Zwitterionic Block Copolymers for the Synthesis and Stabilization of Perovskite Nanocrystals

Abstract

Traditional hot injection methods for the preparation of cesium lead halide perovskite nanocrystals (CsPbX 3 PNCs, where X=Cl, Br, or I) rely on small molecule surfactants to produce PNCs with cube, plate, or rod-like morphologies.Here, we describe a new method whereby zwitterionic block copolymers are employed as macromolecular ligands in PNC synthesis, affording PNCs with excellent colloidal stability, high photoluminescence quantum yield, and in some cases distinctly non-cubic shapes. The block copolymers used in this study -composed of a poly(n-butyl methacrylate) hydrophobic block and zwitterionic methacrylate hydrophilic blocks -dissolve in useful solvents for PNC growth despite containing large mole percentages of zwitterionic groups. PNCs prepared with block copolymer ligands were found to disperse and retain their fluorescence in a range of polar organic solvents and were amenable to direct integration into optically transparent nanocomposite thin films with high PNC content.

Tiny spots to light the future: advances in synthesis, properties, and application of perovskite nanocrystals in solar cells

“…The use of these molecules as ligands in PNCs has been reported to increase chemical stability and PLQY. [168][169][170] As can be seen, there is a plethora of molecules that can be used as surface ligands in PNCs, and it is quite hard to state universal rules for the choice of a proper ligand. In general, what is aimed is a stable and cheap ligand, capable of passivating the surface defects, and conferring colloidal stability to the NCs.…”

“…The use of these molecules as ligands in PNCs has been reported to increase chemical stability and PLQY. 168–170…”

Copolymer Mediated Engineering of Halide Perovskites and Associated Devices: Current State and Future

“…Recently Cueto and co‐workers utilized zwitterionic block copolymers as macromolecular ligands for the synthesis of perovskite nanocrystals with excellent colloidal stability and high PLQY. [ 47 ] The researchers used a copolymer containing a poly(n‐butyl methacrylate) (PBMA) hydrophobic block and a poly (sulfobetaine methacrylate) (PSBMA) or poly(2‐methacryloyloxyethyl phosphorylcholine) (PMPC) zwitterionic block. These TPBMA‐b‐PSBMA and PBMA‐b‐PMPC BCPs were prepared by RAFT polymerization.…”

Phase Sensitivity of All-Inorganic Lead Halide Perovskite Nanocrystals

“…144−147 Zwitter ionic ligands simultaneously coordinate to the surface positive and negative ions of the perovskite nanocrystals. 103,148 This dual binding mode enhances surface passivation and improves the thermal and environmental stability of the nanocrystals. Despite all these reports, the surface chemistry associated with this ligand-induced stabilization is less understood due to the dynamic nature of bonding.…”

“…Hence, identifying the perfect composition to improve the stability and efficacy of the application is critically important, and more research emphasis should be given to these areas. Ligands have a key role in stabilizing these nanocrystals. Alkylammonium ions have shown potential as capping agents to stabilize nanocrystals inside and outside the reaction flask. ,,,− Strong binding of phosphine- and phosphonic acid-based ligands was observed to stabilize CsPbI 3 nanocrystals. − Zwitter ionic ligands simultaneously coordinate to the surface positive and negative ions of the perovskite nanocrystals. , This dual binding mode enhances surface passivation and improves the thermal and environmental stability of the nanocrystals. Despite all these reports, the surface chemistry associated with this ligand-induced stabilization is less understood due to the dynamic nature of bonding.…”