Gd-Based Solvated Shells for Defect Passivation of CsPbBr$_3$ Nanoplatelets Enabling Efficient Color-Saturated Blue Electroluminescence

TL;DR

This study demonstrates that GdBr$_3$-DMF treatment effectively passivates defects in CsPbBr$_3$ nanoplatelets, dramatically improving their photoluminescence and electroluminescence efficiency for blue light-emitting diodes.

Contribution

The paper introduces a novel GdBr$_3$-DMF post-synthetic treatment that passivates defects in CsPbBr$_3$ NPLs, enhancing their optical performance and electroluminescence efficiency.

Findings

Photoluminescence quantum yield increased from 35% to ~100%.

Electroluminescence efficiency reached 2.4% at 464 nm.

Gd$^{3+}$ ions form stable solvation structures that facilitate defect passivation.

Abstract

Reduced-dimensional CsPbBr$_3$ nanoplatelets (NPLs) are promising candidates for color-saturated blue emitters, yet their electroluminescence performance is hampered by non-radiative recombination, which is associated with bromine vacancies. Here, we show that a post-synthetic treatment of CsPbBr$_3$ NPLs with GdBr$_3$-dimethylformamide (DMF) can effectively eliminate defects while preserving the color. According to a combined experimental and theoretical study, Gd$^{3+}$ ions are less reactive with NPLs as a result of compact interaction between them and DMF, and this stable Gd$^{3+}$-DMF solvation structure makes Brions more available and allows them to move more freely. Consequently, defects are rapidly passivated and photoluminescence quantum yield increases dramatically (from 35 to ~100%), while the surface ligand density and emission color remain unchanged. The result is a remarkable electroluminescence efficiency of 2.4% (at 464 nm), one of the highest in pure blue perovskite NPL light-emitting diodes. It is noteworthy that the conductive NPL film shows a high photoluminescence quantum yield of 80%, demonstrating NPLs' significant electroluminescence potential with further device structure design.