Abstract

Extracts from red leave onion (Allium cepa) 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 0.85 mAm^-2 and 0.65 mV, respectively were obtained and effective energy conversion efficiency of 0.29% was achieved. These simple and cheap techniques of cell preparation therefore open up a perspective of commercial feasibility for inexpensive and environmentally friendly dye cells.

Key words: Allium cepa, band-gap, photoelectrochemical solar cell, natural dye, semiconductor.