Low-temperature ozone annealing for dye-sensitized solar cells

[Display omitted] •A method for low-temperature O3 annealing for DSSCs was demonstrated.•O atoms are able to successfully remove the binder from TiO2 photoelectrodes.•O atoms appear to enhance the interparticle connections within the TiO2.•Our simple method to supply O atoms may be useful for other surface treatments as an alternative to UV light or plasma. The process whereby the TiO2 photoelectrode of dye-sensitized solar cells (DSSCs) is manufactured requires an annealing temperature of 450 °C. However, these DSSCs, which contain a low-cost, lightweight, and flexible plastic substrate, limit the annealing temperature to a maximum of 150 °C. This led us to develop a low-temperature (∼150 °C) annealing technique to process the TiO2 photoelectrode. The proposed method, which employs O3 as reactant, is based on the fact that O3 is thermally decomposed at ∼150 °C to produce atomic oxygen (O) atoms, to which the TiO2 photoelectrode is then exposed during annealing. Measurement of the carbon contents remaining on the TiO2 photoelectrode using energy dispersive X-ray spectrometry indicated that the O atoms can remove the organic binders contained in TiO2 paste. In addition, measurement of the energy conversion efficiency indicated that O atoms also have the ability to enhance TiO2 interparticle connections. This simple method to supply O atoms may not only be useful for treating the TiO2 photoelectrode of DSSCs but also for other surface treatments that require the use of O atoms.