This report describes the synthesis and the properties of twelve iodide-conducting Plastic Crystal Electrolytes (PCEs) based on N,N-dimethyl-2-(methylsilyloxy) ethanaminium cations (MESEA(n+)) and I-/I-3(-) anions for application in dye-sensitized solar cells (DSSCs). The PCEs are obtained in three steps. In the first, the MESEA(n+)(Cl-)(n) precursor is prepared by reacting different chlorosilanes (CH3)(4-n)SiCln with 1 <= n <= 4 with N,N-dimethyl ethanolamine (DMEA). In the second step, the MESEA(n+)(I-)(n) PCEs are obtained by treating MESEA(n+)(Cl-)(n) with CH3I. In the final step, the MESEA(n+)(I-)(n) are doped with different aliquots of I-2 to obtain blends of MESEA(n+)(I-)(n) and MESEA(n+)(I-3(-))(n) PCEs bearing the active I-/I-3(-) redox couple. Twelve PCEs based on siloxane cations, with general formula {[MESEA(n+)(I-3(-))(n)](rho%).[MESEA(n+)(I-)(n)](100-rho%)} with 1 <= n <= 4 and 0 <= (rho%) <= 8.3 are obtained. (rho%) is the percentage of I-3(-) on the total anions included in the PCEs. The properties of the PCEs are investigated by vibrational spectroscopy (MIR FT-IR), high-resolution thermogravimetric analysis (HR-TGA), differential scanning calorimetry (DSC) and broadband electrical spectroscopy (BES) in order to study the correlations between the structural features, the conductivity and the composition of the proposed electrolytes. Results show that the PCEs with n = 3 and (rho%) = 3.7 exhibit: (a) a melting temperature below 100 degrees C, which is typically observed in room-temperature ionic liquids; (b) a thermal stability up to 200 degrees C and (c) a conductivity of 0.8.10(-4) S cm(-1) at 50 degrees C. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.