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Hierarchically Engineered Inorganic Nanomaterials from the atomic to supra-nanocrystalline level as a novel platform for SOLution Processed SOLar cells

Periodic Reporting for period 2 - HEINSOL (Hierarchically Engineered Inorganic Nanomaterials from the atomic to supra-nanocrystalline level as a novel platform for SOLution Processed SOLar cells)

Reporting period: 2018-08-01 to 2020-01-31

The control and engineering of the optoelectronic properties of colloidal nanocrystal and quantum dot solids underpins the performance of optoelectronic devices and solar cells that can be produced in low cost and large scale from such a material platform. Solution processed optoelectronics can bring about a revolution in a large spectrum of critical applications ranging from biomedical imaging, spectroscopy, night vision, surveillance and of course photovoltaics. All the above is of paramount importance for they address critical societal needs on health monitoring, safety and security as well as renewable energies. The lack of engineering methodologies of such materials has limited the report of highly performant devices and solar cells, produced thereof, to being based on Pb and Cd containing nanocrystals. The aim of HEINSOL is one hand to investigate and develop advanced engineering methodologies from that atomic to the supra-nanocrystalline levels of such materials and devices in order to reach performance that was previously considered unreachable and further to employ such methodologies to materials that comprise non-toxic and Earth abundant elements to allow for the facile commercialization of this technology in the future with minimal regulatory concerns. Moreover HEINSOL will explore new synthetic routes for such materials that minimize their manufacturing cost and are compatible with large scale volume manufacturing as well as make use of chemicals (solvents, precursors) that are less harmful to the environment and of lower cost in order to further reduce manufacturing costs of the materials employed in the devices.
Heinsol has thus far made important contributions to this end as we have developed novel approaches in colloidal quantum dot and nanocrystal devices with record low trap state densities by simultaneously passivating defects chemically (at the atomic level) and electronically (at the suprananocrystalline level). HEINSOL has demonstrated new ways of engineering nanocomposite structures comprising colloidal quantum dots by control of their energetic landscape and their density of states reaching record performance in infrared LEDs and solar cells. We have also shown that by combining 2D materials with colloidal quantum dots can reach to very high efficiency low cost tandem solar cells. On the other hand, we have further explored and synthesized novel semiconducting metal chalcogenide nanocrystals and quantum dots that are free of Pb and Cd and we envision to apply our developed engineering methodologies to those new materials towards environmentally friendly low cost solar cells. So far, we have further developed synthetic protocols for such environmentally free materials to enable low cost large scale production in the absence of needs for vacuum and high temperatures in order to increase also the manufacturing readiness level of this technology. We have indeed demonstrated solar cells based on AgBiS2 colloidal nanocrystals that are synthesized at room temperature in ambient conditions, with power conversion efficiency on par with that reported from such material produced previously using high temperature and vacuum-based hot injection techniques.
HEINSOL will push the limits of engineering such complex materials and demonstrate real-world high performance devices made of this low cost material platform. In doing so, HEINSOL will discover new physics and mechanisms at play in the nanoscale that in turn may lead to novel device functionalities and performance records not only in solar cells but also in light emitters and lasers. At the same time HEINSOL will develop the synthesis of materials in the colloidal nanocrystal form that had not been explored before and that are based on environmentally friendly elements paving the way for bringing this technology closer to the consumer market