Precipitation-assisted, low-temperature-annealed TiO₂ and its nanocomposites-based photoanode for DSSCs

Titanium Dioxide (TiO₂) is a wide band-gap semiconducting material of prime importance for its use as a transporting layer in renewable energy generation. Despite its widespread applicability, search for newer alternatives have been emphasized to overcome the shortcomings of TiO₂ such as high-temperature requirement for obtaining the photoactive anatase phase, low optical response in the visible range, and high recombination rates. Here in, we report the applicability of low-temperature preparation of TiO₂ photoanodes and its composites using wet-chemical precipitation method for dye-sensitized solar cells (DSSC). To enhance the optical and electrical properties of TiO₂ and to reduce the electron-hole recombination, tuning of band gap was done by preparing photoanode based on copper oxide (CuO) and nickel oxide (NiO)–TiO₂ nanocomposite. The structural, morphological, and bond formation characterization of nanocomposites formed were carried out using XRD, SEM, and FTIR. From scanning tunneling spectroscopy, both the nanocomposites were found to have smaller band gaps and greater particle sizes than TiO₂. Moreover, the reduction of the band gap and PL quenching in nanocomposites imply the formation of modified type-II structure facilitating charge transportation and reduce the recombination rates. From the J–V characteristics, we found that DSSCs using CuO–TiO₂ as photoanode outperform the TiO₂ and NiO-TiO₂ photoanode-based DSSCs and depict a much more stable performance than NiO–TiO₂ when measured against constant illumination over period of time.