Double hole transport layers deliver promising-performance in light-emitting diodes based on MAPbBr₃ nanocrystals

Perovskite Nanocrystal Light Emitting Diodes (PNC-LEDs) are highly regarded as promising candidates for future solid-state lighting and high-definition display applications. To achieve high-performance LEDs, it is essential to have an emitting layer with a high photoluminescence quantum yield (PLQY) and excellent carrier transport properties, along with a well-optimized device structure. In this work, high performance MAPbBr₃ NCs (PLQY>95 %) were synthesized via combination of 4-methoxyphenethylamine and didodecyldimethylammonium bromide, which lead to improved carrier transport of NC emitting layer. Moreover, a double hole transport layers (D-HTL) structure was developed to provide stepwise energy barrier for hole injection, resulting in improved external quantum efficiency (EQE). The green MAPbBr₃ PNC-LED with the D-HTL structure exhibited a maximum EQE of 10.7 % and a current efficiency (CE) of 32.5 cd A⁻¹, outperforming the PNC-LED with the conventional single HTL PTAA (EQE 5.8 %, and CE 17.7 cd A⁻¹) by almost 2 times. These findings showcase a rational strategy to enhance PNC-LEDs performance through device structure engineering, particularly when utilizing a high-performance PNC emitting layer.