Moisture-Stable FAPbI Perovskite Achieved by Atomic Structure Negotiation.

Broad impact in the research community may be anticipated when a material's properties are capable of being manipulated artificially. Such a possibility has been explored here in the FAPbI perovskite structure of perovskite solar cells, which involves undesirable phase transition at working temperature, despite many attempts to resolve the issue. Essential steps have been taken here toward solving this problem by adopting an opposite strategy to incorporate the water molecules into the perovskite structure under the current materials framework by new structural physics maneuvering.

Hysteresis and Instability Predicted in Moisture Degradation of Perovskite Solar Cells.

The degradation of the perovskite solar cell structure was expected recently to be reversible, which opened a new gate to the enhancement of the device lifetime by reversing the process. However, the kinetic details of the structural collapse and recovery are still missing, without which the perovskite reversibility cannot be further explored. Due to the experimental difficulty, a purposeful numerical model was conducted in this report, to simulate the water diffusion process in the perovskite structure in both directions.

Achieving Nonenzymatic Blood Glucose Sensing by Uprooting Saturation.

The saturation of nonenzymatic blood glucose sensors at lower than normal blood glucose levels has blocked their practical applications. The mechanistic understanding of the saturation, however, has long been under debate. Employing cyclic voltammetry, amperometry, and FTIR with various electrolytes of varying concentrations, we were able to uproot the saturation cause.

Promoting Thermodynamic and Kinetic Stabilities of FA-based Perovskite by an in Situ Bilayer Structure.

The commonly employed formamidinium (FA)-containing perovskite solar cells (PSCs) exhibit a severe phase instability problem, thereby limiting their commercial applications. Here, both phase stability and energy efficiency of FA-based PSCs were improved by treating the perovskite surface with pyrrolidinium hydroiodide (PyI) salts, resulting in a 1D perovskite structure (PyPbI), stacked on the original 3D perovskite. By employing in situ XRD measurements, we revealed that the temperature-dependent phase transition activation barrier was enhanced after forming the 1D/3D structure, resulting in a prolonged transition time by 30-40-fold.

Reversing Organic-Inorganic Hybrid Perovskite Degradation in Water via pH and Hydrogen Bonds.

The moisture instability of organic-inorganic hybrid perovskite solar cells has been a major obstacle to the commercialization, calling for mechanistic understanding of the degradation process, which has been under debate. Here we present a surprising discovery that the degradation is actually reversible, via in situ observation of X-ray diffraction, supported by FTIR and SEM. To isolate the hydrogen bond effect, water was replaced by methanol during the in situ experiment, revealing the decomposition to be initiated by the breakdown of N-H-I hydrogen bonds.

Pyrrolidinium lead iodide from crystallography: a new perovskite with low bandgap and good water resistance.

The crystal structure of a new perovskite material, (C4H8NH2)PbI3 was determined and illustrated by single crystal X-ray diffraction. UV spectra, photoluminescence and XRD results show it is a promising alternative to hybrid organic-inorganic perovskites due to it's good water resistance and suitable bandgap.