Amino Acid-Passivated Pure Red CsPbI₃ Quantum Dot LEDs

Abstract

Quantum-confined CsPbI 3 nanocrystals (NCs) are promising materials for the next generation of pure-red displays. Small quantum dots synthesized by colloidal methods often have excess resistive ligands, which reduce the efficiency and long-term stability of the resulting light-emitting diodes (LEDs). Here we developed a facile ligand-exchange method using amino acids to reduce long chain ligands on CsPbI 3 quantum dots and improve the efficiency and stability of LEDs made from these QDs. We also assessed a variety of related amino acids and noted how their structure affects the LED performance. We found that a dual-passivation effect was observed in cysteinepassivated QDs that led to the best performance. The optimized LEDs achieved an external quantum efficiency (EQE) of 18.0% and a T 50 of 87 min, comparable with many of the best reported perovskite QD, pure red LEDs.

Metal Halide Perovskite Nanocrystals for Near-Infrared Circularly Polarized Luminescence with High Photoluminescence Quantum Yield via Chiral Ligand Exchange

“…This indicates that l -cys is successfully attached to the surface of FAPbI 3 PNCs. , Moreover, Figure b shows that the 4f 7/2 and 4f 5/2 of l -cys treated FAPbI 3 PNCs move toward higher binding energies to 137.38 and 142.28 eV, respectively, compared to the 4f 7/2 at 137.29 eV and 4f 5/2 at 142.19 eV of the Pb 4f spectrum in control PNCs. This is due to the strong chemical bonding effect between l -cys and FAPbI 3 PNCs, which leads to changes in the chemical environment on the surface of FAPbI 3 PNCs. , Meanwhile, as shown in Figure S5, the peaks of the 3d 5/2 and 3d 3/2 of the I 3d spectrum in l -cys treated FAPbI 3 PNCs shift to 618.16 and 629.62 eV, respectively, wherever the peaks of control PNCs are located at 618.08 and 629.47 eV. This is caused by the changed chemical bond between Pb and I, which is influenced by the chemical bond effect between Pb and S .…”

“…This indicates that L-cys is successfully attached to the surface of FAPbI 3 PNCs. 27,37 Moreover, Figure 2b shows that the 4f 7/2 and 4f 5/2 of L-cys treated FAPbI 3 PNCs move toward higher binding energies to 137.38 and 142.28 eV, respectively, compared to the 4f 7/2 at 137.29 eV and 4f 5/2 at 142.19 eV of the Pb 4f spectrum in control PNCs. This is due to the strong chemical bonding effect between L-cys and FAPbI 3 PNCs, which leads to changes in the chemical environment on the surface of FAPbI 3 PNCs.…”

“…This is due to the strong chemical bonding effect between L-cys and FAPbI 3 PNCs, which leads to changes in the chemical environment on the surface of FAPbI 3 PNCs. 37,38 Meanwhile, as shown in Figure S5, the peaks of the 3d 5/2 and 3d 3/2 of the I 3d spectrum in L-cys treated FAPbI 3 PNCs shift to 618.16 and 629.62 eV, respectively, wherever the peaks of control PNCs are located at 618.08 and 629.47 eV. This is caused by the changed chemical bond between Pb and I, which is influenced by the chemical bond effect between Pb and S. 27 We additionally employed liquidstate 13 As shown in Figure 2e,f, starting at temperatures of about 175 K, the PL peak position begins to mutate in both control and Lcys treated FAPbI 3 PNCs.…”

All-inorganic lead halide perovskite nanocrystals applied in advanced display devices

“…9b). 210 Resurfacing NCs with inorganic ligands held the promise in realizing α-phase CsPbI 3 at room temperature. KI-exchanged CsPbI 3 QD films were reported presenting superior phase stability and increased thermal transport, which were further applied in PeLEDs exhibiting a maximum EQE of 23%.…”

Multidentate Ligand-Passivated CsPbI3 Perovskite Nanocrystals for Stable and Efficient Red-Light-Emitting Diodes

“…(1) OA and OLA are weakly bonding to the CsPbI 3 NCs surface. They easily fall off during the purification and storage, which results in defects to accelerate CsPbI 3 NCs optoelectronic performance decay and stability degradation. − (2) OA and OLA with long chains act as insulating layers on the CsPbI 3 NCs surface to hinder carrier transport, which decreases their LED performance. ,,− Therefore, the design of suitable ligands to boost CsPbI 3 NCs with high performance, stability, and conductivity is quite challenging and promising for CsPbI 3 LEDs. ,− …”