Glass frit dissolution influenced by material composition and the water content in iodide/triiodide electrolyte of dye-sensitized solar cells

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-/I3- 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% H2O in thin, encapsulated cells. The change in I3- absorbance was assigned to a reaction between the GF and I-/I3- electrolyte and was used to evaluate the chemical stability of the different GFs. The I3- absorbance change was monitored over 100 days. Two out of the four GFs were unstable when H2O was added to the redox electrolyte. The H 2O caused metal ion leaching which was determined from EDX analysis of the inorganic remains of electrolyte samples. A GF based on Bi 2O3-SiO2-B2O3 with low bond strength leached bismuth into electrolyte and formed the BiI3- complex. A ZnO-SiO2-Al2O3-based GF also became unstable when H2O 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 I3- depletion. By applying the test design to different types of GFs, the material suitability in the DSC working environment was investigated. © 2013 Katrine Flarup Jensen et al.