Electrochemical Doping of Halide Perovskites by Noble Metal Interstitial Cations

• Published in: Advanced materials (Weinheim) 2023-07, Vol.35 (29), p.e2302206-n/a
• Main Authors: Kerner, Ross A., Cohen, Ayala V., Xu, Zhaojian, Kirmani, Ahmad R., Park, So Yeon, Harvey, Steven P., Murphy, John P., Cawthorn, Robert C., Giebink, Noel C., Luther, Joseph M., Zhu, Kai, Berry, Joseph J., Kronik, Leeor, Rand, Barry P.
• Format: Article
• Language: English
• Subjects: Beta decay; Cations; Density functional theory; Doping; electrochemical doping; Electron capture; Gold; halide perovskite; Interstitial defects; Interstitials; Iodine; Light emitting diodes; MATERIALS SCIENCE; Memory devices; Metal halides; Noble metals; Perovskites; Photoluminescence; SOLAR ENERGY
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202302206

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, doping of metal halide perovskites is studied by electrochemically formed Au+ interstitial ions, combining experimental data on devices with a computational analysis of Au+ interstitial defects based on density functional theory (DFT). Analysis suggests that Au+ cations can be easily formed and migrate through the perovskite bulk via the same sites as iodine interstitials (Ii+). However, whereas Ii+ compensates n‐type doping by electron capture, the noble‐metal interstitials act as quasi‐stable n‐dopants. Experimentally, voltage‐dependent, dynamic doping by current density–time (J–t), electrochemical impedance, and photoluminescence measurements are characterized. These 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. Control over doping of novel halide perovskite semiconductors has been a challenging research area, mainly due to the inability to directly measure and characterize defects. In this work, experimental and theoretical methods are combined to make a compelling case for the controlled, electrochemical formation of noble metal interstitial defects in halide perovskite materials, and their impact on n‐type doping and optoelectronic properties is demonstrated.