Dye-sensitized solar cells with a micro-porous TiO2 electrode and gel polymer electrolytes prepared by in situ cross-link reaction

Abstract

The ionic conductivities and performances of dye-sensitized solar cells(DSSCs) of gel polymer electrolytes(GPEs) prepared by in situ cross-link reaction with different cross-linkers were investigated. The poly(imidazole-co-butylmethacrylate)-based GPE containing the 1,2,4,5-tetrakis(bromomethyl)benzene (B4Br) cross-linker showed a higher ionic conductivity than that containing cross-linkers with a linear structure, due to the formation of micro-phase separation that resulted in an increase in ion transport paths in the GPE. Moreover, the co-adsorbent((4-pyridylthio) acetic acid, PAA) co-adsorbed with N3 dye on the TiO2 electrode not only reduced dye aggregation, but also reacted with the cross linkers in the GPE at the TiO2/GPE interface. A decrease in the charge transport resistance at the TiO2/GPE interface was noted after forming the gel; thus the value of J(SC) significantly increased from 7.72 to 10.00 m A cm(-2). In addition, in order to reduce the ionic diffusion resistance within the TiO2 electrode, incorporation of monodispersed PMMA in the TiO2 paste was considered. With the optimal weight ratio of PMMA/TiO2 (w/w 3.75), the TiO2 electrode exhibited larger pores (ca. 350 nm) uniformly distributed afters intering at 500 degrees C, and the ionic diffusion resistance within the TiO2 film could significantly be reduced. The cell conversion efficiency increased from 3.61% to 5.81% under illumination of 100 mW cm (-2), an improvement of ca. 55%. (C) 2009 Elsevier B. V. All rights reserved.