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In the synthesis of cesium lead bromide (CsPbBr

Supplementary Data from Targeted Photothermal Ablation of Murine Melanomas with Melanocyte-Stimulating Hormone Analog–Conjugated Hollow Gold Nanospheres

Purpose: To develop melanoma-targeted hollow gold nanospheres (HAuNS) and evaluate their potential utility for selective photothermal ablation in melanoma.Experimental Design: A new class of photothermal coupling agents based on HAuNS was synthesized. HAuNS were stabilized with polyethylene glycol (PEG) coating and attached with α–melanocyte-stimulating hormone (MSH) analog, [Nle4,D-Phe7]α-MSH (NDP-MSH), which is a potent agonist of melanocortin type-1 receptor overexpressed in melanoma. The intracellular uptake of the NDP-MSH–conjugated PEGylated HAuNS (NDP-MSH-PEG-HAuNS) and the distribution of β-arrestin were examined in murine B16/F10 melanoma cells. The biodistribution of NDP-MSH-PEG-HAuNS was assessed at 4 hours post i.v. injection in tumor-bearing nude mice. Photothermal ablation effect of the nanoparticles was evaluated both histologically using excised tissue and functionally by [18F]fluorodeoxyglucose positron emission tomography.Results: NDP-MSH-PEG-HAuNS consist only of a thin gold wall with hollow interior (outer diameter, 43.5 ± 2.3 nm; shell thickness, 3-4 nm), which displays strong and tunable resonance absorption in near-IR region (peak, 808 nm). The nanoparticles were specifically taken up by melanoma cells, which initiated the recruitment of β-arrestins, the adapters to link the activated G-protein–coupled receptors to clathrin, indicating the involvement of receptor-mediated endocytosis. This resulted in enhanced extravasation of NDP-MSH-PEG-HAuNS from tumor blood vessels and their dispersion into tumor matrix compared with nonspecific PEGylated HAuNS. Successful selective photothermal ablation of B16/F10 melanoma with targeted HAuNS was confirmed by histologic and [18F]fluorodeoxyglucose positron emission tomography evaluation at 24 hours post near IR–region laser irradiation at a low-dose energy of 30 J/cm2.Conclusion: NDP-MSH-PEG-HAuNS have the potentials to mediate targeted photothermal ablation of melanoma.

Metal halide perovskite quantum dots (PQDs) and perovskite magic sized clusters (PMSCs) exhibit interesting size- and composition-dependent optoelectronic properties that are promising for emerging applications including photovoltaic solar cells and light-emitting diodes (LEDs). Much work has focused on developing new synthesis strategies to improve their structural stability and property tunability. In this paper, we review recent progress in the synthesis and characterization of PQDs and PMSCs, with a focus on the impact of different molecular ligands on their surface passivation and interconversion. Moreover, the effect of capping ligands on ion exchange during synthesis and doping is discussed. Finally, we present some perspectives on challenges and opportunities in fundamental studies and potential applications of both PQDs and PMSCs.

Antimony-based metal halide hybrids have attracted enormous attention due to the stereoactive 5s2 electron pair that drives intense triplet broadband emission. However, energy/charge transfer has been rarely achieved for Sb3+-doped materials. Herein, Sb3+ ions are homogeneously doped into 2D [NH3(CH2)4NH3]CdBr4 perovskite (Cd-PVK) using a wet-chemical method. Compared to the weak singlet exciton emission of Cd-PVK at 380 nm, 0.01% Sb3+-doped Cd-PVK exhibits intense triplet emission located at 640 nm with a near-unity quantum yield. Further increasing the doping concentration of Sb3+ completely quenches singlet exciton emission of Cd-PVK, concurrently with enhanced Sb3+ triplet emission. Delayed luminescence and femtosecond-transient absorption studies suggest that Sb3+ emission originates from exciton transfer (ET) from Cd-PVK host to Sb3+ dopant, while such ET cannot occur with Pb2+-doped Cd-PVK because of the mismatch of energy levels. In addition, density function theory calculations indicate that the introduced Sb3+ likely replace the Cd2+ ions along with the deprotonation of butanediammonium for charge balance, instead of generating Cd2+ vacancies. This work provides a deeper understanding of the ET of Sb3+-doped Cd-PVK and suggests an effective strategy to achieve efficient triplet Sb3+ emission beyond 0D Cl-based hybrids.

