Guanidine Nitrate (GuNO(3)) as an Efficient Additive in the Electrolyte of Dye-Sensitized Solar Cells

Abstract

Guanidine nitrate (GuNO(3)) was introduced as an additive in I-/I-3(-)-based electrolyte to investigate its photoelectrochemical effects on dye-sensitized solar cells (DSSCs). GuNO(3) induced the enhancement of the power conversion efficiency (PCE) up to ca. 21% by increasing both the photocurrent density and the open circuit voltage (V-oc) of the DSSCs relative to that without additives. Meanwhile the adsorption of guanidinium cation (Gu(+)) induced a positive shift in the conduction band edge of the TiO2 nanoparticles (E-CB,(TiO2)), toward electrochemical potentials by up to similar to 110 mV, the presence of NO3- instead of SCN- in the electrolyte resulted in the shift in E-CB,E-TiO2 in the opposite direction by up to ca. 40 mV, which corresponded to an additional increase in the V-oc up to ca. 30 mV in the DSSCs with GuNO(3) relative to that with GuSCN. The use of GuNO(3) instead of GuSCN as an additive improved the PCE of DSSCs by up to ca. 6% owing to the relatively high values of V-oc and the significant increase of the fill factor (FF) by enhancement of ionic conductivity of electrolyte. (C) 2016 Elsevier Ltd. All rights reserved.