A piperidinium salt stabilizes efficient metal-halide perovskite solar cells

Metal halide perovskites have recently attracted a huge international research effort due to their unique optical and electronic properties. They have been applied to a range of application areas including photovoltaics, light-emitting diodes and solar-to-fuel energy conversion devices. In particular, the rapid improvement in the photovoltaic efficiency has been accompanied by a deeper understanding of the fundamental properties of the materials and the key operational mechanisms of the devices. Ionic liquids have been shown to stabilize organic-inorganic perovskite solar cells with metal oxide carrier-transport layers, but they are incompatible with more readily processible organic analogs. Lin et al. report in Science that an ionic solid, a piperidinium salt, enhanced the efficiency of positive-intrinsic-negative layered perovskite solar cells with organic electron and hole extraction layers. Aggressive aging testing showed that this additive retarded segregation into impurity phases and pinhole formation in the perovskite layer. High resolution 3D SIMS mapping was used to determine the location of the piperidinium salt, and to confirm that it did not decompose during cell manufacture.