Clonorosins A (1) and B (2), two novel indole alkaloids featuring unprecedented 6/5/6/6/5 and 6/5/5 cores, together with seven known indole-linked 2,5-diketopiperazine alkaloids (3-9), were isolated from the soil-derived fungus Clonostachys rosea YRS-06. The new structures were proposed through HR-MS, NMR, and ECD spectroscopic data. They were established by comparing the calculated NMR, ECD, and specific rotation data with the experimental. To assist in determining the absolute configuration of the chiral carbon in the side chain of 2,5-diketopiperazine derivatives, flexible analogues 3i-3iv were synthesized and analyzed. 1 was active against Fusarium oxysporum with an MIC value of 50 μg/mL. 7 and 8 showed excellent activity against human HeLa and HepG2 cells with IC50 values of 0.12-0.60 μM.

We investigated the charge transfer between Au25(SG)18 nanoclusters and metal-organic framework (MOF) supports including Mil-101-Cr, Mil-125-Ti, and ZIF-8 by an X-ray photoemission technique and discussed the influence of resulted charge states of supported Au25(SG)18 nanoclusters on the 4-nitrophenol reduction reaction. Charge transfer from Au25(SG)18 to Mil-101-Cr induces positive charge Auδ+ (0 < δ < 1) while charge transfer from ZIF-8 to Au25(SG)18 generates negative charge Auδ- due to different metal-support interactions. Au25(SG)18 on Mil-125 shows metallic Au0, similar to unsupported Au25(SG)18, due to negligible charge transfer. The resulted charge state of Auδ- inhibits the formation of adsorbed hydride (H-) species because of electrostatic repulsion, while Auδ+ impairs the reductive ability of adsorbed hydride (H-) species due to strong affinity between them. In comparison, metallic Au0 in Au25(SG)18/Mil-125 and unsupported Au25(SG)18 presents the optimum catalytic activity. The current work provides guidelines to design effective metal nanoclusters in heterogeneous catalysis through metal-support interaction exerted by metal-oxo/nitric clusters within MOFs.

Mn2+-doped amino lead halide molecular clusters (MCs) are synthesized using amine (e.g., n-octylamine, or butylamine) as passivating ligand and MnX2 (X = Cl or Br) as the Mn2+ doping source at room temperature. Their optical properties are investigated with UV-visible absorption, photoluminescence (PL), and PL excitation spectroscopy. The Mn2+ precursor plays a vital role in the synthesis of Mn2+-doped MCs. MnCl2 seems to facilitate the incorporation of Mn. The MnCl2 doping causes electronic absorption blue shift and leads to a spin-forbidden 4T1 → 6A1 Mn d-electron emission. With the help of time-resolved PL, Fourier transform infrared, and electron paramagnetic resonance results, a model is proposed to explain the formation mechanism. We suggest that Mn2+ doping replaces Pb2+ is assisted by Cl- ions that replace Br- ions. This study demonstrates the possibility of doping MCs and has important implications in gaining new fundamental insight into the growth mechanisms of perovskite nanostructures.

High defect tolerance has been considered a primary reason for the long charge carrier lifetime and high photoluminescence quantum yield in bulk lead halide perovskites (LHPs). On the other hand, surface defects play a critical role in determining charge carrier dynamics and optical properties, especially for LHP nanocrystals and quantum dots. Understanding the nature of surface defects and developing strategy for their effective passivation are thus of strong interest. Focusing on a prototypical LHP, CsPbBr3, our work uses first-principles calculations to reveal that interstitial sites and antisites can have lower formation energies when they form at the surface while simultaneously creating deep trap states within the bandgap. Meanwhile, the formation of halide vacancies is energetically less favorable. On the basis of a new surface defect model, we demonstrate the explicit role of molecular ligands in passivating these defects, which eliminate trap states in favor of shallow states and enhance photoluminescence.

