Organic–inorganic hybrid perovskites have attracted considerable attention due to their superior optoelectronic properties. Traditional one‐step solution‐processed perovskites often suffer from defects‐induced nonradiative recombination, which significantly hinders the improvement of device performance. Herein, treatment with green antisolvents for achieving high‐quality perovskite films is reported. Compared to defects‐filled ones, perovskite films by antisolvent treatment using methylamine bromide (MABr) in ethanol (MABr‐Eth) not only enhances the resultant perovskite crystallinity with large grain size, but also passivates the surface defects. In this case, the engineering of MABr‐Eth‐treated perovskites suppressing defects‐induced nonradiative recombination in perovskite solar cells (PSCs) is demonstrated. As a result, the fabricated inverted planar heterojunction device of ITO/PTAA/Cs0.15FA0.85PbI3/PC61BM/Phen‐NADPO/Ag exhibits the best power conversion efficiency of 21.53%. Furthermore, the corresponding PSCs possess a better storage and light‐soaking stability.

Van der Waals layered CuInP 2 S 6 (CIPS) is an ideal candidate for developing two-dimensional microelectronic heterostructures because of its room temperature ferroelectricity, although field-driven polarization reversal of CIPS is intimately coupled with ionic migration, often causing erratic and damaging switching that is highly undesirable for device applications. In this work, we develop an alternative switching mechanism for CIPS using flexoelectric effect, abandoning external electric fields altogether, and the method is motivated by strong correlation between polarization and topography variation of CIPS. Phase-field simulation identifies a critical radius of curvature around 5 μm for strain gradient to be effective, which is realized by engineered topographic surfaces using silver nanowires and optic grating upon which CIPS is transferred to. We also demonstrate mechanical modulation of CIPS on demand via strain gradient underneath a scanning probe, making it possible to engineer multiple polarization states of CIPS for device applications.

Magnetic materials and devices that can be folded and twisted without sacrificing their functional properties are highly desirable for flexible electronic applications in wearable products and implantable systems. In this work, a high‐quality single crystalline freestanding Fe3O4 thin film with strong magnetism has been synthesized by pulsed laser deposition using a water‐dissolvable Sr3Al2O6 sacrificial layer, and the resulting freestanding film, with magnetism confirmed at multiple length scales, is highly flexible with a bending radius as small as 7.18 µm and twist angle as large as 122°, in sharp contrast with bulk magnetite that is quite brittle. When transferred to a polydimethylsiloxane support layer, the Fe3O4 film can be bent with large deformation without affecting its magnetization, demonstrating its robust magnetism. The work thus offers a viable solution for flexible magnetic materials that can be utilized in a range of applications.

Correlations between ion migration, charge carrier, and bulk deep-level defect in MAPbI3 perovskites are systematically invesitgated through voltage-dependent thermal admittance spectroscopy and in situ scanning probe microscopy. We show that iodine interstitials construct stable, deep-level bulk defects in the polycrystalline MAPbI3 with an activation energy (E A ) level of 0.495 eV above the valence band maximum. Experimentally, E A varied with depletion region distribution and excess electron from charge transport layers, which can be modulated through external bias. Under forward bias, mobile bulk defects migrate and transform into surface defect states, introducing additional nonradiative recombination pathways. Overall, this study directly reveals electronic correlations between defect ions and charge carriers, pointing out the importance of iodine defect chemistry in surface recombination and degradation in long-term device stabilities.

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Understanding the interplay between ionic migration and defect trapping in photovoltaic perovskites is critical to develop targeted passivation techniques for performances enhancement. Here, systematic poling experiment on Cs0.05(FA0.85MA0.15)0.95Pb(I0.85Br0.15)3 perovskite solar...

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