The grain boundaries of perovskite polycrystalline are regarded as a defect region that not only provides carrier recombination sites but also introduces device degradation pathways. Efforts to enlarging the grain size of a perovskite film and reducing its grain boundary are crucial for highly efficient and stable perovskite solar cells (PSCs). Some effective methods that facilitate grain growth are postdeposition thermal annealing and solvent vapor annealing. However, a detailed understanding of grain growth mechanisms in perovskite films is lacking. In this study, perovskite films were prepared by adding ethylamine hydrochloride (EACl) to the precursor solution. This additive strategy promotes a new grain growth mode, secondary grain growth, in perovskite films. Secondary grain growth leads to much larger grains with a high crystallographic orientation. These excellent properties lead to reduced grain boundaries and the densities of boundary defects. The improved film quality results in a prolonged charge–carrier lifetime and a significantly enhanced power conversion efficiency (PCE). Compared with the 18.42% PCE of the control device, the PCE of the device with EACl additives reaches 21.07%.

The instability of 3D perovskite and the low power conversion efficiency (PCE) of 2D perovskite limit the development of perovskite solar cells (PSCs). Using 2D perovskite to passivate 3D perovskite thin films by heterojunction engineering has become an effective strategy to develop stable and efficient PSCs. Therefore, it is important to find suitable 2D perovskite passivation materials. Herein, a 2D/3D heterojunction perovskite is formed in situ by introducing a long‐chain alkyl phenylbutylammonium (PBA+) cation. The 2D perovskite has the property of n = 2, which passivates the surface defects of the 3D perovskite, resulting in enhanced photoluminescence intensity and prolonged carrier lifetime. Moreover, the 2D layer changes the interface contact and energy‐level arrangement, making it a more n‐type semiconductor, which facilitates the electron transfer between perovskites and electron transport. This strategy significantly improves the open circuit voltage (Voc) and fill factor (FF) of the devices without sacrificing current, and the PCE is improved from 19.22% to 21.76%. The hydrophobic PBA+‐based 2D layer also improves the humidity stability of the films and enhances the working stability of the device. The PCE of the champion heterojunction perovskite device remains 87% of its initial value after illumination for 1000 h. The results show that heterojunction engineering plays an important role in the preparation of efficient and stable PSCs.

Columnar mesogenic dyads consisting of triphenylene and perylene units are a novel kind of single-component photovoltaic materials.

A chiral aromatic amino acid, (S)-3-Amino-4-phenylbutyric acid hydrochloride (s-APACl), was employed as an additive to the active layer in a p-i-n organic-inorganic halide perovskite solar cell. This additive led to...