Interfacial Strategies for Efficient and Stable Spray-Coated Perovskite Solar Cells in Open Air

Interface engineering is a promising strategy to fabricate efficient and stable perovskite solar cells. Tuning the band alignment, chemical affinity, and structural bounding between the perovskite absorber and the charge transporting layers has been the key to fabricate high efficiency devices. These interfacial properties can be modified using surface treatments, implementing additional interlayers, or by using additives in the perovskite ink that selectively settle at the top of the bottom of the perovskite film. In combination, these strategies significantly reduce the formation of interfacial defects that are detrimental to both photovoltaic performance (charge extraction) and stability (degradation centers). While widely studied using the spin-coating process, we lack knowledge on the compatibility of interfacial engineering with open-atmosphere scalable processes such as spray-coating.<br/>In this work, we selected established additive and interfacial engineering approaches and applied them to p-i-n devices (glass/ITO/NiO/FACsPbI₃/C₆₀/BCP/Ag) with a spray-coated perovskite absorber. After screening for compatibility with the spray-coating (additives) and plasma-curing (interfaces), we studied their effect on device performances and stability under accelerated aging. The changes in the perovskite layer properties were monitored using XRD, XPS and SEM. Overall, our screening enables the fabrication of perovskite solar cells yielding power conversion efficiencies over 19 % and open circuit voltages of 1.1 V with improved operational stability. This work demonstrates the relevance of adapting these strategies to scalable processes and paves the way towards highly performing and stable large area modules.