Optical Characterization of Dye-Sensitised Tio2 Thin Films for Solar Cell Applications
Kainyu, Kabuga Pauline
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The use of dye-sensitized solar cells to harness solar energy has gained interest because of their simplicity and are cheaper to manufacture. They can also be glazed on flexible substrates for improved conversion efficiency. Standard DSSC consist of materials made of transparent conducting oxides (TCOs) with titanium dioxide (TiO2) used as semiconducting material. Synthetic dyes or natural dyes are utilized as sensitizers to modify the TiO2 film. The goal of the current study was to find out the potential of organic dyes from blue berry and spinach as sensitizing agents for TiO2 films by investigating their influence on optical properties of the films and energy conversion efficiency of DSSC employing the said films. The blueberry and the spinach dyes were extracted from blueberry fruit and spinach leaves respectively and were taken into the nano-porous titania substrates. The nano-porous TiO2 paste was sourced from Solaronics SA and its film generated on the glass surface by employing screen printing technique. Ruthenium dye was used as a reference dye. Using DUV3700 spectrophotometer the TiO2 film was characterized to obtain its optical properties which were transmittance, reflectance and absorbance for both sensitized and un-sensitized TiO2 films. The optical results showed blue berry sensitized TiO2 had low reflectance, transmittance and high absorbance compared to all other samples both sensitized and un-sensitized. Spinach sensitized TiO2 films had high reflectance, transmittance and low absorbance. On energy conversion efficiency, the DSSC fabricated using Ruthenium dye had the highest efficiency of ~ 2%. The DSSC fabricated with Blue berry dye followed closely at ~ 1.5 % efficiency while the DSSC employing spinach dye had the lowest conversion efficiency of ~ 0.6 %. Diluting the dyes with distilled water improved conversion efficiency for DSSCs fabricated employing the blue berry and spinach dyes. From the study blue berry dye has shown a more promising potential for fabrication of the DSSCs. However, further study is required to optimize the concentration of the dyes as diluting the dyes enhanced the performance of the dye as a DSSC sensitizer.