Fabrication of counter electrodes using surface modified carbon nanotubes for dye-sensitized solar cells and their performances

A well-defined polymeric surface modifier for multi-walled carbon nanotubes (CNTs) was prepared through controlled/"living" radical polymerization procedure. Poly(maleic anhydride-co-p-acetoxystyrene)-block-poly(p-acetoxystyrene) (PAS) copolymer was first prepared through nitroxide mediated polymerization (NMP) technique. The copolymer was then functionalized with pyrene through imidization reaction (SPM). Finally, p-acetoxystyrene units were converted to p-hydroxystyrene units through hydrolysis reaction to afford pyrene functionalized poly(maleic acid-co-p-hydroxystyrene)-block-poly(p-hydroxystyrene) (HSPM). The structural and thermal property of the copolymers were characterized by using gel permeation chromatography (GPC), gas chromatography (GC), proton nuclear magnetic resonance spectroscopy (1H-NMR), fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). Pastes were prepared by using the modified CNTs at various conditions and were employed for the fabrication of CNT based counter electrodes on fluorine doped tin oxide (FTO)-glass through screen printing method. Dye-sensitized solar cells (DSSCs) were then assembled and their performances were investigated.