Fraunhofer FEP will display an industrial-scale transparent conducting oxide (TCO) layer at the international trade fair SVC to be conducted from 19 to 20 April 2011 in Chicago. Titanium dioxide is the base material of the TCO layer that contains small quantities of niobium.
Glass plate with a transparent conducting layer based on titanium dioxide
The TCO layer features similar transparency and conductivity properties as other materials devoid of indium. However, it exhibits better temperature and chemical resistance of up to 550°C. Transparent conducting layers have high electrical conductivity and optical transparency and thus represent a critical component in solar cells and flat displays. However, the TCO layer does not exhibit the superior properties of traditional indium-tin oxide coatings (ITO).
Dr. Torsten Kopte, Head of the Plasma I group at the Fraunhofer FEP, stated that the availability of indium is very limited and China is the only main resource. Since European firms do not want to import raw materials from China and Fraunhofer FEP is engineering indium-free TCO materials to overcome such issues, he added. Titanium dioxide that is utilized in toothpaste and opaque white paint is available abundantly. It has high refractive index and thus suitable for optical applications such as anti-reflective coatings for eyeglasses and heat insulating glass coating.
Manuela Junghähnel, who is producing and evaluating the conducting layers at the Fraunhofer FEP, stated that the TCO layer with high refractive index is ideal for light outcoupling in blue LEDs and for enhanced light trapping in solar cells. Fraunhofer FEP can produce custom TCO layers with enhanced electrical conductivity, refractive index and optical transparency based on the requirement of applications.