Parameter Study on UV-induced Degradation of Dye-sensitized Solar Cells

Abstract

The present work investigates the UV stability of the dye-sensitized solar cell (DSC) by parametrical investigation of the material influence on UV stability. UV illumination has been observed to cause degradation by slow photocatalysis in the DSC. Photooxidized impurities represent an unwanted side reaction with the redox pair of the electrolyte as the released electron will deplete the triiodide concentration. A study on the DSC cell was carried out with intermediate electrical characterization by cyclic voltammetry (CV) and electrical impedance spectroscopy (EIS) to map the influence of UV illumination as a function of the H2O concentration in the electrolyte, the plate distance and the triiodide concentration. The results show that the H2O content has a detrimental influence on the DSC stability during UV illumination. A higher concentration of triiodide can buffer the reaction with impurities, so that a longer-term stability is achieved. A recovery of triiodide in UV aged cells with either no remaining triiodide or with such a low concentration that the cell current has been diffusionlimited, was seen during CV to -0.75 V under illumination. The reappearance of triiodide was accompanied with a production of hydrogen bubbles, which was related to the H2O content in the electrolyte and the exposure to UV. Our approach can be used to test the purity and the UV stability of various electrolytes.

Improved stability and enhanced efficiency of dye sensitized solar cells by using europium doped yttrium vanadate down-shifting nanophosphor

“…6a and 7a, respectively. 14 We observe that the efficiency of control DSSC falls to $80% of its initial efficiency aer 24 h of illumination. 6b and 7b, respectively. The efficiencies of the unsealed devices A1 and A2 degrade gradually with illumination time (see Fig.…”

“…Current density-voltage (J-V) graphs of device pairs A and D are shown in Fig. [13][14][15] The degradation of electrolyte is accelerated under UV illumination. The corresponding variations in device efficiency with illumination time are plotted in Fig.…”

“…13,14 Here, we study the UV effect on the bare and phosphor coated photoanodes alone. 13,14 Here, we study the UV effect on the bare and phosphor coated photoanodes alone.…”

“…1 Extending the short and long wavelength, that is, the ultraviolet (UV) and red-near infrared (NIR) spectral response of DSSCs is required to further increase the energy conversion efficiency. [12][13][14][15][16][17][18] Down-shiing or conversion (DS or DC) of incident high energy UV photons to the visible region is a novel way of enhancing the short-wavelength spectral response and also the UV stability of DSSCs. These include tandem architectures, 2,3 plasmonics 4,5 and use of up-conversion or downconversion/shiing materials.…”

“…[12][13][14][15][16][17][18] In the present work, we have tested bare and phosphor coated photoanodes, and also complete DSSCs, to shed more light on the degradation processes in a DSSC. This has been done in order to identify the degradation mechanism occurring in the most important component of a DSSC (photoanode).…”