Some organic materials could be used in optoelectronics similar to silicon semiconductors. Whether as solar cells, light-emitting diodes or transistors - the so-called band gap, i.e. the energy difference between electrons in the valence band and the conduction band, is important. By means of light or an electrical voltage, charge carriers can be lifted from the valence band into the conduction band - in principle, this is how all electronic components work. Band gaps between 1-2 electron volts are ideal.
A team led by the chemist Dr. Michael J. Bojdys at Humboldt University Berlin has now synthesized a new organic semiconductor material from the carbon nitride family. The triazine-based graphitic carbon nitride or TGCN consists only of carbon and nitrogen atoms and can be grown as a film on a quartz substrate. The C and N atoms together form hexagonal honeycombs, similar to graphene, which consists of pure carbon. As with graphene, the crystalline structure of TGCN is two-dimensional. With graphene, however, the conductivity in the plane is excellent, perpendicular to it very poor. With TGCN it is exactly the other way round: the conductivity perpendicular to the plane is about 65 times greater than in the plane itself. With a band gap of 1.7 electron volts, TGCN is a good candidate for applications in optoelectronics.