Bright and Efficient Perovskite Light Emitting Electrochemical Cells Leveraging Ionic Additives

TL;DR

This paper demonstrates that incorporating a lithium dopant and a poly(ethylene oxide) electrolyte in CsPbBr3 perovskite films significantly enhances the brightness and efficiency of light-emitting electrochemical cells by improving film quality and charge transport.

Contribution

It introduces a novel approach using ionic additives in perovskite films to boost PeLEC performance, achieving record brightness and efficiency.

Findings

Optimal LiPF6 concentration improves electrical double layer formation.

Enhanced film morphology reduces voids and charge traps.

Achieved high efficiency of 22 cd/A and brightness of 15000 cd/m2.

Abstract

Perovskite light-emitting diodes (PeLEDs) have drawn considerable attention for their favorable optoelectronic properties. Perovskite light-emitting electrochemical cells (PeLECs) _ devices that utilize mobile ions _ have recently been reported but have yet to reach the performance of the best PeLEDs. We leveraged a poly(ethylene oxide) electrolyte and lithium dopant in CsPbBr3 thin films to produce PeLECs of improved brightness and efficiency. In particular, we found that a single layer PeLEC from CsPbBr3:PEO:LiPF6 with 0.5% wt. LiPF6 produced highly efficient (22 cd/A) and bright (~15000 cd/m2) electroluminescence. To understand this improved performance among PeLECs, we characterized these perovskite thin films with photoluminescence (PL) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). These studies revealed that this optimal LiPF6 concentration improves electrical double layer formation, reduces the occurrence of voids, charge traps, and pinholes, and increases grain size and packing density.