Highly porous Ba3Ti4Nb4O21 perovskite nanofibers as photoanodes for quasi-solid state dye-sensitized solar cells

•Novel highly porous Ba3Ti4Nb4O21 plasmonic perovskite nanofibers were fabricated.•The fabricated nanofibers were tested as anodes in full solar cell devices.•The porosity of the nanofibers increases with increasing the annealing temperature.•The impedance decreases with increasing the annealing temperature.•The efficiency depends mainly on the porosity and crystallinity of the Ba3Ti4Nb4O21 nanofibers.