A selective co-sensitization approach to increase photon conversion efficiency and electron lifetime in dye-sensitized solar cells.

Ruthenium-based C106 and organic D131 sensitizers have been judicially chosen for co-sensitization due to their complementary absorption properties and different molecular sizes. Co-sensitization yields a higher light-harvesting efficiency as well as better dye coverage to passivate the surface of TiO(2). The co-sensitized devices C106 + D131 showed significant enhancement in the performance (η = 11.1%), which is a marked improvement over baseline devices sensitized with either D131 (η = 5.6%) or C106 (η = 9.5%). The improved performance of the co-sensitized cell is attributed to the combined enhancement in the short circuit current, open circuit voltage, and the fill-factor of the solar cells. J(sc) is improved because of the complementary absorption spectra and favorable energy level alignments of both dyes; whereas, V(oc) is improved because of the better surface coverage helping to reduce the recombination and increase the electron life time. The origins of these enhancements have been systematically studied through dye desorption, absorption spectroscopy, and intensity modulated photovoltage spectroscopy investigations.

Iron pyrite thin film counter electrodes for dye-sensitized solar cells: high efficiency for iodine and cobalt redox electrolyte cells.

Iron pyrite has been the material of interest in the solar community due to its optical properties and abundance. However, the progress is marred due to the lack of control on the surface and intrinsic chemistry of pyrite. In this report, we show iron pyrite as an efficient counter electrode (CE) material alternative to the conventional Pt and poly(3,4-ethylenedioxythiophene (PEDOT) CEs in dye-sensitized solar cells (DSSCs). Pyrite film CEs prepared by spray pyrolysis are utilized in I3(-)/I(-) and Co(III)/Co(II) electrolyte-mediated DSSCs. From cyclic voltammetry and impedance spectroscopy studies, the catalytic activity is found to be comparable with that of Pt and PEDOT in I3(-)/I(-) and Co(III)/Co(II) electrolyte, respectively. With the I3(-)/I(-) electrolyte, photoconversion efficiency is found to be 8.0% for the pyrite CE and 7.5% for Pt, whereas with Co(III)/Co(II) redox DSSCs, efficiency is found to be the same for both pyrite and PEDOT (6.3%). The excellent performance of the pyrite CE in both the systems makes it a distinctive choice among the various CE materials studied.