SYNTHESIS AND CHARACTERIZATION OF POLY[3-(2',5'-DIHEPTYLOXY- PHENYL)THIOPHENE] FOR USE IN PHOTOELECTROCHEMICAL CELLS

Abstract

Poly[3-(2\',5\'-diheptyloxyphenyl)thiophene], PDHOPT, has been prepared electrochemically from its monomer for solar cell application. PDHOPT exhibits a band gap of 2.1 eV. The redox properties of PDHOPT were characterized using cyclic voltammetry. The estimated energy levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) are -5.3 eV and -3.2 eV, respectively. PDHOPT sensitizes nanocrystalline titanium dioxide (nc-TiO₂) in liquid-state photoelectrochemical cells. Devices where the photoactive electrode consists of nc-TiO₂/PDHOPT composite film show improved performance over those that consist of only PDHOPT. Devices made of TiO₂/PDHOPT composite film produced an open-circuit voltage of 0.52 V, a short-circuit current of 29 μA/cm², and a fill factor of 0.54 when illuminated with white light intensity of 80 mW/cm².

KEY WORDS: Liquid-state photoelectrochemical cell, Nanocrystalline titanium dioxide, PDHOPT, I₃^-/I^- redox couple


Bull. Chem. Soc. Ethiop. 2007, 21(3), 405-417.