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Using mixed-halide perovskite quantum dots (QDs), with facile spectrum adjustment and extremely high color purity, is one of the most promising ways to achieve blue emission. Nevertheless, the substantial trap states and halide migration-induced phase separation enhance the instability of QDs, which seriously restricts their practical application. To overcome these issues, we creatively develop a strategy for in situ passivation based on a small organic molecule, diphenylphosphorylhydroxylamine (DPH). The strong coordination and hydrogen bonds work in concert to regulate the crystallization process of QDs and saturate vacancy defects to form a ligand-rich surface, thereby achieving more efficient exciton recombination. The resulting QDs are resistant to stronger external stimulation. Thanks to the effective passivation of DPH, the obtained blue PeLEDs with 478 nm emission exhibit extremely high color purity (full width at half maximum of 18 nm) and a maximum external quantum efficiency (EQE) of up to 4.88%. In parallel, the spectrum remains unchanged at an operating voltage of 8 V. This work provides a feasible method for realizing efficient and spectrally stable blue PeLEDs. [ABSTRACT FROM AUTHOR]

Blue‐emitting perovskite nanocrystals (NCs) are important components of high‐definition display device, but their instability to light and moisture severely hinders the commercial application. Here, a dual‐site passivation strategy is proposed and the halogen–halogen bond to surface capping molecules is applied. The bi‐functional molecule with a fluorine group and carboxyl group on the phenyl ring, would form a shell‐like molecular structure covering the nanocrystal surface at halogen and lead site via halogen‐halogen bond and coordination effect, respectively. Considering the binding strength and acid dissociation constant of several fluoro acids, the optimal optical properties and film stability confirm the para‐fluorobenzoic acid molecule provides the most effective protection for initial perovskite products account for their stronger anchoring affinity and more comprehensive surface coverage. Consequently, this work sheds light on the molecular functionality and configuration are crucial for surface properties of perovskite NCs. [ABSTRACT FROM AUTHOR]

In the era of intelligence, the output colors of foundational phosphors are expected to be controlled by programs, while current activators‐determined afterglow candidates with fixed spectral channel have limitations in creating customized colors. Here, a long‐lived warm‐white emission is successfully demonstrated originating from self‐trapped excitons (STEs) in non‐toxic Cs2NaInCl6:Ag,Bi, ranging from 400 to 850 nm, of which the afterglow color can be easily customized using filters. This investigation indicates that 3% of Ag alloying breaks the dark STEs and introduces traps for efficient afterglow, while 3% Bi doping further improves the quantum yield to ≈100% and greatly enhances afterglow by ≈100‐fold compared with the initial intensity, allowing for an impressive afterglow persistence of over 20,000 s. Intriguingly, the self‐trapped defect bands from Jahn‐Teller distortions are prolonged from hundreds of femtoseconds to several hours, and they are first detected in the steady‐state absorption spectra after the cessation of excitation sources, contributing to the concluded dynamic afterglow model for STEs. And its intelligent application is corroborated by designed multi‐channel information system. These findings offer a novel scheme for understanding dynamic luminescence of STEs and supply an exemplification of designing white afterglow phosphors. [ABSTRACT FROM AUTHOR]

Recently, metal-halide perovskites have rapidly emerged as efficient light emitters with near-unity quantum yield and size-dependent optical and electronic properties, which have attracted considerable attention from researchers. However, the ultrafast nucleation rate of ionic perovskite counterparts severely limits the in-depth exploration of the growth mechanism of colloidal nanocrystals (NCs). Herein, we used an inorganic ligand nitrosonium tetrafluoroborate (NOBF 4 ) to trigger a slow post-synthesis transformation process, converting non-luminescent Cs 4 PbBr 6 NCs into bright green luminescent CsPbBr 3 NCs to elucidate the concrete transformation mechanism via four stages: (i) the dissociation of pristine NCs, (ii) the formation of Pb-Br intermediates, (iii) low-dimensional nanoplatelets (NPLs) and (iv) cubic CsPbBr 3 NCs, corresponding to the blue-to-green emission process. The desorption and reorganization of organic ligands induced by NO + and the involvement of BF 4 - in the ligand exchange process played pivotal roles in this dissolution-recrystallization of NCs. Moreover, controlled shape evolution from anisotropic NPLs to NCs was investigated through variations in the amount of NOBF 4 . This further validates that additives exert a decisive role in the symmetry and growth of nanostructured perovskite crystals during phase transition based on the ligand-exchange mechanism. This finding serves as a source of inspiration for the synthesis of highly luminescent CsPbBr 3 NCs, providing valuable insights into the chemical mechanism in post-synthesis transformation.