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358 || AWSAR Awarded Popular Science Stories - 2019
injects the electron in the conduction band of the semiconductor leaving it sensitized in its oxidized state. The electrolyte which is in contact with the photosensitizer regenerates the sensitizer and diffuses
towards the counter electrode
where the reduction process
takes place and electrolyte
restores in its initial stage by
accepting an electron from
external circuits. Besides, these
reactions some undesirable
reactions, like recombination of
injected electrons with oxidized
sensitizer or electrolyte occur
in the cell, which decrease the
cell efficiency. The parameters
which govern the performance
of cell are electrical conversion efficiency (η), open-circuit voltage (Voc), fill factor (FF) and close circuit current density (Jsc). The best
Fig. 1: Schematic diagram and working principle of dye-sensitized solar cell
efficiency achieved by DSSCs is over 11%.” “Look, this is a schematic diagram of the energy flow in the dye-sensitized solar cell,” I showed him a solar cell diagram in my laptop
(see fig 1).
“So, you make these DSSCs in your research lab,” Abhinav asked.
“Yes, we prepare the components of DSSC
separately and then stack them to make DSSCs. But our main focus is on mesoporous semiconductor film, which needs nanomaterials like ZnO, TiO2,” I said.
“What you have done in your lab till now?” Abhinav asked.
“We have prepared ZnO and doped ZnO nanoparticles with different morphologies by changing synthesis conditions. We have prepared ZnO-based nanomaterials via chemical and green/bio method. Green or biosynthesis of nanomaterials uses plant extract as a stabilizing and capping agent, which avoid toxic byproducts as in the case of chemical
   In 1991, O’Regan and Michael
Gratzel invented a new kind of photovoltaic cell working on the principle of plant photosynthesis and reported the efficiency of 7.1-7.9%, called dye-sensitized solar cells.
  method. We
plants and fruits to avoid high cost, toxicity and scarcity problem of the metal oxide-based photosensitizer. We prepared electrolyte and counter electrode. Now only the stacking of DSSC remains and we are working on it,” I told
him.“How DSSCs are advantageous than other photovoltaic cells?” Abhinav interrupted. “Oh, I forgot to tell you,” I continued, “”the DSSCs get attention due to their several valuable qualities like average efficiency, low cost, good performance under diffuse light, easy to fabricate and lightweight product. DSSCs provide a great opportunity to replace the silicon-based bulk, high-cost solar cell which dominates the current photovoltaic market, due to its special features like semi- transparent, multicoloured options, and
flexibility.”
“Wow! It will work under diffuse light with
semi-transparent, flexible and multicolour option, that’s great,” Abhinav wondered.
“Yes, its semi-transparent and multicolour features make it very interesting and open it for commercial purpose. Since multi-coloured
extracted natural dyes from
 
































































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