Efficiency and stability improvement of natural dye-sensitized solar cells using the electrospun composite of TiO2 nanofibres doped by the bio-Ca nanoparticles

The dye-sensitized solar cells (DSSCs) can be effectively improved and stabilized by outstanding electrical and morphological characteristics of TiO2 nanofibres combined with bio-calcium doping. The pristine and bio-Ca-doped TiO2 nanofibres were fabricated using a cost-effective electrospinning technique. Biocompatible calcium carbonate nanoparticles (bio-Ca) were synthesized from the cuttlebone of Sepia Pharaonis. Moreover, a facile one-step procedure was employed to fabricate efficient TiO2 nanofibres-based DSSCs using a Pechini-type sol. This approach produced a highly porous dense film of TiO2 upon sintering without the need for the hot-pressing or adhesion layer steps. Based on the results, the DSSCs fabricated by the bio-Ca-doped TiO2 nanofibres showed the highest Isc$$ {I}_{sc} $$, Voc$$ {V}_{oc} $$, and eta$$ \eta $$ of 2.19 mA, 0.41 V, and 1.48% respectively. This superiority could be due to the higher specific surface area and the relatively smaller average diameter observed for bio-Ca-doped TiO2 nanofibres, which improved dye-loading and guided electron transport respectively. In addition, Ca2+ doping significantly suppressed the photocatalytic activity in the bio-Ca-doped TiO2 nanofibres owing to the formation of the TiO2 rutile-anatase combined phase. Besides, the substitution of Ti4+ with Ca2+ positively affects the conduction band of TiO2 and causes trap sites that retard the charge recombination. Our results also demonstrated that the bio-Ca-doped TiO2 nanofibres-based DSSC maintained about 78.38% of its initial efficiency after two weeks, while DSSCs fabricated by the TiO2 nanofibres and TiO2 nanoparticles retained 63.71% and 27.38% respectively. The superior stability could be due to the combined effect of nanoparticles into nanofibres transformation and bio-Ca doping.