As a novel zero-dimensional (0D) material, metal carbides and/or carbonitrides (MXenes) quantum dots (MQDs) show unique photoluminescence properties and excellent biocompatibility. However, due to the limited synthesis methods and research to date, many new features have yet to be uncovered. Here, to explore their new properties and expand biological applications, chlorine and nitrogen co-doped Ti3C2 MXene quantum dots (Cl, N-Ti3C2 MQDs) were designed and synthesized, and their hydroxyl radical scavenging properties were investigated for the first time, revealing outstanding performance. Cl, N-Ti3C2 MQDs was directly stripped from bulk Ti3AlC2 by electrochemical etching, while N and Cl are successfully introduced to carbon skeleton and Ti boundaries in the etching process by electrochemical reactions between selected electrolytes and Ti3C2 skeleton, respectively. The obtained Cl, N-Ti3C2 MQDs exhibit large surface-to-volume ratio due to small particle size (ca.3.45 nm) and excellent higher scavenging activity (93.3 %) and lower usage (12.5 μg/mL) towards hydroxyl radicals than the previous reported graphene-based nanoparticles. The underlying mechanism of scavenging activity was also studied based on the reduction experiment with potassium permanganate (KMnO4). The reducing ability of the intrinsic Ti3C2 structure and electron donation of double dopants are the main contributors to the outstanding scavenging activity.

A novel free radical scavenger, multi-layered Ti3C2Tx MXene (ML-Ti3C2Tx), has been studied by evaluating its scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH•). It exhibits high scavenging efficiency (95% in 10 min) at low dosage (0.06 mg/mL). Based on the analysis of structure and surface states of ML-Ti3C2Tx before and after reaction with DPPH• and a series of comparative experiments, including few-layered Ti3C2Tx MXene (FL-Ti3C2Tx), original Ti3AlC2, and soluble Ti species derived from ML-Ti3C2Tx, the observed high scavenging activity is attributed to the intrinsic reducing property of ML-Ti3C2Tx rather than the hydrogen donation ability from surface functional groups. A model is proposed to explain the scavenging mechanism.

Here, we demonstrate the use of Raman spectroscopy for real-time monitoring and analysis of the reduction of nitroarenes and ketones in an aqueous medium using an external fiber optic probe. In one case, the catalytic reduction of nitroarenes using hydrazine hydrate and a nickel boron composite catalyst was studied by monitoring the disappearance of the distinct nitro stretching frequency at 1350 cm–¹. Quantitative Raman spectroscopic techniques showed that the aqueous reduction reaction proceeds with pseudo-first-order kinetics. The biphasic reduction of cyclic ketones by aqueous dimethylamine borane (DMAB) was also examined. A nonpolar carbonyl compound and aqueous DMAB were mixed and an external Raman probe monitored the loss of the starting material via the carbonyl stretch at 1713 cm–¹ in the top organic phase. We also found that saturated aliphatic carbonyl compounds were reduced much faster than α,β-unsaturated and aromatic carbonyl compounds. Additionally, DMAB was found to be unreactive toward epoxides and esters, allowing for selective reduction of aliphatic ketones. Density functional theory analysis suggests that carbonyl reduction occurred through a dissociation mechanism followed by a concerted hydride transfer pathway.

The choice of ligand is an important parameter in the synthesis of metal halide perovskites such as methylammonium lead bromide (MAPbBr3) perovskite nanocrystals (PNCs). In this work, phenylalanine...

Quasi-metallic tungsten oxide (W18O49) with unique surface plasmon resonance shows great promise for photocatalysis. In this work, the localized surface plasmon resonance (LSPR) of W18O49 nanostructures is tuned through morphology control to improve the performance in photocatalytic reduction of Cr(VI). Their morphology change from nanowires to nanobundles and urchin-like nanospheres results in a gradual blue shift and an intensity increase in their corresponding LSPR bands due to the decreased aspect ratio and the increased oxygen vacancy concentrations of the nanostructures. The three-dimensional finite element simulation demonstrates enhanced localized electric fields from nanowires to nanobundles and urchin-like nanospheres, confirming the experimental results. Benefiting from the blue-shifted and enhanced light extinction from the LSPR in the visible-NIR region, the urchin-like W18O49 nanospheres show enhanced photocatalytic activity in the photoreduction of Cr(VI) by 21.6% compared to the nanowires under visible-NIR light illumination. The mechanism leading to the enhanced photocatalytic performance is elucidated based on the unique electronic band structure of W18O49.

