Tailoring perovskite crystallization and interfacial passivation in efficient, fully textured perovskite silicon tandem solar cells
Oussama Er‐raji, Mohamed A. A. Mahmoud, Oliver Fischer, Alexandra J. Ramadan, Dmitry Bogachuk, A. Reinholdt, Angelika Schmitt, Bhushan P. Kore, Thomas W. Gries, Artem Musiienko, Oliver Schultz‐Wittmann, Martin Bivour, Martin Hermle, Martin C. Schubert, Juliane Borchert, Stefan W. Glunz, Patricia S. C. Schulze
Abstract
Fully textured perovskite silicon tandem solar cells are promising for future low-cost photovoltaic deployment. However, the fill factor and open-circuit voltage of these devices are currently limited by the high density of defects at grain boundaries and at interfaces with charge transport layers. To address this, we devise a strategy to simultaneously enhance perovskite crystallization and passivate the perovskite/C 60 interface. By incorporating urea (CO(NH 2 ) 2 ) as an additive in the solution step of the hybrid evaporation/spin-coating perovskite deposition method, the crystallization kinetics are accelerated, leading to the formation of the desired photoactive phase at room temperature. With that, perovskite films with large grain sizes (>1 μm) and improved optoelectronic quality are formed at low annealing temperatures (100°C). Concurrently, remnant urea molecules are expelled at the perovskite surface, which locally displaces the C 60 layer, thus reducing interfacial non-radiative recombination losses. With this strategy, the resulting tandem solar cells achieve 30.0% power conversion efficiency.