Abstract
We address the behavior in which a bias voltage can be used to switch on and off the photoluminescence of a planar film of methylammonium lead triiodide perovskite (MAPbI3) semiconductor with lateral symmetric electrodes. It is observed that a dark region advances from the positive electrode at a slow velocity of order of 10 μm s–1. Here we explain the existence of the sharp front by a drift of ionic vacancies limited by local saturation, that induce defects and drastically reduce the radiative recombination rate in the film. The model accounts for the time dependence of electrical current due to the ion-induced doping modification, that changes local electron and hole concentration with the drift of vacancies. The analysis of current dependence on time leads to a direct determination of the diffusion coefficient of iodine vacancies and provides detailed information of ionic effects over the electrooptical properties of hybrid perovskite materials.
Highlights
We address the behavior in which a bias voltage can be used to switch on and off the photoluminescence of a planar film of methylammonium lead triiodide perovskite (MAPbI3) semiconductor with lateral symmetric electrodes
We show that the model matches well with experimental data of the advancement of a dark edge in a wide variety of material samples, and more importantly, it directly relates the PL effects to the ionic drift controlled by a local saturation effect of defects, allowing the direct determination of defect densities and ionic diffusion constants
To further understand the mechanism, we carry out the following experiments and establish the electrical model
Summary
The model accounts for the time dependence of electrical current due to the ion-induced doping modification, that changes local electron and hole concentration with the drift of vacancies. Leitjens et al.[5] observed that an applied electrical field across the perovskite layer can either enhance or suppress the luminescence in lateral interdigitated electrode devices. These findings were described in terms of a simple mechanism common to both fully inorganic and organic semiconductors[6,7], in which photogenerated electrons and holes drift to opposite sides of the device, reducing the bulk recombination rate and PL intensity. We show that the model matches well with experimental data of the advancement of a dark edge in a wide variety of material samples, and more importantly, it directly relates the PL effects to the ionic drift controlled by a local saturation effect of defects, allowing the direct determination of defect densities and ionic diffusion constants
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