Improvement of photovoltaic efficiency of dye-sensitized solar cell by introducing highly transparent nanoporous Ti0 ₂ buffer layer

13 nm-sized highly-dispersible TiO ₂ nanoparticle was synthesized by solvothermal reaction of titanium isopropoxide in a basic condition with tetrabutylammonium hydroxide (TBAH). The prepared TiO ₂ nanoparticle was applied to fabrication of the transparent nanoporous TiO ₂ layer with 1.2 μm-thickness. By introducing this buffer layer between FTO and main TiO ₂ layer in the dye-sensitized solar cell (DSSC), the photovoltaic conversion efficiency was improved from 5.92% to 7.13%. Due to the excellent antireflective role of nanoporous TiO ₂ buffer layer, the transmittance of FTO glass was increased by 9.2%, and this seemed to be one of the major factors in enhancing photovoltaic conversion efficiency. Moreover, the presence of nanoporous TiO ₂ buffer layer induces excellent adhesion between FTO and main TiO ₂ layer, as well as it suppresses the back reaction by blocking direct contact between I ₃ ^- and FTO electrode.