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Photosynthesis (/ ˌ f oʊ t ə ˈ s ɪ n θ ə s ɪ s / FOH-tə-SINTH-ə-sis) [1] is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabolism.
The initial stages occur within picoseconds, with an efficiency of 100%. The seemingly impossible efficiency is due to the precise positioning of molecules within the reaction center. This is a solid-state process, not a typical chemical reaction. It occurs within an essentially crystalline environment created by the macromolecular structure of ...
The photosynthetic efficiency (i.e. oxygenic photosynthesis efficiency) is the fraction of light energy converted into chemical energy during photosynthesis in green plants and algae. Photosynthesis can be described by the simplified chemical reaction 6 H 2 O + 6 CO 2 + energy → C 6 H 12 O 6 + 6 O 2
Scientists used solar cells constructed of highly conductive photovoltaic materials such as gallium, indium, phosphide and gallium arsenide that increased total efficiency by over 30%. By the end of the century, scientists created a special type of solar cells that converted upwards of 36% of the sunlight it collected into usable energy.
Any energy lost in a cell is turned into heat, so any inefficiency in the cell increases the cell temperature when it is placed in sunlight. As the temperature of the cell increases, the outgoing radiation and heat loss through conduction and convection also increase, until an equilibrium is reached.
In the process of photosynthesis, the phosphorylation of ADP to form ATP using the energy of sunlight is called photophosphorylation. Cyclic photophosphorylation occurs in both aerobic and anaerobic conditions, driven by the main primary source of energy available to living organisms, which is sunlight.
This process takes place in 10 picoseconds (10 −11 seconds). [1] The charges on the P + and the BPh − could undergo charge recombination in this state, which would waste the energy and convert it into heat. Several factors of the reaction center structure serve to prevent this.
To use sunlight in this process, a photoelectrochemical cell can be used, where one photosensitized electrode converts light into an electric current that is then used for water splitting. One such type of cell is the dye-sensitized solar cell. [10] This is an indirect process, since it produces electricity that then is used to form hydrogen.