Professor Wolfgang Schnick of the University of Munich, Germany

Tuesday, April 20, 2021 - 10:45am

"Shine a Light on Nitrides - From Exploratory Research to Application in Advanced LEDs"

Due to the omnipresence of oxygen and water on our planet, oxides and related compounds have predominantly been investigated in the past. Contrary, nitrogen represents the main constituent (78 %) of our atmosphere, but typically remains unreactive due to the high stability of the N2 molecule. However, in recent years, nitrides arose as modern advanced synthetic materials with applications as special ceramics (Si3N4), flame retardants (P3N5), heat conductors (AlN) or novel semiconductors for LED applications and ultrafast electronics (GaN). Starting from a broad and fundamental exploratory search for novel nitrides we came across the exciting materials class of nitridosilicates. During screening of their materials
properties, we became aware of strong red luminescence in Eu2+-doped nitridosilicates of formula type M2Si5N8 (M = Sr, Ba). In cooperation with lighting industry development of unprecedented luminescent materials (phosphors) became possible, which in the meantime, found worldwide application in warm white luminaires, signal lamps, automotive turn indicators and smartphone dual flash. Subsequently, we extended our search strategy to narrow-band red emitting LED phosphors and discovered the nitridolithoaluminate Sr[LiAl3N4]:Eu2+. [2] This novel material pushed the limitations of highly efficient advanced LEDs with superior color rendition.[3] Synthesis of advanced nitride materials only became possible by continuous advancement and development of synthesis tools. Recent progress in fundamental exploratory synthesis of nitrides will be reviewed in this talk with emphasis on both fundamental research and industrial applications.

[1] Nitridosilicates and Oxonitridosilicates: From Ceramic Materials to Structural and Functional Diversity, M. Zeuner, S. Pagano, W. Schnick, Angew. Chem. Int. Ed. 2011, 50, 7754.
[2] Narrow-Band Red-Emitting Sr[LiAl3N4]:Eu2+ as a Next-Generation LED-Phosphor Material, P. Pust, V. Weiler, C. Hecht, A. Tücks, A.S. Wochnik, A.-K. Henß, D. Wiechert, C. Scheu, P.J. Schmidt, W. Schnick, Nat. Mater. 2014, 13, 891.
[3] A Revolution in Lighting, P. Pust, P.J. Schmidt, W. Schnick, Nat. Mater. 2015, 14, 454.