Efficient, Patternable Full-Color Perovskite Quantum Dot LEDs via Defect-Passivating Film-State Ligand Engineering

Perovskite quantum dots (PeQDs) are promising materials for next-generation displays, due to their superior optoelectronic properties. A critical step in fabricating PeQD-based light-emitting diodes (LEDs) involves the strategic modification of surface ligands to effectively passivate surface defects and improve charge injection. However, conventional film-state ligand exchange processes (C-FLEPs) are often insufficient in fully passivating surface defects, thereby limiting LED performance. In this study, we present an advanced FLEP (A-FLEP), which introduces a multi-ligand passivation strategy to more effectively address surface defects and improve the electrical properties of PeQD LEDs. In addition, the polarity of the ligand solution is carefully modulated to prevent unintended ligand detachment during the A-FLEP. As a result, A-FLEP achieved high-performance of PeQD LEDs: an external quantum efficiency (EQE) of 21.44% and luminance (L) of 35,960 cd m^-2 for green, an EQE of 13.23% and L of 1,295 cd m^-2 for red; an EQE of 1.86% and L of 720 cd m^-2 for blue PeQD LEDs.