Extracts from red kola nut (cola nitida) were used as natural sensitizers of a wide band-gap semiconductor (TiO2) in photoelectrochemical solar cells. The natural dye, adsorbed onto the semiconductor surface, absorbs visible light and promotes electron transfer across the dye/semiconductor interface. Photogenerated current density and voltage as high as 3.42 mAm-2 and 422 mV respectively were obtained and effective energy conversion efficiency of 0.53% was achieved. This simple and cheap techniques of cell preparation therefore open up a perspective of commercial feasibility for inexpensive and enviromentlly friendly dye cells.
