Donor–Acceptor Competition via Halide Vacancy Filling for Oxygen Detection of High Sensitivity and Stability by All‐Inorganic Perovskite Films

Abstract

Oxygen detection by organic–inorganic halide perovskites (OIHPs) has demonstrated advantages in operating temperature, response time, and reversibility over traditional materials. However, OIHPs can only sense O2 in light and the unavoidable O2 exposure during detection easily induces the degradation of OIHPs. The trade‐off between sensitivity and stability makes the OIHP‐based oxygen sensors impractical. By replacing organic groups with Cs, the compact films of all‐inorganic halide perovskites (AIHPs) that can adsorb O2 at grain boundaries in dark are developed. AIHPs show conductance increase of 1875.5% from 1 × 10−5 to 700 Torr of O2 pressure, associated with full reversibility and long‐term stability. Combining experiments and modeling, this work reveals the donor–acceptor competition via halide vacancy filling leading to the modulation of carrier concentration and mobility. This work offers understandings on oxygen sensing by perovskite materials and paves the way for further optimization of AIHPs as promising oxygen sensors with high sensitivity and stability.

Organic Cation Diffusion-Induced Heterogeneous Viscoelasticity in Organic–Inorganic Hybrid Perovskite Polycrystalline Films

“…Structure. To study the mechanical properties of OIHP polycrystalline films, we fabricated the representative MAPbBr 3 films via spin-coating with the one-step solution method 26 and performed nanoindentation creep tests by atomic force microscope (AFM) 27 (Figure 1a). The scanning electronic microscopy (SEM) image (Figure 1b) shows that the surface of the MAPbBr 3 polycrystalline film is flat and cavity-free with a clear grain structure.…”

“…■ METHODS Sample Preparation. The MAPbBr 3 polycrystalline film was synthesized by the one-step solution method 26 on a glass substrate. The glass substrate was sequentially washed by isopropanol, acetone, distilled water, and ethanol and gently dried with a nitrogen flow afterward.…”