Metal halide perovskites, such as methylammonium lead halide (CH3NH3PbBr3), have recently attracted tremendous attention due to their outstanding properties and promising applications. Here, CH3NH3...

We investigate the mechanisms of energy transfer in Mn2+-doped ethylammonium lead bromide (EA2PbBr4:Mn2+), a two-dimensional layered perovskite (2DLP), using cryogenic optical spectroscopy. At temperature T > 120 K, photoluminescence (PL) is dominated by emission from Mn2+, with complete suppression of band edge (BE) emission and self-trapped exciton (STE) emission. However, for T < 120 K, in addition to Mn2+ emission, PL is observed from BE and STEs. Data further reveal that for 20 K < T < 120 K, STEs form the most dominant routes in assisting energy transfer (ET) from 2DLP to Mn2+ dopants. However, at higher Mn2+ concentration, higher activation energies indicate defect states come into play, successfully competing with STEs for ET both from BE to STE states and from STE to Mn2+. Finally, using polarization-resolved spectroscopy, we demonstrate optical spin orientation of the Mn2+ ions via ET from 2DLP excitons at zero magnetic field. Our results reveal fundamental insights on the interactions between quantum confined charge carriers and dopants in organometal halide perovskites.

Lead-free double perovskites (DPs) with excellent moisture, light, and heat stability have been explored as alternatives to toxic lead halide perovskite (APbX3) (A for monovalent cation and X for Cl, Br, or I). However, the bandgaps of the current DPs are generally larger and either indirect or direct forbidden, which leads to weak visible light absorption and limitation for photovoltaic and other optoelectronic applications. Herein, we demonstrate the first synthesis of Cu2+-doped Cs2AgInCl6 double perovskite nanocrystals via a facile hot-injection solution approach. The electronic bandgap can be dramatically tuned from ∼3.60 eV (Cs2AgInCl6, parent) to ∼2.19 eV (Cu2+-doped Cs2AgInCl6) by varying the Cu2+ doping amount. We conclude that the decrease of bandgap is attributed to the overlap of the Ag-d/In-p/Cl-p orbitals and the Cu-3d orbitals in the valence band. The wide tunability of the optical and electronic properties makes Cu2+-Doped Cs2AgInCl6 DP NCs promising candidates for future optoelectronic device applications.

Low-dimensional hybrid lead halide perovskites (LHPs) with broadband emission (BE) have been developed as promising candidates for single-source white-light-emitting diodes. However, the underlying origin of such BE is poorly understood. Herein, dual-emissive [NH3(CH2)8NH3]PbBr4 perovskite microsheets (PMSs) with good dispersibility are successfully prepared. Besides the general narrowband emission (NE) originating from free excitons, BE (∼522 nm) is generated under a Br-poor condition, which is not observed in the single-crystal sample. Unlike self-trapped exciton emission, the BE observed in PMSs is experimentally determined to be related to bromide vacancies (VBr), thereby exhibiting quasisaturation under high excitation intensity. Femtosecond transient absorption spectroscopy first shows that the trapping time of the photogenerated electrons by acceptor-like VBr- is ∼15 ps, slower than that by surface defects (

Design of metal–semiconductor interfaces and heterostructures is of strong interest for various catalytic applications including photocatalysis. In this work, a series of hollow Au nanosphere (HGN)...

Hollow gold nanospheres (HGNs) have been used as the template for seed-mediated growth of multibranched hollow gold nanostars (HNS). The HGNs were synthesized via anerobic reduction of cobalt chloride to cobalt nanoparticles and then formation of a gold shell via galvanic replacement followed by the oxidation of the cobalt core. We obtained control of the inner core size of the HGNs by increasing the size of the sacrificial cobalt core and by varying the ratio of B(OH)3/BH4 using boric acid rather than 48 h aged borohydride. We synthesized the HNS by reducing Au3+ ions in the presence of Ag+ ions using ascorbic acid, creating a spiky morphology that varied with the Au3+/Ag+ ratio. A broadly tunable localized surface plasmon resonance was achieved through control of both the inner core and the spike length. Amyloid beta (Aβ) was conjugated to the HNS by using a heterobifunctional PEG linker and identified by the vibrational modes associated with the conjugated ring phenylalanine side chain. A bicinchoninic acid assay was used to determine the concentration of Aβ conjugated to HNS as 20 nM, which is below the level of Aβ that negatively affects long-term potentiation. Both the core size and spike length were shown to affect the optical properties of the resulting nanostructures. This HGN templated method introduced a new parameter for enhancing the plasmonic properties of gold nanostars, namely, the addition of a hollow core. Hollow gold nanostars are highly desirable for a wide range of applications, including high sensitivity disease detection and monitoring.

