Glass Frit Dissolution Influenced by Material Composition and the Water Content in Iodide/Triiodide Electrolyte of Dye-Sensitized Solar Cells. (22nd July 2013) - Jensen, Katrine Flarup
Abstract : To ensure long-term stable dye-sensitized solar cells (DSCs) and modules, a hermetic sealing is required. This research investigates the chemical stability of I - / I 3 - redox electrolyte and four different glass frits (GFs). Sintered GF layers were openly exposed to nonaqueous redox electrolyte and redox electrolyte with 1, 5, and 10 wt% H2 O in thin, encapsulated cells. The change in I 3 − absorbance was assigned to a reaction between the GF and I - / I 3 - electrolyte and was used to evaluate the chemical stability of the different GFs. The I 3 − absorbance change was monitored over 100 days. Two out of the four GFs were unstable when H2 O was added to the redox electrolyte. The H2 O caused metal ion leaching which was determined from EDX analysis of the inorganic remains of electrolyte samples. A GF based on Bi2 O3 –SiO2 –B2 O3 with low bond strength leached bismuth into electrolyte and formed the Bi I 3 - complex. A ZnO–SiO2 –Al2 O3 -based GF also became unstable when H2 O was added to the redox electrolyte. Leaching of zinc ions due to exchange with H + resulted in the formation of a zinc-iodine compound which caused I 3 − depletion. By applying the test design to different types of GFs, the material suitability in the DSC working environment was investigated.