Surface Stabilization of Colloidal Perovskite Nanocrystals via Multi-amine Chelating Ligands

Abstract

Developing pathways to stabilize the intrinsically dynamic surface of metal halide perovskite nanocrystals (PNCs), especially metastable lead iodide PNCs, is an important but challenging task. Herein, we have realized ultra-stable colloidal CsPbI 3 PNCs based on a multi-amine chelating ligand, N′-(2aminoethyl)-N′-hexadecylethane-1,2-diamine (AHDA). The protonated AHDA can anchor the PNC surface lattice with a high binding energy of 2.36 eV, much larger than the 1.47 eV achieved with the commonly used oleylammonium ligands. The chelation effect greatly inhibits dynamic desorption of surface ligands and enables stabilization of CsPbI 3 PNCs under various ambient stimuli, such as repeated purification (up to 15 cycles), polar solvents, heat, and light.The stable yet easily accessible surface of the AHDA-capped CsPbI 3 PNCs renders them a robust photocatalyst in a stereoselective C−C oxidative coupling reaction. Furthermore, we show that the AHDA ligand can also be used to synthesize PNCs of several other compositions, namely CsPbCl 3 , CsPbBr 3 , CsPbBrI 2 , and hybrid FAPbI 3 (FA = formamidine), with remarkably stable emission characteristics.

UV-Assisted Conversion of 2D Ruddlesden–Popper Iodide Perovskite Nanoplates into Stable 3D MAPbI3 Nanorods

“…Under UV exposure, the oleylammonium ion gets desorbed from the NPl surface and produces a bare NPl structure. The hard acid nature of the oleylammonium cation and the soft basic nature of the iodide are believed to accelerate this process. , The PL study revealed that the formation of 3D NR already started after 2 h of UV exposure. This hints that the bare NPls get associated to form a 3D nanostructure.…”

Ultrastable Perovskite through a SiO2 and PbSO4 Double Protection Strategy

“…Metal halide perovskites (LHPs) exhibit high PLQY, tunable bandgaps, and narrow emission line width that show promising application in light-emitting diodes (LEDs). − After years of booming development, the external quantum efficiency (EQE) of perovskite-based LEDs has reached more than 23%, becoming the candidates of next-generation solid-state lightings and displays. − Although a huge breakthrough of efficiency is achieved, the stability of perovskites is the main obstacle to the development of their commercial application. The origin of the instability of perovskites is generally associated with low formation energy, which makes them extremely susceptible to light, heat and oxygen, and moisture. − In addition, the ionic nature of perovskites also causes degradation when encountering polar solvents such as water and alcohol. ,, …”

Highly Emitting Perovskite Nanocrystals with 2-Year Stability in Water through an Automated Polymer Encapsulation for Bioimaging

“…Therefore, many strategies have been reported to preserve the NCs for longer times at ambient conditions by isolating them from the environment. Examples are polymer-SiO 2 shelling, amphiphilic polymer or solid–lipid encapsulation, , synthesis of structures with reduced dimensionality, doping, use of bulky ligands, − incorporation of NCs in a polymeric matrix, − or their preparation within polymeric nanoreactors, , which had recently allowed reversible halide exchange . While all these techniques have clear advantages, it remains a challenge to simultaneously preserve the high PLQY and synthetic flexibility of the original colloidal NCs while also providing a stable dispersion in water over long times.…”