Electrospraying tuned photoanode structures for dye-sensitized solar cells with enhanced energy conversion efficiency

Nanocrystalline TiO2 electrodes have been fabricated using comercially available powers (P25) by electrospray coating (ESC) method. The structures and morphologies of the film, which ultimately influence the cell performance, can be controlled by changing the distance between the capillary nozzle and the FTO substrate (spraying distance). A possible mechanism of the evolution of the structures and morphologies has been discussed in detail. The optimized spraying distance for the maximum short-circuit photocurrent density of the cells is 6cm, while accompanying with the lowest fill factor. The improvement of short-circuit photocurrent density can be mainly ascribed to the better ion-diffusion path, which is caused by presence of the electrolyte "relay stations" in the film. The low fill factor may be attributed to the increase of the resistance at FTO/TiO2 interface, which may be caused by the secondary spheres in the film. In addition, enhanced energy conversion efficiencies have been observed by using a double-layer structure, which consists of a doctor-bladed 7-mu m bottom layer and an electrospray coated 10-mu m top layer. (C) 2010 Elsevier B.V. All rights reserved.