Photosynthesis and Semiconductor-based solar cell
Robyn Beavon
Strayer Univestity
SCI
115
Professor Meri Stanec
July 23, 2012
Photosynthesis and Semiconductor-based solar cell
Photosynthesis, by definition, “is a process used by plants and other organisms to convert the light energy captured from the sun into chemical energy that can be used to fuel the organism's activities”. (http://en.wikipedia.org/wiki/Photosynthesis) A solar cell “is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect. (http://en.wikipedia.org/wiki/Solar_cell) Photosynthesis and a semiconductor-based solar cell have several similarities and differences. Photosynthesis and solar cells both require solar energy or sunlight for the process to begin. We rely on both processes for survival, photosynthesis produces us oxygen, food and materials for living on Earth (fiber for clothes, wood for our homes, ect) and solar cells provide us with electricity. Another similarity is that they both lose electron during the process. When the electrons are lost in solar cells they are replenished once the electrical circuit is complete. In photosynthesis the electrons lost by the pigments are replaced by splitting water. Splitting water occurs in both plant cells and solar cells, a chemical reaction in which water is separated into oxygen and hydrogen. Water splitting occurs naturally in the process of photosynthesis, however, Penn State researchers have a proof-of-concept device that can split water and produce recoverable hydrogen. The two systems work well when they are perpendicular to the sun rays. Some of the differences of the two is that semiconductors convert the energy trapped into electricity and plants convert the energy trapped into chemical energy. Photosynthesis takes place naturally as the plants are able to harness energy naturally and convert it, whereas semiconductors are man made and are made to trap energy and convert it to electricity. Plants are the main composite of photosynthesis. Silicon is the main composite of solar cells and panels. The laws of thermodynamics: Photosynthesis transforms solar energy into the chemical energy of a carbohydrate and a solar cell converts the energy of light directly into electricity, therefore the first law of thermodynamics is applied. The first law states that “energy can neither be created nor destroyed, it can change forms and energy can flow from one place to another”. Semiconductors also follow the second and third law of thermodynamics, in semiconductor-based solar cells the solar cell is unable to exceed the power of light that is landing on it. The second law tells us that the ratio of heat to work can never equal 100% during both processes not all the energy is converted some of it is lost as heat output to our surroundings. Because energy is lost it also brings us to the third law because to keep the system going it takes a regular stream of energy.
