were purchased from Sigma–Aldrich and used as
received. Molecular structures of MEH-PPV, PCPDTBT and TiO2 are
depicted in Fig. 1(a)–(c), respectively. To prepare photoanode layer,
360 mg TiO2 nanoparticles (size
25 nm from Sigma–Aldrich)
were added in 120 mg of poly(ethylene glycol) (PEG) and 240 ml
acetic acid followed by the 600 ml ethanol addition. The white
mixture was sonicated in an ultra-sonic bath for 15 min at 35 C,
resulting in a dispersed-viscous TiO2 paste. The viscous paste was
coated on the cleaned ITO coated glass substrates using doctor-
blade method. The commercially available ITO substrates were
first
cleaned by ultra-sonication in soap water, deionized water,
acetone and isopropanol, sequentially. The substrates were dried
by nitrogen blow. The dimensions and the sheet resistance of the
ITO substrates were 1
2 cm2 and 10 V/cm2, respectively. The
thickness and area of the TiO2 film were
9 mm and 0.25 cm2