Large efficiency improvement in nanoporous dye-sensitized solar cells via vacuum assistant dye adsorption

The positive effects of the vacuum assistant dye adsorption (VADA) process on the performances of the dye-sensitized solar cells (DSSCs) were investigated experimentally. Using commonly used materials and processes as a demonstration, nanoporous films and the resulted solar cells with different dye adsorption processes were fabricated and characterized for comparison. The amounts of dyes adsorbed by the TiO2 nanoporous films were found to be enhanced greatly compared with dyes adsorbed in ambient condition. In accordance, a relative increase of about 29% for the short-circuit currents (I-sc) and 32% for the efficiencies (eta) were observed for the resulted DSSCs. Photocurrent-voltage measurement indicated that the lifetime of the photogenerated charge carriers changed little. Hence, such improvements were originated from the application of VADA process, which realized full contact between the dye solution and TiO2 nanoparticles by driving away the air bubbles concealed in the nanoporous film. The VADA process may be also applied in other kinds of solar cells, such as solid state DSSCs and organic or flexible solar cells to enhance the dye adsorption and further increase their efficiencies. (C) 2011 Elsevier Ltd. All rights reserved.