PbS quantum dots embedded TiO2 nanofibers for dye-sensitized solar cells

We report a new type of dye-sensitized solar cells (DSSCs) fabricated using PbS quantum dots (QDs) embedded TiO₂ fibers as the photoanodes. QDs have shown great potential as an efficient light absorbing material with very high extinction coefficient. However, to obtain an efficient photoinduced charge transfer from QDs to TiO₂, a stable linker is needed to attach QDs to TiO₂. Unlike Ru based or all-organic dyes having a carboxylic group to function as the linker, it is a challenge to establish a strong attachment between QDs and TiO₂. In this work, we used electrospinning technique to form TiO₂ nanofibers embedded with PbS QDs without the need of a carboxylic group or any other linker. The QDs embedded TiO₂ nanofibers were mixed with an organic binder and then deposited onto fluorine-doped tin dioxide (FTO) glass substrates by doctor blading. To harvest both visible and infrared light, the photoanodes were further sensitized with a Ru complex dye (Z-907). DSSC devices were fabricated using platinum as a counter-electrode catalyst for triiodide reduction. The cells achieved overall energy conversion efficiency of 2.8% with Voc = 0.81 V and FF = 0.61 under illumination of 100 mW/cm² with an AM 1.5 filter.