Photovoltaic characteristics of natural light harvesting dye sensitized solar cells

In this work of research, anthocyanin as a natural dye obtained from raspberry fruits, was used and tested as a photon harvesting/electron donating dye in titanium dioxide nanoparticle-based DSSCs. A working photoelectrode made from TiO₂ nanoparticles with an average particle size (10-40nm) that is coated on Florine doped tin-oxide substrate, was prepared via a simple and low cost hydrothermal method. A detailed structural and morphological analysis of the TiO₂ photoactive electrode was investigated by X-ray diffraction (XRD), diffuse reflectance spectrometer, transmission electron microscope (TEM) and scanning electron microscope (SEM). Complete photovoltaic characteristics including (current, voltage, outpower, and responsivity) of the natural anthocyanin based dye sensitized solar cell have been investigated under different illumination intensity ranging from 10 to 100mW.cm^-2. The cell responsivity and efficiency of the fabricated solar cell under different illumination intensity were found to be in the range (R=15.6-23.8mA.W^-1 and η=0.13-0.25) at AM=1.5 conditions. This study is important for enhancing the future applications of the promising DSSC technology.

Photostability of low cost dye-sensitized solar cells based on natural and synthetic dyes

This paper deals with the use of some natural pigments as well as synthetic dyes to act as sensitizers in dye-sensitized solar cells (DSSCs). Anthocyanin dye extracted from rosella (Hibiscus sabdariffa L.) flowers, the commercially available textile dye Remazole Red RB-133 (RR) and merocyanin-like dye based on 7-methyl coumarin are tested. The photostability of the three dyes is investigated under UV-Vis light exposure. The results show a relatively high stability of the three dyes. Moreover, the photostability of the solid dyes is studied over the TiO2 film electrodes. A very low decolorization rates are recorded as; rate constants k=1.6, 2.1 and 1.9×10(-3)min(-1) for anthocyanin, RR and coumarin dyes, respectively. The stability results favor selecting anthocyanin as a promising sensitizer candidate in DSSCs based on natural products. Dyes-sensitized solar cells are fabricated and their conversion efficiency (η) is 0.27%, 0.14% and 0.001% for the anthocyanin, RR and coumarin dyes, respectively. Moreover, stability tests of the sealed cells based on anthocyanin and RR dyes are done under continuous light exposure of 100mWcm(-2), reveals highly stable DSSCs.

Synthesis, characterization and color performance of novel Co²+-doped alumina/titania nanoceramic pigments

Blue-green nanoceramic pigments from Co(2+)-doped alumina-titania (xCo(2+)-Al(2)O(3)/TiO(2)) have been synthesized by alkoxide sol-gel route from a mixture of titania and boehmite sols that derived from titanium isopropoxide and aluminum nitrate precursors. The composition of the alumina/titania (AT) matrix is 3:1M ratio. A series of xCo(2+):3TiO(2):1Al(2)O(3) mixed oxides with different Co(2+)-dopant ion concentration has been prepared. The molar ratio of the Co(2+)-dopant ion in the Al(2)O(3)/TiO(2) matrix is from x=0 to 0.5M ratio relative to the titania composition. Characterizations of Co(2+)-doped alumina/titania nanocomposites are carried out using reflectance spectroscopy, transmission electron microscope (TEM), scanning electron microscopy (SEM-EDS), thermo-gravimetric analysis (TGA) and X-ray diffractometer (XRD). The experimental results demonstrated that the prepared Co(2+)-doped alumina-titania nanocomposites fulfill the current technological requirements for ceramic pigment applications that exhibit a high physico-chemical and thermal stabilities at high firing temperatures.