Rapid fabrication of mesoporous TiO2 thin films by pulsed fibre laser for dye sensitized solar cells

Highlights: • Mesoporous TiO₂ thin films on ITO glass were fabricated by ms pulsed laser sintering. • Laser fabricated TiO₂ films exhibited improved interconnection between TiO₂ nanoparticles. • Optimised laser-sintered TiO₂ films showed higher dye adsorption than the furnace-sintered. • Optimised laser-sintered TiO₂ films exhibited lower R_ct and longer electron lifetime than the furnace sintered. • DSSC with optimised laser-sintered TiO₂ photoanode showed higher PCE than that with the furnace-sintered. In this paper we demonstrate for the first time that a fibre laser with a wavelength of 1070 nm and a pulse width of milliseconds can be applied to generate mesoporous nanocrystalline (nc) TiO₂ thin films on ITO coated glass in ambient atmosphere, by complete vaporisation of organic binder and inter-connection of TiO₂ nanoparticles, without thermally damaging the ITO layer and the glass substrate. The fabrication of the mesoporous TiO₂ thin films was achieved by stationary laser beam irradiation of 1 min. The dye sensitized solar cell (DSSC) with the laser-sintered TiO₂ photoanode reached higher power conversion efficiency (PCE) of 3.20% for the TiO₂ film thickness of 6 μm compared with 2.99% for the furnace-sintered. Electrochemical impedance spectroscopy studies revealed that the laser sintering under the optimised condition effectively decreased charge transfer resistance and increased electron lifetime of the TiO₂ thin films. The use of the fibre laser with over 40% wall-plug efficiency offers an economically-feasible, industrial viable solution to the major challenge of rapid fabrication of large scale, mass production of mesoporous metal oxide thin film based solar energy systems, potentially for perovskite and monolithic tandem solar cells, in the future.