This work examines the profilometry characterization of fluorine doped tin oxide (FTO) film and mesoporous (MTiO₂) film using organic dye from Senna plant as photosensitizer. Fluorine doped tin oxide (FTO) film was grown on the substrate using chemical vapour deposition method. Tin-iv-chloride (60%) and hydrofluoric acid (40%) were deposited to the substrate as precursors using two set of bubblers and Nitrogen gas was supply to the same pipe carrying the precursors as a carrier gas. The whole set up was connected to air compressor, which pumps air to the system. The deposited precursors (FTO) were later sintered at 550°C. The first flow meter deposition time is 6 minutes and the flow rate is one (1) litre per minute. The second flow meter connected to the system measured the volume of air that flows into the pipe per time. The grown fluorine doped tin oxide (FTO) film was characterized to find out the thickness and area of the spectra grown on the substrate.

Dye -sensitization solar cell is a device that converts visible light into electricity based on the photosensitization of wide band gap metal oxide-semiconductors using dye molecules. Dye-sensitized solar cell operation is based on a semiconductor formed between a photon-sensitized anode and an electrolyte, a photo electrochemical system. Dye sensitized solar cells are environmentally friendly, biodegradable, non-toxic and can be developed using simple methods and used without any purification. Dye molecules rather than an inorganic semiconductor material are responsible for light absorption. 

The soda lime glass was carefully cleaned using wool and piranha solution to remove any dirty particles on the soda lime glass. Fluorine doped Tin oxide thin films were deposited on the soda lime glass substrates (Axion Medicals UF) using chemical vapour deposition (CVD) Method. 60% of Tin (IV) Chloride (SnCl₄) and 40% of hydrofluoric acid were deposited on the cleaned soda lime glass as precursors and Nitrogen gas was used as a carrier gas. Nitrogen gas was fed from a cylinder through a pressure regulator (Glook scientific) set at 0.5 Bars and then through a mass flow controller (Alicat Scientific). The flow rate is set at one (1) litre per minute and then through a bubbler containing SnCl₄ (anhydrous). The two gas streams converge on the substrate maintained at 550°C by means of a thermocouple and temperature controller (Rex C-900). A chemical reaction takes place leading to the deposition of a transparent and conductive fluorine doped tin oxide (FTO) thin film. The deposition time is varied between one minute and 5 minutes to generate films of transparent and conductive qualities.

It was noticed that as the wavelength increases the absorbance decrease. The liquid samples recorded the highest absorbance and they absorb more cells compared to the solid samples. The liquid sample recorded absorbance above 2.0 A.U. while the solid sample as an absorbance within 0.1 – 0.27. From the plot, the solid sample absorbance will be suitable for solar application while the liquid sample will be for photovoltaic application.

It was seen from the characterization that the optical properties of the film were determined. The solar simulation of Dye-sensitized solar cell (DSSCs) developed in this work show the following electrical characteristics (Isc) = 0.217 mA, (Voc) = 0.362 V, FF (%) = 35.99 %, ɳ (%) = 0.028% and MPPT (mW) = 0.028 mW for senna dyed TiO₂. The optical properties of these films and electrical characteristics made the material to have wide range of applications especially in optical and electronic systems. The profilometry analysis shows that fluorine doped tin oxide (FTO) Film and the mesoporous TiO₂ structure have 1.7 times of photovoltaic current than those from the nanocrystalline films in the same thickness.

It was found out that the liquid samples recorded the highest absorbance and thus absorbing more cells when compared to the solid samples. The transmittance was found to increase as the wavelength of the incident radiation increases. The absorption coefficients show sharp edges at the lower energies.

With Regards,
Joseph Kent
Journal Manager
Journal of Der Chemica Sinica