title: Evidence for ion migration in hybrid perovskite solar cells with minimal hysteresis.
abstract: Ion migration has been proposed as a possible cause of photovoltaic current-voltage hysteresis in hybrid perovskite solar cells. A major objection to this hypothesis is that hysteresis can be reduced by changing the interfacial contact materials; however, this is unlikely to significantly influence the behaviour of mobile ionic charge within the perovskite phase. Here, we show that the primary effects of ion migration can be observed regardless of whether the contacts were changed to give devices with or without significant hysteresis. Transient optoelectronic measurements combined with device simulations indicate that electric-field screening, consistent with ion migration, is similar in both high and low hysteresis CH3NH3PbI3cells. Simulation of the photovoltage and photocurrent transients shows that hysteresis requires the combination of both mobile ionic charge and recombination near the perovskite-contact interfaces. Passivating contact recombination results in higher photogenerated charge concentrations at forward bias which screen the ionic charge, reducing hysteresis.
authors.affiliation: Department of Physics, Imperial College London, London SW7 2AZ, UK.|Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, UK.
authors.forename: Philip
authors.initials: P
authors.lastname: Calado
authors.affiliation: Department of Physics, Imperial College London, London SW7 2AZ, UK.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Telford
authors.affiliation: Department of Chemistry, Imperial College London, London SW7 2AZ, UK.|SPECIFIC, Swansea University, Swansea SA12 7AX, UK.
authors.forename: Daniel
authors.initials: D
authors.lastname: Bryant
authors.affiliation: Department of Chemistry, Imperial College London, London SW7 2AZ, UK.
authors.forename: Xiaoe
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Physics, Imperial College London, London SW7 2AZ, UK.|Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, UK.|Department of Chemistry, Imperial College London, London SW7 2AZ, UK.
authors.forename: Jenny
authors.identifier: 0000-0003-1048-1330
authors.initials: J
authors.lastname: Nelson
authors.affiliation: Sunlight Scientific, 1190 Oxford Street, Berkeley, California 94707, USA.
authors.forename: Brian C
authors.initials: BC
authors.lastname: O'Regan
authors.affiliation: Department of Physics, Imperial College London, London SW7 2AZ, UK.|Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, UK.
authors.forename: Piers R F
authors.initials: PR
authors.lastname: Barnes