Lead halide perovskites: from passivated nanocrystals to naked colloids for conductive film preparation

GONZALEZ-CARRERO, SORANYEL; SCHMIDT LUCIANA CARINA; ROSA-PARDO, IGNACIO; MARTINEZ-SARTI, LAURA; SESSOLO, MICHELE; GALIÁN, RAQUEL E; PEREZ-PRIETO, JULIA

Conferencia; 27th International Symposium on Photochemistry (PhotoIUPAC); 2018

International Union of Pure and Applied Chemistry (IUPAC)

Preparation of lead halide perovskites with desirable optical and electronic is relevant for their optoelectronic applications. These materials have exceeded 22% power conversion efficiency and more recently, they have been used in light emitting devices (LEDs) and photodetectors.[1] Lead halide perovskites present a general chemical formula APbX3, where A is an organic or inorganic monovalent cation such as methylammonium (CH3NH3+, MA), formamidinium (HC(NH2)2+) or cesium Cs+ and X is the halide anion (Cl-, Br -, or I-).[2] The first synthesis of colloidal nanocrystals of hybrid MAPbBr3 perovskite was reported in 2014, by using medium and long alkylammonium bromide as the organic capping to confine the perovskite at the nanoscale (ca. 6 nm) and allow their dispersability in low-to-medium polar organic solvents.[3] Later, a ligand reprecipitation procedure combined with the use of other organic ligands with different shape (adamantlyammonium salt) and length (octyl- or octadecylammonium salt), and different molar ratios between precursors provided high control on their crystallization, stoichiometry, size, and therefore on their optical performance.[4]There is a great interest in the use of colloidal perovskite nanoparticles for thin film preparation with high reproducibility of their morphology and excellent optoelectronic properties. One of the current challenges is the preparation of organic ligand-free perovskite nanocrystals to improve the efficiency in the charge transport between the nanoparticles. Herein, we report the synthesis of ?naked? colloidal nanoparticles stabilised by K+. The nanoparticles showed a low tendency to aggregate in solution and self-assembled on a substrate efficiently, leading to conductive nanoparticle solid films.[