Prof. Dr. Tobias Voß 

TU Braunschweig

Conductive Polymers and Molecular Quantum Emitters as Building Blocks for Hybrid GaN-Based Optoelectronics

The combination of inorganic wide-bandgap semiconductors with organic functional layers opens new routes toward complex optoelectronic devices. This talk presents two classes of organic building blocks for hybrid integration with gallium nitride. First, the hole-conductive polymer PEDOT, grown by oxidative chemical vapor deposition (oCVD), forms conformal and pinhole-free coatings on planar and three-dimensional GaN structures. On n-GaN, these layers create Schottky junctions with rectification ratios up to 10⁷, low ideality factors, and excellent thermal and temporal stability. Replacing p-GaN with oCVD PEDOT yields hybrid LEDs with enlarged light-emitting areas due to improved lateral current spreading, demonstrated on planar devices and on three-dimensional core-shell microrod arrays. Second, zinc phthalocyanine molecules embedded in a tetratetracontane matrix and grown by organic molecular beam epitaxy act as molecular quantum emitters. Reducing the layer thickness below one monolayer suppresses excitonic coupling and produces intense monomer-like emission, which can be efficiently excited with commercial GaN-based UV-LEDs. Together, these results outline paths toward integrated hybrid inorganic/organic optoelectronics.