High performance dye-sensitized solar cells based on platinum nanoparticle/multi-wall carbon nanotube counter electrodes: The role of annealing

Abstract

A composite film is coated on the FTO using a solution, containing a synthesized dispersant, poly(oxyethylene)-segmented imide (POEM), dihydrogen hexachloroplatinate (H2PtCl6), and multi-wall carbon nanotube(MWCNT); the thus coated FTO is used as the counter electrode (CE) for a dye-sensitized solar cell (DSSC). The annealing temperature of the composite film, in the range of 110-580 degrees C, is found to be crucial for optimizing its catalytic ability to obtain the best possible performance for the DSSC. About 47% loss in mass for the POEM/H2PtCl6/MWCNT composite is observed from 110 to 390 degrees C, due to not only the progressive formation of PtNPs from H2PtCl6 but the decomposition of POEM. Therefore, the efficiencies (eta) of DSSCs applying these CEs are enhanced from 1.28 +/- 0.08% (110 degrees C) to 8.47 +/- 0.21% (390 degrees C). The mass of the composite loses dramatically under heating above 390 degrees C, due to the decomposition of MWCNTs. The eta decreases to 7.77 +/- 0.15% at 450 degrees C because the decrease in surface roughness of film. PtNPs grow in sizes from 450 to 580 degrees C, resulting in the further decrease in catalytic ability of film and the observed eta from 7.77 +/- 0.15% to 7.19 +/- 0.21%. (C) 2011 Elsevier B.V. All rights reserved.