Green synthesis of hematite nano flakes and their application as a counter electrode in dye-sensitized solar cells.

This study pioneers using hematite nanoflakes as a viable alternative to traditional platinum counter-electrodes in dye-sensitized solar cells (DSSCs), demonstrating its effectiveness for the first time. Besides such a novelty, the used hematite nanoflakes were bio-engineered using ginger extract as an effective chelating reducing agent. From the X-ray diffraction studies, it was observed that the sample annealed at 700 °C formed a highly crystalline α-Fe2O3, with a crystallite nano-scaled size of the order of 46.3 nm. The scanning electron microscopy investigations indicated a preferred layered nanoflakes morphology while the optical properties revealed a direct band gap of 2.30 eV. Using N-719 dye as a sensitizer on TiO2 photoanode and I-/I3- as electrolyte, the DSSC was fabricated. Such a cell exhibited significant DSSC responses, namely; a short circuit current density (JSC) of 7.0 mAcm-2, an open circuit voltage (VOC) of 389 mV, and a fill factor (FF) of 75.3% in addition to an efficiency (η) of 2.05%. Based on such a significant photo-conversion response using bio-engineered active counter electrodes, this study provides a cost-effective approach for synthesizing hematite NFs that have potential applications not only in DSSC but also in sensors, water splitting, and electrochemical devices.