High-efficiency dye-sensitized solar cells based on nitrogen and graphene oxide co-incorporated TiO2 nanofibers photoelectrode

For DSSCs application, highly efficient photoelectrode based on nitrogen (N) and graphene oxide (GO) co-incorporated TiO2 nanofibers were synthesized successfully by two simple successive methods; electrospinning followed by hydrothermal processes. The influence of the N and GO co-incorporation on the morphology, crystal structure and optical behavior of TiO2 nanofibers were characterized by various advanced techniques. The results showed that the modified TiO2 nanofibers exhibit higher conversion energy in comparison to the mono-incorporated and pristine TiO2 nanofibers. Optical and electrochemical properties study indicated that, compared to other GO contents, the 0.5 wt% GO content provides higher surface area, more active sites for the dye absorption, and numerous hot electron transport paths to the FTO substrate which consequently improves the cell performance. On the other hand, N atoms incorporation causes positive shift of the flat band potentials (V-fb) which leads to fast electron transport in TiO2 nanofiber films and inhibits the charge recombination rate of photon-generated electrons. Accordingly, TiO2 nanofibers co-incorporated by nitrogen and GO (0.5 wt%) exhibit the best performance as photoanode in the DSSC, the corresponding conversion efficiency was 5.72% compared to 4.52% and 1.54% in case of nitrogen-free 0.5 wt% GO-incorporated and pristine TiO2 nanofibers, respectively. Overall, this study introduces nitrogen and graphene oxide co-incorporation in the titanium oxide nanofibers as novel strategy for enhancing the solar-to-electrical energy conversion in the DSSCs. (C) 2015 Elsevier B.V. All rights reserved.