Modular Zwitterion-Functionalized Poly(Isopropyl Methacrylate) Polymers for Hosting Luminescent Lead-Halide Perovskite Nanocrystals

Abstract

Inorganic lead-halide perovskite nanocrystals (NCs) are an exciting class of luminescent materials with high defect tolerance and broad spectral tunability, but such NCs are vulnerable to degradation under ambient conditions. Here, we report a class of modular zwitterion-functionalized isopropyl methacrylate polymers designed to stabilize a wide variety of perovskite NCs of different compositions, while also enabling processing in green solvents. Specifically, we report polymers in which the zwitterion spacing is tuned to accommodate the different lattice parameters of CsPb(Cl<sub>1-<i>x</i></sub>Br<i><sub>x</sub></i>)<sub>3</sub> and CsPbI<sub>3</sub> NCs, and we report partially fluorinated polymers prepared to accommodate the needs of infrared-emitting NCs. We show that as-synthesized CsPbBr<sub>3</sub>, CsPbI<sub>3</sub>, and Yb<sup>3+</sup>:CsPbCl<sub>3</sub> NCs are easily transferred into these zwitterionic polymers <i>via</i> a simple ligand-exchange procedure. These NC/polymer composites were then cast into thin films that showed substantially improved photoluminescence (PL) and stability compared with more conventional NC/polymer films. Specifically, CsPbBr<sub>3</sub> and CsPbI<sub>3</sub> NCs in films of their appropriately designed polymers had PL quantum yields of ~90% and ~80%, respectively. PL quantum yields decreased under continuous illumination, but self-healed completely after dark storage. We also found that all the NC compositions studied here maintain their PL quantum yields in NC/polymer composite films even after 1 year of ambient storage. These encouraging results demonstrate the utility of such modular zwitterion-functionalized polymers for hosting specific perovskite NCs, potentially opening avenues for robust new photonic applications of this important class of NCs.

Weakening Ligand–Liquid Affinity to Suppress the Desorption of Surface-Passivated Ligands from Perovskite Nanocrystals

“…To retard the migration, a series of ligands such as multidentate, 31,32 zwitterionic, 33,34 chelating, 35,36 phosphonic, 37−39 and sulfonic molecules 40,41 stability via lowering μ solid . As another alternative approach, increasing μ liquid is also feasible in principle to suppress the migration of ligands by weakening ligand−solvent affinity (Scheme 1).…”

Coherent Spin Precession and Lifetime-Limited Spin Dephasing in CsPbBr3 Perovskite Nanocrystals

“…(c) Room-temperature XRD data for the CsPbBr 3 nanocrystals examined here. Black sticks illustrate reference reflections for orthorhombic CsPbBr 3 .For variable-temperature spectroscopic measurements described in the main text, these CsPbBr 3 nanocrystals were embedded in films of zwitterion-functionalized fluoropolymer (ZFP3)37 on c-plane sapphire that showed negligible photon scattering (see the SI for details). The TRFR measurement is extremely sensitive to the polarization of the probe pulse, and scattering scrambles this polarization information.…”

In Situ Photocatalyzed Polymerization to Stabilize Perovskite Nanocrystals in Protic Solvents

“…17 −28 In the last case, a general strategy was applied to replace the labile OLA and OAm ligands using various high-affinity ligands during either the PNC synthesis step or the postsynthesis ligand exchange step, although delicate surface chemistry was needed to avoid cross-particle coupling or formation of PNC− polymer composites. 25,26,28 Alternatively, Lin's group reported the use of amphiphilic star block copolymers as unimolecular templates for in situ synthesis of PNCs from salt precursors. 29,30 However, achieving surface-protected PNCs as suspended nanoparticles in polar protic solvents for photocatalytic applications (e.g., water splitting) still remains a grand challenge.…”