Periodic Reporting for period 1 - CIGNUS (CuInGaSe Nanowires Under the Sun)
Reporting period: 2019-11-04 to 2021-11-03
Sustainable energy conversion is thus an essential challenge for the future of humanity, as a global shift from fossil fuels to renewable energy is underway as a result of striking climate change concerns. Photovoltaics and battery technologies are at the core of solutions for this issue, and the effort for increased performance, sustainability and affordability is currently at its peak.
Nanowires enable novel paths for this unprecedented situation by reducing necessary resources and pioneering novel science and unique phenomena. In this project, we plan to exploit their properties to save material and improve photovoltaic efficiency by using Se-based materials, which have been proven to have excellent performance in polycrystalline thin films.
Three key project objectives can be identified: the investigation of the growth mechanism and control of the deposition of the nanowires; the study of their optical, electronic, and structural properties; and the fabrication of devices based on them. These challenges were engaged within three main tasks, which are closely interconnected by a continuous feedback of design, fabrication and characterization to constantly improve material quality and application potential.
In WP1, the fellow developed the substrate fabrication and the growth of CuInSe isolated nanostructures and regular holed material. During the fellowship, CuBiSe thin film materials were investigated as well. In WP2, the fellow characterized in depth the material deposited using several different techniques (among which Raman spectroscopy, XRD, and electron microscopy). WP3 was focused on developing devices based on the isolated nanostructures.
After the first 3 months during which the fellow was trained in the cleanroom and in the details of Molecular Beam Epitaxy (MBE), he focused on developing data analysis programming during the first COVID lockdown. Once experimental work was allowed again, he used a magnetron sputtering system to deposit material to test the substrates fabricated in the cleanoom. After 9 months from the start of the project, the MBE machine was available again for use once the fellow assisted other colleagues during maintenance on the system. Several growth conditions were tested, and it was quickly realized that a high substrate temperature was crucial for selective area growth. Using different substrates with different growth masks and designs, isolated CuInSe nanostructures with precise position control were demonstrated on aluminium oxide islands.
Within WP4, the results from the project are planned to be published in 2 journal publications, one focused on the growth analysis of the deposition of CuInSe nanostructures and their characterization, and one on the material developed based on CuBiSe thin films. Furthermore, the fellow presented his work at 3 international conferences (E-MRS, ACCGE, ICMBE) and several workshops and meetings, such as EuroNanoForum and INL Symposia.
In the framework of WP5, the fellow participated in several outreach activities, including participation in the online 2021 Science is Wonderful event and the International Day of Light.
WP6 was focused on project management, where the fellow learned how to take care of the resources available during the project and to organize funding.