Veranstaltung

New photovoltaic (PV) technologies, delivering high performances at low price, are ideal candidates to sustain the actual paradigm shift towards a carbon-free economy. In this context, Perovskite Solar Cells (PSCs), pioneered by methylammonium lead-iodide (CH3NH3PbI3) perovskite, are leading the photovoltaic scenario, showing impressive power conversion efficiency beyond 22% reached upon only six years of research.[1] PSCs consist of a layered device where the perovskite is sandwiched between an electron transport layer (i. e. mesoporous titanium oxide), and an organic hole transporter.[2] Light is absorbed by the perovskite, free carriers are generated and injected into the selective contacts. High performances have been obtained by fine-tuning the perovskite composition and by engineering the device interfaces. However, poor device stability (=short lifetime) mainly due to water-induced degradation, is the actual challenge.

I will present our innovative approach to realize efficient and stable devices by controlling the fundamental photophysical processes, such as charge injection, trapping, charge recombination, (happening over timescales form femtoseconds to nanoseconds), at the device interfaces and manipulating them to create new  functionalities. To this regard, we propose a new multidimensional PSC by designing new hydrophobic compounds - to reduce the water induced degradation - and by engineering stable multidimensional interfaces. The multi-dimensional PSC deliver high efficiency (over 20%) and a record stability value of 11,000 hours, corresponding to more than one year operation, with zero efficiency losses. [2]
References:
[1] http://www.nrel.gov/ncpv/images/efficiency_chart.jpg, “National Renewable Energy Laboratory Best Research-Cell Efficiencies”.
[2] G. Grancini et al. “One-Year stable perovskite solar cells by 2D/3D interface engineering” Nat. Comm. 8 (15684), (2017)

Link zur Website: https://memento.epfl.ch/event/interface-engineering-and-physics-therein-for-high/

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