Dipole Modulation Engineering Enhances Structural Order of PEDOT:PSS for Efficient and Stable InP-Based QLEDs

Indium phosphide (InP)-based quantum dot light-emitting diodes (QLEDs) are promising for future lighting and display applications due to their high color purity and brightness. However, their efficiency and stability are often limited by the disordered structure of the widely used poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), which impairs charge transport. Herein, we present a strategy to enhance the performance of InP-based QLEDs by modifying PEDOT:PSS through interfacial dipole modulation using molybdenum oxide (MoO_x) nanoparticles. The strong hydrogen bonding between MoO_x and PSS creates strong dipole-dipole interactions, reducing the separation of PEDOT-rich regions, enhancing π-π stacking and conductivity. This optimization facilitates balanced electron and hole injection, increasing external quantum efficiency (EQE) from 12.2% in control devices to 17.8% in the treated devices, along with a brightness enhancement from 32,998 to 43,567 cd m^-2. Notably, our treated devices exhibit a reduction in efficiency attenuation compared to other reported InP-based QLEDs, particularly at high brightness levels of 5000 and 10,000 cd m^-2, with EQE attenuation of only 4 and 9%, respectively, compared to 16 and 30% for controls. This work highlights the potential of dipole engineering in advancing InP-based QLED technology, providing a pathway for developing high-performance, stable, and eco-friendly lighting and displays.