Herein, we develop an effective approach for incorporating lead (Pb) ions into manganese (Mn) halide perovskite-analogue nanocrystals (PA NCs) of CsMn(Cl/Br)3·2H2O via room-temperature supersaturation recrystallization. Pb2+-incorporated Mn-PA NCs exhibit strong orange emission upon UV light illumination, a peak centered at 600 nm assigned to Mn2+ transition (4T1g → 6A1g) with a photoluminescence quantum yield (PLQY) of 41.8% compared to the pristine Mn-PA NCs with very weak PL (PLQY = 0.10%). The significant enhancement of PLQY is attributed to the formation of [Mn(Cl/Br)4(OH)2]4--[Pb(Cl/Br)4(OH)2]4--[Mn(Cl/Br)4(OH)2]4- chain network structure, in which Pb2+ effectively dilutes the Mn2+ concentration to reduce magnetic coupling between Mn2+ pairs to relax the spin and parity selection rules. In addition, excited energy can effectively transfer from the [Pb(Cl/Br)4(OH)2]4- unit to Mn2+ luminescence centers owing to the low activation energy. Pb2+-incorporated PA NCs also exhibit excellent stability. The combined strong PL and high stability make Pb2+-incorporated Mn-based PA NCs an excellent candidate for potential optronic applications.

Antimony-based metal halide hybrids have attracted enormous attention due to the stereoactive 5s

Compared to bulk perovskites, charge transport in perovskite quantum dot (PQD) solids is limited. To address this issue, energetically aligned capping ligands were used to prepare methylammonium le...

In this study, a hybrid semiartificial photosynthesis system based on chloroplast (CLP) and titanium oxide nanoparticles (TiO2 NPs) was constructed. 2,6-Dichlorophenolindophenol (DCPIP) reduction by TiO2/CLP complex and methylene blue (MB) reduction by TiO2 were used to determine enhanced photogenerated electron transfer in this hybrid system. The DCPIP reduction by the TiO2/CLP complex showed the same trend as MB reduction by TiO2 as a function of concentration of TiO2 NPs, indicating interception of photogenerated electrons in TiO2 by CLP that leads to enhanced photosynthesis efficiency. Decreased photoluminescence intensity and shortened excited-state lifetime of the TiO2/CLP complex compared to that of pure TiO2 also support electron transfer from TiO2 to CLP. Longer visible light absorption wavelength and increasing valence band edges reveal the narrower band gap of TiO2/CLP, which finally results in the enhanced electron transfer from TiO2 to CLP. Higher ferricyanide reduction and enhanced ATP formation with the TiO2/CLP complex demonstrate the accelerated electron-transfer rate of the electron-transfer chain. This study reveals the mechanism of how TiO2 interacts with CLP to enhance the photosynthesis via constructing a semiartificial photosynthesis system.

Graphene and graphene-like two-dimensional (2D) nanomaterials, such as black phosphorus (BP), transition metal carbides/carbonitrides (MXene) and transition metal dichalcogenides (TMD), have been extensively studied in recent years due to their unique physical and chemical properties. With atomic-scale thickness, these 2D materials and their derivatives can react with ROS and even scavenge ROS in the dark. With excellent biocompatibility and biosafety, they show great application potential in the antioxidant field and ROS detection for diagnosis. They can also generate ROS under light and be applied in antibacterial, photodynamic therapy (PDT), and other biomedical fields. Understanding the degradation mechanism of 2D nanomaterials by ROS generated under ambient conditions is crucial to developing air stable devices and expanding their application ranges. In this review, we summarize recent advances in 2D materials with a focus on the relationship between their intrinsic structure and the ROS scavenging or generating ability. We have also highlighted important guidelines for the design and synthesis of highly efficient ROS scavenging or generating 2D materials along with their biomedical applications.

