Polymer Nanoreactors Shield Perovskite Nanocrystals from Degradation

TL;DR

This paper introduces a polymer micelle nanoreactor method to synthesize perovskite nanocrystals with greatly enhanced stability against water and halide migration, enabling longer-lasting optoelectronic applications.

Contribution

The study presents a novel polymer encapsulation technique that significantly improves the environmental stability and optical performance of perovskite nanocrystals.

Findings

Nanocrystals show over 15-fold increased lifespan in ambient conditions.

NCs remain stable in water for over 75 days.

Quantum yields reach up to 63% with tunable emission.

Abstract

Halide perovskite nanocrystals (NCs) have shown impressive advances, exhibiting optical properties that outpace conventional semiconductor NCs, such as near-unity quantum yields and ultrafast radiative decay rates. Nevertheless, the NCs suffer even more from stability problems at ambient conditions and due to moisture than their bulk counterparts. Herein, we report a strategy of employing polymer micelles as nanoreactors for the synthesis of methylammonium lead trihalide perovskite NCs. Encapsulated by this polymer shell, the NCs display strong stability against water degradation and halide ion migration. Thin films comprising these NCs exhibit a more than 15-fold increase in lifespan in comparison to unprotected NCs in ambient conditions and even survive over 75 days of complete immersion in water. Furthermore, the NCs, which exhibit quantum yields of up to 63% and tunability of the emission wavelength throughout the visible range, show no signs of halide ion exchange. Additionally, heterostructures of MAPI and MAPBr NC layers exhibit efficient F\"orster resonance energy transfer (FRET), revealing a strategy for optoelectronic integration.