The Function of TiO₂ with Respect to Sensitizer Stability in Nanocrystalline Dye Solar Cells

Abstract

Dyes of characteristically different composition have been tested with respect to long-term stability in operating standardized dye sensitized cells during a time period of up to 3600 hours. Selective solar illumination, the use of graded filters, and imaging of photocurrents revealed that degradation is linked to the density of photocurrent passed. Photoelectrochemical degradation was observed with all sensitizers investigated. Sensitization was less efficient and sensitizers were less photostable with nanostructured ZnO compared to nanostructured . The best performance was confirmed for cis- on . However, it was 7–10 times less stable under other identical conditions on ZnO. Stability is favored by carboxylate anchoring and metal-centred electron transfer. In presence of , it is enhanced by formation of a stabilizing charge-transfer complex between oxidized Ru dye and back-bonding interfacial states. This is considered to be the main reason for the ongoing use of expensive Ru complexes in combination with . The local surface chemistry of the nanocrystalline turned out to be a crucial factor for sensitizer stability and requires further investigation.

Does Iodine or Thiocyanate Play a Role in p‐Type Dye‐Sensitized Solar Cells?

“…This has also been proposed by Tributsch et al. to explain the bleaching of the electrolyte in n‐DSCs over time . However, at this stage we favor Equation (9) because this is consistent with the formation of I 3 − .…”

UV Filtering of Dye-Sensitized Solar Cells: The Effects of Varying the UV Cut-Off upon Cell Performance and Incident Photon-to-Electron Conversion Efficiency

“…One of the most important considerations for those working towards the commercialisation of dye-sensitized solar cells (DSCs) is their long-term stability. The importance has been recognised by many and some notable works have been published [1][2][3][4][5][6][7][8][9] as well as an extensive review of DSC stability published in 2010 [10]. Dye stability has historically been given particular consideration and was recognised as an important factor in O'Regan's and Grätzel breakthrough paper of 1991 [11].…”

Rapid, low-temperature processing of dye-sensitized solar cells

“…Photocurrent mapping techniques have suggested that localized degradation can occur in unmasked parts of a partially masked cell when exposed to light soaking conditions (Barkschat et al , 2008). Elevated temperatures have also been linked to dye desorption (Hinsch et al , 2001;Sommeling et al , 2004) which is important for BIPV applications as roof temperatures in summer (even in temperate climates such as the UK) can reach 80°C.…”