Electroluminescence of Perovskite Nanocrystals with Ligand Engineering

Narrow-Band Violet-Light-Emitting Diodes Based on Stable Cesium Lead Chloride Perovskite Nanocrystals

“…We performed further investigations to gain more insights into the mechanisms responsible for the observed excellent optical properties and unprecedented stability of PhPOCl 2 -based CsPbCl 3 NCs. As we know, despite the acknowledged defect tolerance merit of lead halide perovskite materials, the surface capping ligands of perovskite NCs play a crucial role in optoelectronic properties and stability. , Considering the uniform NC size, morphology, and crystal structure of the PhPOCl 2 -based CsPbCl 3 NCs compared to the reported samples, we hypothesize that the high-quality PhPOCl 2 -based CsPbCl 3 NCs could be attributed to their distinct surface chemistry because of the P=O-containing Cl precursor that was used. According to many previous reports, P=O can regulate the perovskite NC surface through either (1) direct passivation with lead (P=O: Pb) or (2) alter the binding motif of original ligands (OA and/or OLA) on the NC surface. ,, To clarify whether P=O binds directly on the NC surface, we employed the FTIR and nuclear magnetic resonance (NMR) spectroscopic techniques for characterization.…”

High-Brightness Perovskite Light-Emitting Diodes Based on FAPbBr3 Nanocrystals with Rationally Designed Aromatic Ligands

“…Metal halide perovskite nanocrystals (PeNCs) have recently emerged as promising candidates for low-cost and high-performance light-emitting diodes (LEDs). − Owing to their unique high defect tolerance property, high-quality PeNCs with near-unity photoluminescence quantum yields (PLQYs) can be obtained under mild synthesis conditions. − Additionally, the light emission of PeNCs exhibits wide tunability and narrow emission line width in the whole visible spectrum, leading to an ultrawide color gamut covering around 100% of the Rec. 2020 color space, − making them superior candidates for applications in high-resolution displays. During the past several years, with extensive research efforts in the material synthesis and surface passivation of PeNCs, external quantum efficiencies (EQEs) of the associated LEDs have rapidly improved from around 0.1% to high values of greater than 20%, comparable with those of commercial light-emitting technologies. − …”

Advances and Challenges in Tin Halide Perovskite Nanocrystals

“…121 In addition, other appropriate ligands can also passivate surface defects, resulting in highly luminescent perovskite NCs and/or notable enhancement of structural stability. 17,122 Besides, some application-minded scientists and engineers are always committed to finding appropriate conductive ligands to enhance their performance in solar cells or LED devices. 123,124 To address the structural instability of THP NCs, it is necessary to exchange the OAm and OA with some peculiar ligands that can effectively protect NCs.…”

“…The traditional ligands for colloidal halide perovskite NCs are long-chain OAm and OA, which maintain the cubic morphology as well as crystal structure of NCs, while some short-chain ligands like octylamine and octanoic acid could induce the low-dimensional morphologies such as nanosheets . In addition, other appropriate ligands can also passivate surface defects, resulting in highly luminescent perovskite NCs and/or notable enhancement of structural stability. , Besides, some application-minded scientists and engineers are always committed to finding appropriate conductive ligands to enhance their performance in solar cells or LED devices. , To address the structural instability of THP NCs, it is necessary to exchange the OAm and OA with some peculiar ligands that can effectively protect NCs. For example, perfluorooctanoic acid (PFOA) with a strong electron-withdrawing group was reported to act as an effective ligand to stabilize Sn 2+ species in THP NCs .…”