Key words: Organic photosensitizer, natural porphyrin, titanium dioxide anatase, phorocurrent
Abstract: A set of organic photodetector devices arranged as indium doped tin oxide (TTO)/porphyrin/TiOialuminum has been
fabricated and its performance has been tested in dark and under various illumination of visible light intensity from 20-100 mW/cm2.
Four devices were prepared using natural porphyrin by I, 3, 5 and 7 times of spin coating. First, porphyrin film was deposited onto
indium doped tin oxide (!TO)-covered glass substrate by spin coating technique. Second, titanium dioxide (Ti02) film was deposited on
top of the porphyrin film using similar technique. Porphyrin was isolated from spirulina microalgae and Ti02 nanoparticle was
prepared by controlled hydrolysis technique using titanium(IV) etoxide, Ti(OC2Hj)4, and potassium chloride. The films were
characterized by UV-vis spectrophotometer to investigate their absorption spectra. The porphyrin film has maximum absorbance at 660
nm, which is in the red region. Then, an aluminum electrode was prepared on top of TjO, film by electron beam evaporation technique.
The resulting device shows rectification property in dark and shows photosensitizing effect under illumination. The device prepared by
3 times of spin coating of porphyrin films shows the highest current density, J,c, of 5. 76 rlA/clll2 and open circuit potential, V"c, of 648
mV, respectively
