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Aggregation-induced emission (AIE) is an effective strategy for improving the photoluminescence (PL) performance of metal nanoclusters (MNCs). However, the origin of AIE in MNCs is still not fully understood, which is pivotal for the design of AIE luminogens (AIEgens). Here, water soluble silver nanoclusters (Ag NCs) with AIE properties were synthesized. These as-synthesized non-luminescent Ag NCs will become photoluminescent when transferred from water to ethanol, and the emission peak was redshifted from ∼560 to ∼600 nm and largely intensified with the addition of Cu2+. The addition of Cu2+ makes a big difference in the PL properties of Ag NCs. That is, the PL will be enhanced if Cu2+ is added with the sequence "Ag NCs + Cu2++EtOH." In contrast, the PL will be quenched if Cu2+ is added with the sequence "Ag NCs + EtOH + Cu2+." The PL was from the supramolecular clusters formed by the assembly of capping ligands on the confined surface of individual silver clusters through weak interactions. The addition of Cu2+ could regulate the assembly structure and further affect the energy lever (p-band) through space electron interactions. These results provide new insights into the AIE process in metal nanoclusters. [ABSTRACT FROM AUTHOR]

Nontraditional intrinsic luminescence (NTIL) which always accompanied with aggregation‐induced emission (AIE) features has received considerable attention due to their importance in the understanding of basic luminescence principle and potential practical applications. However, the rational modulation of the NTIL of nonconventional luminophores remains difficult, on account of the limited understanding of emission mechanisms. Herein, the emission color of nonconjugated poly(methyl vinyl ether‐alt‐maleic anhydride) (PMVEMA) can be readily regulated from blue to red by controlling the alkalinity during the hydrolysis process. The nontraditional photoluminescence with AIE property is from the new formed p‐band state, resulting from the strong overlapping of p orbitals of the clustered O atoms through space interactions. Hydrated hydroxide complexes embedded in the entangled polymer chain make big difference on the clustering of O atoms which dominates the AIE property of nonconjugated PMVEMA. These new insights into the photoluminescence mechanism of NTIL should stimulate additional experimental and theoretical studies and can benefit the molecular‐level design of nontraditional chromophores for optoelectronics and other applications. [ABSTRACT FROM AUTHOR]

Cesium lead halide-based perovskite (CsPbX 3 , X = Cl, Br, I) nanoparticles (NPs) have received considerable attention for their outstanding photophysical properties and promising applications in optoelectronic devices. However, the optoelectronic performance of CsPbX 3 NPs synthesized by most of present strategies are susceptible to external factors when exposed in atmosphere. Herein, benefiting from the unique open 3D porous architecture of dendritic mesoporous silica nanospheres (DMSNs) with cage-like spherical nanopores, highly dispersed and pure cubic CsPbX 3 NPs were successfully immobilized onto the mesoporous networks. A strategy of combining chemical anchoring and spatial isolation is designed for the one-pot synthesis of CsPbX 3 NPs. These as-fabricated CsPbX 3 @HA-DMSNs exhibit excellent luminescence property (tunable emission color and high quantum yield (QY reached a maximum of 55%)) and enhanced stability (especially for the water resistance capacity). The photoluminescence (PL) was sustained without any distinct change after 100 d storage under ambient conditions, even 90% PL intensity was maintained after continuous UV irradiation for 45 h and no obvious PL reduction was observed when soaked in water for 7 h. Most importantly, the resulting CsPbX 3 @HA-DMSNs could be easily purified by filtration without aggregation and easy to scale up production compared with the conventional solution-phase mediated synthesis, which provides an alternative for the effective fabrication of perovskite-based devices, for example, here, the white light emitting devices (LEDs). Spatial and Chemical Confined Ultra-small CsPbBr 3 Perovskites NPs in Dendritic Mesoporous Silica Nanospheres with tuning emission colors and super water-resistant stability. Image 1 • Mesoporous silica with cage-like spherical pores were used as matrices. • CsPbBr 3 perovskite nanoparticles grew in the confined nanosapce by one-pot method. • Spatial and Chemical Confined CsPbBr 3 have ultra-small size and pure cubic phase. • The nanocomposites have enhanced stability resisting moisture and irradiation. [ABSTRACT FROM AUTHOR]

The availability of a range of excited states has endowed low dimensional quantum nanostructures with interesting luminescence properties. However, the origin of photoluminescence emission is still not fully understood, which has limited its practical application. Here we judiciously manipulate the delicate surface ligand interactions at the nanoscale interface of a single metal nanocluster, the superlattice, and mesoporous materials. The resulting interplay of various noncovalent interactions leads to a precise modulation of emission colors and quantum yield. A new p-band state, resulting from the strong overlapping of p orbitals of the heteroatoms (O, N, and S) bearing on the targeting ligands though space interactions, is identified as a dark state to activate the triplet state of the surface aggregated chromophores. The UV-Visible spectra calculated by time-dependent density functional theory (TD-DFT) are in quantitative agreement with the experimental adsorption spectra. The energy level of the p-band center is very sensitive to the local proximity ligand chromophores at heterogeneous interfaces. The basic principles behind the optoelectronic properties of metal nanoclusters are still not fully understood. Here the authors manipulate the surface ligand interactions on single metal nanoclusters, within self-assembled superlattices, and in confined nanopores to achieve precise modulation of emission colors and quantum yields. [ABSTRACT FROM AUTHOR]

All-inorganic CsPbX3 (X = Cl, Br, I) nanocrystals (NCs) are widely recognized as promising materials for optoelectronic devices. This is due to their ability to exhibit a variable band gap, narrow emission properties, and high photoluminescence quantum yield (PLQY). However, the use of traditional ligands like alkyl acid and amine could not anchor NCs tightly. Consequently, this has led to inefficient passivation of surface defects and poor stability of CsPbX3 NCs. In this study, we present the preparation of CsPbBr3 nanocrystals using the room temperature saturation recrystallization method with urea as a co-ligand. Urea, a small molecule ligand with bifunctional groups, acts as a zwitterionic ligand and effectively modifies the surface state of CsPbBr3 nanocrystals through its C=O and N–H functional groups. The as-prepared CsPbBr3 nanocrystals, with a photoluminescence quantum yield (PLQY) of up to 80%, exhibit improved water stability compared to pristine CsPbBr3 nanocrystals. X-ray diffraction and photoluminescence (PL) results demonstrate that the addition of urea as a co-ligand promotes crystallization and enhances the emission intensity of CsPbBr3. Meanwhile, the photoluminescence mechanism of CsPbBr3 NCs was investigated using ultrafast transient absorption and time-resolved photoluminescence spectroscopy. This study presents a straightforward ligand-assisted method for preparing stable CsPbBr3 NCs with high PLQY, while also enhancing the understanding of the interaction between ligands and the PL properties of CsPbBr3 NCs. [ABSTRACT FROM AUTHOR]