P HOTOVOLTAIC C ELLS Parth Bhide

What is a Photovoltaic Cell? How do Photovoltaic Cells Work? Why are Photovoltaic Cells not 100% Efficient? What Technologies and Materials Help Boost the Efficiency of Photovoltaic Cells. The Use of Nanotechnology S UMMER R ESEARCH Microsoft Office Clip Art

W HAT IS A P HOTOVOLTAIC C ELL ? A photovoltaic (PV) cell. Uses energy in photons (solar energy) and converts it to electricity. Most PV cells contain the semiconductor silicon. The silicon found in PV cells is unpurified (doped) with boron and phosphorous using an ion implanter.

H OW DO P HOTOVOLTAIC C ELLS W ORK ? The silicon doped with phosphorous creates a negative charge (n-layer), and the silicon doped with boron creates a positive charge (p-layer). The junction between the layers allows for the passage of electrons from the n-layer to the p-layer. As photons excite electrons, the electrons move from the n-layer to the p-layer, through a separate wire, creating electricity.

W HY ARE P HOTOVOLTAIC C ELLS NOT 100% E FFICIENT ? The efficiency of PV cells depends on many factors. Band Gap- The amount of energy needed to break electrons from their atoms. Impurity Ratio- To prevent recombination of electrons into other nuclei. The reflection of light off the silicon cells.

W HAT T ECHNOLOGIES AND M ATERIALS H ELP B OOST THE E FFICIENCY OF P HOTOVOLTAIC C ELLS. To widen the band gap range, research is being done to use different materials and combinations of ions to increase the usable energies of photons. With the challenge of new materials comes the challenge of maintaining basic particle and chemical interaction. Layers of antireflective materials to prevent the reflection of incoming photons

T HE U SE OF N ANOTECHNOLOGY Nanotechnology is being developed in photovoltaic advancement Nano-sized holes, smaller than photons used to keep light from being reflected. Odd geometry and small 100-nm holes to increase the anti-reflectivity. Underdeveloped technologies, including a paint that acts as a solar cell.

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C ONCLUSION Photovoltaic cells convert solar energy into electrical energy. Although complex, PV cells remain approximately 20% efficient and very expensive. Different materials and structures can influence the efficiency of the cell. Several factors that need to be improved are antireflectivity, compositional uniformity, and band gap of the material.

R EFERENCES "How Solar Energy Works." Union of Concerned Scientists, n.d. Web.. Kiger, Patrick J. "Sun Plus Nanotechnology: Can Solar Energy Get Bigger by Thinking Small?" National Geographic Daily News. National Geographic, n.d. Web Knight, Matthew. "New Nano Coating Boosts Solar Efficiency." CNN. Cable News Network, n.d. Web "Photovoltaic Cell Conversion Efficiency." Eere.energy.gov. United States Department of Energy, n.d. Web.. Preuss, Paul. "A Step Closer to the Optimum Solar Cell." A Step Closer to the Optimum Solar Cell. Science Beat, n.d. Web Rubin, Leonard, and John Poate. "Ion Implantation in Silicon Technology - The Industrial Physicist." Ion Implantation in Silicon Technology - The Industrial Physicist. The Industrial Physisist, n.d. Web "Types of Silicon Used in Photovoltaics." Energy Basics:. US Department of Energy, n.d. Web

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