Efficient and Stable CF₃PEAI-Passivated CsPbI₃ QDs toward Red LEDs

Abstract

Oleylamine and oleic acid are common organic capping ligands used in the hot injection preparation of perovskite quantum dots (QDs). Their labile nature is responsible for the poor colloidal stability and conductivity that affect the performance of perovskite QD light-emitting diodes (LEDs). We introduced 4trifluoro phenethylammonium iodide (CF 3 PEAI) directly in the synthesis and found that CF 3 PEAI efficiently modified the I − vacancy defects on the QD surface and partially substituted the surface capping ligand oleylamine. The strong electron pulling ability of F in CF 3 PEAI results in a more positive −NH 3 + terminal compared to that of PEAI, which promotes tight bonding of CF 3 PEAI on the surface of CsPbI 3 QDs. As a result, we achieved bright QDs with a photoluminescence quantum yield of 92% and efficient red LEDs. The maximal luminance was improved to 4550 cd m −2 for 685 nm red light, which was nearly 4.6-fold of the LEDs with plain CsPbI 3 QDs. Additionally, the peak external quantum efficiency reached 12.5%.

Engineering Coinage Metal Nanoclusters for Electroluminescent Light-Emitting Diodes

“…As a new generation of lighting and display devices, LEDs have received extensive attention from scientific research and industrial circles in recent years [ 26 , 27 , 28 ]. According to different light-emitting principles, LEDs can be divided into two categories: photoluminescent LEDs and electroluminescent LEDs.…”

P‐9.3: High‐Performance Red Perovskite QLEDs Based on Low‐Toxicity Zn‐Pb Alloy Perovskite QDs Passivated by Inorganic Ligands

“…However, a large amount of long-chain insulating ligands oleic acid and oleylamine are usually introduced during the synthesis of perovskite quantum dots. The poor conductivity of long-chain ligands such as oleylamine (OLA) and oleic acid (OA) can hinder charge transport thereby increasing the barrier for carrier injection [13] . Introducing new short-chain ligands is effective for improving QD quality and LED performance.…”

Amino Acid-Passivated Pure Red CsPbI3 Quantum Dot LEDs

“…We attribute the decrease in luminance to the bulky exchange groups, which hinder ligand exchange, and the lack of balance between the ammonium and carboxylate groups, both of which are necessary for passivation . Previous reports showed that fluorinated ligands can induce a strong ligand–metal bonding and passivate traps, and we assessed two characteristic fluoro-amino acids (4-fluoro-phenylalanine and 3,3,3-trifluoroalanine) for their effects. Unfortunately, this strategy is ineffective in our CsPbI 3 QDs, as all the samples showed low current density and luminance.…”

“…The elemental analysis by the X-ray photoelectron spectroscopy (XPS) method shows a deficiency in cesium, indicating that the surface of QDs is terminated by lead (Table S2). ∼8% of Mn is doped in the crystal lattice, which helps to stabilize the α-phase of CsPbI 3 and blue-shifts the PL wavelength from 690 to 650 nm. ,, ZnI 2 was added as an additive to improve the uniformity of the NCs sizes, while the zinc ion is inert and was not detectable in the QDs . A high ratio of carbon was also detected, suggesting that the nanocrystals are protected and capped by OA/OLA ligands.…”