer constants (k°) and cathodic transfer coefficients (∝c) obtained for the semi-reaction I3 - + 2e­ - --> 3I- at ITO/C and ITO/PtOx cathodes. Electrolyte: 0.015M I2 plus 0.285M LiI contained in a binary mixture 75:25 of PC:MPN at 25°C. A polycrystalline Pt cathode was also employed for comparison purposes. cathode Electron transfer kinetic parameters k°/10-4 (cm/s) and ∝ c Pt 5.31 0.27 ITO/PtOx 3.35 0.26 ITO/C 2.70 0.23 On the other hand, a detailed revision of Table 2 reveals that the photovoltaic responses of porphyrin-sensitized solar cells containing ITO/C and ITO/PtOx cathodes were comparable under simulated solar light (AM1.5, 100mW/cm2). These interestingly results confirmed that TorayTM/TGP-H-060 carbon – modified ITO cathodes are promising to substitute those PtOx – modified ITO cathodes typically employed for constructing dye-sensitized solar cells. Table 2. Photovoltaic responses obtained for porphyrin-sensitized solar cells containing ITO/C and ITO/PtOx cathodes, where: Eoc, jsc, ff and ξ are open-circuit potential, short-circuit photocurrent, fill-factor and global conversion efficiency, respectively, under simulated solar light (AM1.5, 100mW/cm2). cathode Eoc (V) jsc (m A/cm2) ff ξ(%) ITO/PtOx -0.30 1.23 0.39 0.17 ITO/C -0.35 1.18 0.40 0.19 References U.López-García, O.A.Castellanos, L.A.Godínez, J.Manríquez, “Electrophoretically-Assisted Deposition of Mesoporphyrin IX on Nanoparticulate TiO2 Films for Constructing Efficient Dye-Sensitized Solar Cells”, Journal of The Electrochemical Society, 158 (2011) F100-F105.