# Enhancing Sky-Blue Perovskite Light-Emitting Diode Performance through Guanidinium-Based Dual-Functional Molecular Engineering

## TL;DR

Researchers improved blue perovskite LEDs by using a guanidinium compound to enhance performance and stability.

## Contribution

A dual-functional molecular strategy using GBAC is introduced to improve blue PeLED performance and stability.

## Key findings

- GBAC improves film morphology and energy alignment at the buried interface.
- GBAC suppresses nonradiative recombination and promotes high-n phase growth in perovskite films.
- Devices with dual GBAC treatment achieved 10.6% external quantum efficiency in sky-blue emission.

## Abstract

Perovskite light-emitting
diodes (PeLEDs) have emerged as promising
candidates for next-generation display and lighting technologies due
to their high photoluminescence quantum yield, tunable emission characteristics,
and narrow spectral bandwidth. However, achieving efficient and stable
blue emission remains a significant challenge, primarily due to poor
phase purity, excessive trap density, and unfavorable energy level
alignment. Herein, we propose a dual-functional molecular engineering
strategy utilizing 4-guanidinobenzoic acid hydrochloride (GBAC) as
both a buried interfacial layer and a bulk additive. When employed
at the buried interface, GBAC enhances surface wettability and precursor
spreading, thereby improving film morphology and crystallinity. This
additional layer also helps optimize energy level alignment between
the hole transport layer and the perovskite emissive layer, reducing
the injection potential barrier. Simultaneously, when acting as an
additive in the bulk phase, GBAC’s guanidinium group binds
to undercoordinated Pb2+ trap states via electrostatic
coordination, suppressing nonradiative recombination; while its carboxylic
group forms hydrogen bonds with the ammonium end of phenethylammonium
bromide, reducing the formation of low-n (n = 1–2) phases and promoting growth in the medium-to-high
n-value domains, thereby enhancing energy funneling efficiency. Leveraging
these advantages, the device fabricated with dual GBAC treatment exhibits
enhanced spectral stability, reduced turn-on voltage, and achieves
an external quantum efficiency of up to 10.6% in the sky-blue emission
band (∼489 nm), representing a > 60% improvement
over the pristine device.