Highly efficient dye-sensitized solar cells with TiO 2 -coated silver nanowire-incorporated tri-layered photoanode

This study is about investigating the effect of adding TiO 2 -coated silver nanowires into a tri-layered photoanode of dye-sensitized solar cells (DSSCs) to improve the photovoltaic performance. Face-centred cubic silver nanowires (AgNWs) were synthesized via a rapid, scalable and green pathway method. The average length and diameter of AgNWs were 5 μm and 70 nm, respectively. AgNWs were coated with titanium dioxide (TiO 2 ) using 2-mercaptoethanol as the binder. AgNW@TiO 2 core-shell structure was formed by the hydrothermal method and the average diameter of the coated TiO 2 was observed to be 14 nm. TiO 2 shell showed anatase phase, which was a significant advantage for higher dye absorbance leading to a higher power conversion efficiency (PCE). The PCE for a DSSC with single-layered TiO 2 photoanode increased from 6.70 to 8.87% due to AgNW@TiO 2 core-shell structured photoanode, reflecting a 32.3% enhancement. The PCE for a DSSC with tri-layered AgNWs@TiO 2 core-shell structured photoanode was 10.5% showing an impressive enhancement of 49.6% compared to the DSSC with a pure tri-layered TiO 2 photoanode. TiO 2 shell appears to act as a protective shell around AgNWs by both resisting redox chemical corrosion of Ag by iodide ions in the electrolyte and increasing the thermal stability of AgNWs against annealing at high temperatures. Further, TiO 2 -coated AgNWs facilitate increased photoelectron generation by plasmonic effect, reduce the recombination and enhance the electron lifetime while providing a direct pathway for excited electrons leading to a significant improvement in the PCE of DSSC.