Electrochemical and Thermal Etching of Indium Tin Oxide by Solid-State Hybrid Organic–Inorganic Perovskites

We show that tin-doped indium oxide (ITO) can be thermally etched by the Bronsted acid salts methylammonium iodide (MAI), methylammonium lead triiodide (MAPbI3), and formamidinium lead triiodide (FAPbI3) in solid-state films and devices at common processing temperatures. More importantly, a series of reactions within an ITO/hybrid perovskite/Au device can be electrochemically induced near room temperature by applied cathodic voltages as low as −1.2 V. Cyclic voltammetry in this range leads to eventual In3+ leaching into the perovskite layer in the form of InI3, unambiguously identified by a binding energy signature of 445.9–446.3 eV measured by X-ray photoelectron spectroscopy. Furthermore, the etching is exacerbated by defects generated by O2-plasma treatment of the ITO compared to UV-ozone cleaning, lowering the reaction potential and the electrochemical stability window of an ITO/MAPbI3/Au device. Low-temperature, electrochemical reactivity at this interface has implications on operational stability, f...