Abstract
This paper presents a rapid sintering technique to generate mesoporous nc-TiO2 thin films on ITO-glass using a fibre laser with a wavelength of 1070nm and pulse width of 100ms. Such sintering process was achieved by complete vaporisation of organic binder and inter-connections of TiO2 nanoparticles, without thermally damaging the ITO layer and glass substrate. Compared with a conventional furnace-sintered, DSSC with the laser-sintered TiO2 photoanode reached a higher power conversion efficiency.
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•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 Rct 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 1070nm 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 1min. 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 6μm 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.