The power conversion efficiency of organic-inorganic hybrid perovskite solar cells has increased rapidly, but the device stability remains a big challenge. Previous studies show the grain boundary (GB) can facilitate ion migration and initiate device degradation. Herein, methimazole (MMI) is employed for the first time to construct a surface "patch" by in situ converting residual PbI at GBs. The resultant MMI-PbI complex can effectively suppress ion migration and inhibit diffusion of the metal electrodes. The origin of the surface "patch" effect and their working mechanisms are investigated experimentally and theoretically at the microscopic level. It hence demonstrates a simple and effective method to prolong the device stability in the context of GB engineering, which could be extensively applied to perovskite-based optoelectronics.

Organic−inorganic hybrid perovskite materials have had remarkable success in photovoltaics due to their superior optoelectronic properties and compositional abundance. Most advances focus on the improvement of the heterojunction, in which nonperovskite materials are employed at the pertaining interfaces. Herein we demonstrate the modification of perovskite absorber by incorporation of CsPbBr 3 nanocrystals, which is congeneric to the absorber in terms of crystal structure and stoichiometry. It led to significant enhancement in photovoltaic performance in the corresponding devices, which was mainly attributed to the improved carrier dynamics over the resultant heterojunction. Therefore, a different strategy is suggested for further improvement of the perovskite heterojunction by using congeneric materials.

As one of next-generation semiconductors, hybrid halide perovskites with tailorable optoelectronic properties are promising for photovoltaics, lighting, and displaying. This tunability lies on variable crystal structures, wherein the spatial arrangement of halide octahedra is essential to determine the assembly behavior and materials properties. Herein, we report to manipulate their assembling behavior and crystal dimensionality by locally collective hydrogen bonding effects. Specifically, a unique urea-amide cation is employed to form corrugated 1D crystals by interacting with bromide atoms in lead octahedra via multiple hydrogen bonds. Further tuning the stoichiometry, cations are bonded with water molecules to create a larger spacer that isolates individual lead bromide octahedra. It leads to zero-dimension (0D) single crystals, which exhibit broadband ‘warm’ white emission with photoluminescence quantum efficiency 5 times higher than 1D counterpart. This work suggests a feasible strategy to modulate the connectivity of octahedra and consequent crystal dimensionality for the enhancement of their optoelectronic properties.

Halide perovskite nanocrystals (NCs) and quantum dots (QDs) have received considerable attention, due to their superior photoluminescence quantum yields close to unity, variable morphologies, and tunable optical bandgaps achieved by modifying their composition, size and dimensionality.