2022/01/30 by Tassilo Naujoks, Naujoks, Tassilo, Roshini Jayabalan +21
Engineering · Materials Science · Psychology · #Applied Physics (physics.app-ph) #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Perovskite Materials and Applications #Quantum Dots Synthesis And Properties #Technostress in Professional Settings
paper · pdf · doi:10.48550/arxiv.2201.12751
openalex publication_date 2022/01/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Surface-defect passivation is key to achieving high photoluminescence quantum yield in lead halide perovskite nanocrystals. However, in perovskite light-emitting diodes these surface ligands also have to enable balanced charge injection into the nanocrystals to yield high efficiency and operational lifetime. In this respect, alkaline halides have been reported to passivate surface trap states and increase the overall stability of perovskite light emitters. On the one side, the incorporation of alkaline ions into the lead halide perovskite crystal structure is considered to counterbalance cation vacancies, while, on the other side, the excess halides are believed to stabilise the colloids. Here, we report an organic lithium salt, viz. LiTFSI, as a halide-free surface passivation on perovskite nanocrystals. We show that the treatment LiTFSI has multiple beneficial effects on lead halide perovskite nanocrystals and LEDs derived from them. We obtain higher photoluminescence quantum yield and longer exciton lifetime, and a radiation pattern that is more favourable for light outcoupling. The ligand-induced dipoles on the nanocrystal surface shift their energy levels toward lower hole-injection barrier. Overall, these effects add up to a four- to seven-fold boost of the external quantum efficiency in proof-of-concept LED structures, depending on the color of the used lead halide perovskite nanocrystal emitters.