Eu-doped CsSrCl$_3$ Large Nanocrystal Clusters with Self-Reduction Effect and Near-Unity Quantum Yield

TL;DR

This paper reports a novel synthesis of Eu-doped CsSrCl3 nanocrystal clusters with high quantum yield and stability, achieved through a self-reduction process, advancing environmentally friendly blue-emitting materials.

Contribution

Introduces a one-step synthesis method for Eu2+-doped CsSrCl3 nanocrystals with high PLQY and stability, eliminating the need for conventional reductants and enhancing emission efficiency.

Findings

PLQY of ~40% initially, enhanced to ~97% with surface passivation

Nanocrystals emit at 430 nm with 25 nm FWHM

Enhanced stability with ZnS shell growth

Abstract

Europium halide perovskites have emerged as promising candidates for environmental-friendly blue-emitting materials. However, their development is hindered by relative low photoluminescence quantum yields (PLQY, e.g. ~2-5% for intrinsic CsEuCl3) and poor stability against air. Here, we introduce a one-step-procedure for synthesizing Eu$^{2+}$-doped CsSrCl$_3$ large nanocrystal clusters (LNCs) with the effect of self-reduction, therefore eliminating the use of conventional reductant oleylamine (OAm) and ensuring phase purity. The CsSrCl$_3$:Eu LNCs shows photoluminescence emission centered at 430 nm with a full width at half-maximum (FWHM) of 25 nm and a PLQY of ~40%, which can be further enhanced to ~97% after passivating the surface defects by adding trioctylphosphine (TOP), the highest among all reported lead-free blue-emitting perovskite nanocrystals. The stability of CsSrCl$_3$:Eu can also be improved significantly by epitaxially growing ZnS shell on the surface. This work will shed more light on lanthanide and alkaline-earth metal (AEM)-based perovskites for nontoxic light-emitting materials.