organic solar cell (OSC)
Solar cells made of organic photovoltaics have the advantage over inorganic, silicon-based solar cells that they can be produced cheaply. Hydrocarbon compounds with electrically conductive properties are used as the organic material. The finished organic solar modules are extremely flexible and can be laid over large areas.
Organic solar cells consist of several layers for energy conversion and two electrodes at which the generated voltage is tapped. The bottom and top layers of the solar film, which is only 0.2 µm thick, are transparent electrodes made of conductive oxide layers for the current connection.
The lowest transparent layer consists of indium tin oxide( ITO). Between these two electrodes, where the photovoltaic voltage is tapped, there are three other layers: Two charge layers and transport layers that enhance the extraction of charge carriers, and in between, a photoactive layer of light-absorbing polymers that convert the absorbed light into electrical voltages. This is done by creating an electron-hole pair on the polymer when a photon is absorbed. The absorption itself already takes place in the first 100 nm to 200 nm of the photoactive layer, which means that the absorption layer can be kept extremely thin.
As far as the electrodes are concerned, one of the two electrodes is translucent, the other is made of the thinnest aluminum or silver and is reflective. This has the advantage that the reflected light passes through the photoactive layer a second time and is thus better utilized. The entire organic solar cell is transparent and can also be used in windows.
The efficiency of organic solar cells is constantly being improved through enormous development efforts, which are mainly reflected in the modification of the molecular structures, and reached a value of over 10 % in 2012.