The manipulation of crystal orientation from the thermodynamic equilibrium states is desired in layered hybrid perovskite films to direct charge transport and enhance the perovskite devices performance. Here we report a templated growth mechanism of layered perovskites from 3D-like perovskites which can be a general design rule to align layered perovskites along the out-of-plane direction in films made by both spin-coating and scalable blading process. The method involves suppressing the nucleation of both layered and 3D perovskites inside the perovskite solution using additional ammonium halide salts, which forces the film formation starts from solution surface. The fast drying of solvent at liquid surface leaves 3D-like perovskites which surprisingly templates the growth of layered perovskites, enabled by the periodic corner-sharing octahedra networks on the surface of 3D-like perovskites. This discovery provides deep insights into the nucleation behavior of octahedra-array-based perovskite materials, representing a general strategy to manipulate the orientation of layered perovskites.

While energy shortage is always an issue, the impending exhaustion of fossil fuel sources makes it an ever increasingly pressing one.

Inorganic-organic hydride perovskites bring the hope for fabricating low-cost and large-scale solar cells. At the beginning of the research, two open questions were raised: the hysteresis effect and the role of chloride. The presence of chloride significantly improves the crystallization and charge transfer property of the perovskite. However, though the long held debate over of the existence of chloride in the perovskite seems to have now come to a conclusion, no prior work has been carried out focusing on the role of chloride on the electronic performance and the crystallization of the perovskite. Furthermore, current reports on the crystal structure of the perovskite are rather confusing. This article analyzes the role of chloride in CH3NH3PbI3-xClx on the crystal orientation and provides a new explanation about the (110)-oriented growth of CH3NH3PbI3 and CH3NH3PbI3-xClx.

Dion–Jacobson (DJ)‐type quasi‐two‐dimensional perovskites exhibit improved stabilities than their 3D counterparts but meanwhile limited charge transport properties. Knowledge to manipulate the crystal orientation and crystallinity is the primary issue for DJ perovskite with high power conversion efficiencies (PCEs). Herein, the nucleation of DJ perovskite films is divided into three stages and the formation of PbI2–N,N‐dimethylformamide (DMF)‐based solvated phase (PDS) is highlighted as the initial stage. For the first time, it is demonstrated that regulating the amount of PDS precipitation in stage I by MACl additive is the key to ensure the downward growth of DJ perovskites with out‐of‐plane orientation and high crystallinity in stage III, which is valid for DJ perovskites with different bukly organic cations including p‐phenylenediamine (PPD), p‐xylylenediamine (PXD), and propane‐1,3‐diammonium (PDA). For (PXD)(MA)2Pb3I10‐based perovskite solar cells, the PDS engineering lead to a dramtically improved PCE from 1.2% to 15.6%. Moreover, based on temperature‐dependent ionic conductivity measurement, it is confirmed that the ion migration in DJ perovskite films is efficiently suppressed, despite the possible coexisting 3D perovskite phase. The unencapsulated PXD‐based DJ perovskite devices retain over 90% efficiencies after 700 h of continuous illumination or 1500 h of storage in glove box.

Lead halide perovskite solar cells (PSCs) with solution processability, low defect concentration, low cost and high output manufacturing have emerged as promising third-generation photovoltaic technologies. After an unprecedented speed of development, the power conversion efficiencies of small-area PSCs have exceeded 25%, and meanwhile large-scale perovskite modules are also on a rapid rise. At this stage, considering the significant progress in the fabrication of perovskite films with controllable morphology and crystallinity, it is necessary to conduct reviews on the updated understandings of the nucleation and crystal growth behaviors of perovskites. This review aims to clarify the related mechanisms of the complex perovskite formation process, and is devoted to giving a timely summary of the recent advances. Strategies for controlling perovskite nucleation and crystal growth are also discussed.