The research activities I am conducting at the Jean Lamour Institute are focused on the physico-chemistry of thin films synthesized by physical vapor deposition methods. A special attention is paid to the influence of the local structure/chemistry down to the atom scale on the functionnal properties of thin transparent conductive oxides and metal-oxide nanocomposite films. Moreover, strategies are developed to improve the film properties.
Transparent conductive oxides
My interest is mostly on the synthesis and improvement of transparent conductive oxide films deposited without thermal assistance for transparent electronics or electro-optical devices. The challenge is to find an alternative to indium tin oxide (ITO) transparent electrodes that is getting to costly for most applications and based on hardly recyclable indium. Graphene, metal grids and nanowires are seen as potential candidates to replace ITO but the processing technology is not mature and adapted to large surface areas in case of graphene and metal grids and nanowires suffer from low long term stability. Our approach is to rely on an another transparent conductive oxide, doped zinc oxide, and more particularly aluminum-doped zinc oxide (AZO). We focuse on low synthesis temperature in order to functionalize flexible supports and to prevent thermal damage to active components (e.g. CIGS absorber in solar cells, …). Targeted applications are transparent electronics, new photonic devices and solar cells. We could demonstrate the possibility to control to a large extent the microstructure and properties of pure and doped ZnO thin films synthesized without thermal assistance. The following findings can be highlighted:
– It is possible to synthesize homogenously highly conductive Al-doped of equivalent properties to best ITO and intrinsic ZnO as well as to modify the optical UV and NIR absorptions without thermal assistance
– Relative amplitudes of the optical emissions in the ultraviolet and visible ranges can be controlled by changing the nature of dominant point defects in intrinsic ZnO.
– Excitons can be confined in ultrathin films to modify the NBE energy.
– ZnO films can be grown epitaxially without thermal assistance.
These findings opens up new possibilities to improve transparent electrodes and related devices without the need of thermal assistance. We evaluate these possibilities using a multidisciplinary approach involving synthesis and characterization of the electrical, optical properties, structure and electronic structure.
Metal-oxide nanocomposite films (under construction)
This research topic is dedicated to the relationship between the local structure/chemistry and the functional properties of metal-oxide nanocomposite films. More particularly, investigations are focused on the optical and electrical response of plasmonic nanocomposite architectures.