Determination of the Light-Induced Degradation Rate of the Solar Cell Sensitizer N719 on TiO₂ Nanocrystalline Particles

Abstract

The oxidative degradation rate, kdeg, of the solar cell dye (Bu4N+)2[Ru(dcbpyH)2(NCS)2]2-, referred to as N719 or [RuL2(NCS)2], was obtained by applying a simple model system. Colloidal solutions of N719-dyed TiO2 particles in acetonitrile were irradiated with 532-nm monochromatic light, and the sum of the quantum yields for the oxidative degradation products [RuL2(CN)2], [RuL2(NCS)(CN)], and [RuL2(NCS)(ACN)], Phideg, was obtained at eight different light intensities in the range of 0.1-16.30 mW/cm2 by LC-UV-MS. The Phideg values decreased from 3.3 x 10-3 to 2.0 x 10-4 in the applied intensity range. By using the relation kdeg = Phidegkback and back electron-transfer reaction rates, kback, obtained with photoinduced absorption spectroscopy, it was possible to calculate an average value for the oxidative degradation rate of N719 dye attached to TiO2 particles, kdeg = 4.0 x 10-2 s-1. The stability of N719 dye during solar cell operation was discussed based on this number, and on values of the electron-transfer rate between [Ru(III)L2(NCS)2] and iodide ion that are available in the literature.

The Effect of Electrolyte Purification on the Performance and Long-Term Stability of Dye-Sensitized Solar Cells

“…The photoelectrodes of the cells degraded only marginally. Despite that, we interestingly found dye degradation products that have previously been reported only at elevated temperatures 39,40,41,43 in cells aged under UV and visual irradiation below 40…”

“…39,40,41,43 In this work these degradation products were detected in cells aged at a temperature below 40…”

“…N719 was found to degrade by ligand substitution reactions between the dye and solar cell components such as solvent and electrolyte additives. The ruthenium complexes present in the extract were identified on the basis of their m/z ratio, fragmentation pattern, and comparison with data presented in the literature [39][40][41] as [RuL 2 2 ]. The amount of these degradation products could be determined only roughly by LC-MS analysis.…”

Fotovoltai̇k Üreti̇m Teknoloji̇leri̇ Üzeri̇ne Bi̇r Araştirma

“…Representation of a dye-sensitized Graetzel type TiO2 solar cell and the processes involved in energy conversion [6].…”

Polyiodides formation in solvent based Dye Sensitized Solar Cells under reverse bias stress

“…[5][6][7] Several studies addressed the stability of the different components forming the DSSC: dye, [3] , [8,9] electrolyte, [7,10] catalyzer. [11][12][13] Those studies showed that electrolyte stability represents one of the most important requirement for long term reliability of DSSCs.…”