EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The main objective of this work is to take advantage of the specificities of Zinc Oxide (ZnO) Nanowires (NWs) array (porosity, specific surface…) for LED lighting. The ZnO NWs were grown by hydrothermal synthesis from a ZnO seed layer directly deposited on the sol-gel derived Ce3+-doped yttrium aluminum garnet (Y3Al5O12 :Ce or YAG :Ce) coatings. Highly dense array of vertical ZnO NWs was evidenced on the top of YAG:Ce coating by optical and electron microscopy. ZnO NWs elaboration process was also optimized to achieve networks with controlled optogeometrical properties (profile, height, width and pitch) The use of NWs networks instead of plenary array was expected to influence heterostructure features, notably their optical properties. Classical but also original techniques such as Atomic Force Microscopy (AFM) have been carried out to study the structural, morphological and optical properties of these functional coatings. In particular, the optical study showed that this original design leads to a different angular distribution of light together with an increase in emission efficiency of YAG:Ce coating upon blue excitation compared to the flat coating. These improvements will be discussed in reliance on multiscattering events for photons within the structure, allowing them to escape the phosphor layer by taking optical paths different from those of the flat coating.
Acknowledgements

The authors acknowledge the French Agence Nationale de la Recherche for its financial support in the frame of the ANR SMARtLEDs project (ANR-19-CE08-0001).