Giant persistent photoconductivity at room temperature in Sn-based perovskites

Abstract

Long avoided due to adverse effects in traditional optoelectronic devices, persistent photoconductivity (PPC) is now sought-after for emerging technologies, including artificial synapses and coupled solar batteries. We report on a giant PPC effect at room temperature in the mixed Sn/Pb-based perovskite MAPb0.5Sn0.5I3 (MA = methylammonium). Using Hall and photo-Hall measurements, we identify macroscopic separation of negative and positive carriers as the most likely origin for delayed photoconductivity decay, with a strong electron localization expected at grain boundaries or cracks within the polycrystalline films. Additionally, measurements on perovskite films with varying morphology and SnF2 additive content reveal that large apparent grain size (>5 μm) and effective passivation of recombination centers combine to provide a path for achieving PPC extending over 100 h at room temperature.