Electrochemical Doping of Halide Perovskites by Noble Metal Interstitial Cations.

Metal halide perovskites are an attractive class of semiconductors, but it has proven difficult to control their electronic doping by conventional strategies due to screening and compensation by mobile ions or ionic defects. Noble-metal interstitials represent an under-studied class of extrinsic defects that plausibly influence many perovskite-based devices. In this work, we study doping of metal halide perovskites by electrochemically formed Au interstitial ions, combining experimental data on devices with a computational analysis of Au interstitial defects based on density functional theory. Analysis suggests that Au cations can be easily formed and migrate through the perovskite bulk via the same sites as iodine interstitials (I ). However, whereas I compensates n-type doping by electron capture, the noble-metal interstitials act as quasi-stable n-dopants. Experimentally, we characterize voltage-dependent, dynamic doping by current density-time (J-t), electrochemical impedance, and photoluminescence measurements. Our results provide deeper insight into the potential beneficial and detrimental impacts of metal electrode reactions on long-term performance of perovskite photovoltaic and light emitting diodes, as well as offer an alternative doping explanation for the valence switching mechanism of halide perovskite-based neuromorphic and memristive devices. This article is protected by copyright. All rights reserved.