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

Abstract

CsPbCl3 nanocrystals are potential ultrapure emitters. But it is challenging to synthesize CsPbCl3 nanocrystals with sufficient stability, which impedes their application in light-emitting devices. In this work, we report a facile phosphoryl-chemistry-mediated synthesis approach to synthesizing stable CsPbCl3 nanocrystals, in which the phenylphosphonic dichloride (PhPOCl2) precursor is employed. In addition to the high reactivity of the P–Cl bond of PhPOCl2 for providing adequate Cl, the derived P=O with good proton affinity facilitates the formation of a distinct nanocrystal surface with the nonprotonated oleylamine (OLA) ligand. Accordingly, the L-type-ligand-capped CsPbCl3 nanocrystals exhibited not only bright luminance but also good stability that endured repeated purification up to 10 cycles. Based on the stable CsPbCl3 nanocrystals, we achieved violet LEDs with extremely narrow electroluminescence spectra (full width at half-maximum ≈ 10.6 nm).

Strong violet emission from ultra-stable strontium-doped CsPbCl3 superlattices

“…For optoelectronic device applications, appropriate purification steps are necessary to remove the excess insulating organic ligands of PQDs with the assistance of anti-solvents, which yet often deteriorate the optical properties of PQDs. 40 With this in mind, we then purified PQDs repeatedly with ethyl acetate as the anti-solvent. It was found that small PQDs converted into perovskite nanosheets (PNSs) with various lateral sizes after five cycles of purification (Fig.…”

Halogen‐content‐dependent photoluminescence of Mn2+‐doped CsPbCl3 nanocrystals

“…8,9,25,32,33 The extremely narrow emission with FWHM of ∼ 10 nm of excitonic emission is a record value for CsPbCl 3 NCs, which can be attributed to the intrinsic advantage of the anion injection method. 4,14,16 As shown in Figure 3B, the optical properties of Mn 2+ -doped CsPbCl 3 NCs are highly dependent on the OAm-Cl content. In particular, the total PL QYs increases firstly, reaching a maximum value of 56% for S5 with OAm-Cl of 1.0 mL, and then slightly decreases with further increasing OAm-Cl content (Figure 3C).…”

“…The emission band centered at ∼ 410 nm with the full width at half‐maximum (FWHM) of ∼ 10 nm can be assigned to the excitonic recombination of CsPbCl 3 host and the broad band orange emission with FWHM of ∼ 78 nm originates from 4 T 1 → 6 A 1 transition of the doped Mn 2+ ions, respectively 8,9,25,32,33 . The extremely narrow emission with FWHM of ∼ 10 nm of excitonic emission is a record value for CsPbCl 3 NCs, which can be attributed to the intrinsic advantage of the anion injection method 4,14,16 . As shown in Figure 3B, the optical properties of Mn 2+ ‐doped CsPbCl 3 NCs are highly dependent on the OAm‐Cl content.…”

“…All inorganic CsPbX 3 (X = Cl, Br, or I) perovskite nanocrystals (NCs) are a promising class of optoelectronic materials owing to their highly tunable emission peaks with nearunity photoluminescence quantum yields (PL QYs), exceptional defect tolerance, high carrier mobility with long diffusion lengths, and low-cost solution processing. [1][2][3] Therefore, they have shown wide applications in light-emitting diodes (LEDs), 4,5 display backlights, 6 and photodetectors. 7 Doping of transition metal Mn 2+ ions into perovskite (Mn 2+ -doped perovskite) NCs with PL QYs of ∼ 60% were first reported by Son's group 8 and Klimov's group 9 in 2016.…”

“…22,23 However, generally, the MnX 2 and PbX 2 salts were employed as both manganese, lead, and halide precursors which cannot independently adjust the amount of reaction species and thus difficult to separately regulate the amount of halogen with fixed Mn content. 8,10 Thanks to the recently developed synthesis approach of "halogen-hot-injection" for CsPbX 3 (X = Cl, Br, I) NCs, 4,14 which can independently control halogen content to optimize the optical quality of pure CsPbX 3 NCs. Inspired by above results, Chen et al used halogen-hot-injection to synthesize Mn 2+doped CsPbX 3 NCs and studied the competitive luminescence between perovskite host and Mn 2+ dopants in the NCs with various halogen types and ratios.…”