Page 381 - AWSAR 2.0

“What is the name of this nanopowder sir?” Abhinav continued.
“This is ZnO nanomaterial,” I responded, and showed some TEM and SEM images to him on my laptop.
“Oh, this structure looks like a rod and that one like a hexagon,” Abhinav remarked with surprise in his eyes.
“Yes, you can see ZnO nanorods in a SEM image and ZnO hexagonal nanostructure in a TEM image. ZnO is morphologically rich and depending upon different morphologies like nanospheres, nano- triangles, and hexagonal nanorods. It has several applications because some properties of the materials are morphology dependent,” I replied.
“Where will you use this ZnO nanomaterial?” Abhinav asked enthusiastically.
“Actually, my research focuses on the development of cost-effective nanomaterials with enhanced properties
for dye-sensitized solar cells (DSSCs),” I responded.
“What are dye-sensitized solar cells? I have never heard of them, tell me in detail how it works?”, Abhinav asked eagerly.
“Ok, please sit down and
listen,” I started to explain
about DSSCs. “The increasing
demand of energy is one
of the biggest challenges
ahead of humankind. The
short storage and pollution
problem associated with fossil
fuel forced us to think about
other options of clean and
renewable energy sources. The
solar energy is the best option
among all the clean, renewable
and sustainable energy
sources such as tidal power and hydropower.
Mr. Raj Kamal Yadav || 357
Several types of photovoltaic-based devices like organic, inorganic and hybrid cells have been developed to harness solar energy. High cost, toxicity and large energy consumption in fabrication create problem for commercially available inorganic solar cells. These problems compelled us to seek other options that provide a clean environment as well as low-cost clean energy for all and future generations. 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.”
“Oh, it works just like photosynthesis? How is that?” curious, Abhinav asked.
“Listen, you know about plant photosynthesis in which chlorophyll absorbs light energy from the sun and converts it into chemical energy, now similar to that just imagine artificial photosynthesis in which light
energy from the sun converts into electrical energy,” I responded.
I continued, “In dye- sensitized solar cells, dyes or natural pigments absorb solar light energy, which excites electrons, which can flow towards the electrode and this electron flow can then be used to power other devices, like light bulbs or cars. So, similar to plant photosynthesis the working method of DSSCs is like artificial photosynthesis. Actually, DSSCs contain mainly five components: transparent conductive substrate, mesoporous semiconductor film, photosensitizer, electrolyte, and counter electrode. After absorption of photoenergy,
the sensitizer goes into an excited state and
An optical microscope uses a light beam whereas an electron microscope uses an electron beam, due to which electron microscope gives highly magnified image than optical microscope. In SEM, electron beam scans over the surface of the sample and gives three- dimensional morphological image of the sample while in TEM electron beam passes through the thin sample and provides a two-dimensional projection of the sample