A photoelectrode was fabricated by spin-coating Ti(IV) bis(ethyl acetoacetato)diisopropoxide solution (2 wt.% in n-butanol) onto to the conductive fluorine-doped tin oxide (FTO) glass (TEC8, 8Ω/□, Pilkington), followed by heating at 450 °C for 30 min. The TiO 2 layer of 12 μm thickness was then deposited over the FTO glass by a doctor blade and successive sintering at 450 °C for 30 min using TiO 2 paste (13 nm, Ti-Nanoxide D/SP Solaronix). The thin film of TiO 2 was dipped in a 0.3 mM N719 dye

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... Solaronix) solution (1:1 acetonitrile and tert-butanol) for 18 hours at 30 °C. The residual dye solution was rinsed with acetonitrile and dried with N 2 gas. Then, an appropriate amount of dendron solution (Aldrich) was dropped onto the top of the dye-dipped cell and dried at room temperature for one day. The Pt counter electrodes were prepared by spin coating a H 2 PtCl 6 solution (0.01 M in isopropanol) onto the conductive FTO glass and successive sintering at 450 °C for 30 min. Liquid electrolyte solution was prepared with 1-methyl-3-propyl imidazolium iodide (PMII) and I 2 (0.6 M:0.025 M) in acetonitrile. For assembling cells, two electrodes were sealed together by surlyn (SX1170-25, thickness of 25 μm, Solaronix) heated in a press at 90 °C. The active area of DSSC was 0.16 cm 2 . The photovoltaic parameters were measured using a 300 W xenon light source to give an irradiance of 100 mW cm -2 (the equivalent of one sun at AM 1.5) using a mask with an aperture area of 0.25 cm 2 . IPCEs (PV Measurement Inc.) were measured using a halogen source for monochromatic light and a broadband bias light for approximating 1 sun light intensity. The work function of the film is measured by a photon electron spectrometer (AC-2, Riken Keiki Co., Ltd)