Nanoscale Phase Segregation in Supramolecular π-Templating for Hybrid Perovskite Photovoltaics from NMR Crystallography.

The use of layered perovskites is an important strategy to improve the stability of hybrid perovskite materials and their optoelectronic devices. However, tailoring their properties requires accurate structure determination at the atomic scale, which is a challenge for conventional diffraction-based techniques. We demonstrate the use of nuclear magnetic resonance (NMR) crystallography in determining the structure of layered hybrid perovskites for a mixed-spacer model composed of 2-phenylethylammonium (PEA) and 2-(perfluorophenyl)ethylammonium (FEA) moieties, revealing nanoscale phase segregation.

Vapor-assisted deposition of highly efficient, stable black-phase FAPbI perovskite solar cells.

Mixtures of cations or halides with FAPbI (where FA is formamidinium) lead to high efficiency in perovskite solar cells (PSCs) but also to blue-shifted absorption and long-term stability issues caused by loss of volatile methylammonium (MA) and phase segregation. We report a deposition method using MA thiocyanate (MASCN) or FASCN vapor treatment to convert yellow δ-FAPbI perovskite films to the desired pure α-phase. NMR quantifies MA incorporation into the framework.

Phenanthrene-Fused-Quinoxaline as a Key Building Block for Highly Efficient and Stable Sensitizers in Copper-Electrolyte-Based Dye-Sensitized Solar Cells.

Dye-sensitized solar cells (DSSCs) based on Cu bipyridyl or phenanthroline complexes as redox shuttles have achieved very high open-circuit voltages (V , more than 1 V). However, their short-circuit photocurrent density (J ) has remained modest. Increasing the J is expected to extend the spectral response of sensitizers to the red or NIR region while maintaining efficient electron injection in the mesoscopic TiO film and fast regeneration by the Cu complex.