Synergistic effects of high temperature and impact compaction on the nano-TiO2 film for the significant improvement of photovoltaic performance of flexible dye-sensitized solar cells

Highlights: ► Electron transport property was significantly improved by in situ heating methods. ► An equivalent model is proposed to clarify the relationship between the Rt and Jsc. ► Synergistic effects of heating and pressing on TiO2 film were reported. ► In situ particle heating can be used for highly efficient plastic solar cells. - Abstract: The electron transport property in TiO2 film was investigated to understand the significant improvement of the photovoltaic performance of dye-sensitized solar cells (DSCs) by using in situ substrate heating and in situ particle heating approaches through the vacuum cold spraying technology, which accelerates the powder to impact on the substrate surface and form a film. Results showed that the particle connection and thereby electron transport property in TiO2 film was improved more significantly by in situ particle and substrate heating than by conventional post-sintering of TiO2 film. An equivalent circuit model was proposed to explain the relationship between the short-circuit current density and electron transport property. The result suggested the existence of synergistic effects of high temperature and impact compaction on the nano-TiO2 film in vacuum cold spray process. Furthermore, due to the ability of retaining substrate at a low temperature, in situ particle heating approach could be applied to deposit the TiO2 film for plastic-based flexible solar cells, presenting a high efficiency of 4.4%.