Protocol for isothermal crystallization of photovoltaic perovskite films based on volatile solvents.

The efficient functioning and stability of a perovskite photoactive layer are paramount to the performance of solar cell devices. Here, we present a protocol for the synthesis of a high-performance exemplified methylammonium lead iodide (CHNHPbI or MAPbI) perovskite photoactive layer. We describe steps for preparing the requisite ratios of the precursor powders, synthesizing MAPbI single crystals, and selecting a suitable preparation technique.

Balancing Lattice Strain by Embedded Ionic Liquid for the Stabilization of Formamidinium-Based Perovskite Solar Cells.

Formamidinium (FA)-based perovskites remained state-of-the-art in the field of perovskite solar cells (PSCs) owing to the exceptional absorption and carrier transport properties, while the transition from photoactive (α-) to photoinactive (δ-FAPbI) phase is the impediment that causes performance degradation and thus limits the deployment of FA-based PSCs. The unfavorable phase transition originates from tensile strain in the FAPbI crystal lattice, which undergoes structural reorganization for lattice strain balancing. In this work, we found that the ionic liquid (IL) could be used as the strain coordinator to balance the lattice strain for stability improvement of FAPbI perovskite.

Avoid Pitfalls in Identifying Perovskite Grain Size.

Perovskite grain size has been used as one of the indicators to evaluate the morphological quality of perovskite films. Large grain size is customarily regarded as an indicator of high photovoltaic performance because it is thought to result in superior charge carrier transport properties due to less carrier scattering by the grain boundaries (GBs). Consequently, the characterization of perovskite grain size has become routine in perovskite solar cell research, and large grain size is in general pursued.

β-Alanine-Anchored SnO Inducing Facet Orientation for High-Efficiency Perovskite Solar Cells.

SnO films as a promising electron transport layer (ETL) have been widely used in planar-type perovskite solar cells to achieve an impressive improvement in the conversion efficiency. However, compared with a mesoporous ETL, the interfacial charge carrier transfer of the SnO ETL is severely limited due to the issues of oxygen vacancy defects and crystal lattice mismatch between SnO and the perovskite, which generally leads to the growth of randomly stacked and porous perovskite layers and subsequently impacts the charge transport and transfer properties. In this work, we developed a facile approach by inducing a bifunctional molecule, β-alanine, into the SnO ETL, which can serve as a bridge to modulate the interfacial charge transfer and the perovskite crystallization kinetics.