Effects of organic ligands on efficiency and stability of perovskite light-emitting diodes

Abstract

Perovskite light-emitting diodes (PeLEDs) have attracted considerable attention due to their low cost, high efficiency and narrowband emission. However, poor operational lifetime limits their practical application and the degradation mechanism is not yet clear. Herein, the effect of typical phenylalkylamine and alkylamine ligands on optoelectrical properties and operational stability of cesium/methylammonium lead bromide PeLEDs were systematically investigated. The phenylethylamine (PEA) modified PeLED shows a champion maximum external quantum efficiency (EQE) of 9.35%, which is much better than that of phenylmethylamine (PMA) and phenylbutylamine (PBA) modified devices. For alkylamine-based devices, the maximum EQEs gradually rise from 2.72 to 6.33% and 6.66% as increase of alkyl chain length. PEA modified device exhibits the best half-lifetime of 114 min and alkylamine-based devices exhibit almost equal T 50 of approximately 20 min. X-ray diffraction measurements show that the dominant diffraction peaks of pervoskite films disappear or shift and scanning electron microscope detected that many pinholes appeared in perovskite films after operation. Combining with the results of X-ray photoelectron spectroscopy, we conclude that the recrystallization of perovskite occurred during the operation causes the film change in morphology and crystallinity, ultimately result in the degradation of PeLEDs.

Multifunctional π‐Conjugated Additives for Halide Perovskite

“…Reproduced with permission. [ 122 a] Copyright 2018, Springer Nature. e) Modular molecular design of the ammonium iodide cation.…”

Phosphine Oxide Additives for High‐Brightness Inorganic Perovskite Light‐Emitting Diodes

“…In comparison to other devices using a small molecule additive of category NOA2 and such a simple device stack, for example, devices using lecithin or PEA additive, [30,31] our PeLEDs show superior brightness, but reduced current efficiency (see Table S3, Supporting Information). Possibly, this is a result from the ionic character of lecithin or the higher surface coverage of the lecithin-and PEA-containing devices.…”

“…[30] Zhang et al tested different organic small molecules and showed a champion EQE of 9.4% for phenylethylamine (PEA) modified CsPbBr 3 :MABr layers. [31] Here, the amine group of PEA coordinates to the perovskite crystals. NOA3) Small pi-conjugated molecules can be used to improve PeLED efficiency.…”

Reversible Pressure‐Dependent Mechanochromism of Dion–Jacobson and Ruddlesden–Popper Layered Hybrid Perovskites

“…Furthermore, quantum confinement can be tuned by the width of the potential barrier, which is controlled by the spacer size that further affects their optoelectronic properties. [ 11,12 ]…”

“…Furthermore, quantum confinement can be tuned by the width of the potential barrier, which is controlled by the spacer size that further affects their optoelectronic properties. [11,12] It would be of interest to control these effects on the potential barrier width without changing the perovskite composition, which can be achieved by relying on their mechanical properties and responsiveness to external stimuli, such as pressure. [13,14] Thus, understanding the structure-property relationships in such layered perovskites can serve as a guide to design materials with specific properties, whereas understanding the behavior of n = 1 layered 2D perovskites provides a limiting case for the analysis of n > 1 systems.…”