Organic photovoltaics—what should photonics experts know about it?
Photonics question of the month
OPV cells have many advantages: Production is very efficient with regard to energy and raw materials: Heliatek applies only tiny quantities (1g/m²) of the organic base material—and the cells recover the energy used within three months. The light weight of OPV cells allow integration into membrane roofs, tents, or vehicle bodies. You can also choose any color. Transparent cells are also possible, which would be ideal for (glass) facades, windows, or greenhouses. This opens up completely new horizons for sustainable energy generation. Laser technology is paving the way for this.
Interesting secondary aspect: OLED technology is a chance discovery from early research into organic photovoltaics. During their research, two Kodak scientists, Ching Tang and Steven van Slyke, accidentally discovered this option for using electroluminescent organic materials and, in 1987, published the world’s first OLED paper, “Organic electroluminescent Diodes.” Worth reading: Article on “Three decades of OLED history” by Sri Peruvemba in the LEDs Magazine.
Technical background: Organic semiconductor molecules are based on carbon structures that are extended with small molecules and, in terms of many free charge carriers, with more molecules. Compared to inorganic electronics, these organic molecular bonds have the benefit that, when they are excited, quasiparticles (known as excitons) are formed, which pass on the excitation energy from molecule to molecule. OPV cells convert excitons that are excited by photons into free charge carriers. Vice versa, when subject to electrical excitation, the organic materials in OLEDs create excitons that emit their energy in the form of light as soon as they become unstable. The Introduction to organic electronics on the website of Organic Electronics Saxony e.V. explains the most important areas of application and the way they function in an understandable manner.