Solid-State Dye-Sensitized Solar Cells Using Mesoporous TiO<sub>2</sub> Films Fabricated with Amphiphilic Rubbery Random Copolymer

Abstract

An amphiphilic copolymer, PLMA-POEM, was synthesized with hydrophobic poly (lauryl methacrylate) (PLMA) and hydrophilic poly (oxyethylene methacrylate) (POEM), which is cheap and rubbery state. The copolymers were characterized by using Fourier transform infra-red spectroscopy (FT-IR),1H-nuclear magnetic resonance (1H-NMR) and gel permeation spectroscopy (GPC). The copolymers were used as sacrificial agent to fabricate anatase mesoporous TiO2films and, by varying amounts of TiO2particles, polymer molecular weight (MW), concentration of the copolymers, various mesoporous TiO2films were fabricated. With a low MW polymer, the TiO2formed a worm-like structure with smaller pores, whereas an aggregated honeycomb-like TiO2with bimodal pores was obtained for the high MW system, characterized by scanning electron microscopy (SEM), grazing incidence small-angle X-ray scattering (GI-SAXS) and N2adsorptiondesorption measurement. With 2μm-thick TiO2film, efficiency was 4.2% due to better pore filling of the solid electrolyte and improved light scattering properties. By using a layer-by-layer method, the efficiency was further improved to 5.0% at 7μm thickness.