In this work, a new two-dimensional Cd-based (F2CHCH2NH3)2CdBr4 perovskite (Cd–P) with indirect bandgap and a direct Pb-based (F2CHCH2NH3)2PbBr4 (Pb–P) are successfully synthesized with isostructur...

Ternary nickel cobalt iron layered double hydroxide nanosheet arrays are synthesized on nickel foam (NiCoFe-LDH/NF) and applied as an oxygen evolution reaction electrocatalyst. The oxidative etching and cation exchange caused by Fe-incorporating induce the change of morphology and the formation of Ni3+, thus increase the specific surface area and expose more active sites, finally greatly enhance the electrocatalytic OER performance. As a result, the Ni2CoFe0.5-LDH/NF electrode exhibits significantly enhanced oxygen evolution reaction performance with a small overpotential of 240 mV at the current density of 10 mA cm−2, a small Tafel slope of 65 mV dec−1 as well as an excellent durability in alkaline conditions for 72 h. Especially, the overpotential of Ni2CoFe0.5-LDH/NF is only 269 mV and 291 mV at 50 and 100 mA cm−2, respectively. This work provides a good paradigm for the design and fabrication of ternary NiCoFe-based functional electrocatalysts, and demonstrates the great practical potential of the Ni2CoFe0.5-LDH/NF electrocatalyst in oxygen evolution reaction.

With porous shells and mobile cores, yolk-shell nanostructures provide great structural advantage for mass transport-related applications such as photocatalysis. In this work, Au–Cu7S4 yolk-shell nanostructures are synthesized from Au–Cu2O core-shell templates. The Cu7S4 shell is then converted to CdS through a cation exchange process to produce Au–CdS yolk-shell photocatalysts for hydrogen generation. Ultrafast transient absorption and finite-difference time-domain simulation are used to investigate electronic interaction between Au nanoparticle core and the surrounding CdS shell. Additionally, a new method is presented to simulate chemical transport and quantitatively compare diffusion kinetics by monitoring mass transport through the porous CdS shell with dye molecules as optical probes. The highest hydrogen generation rate of 3390 μmol g−1 h−1, corresponding to an adequate apparent quantum yield of 4.22% at 420 nm, is achieved for Au–CdS with the largest void size. The enhancement in photocatalytic performance with increase in void size is mostly attributed to improved mass transport kinetics, with additional gains from more efficient charge transfer and stronger surface plasmon resonance-mediated near-field effects. This comprehensive study demonstrates that void size is a critical structural parameter in optimizing the performance of yolk-shell nanostructures for photocatalysis or other mass-transport related applications.

We report the first demonstration of using trivalent metal hydrated nitrate coordination complexes (TMHNCCs) as novel passivation ligands to control the synthesis of magic sized clusters (MSCs) and quantum dots (QDs) of CsPbBr3 perovskite at room temperature. We can easily tune from QDs to MSCs or produce a mixture of the two by changing the amount of TMHNCC ligands used, with more ligands favoring MSCs. The original TMHNCC introduced, aluminum nitrate nonahydrate [ANN, Al(NO3)3·9H2O], led to the production of aluminum dihydroxide nitrate tetrahydrate {ADNT, [Al(OH)2(NO3)]·4H2O}, with the assistance of oleic acid (OA) and oleylamine (OAm). Through several control experiments, we determined that ADNT is the primary ligand for effectively passivating the MSCs and QDs, with OAm being essential for deprotonating ANN and OA for adjusting the pH of the reaction system. We suggest that ADNT is planar on the surface of the MSCs or QDs with its NO3- and OH- groups binding to the Cs+ and Pb2+ defect sites and Al3+ binding to the Br- defect sites of the MSCs or QDs.

Magic sized clusters (MSCs), small nanoparticles with a single size or narrow size distribution, possess unique chemical and physical properties. CH3NH3PbBr3 perovskite MSCs (PMSCs) were synthesize...

In this work, Mn2+ has been efficiently and homogeneously doped into two-dimensional (2D) distorted single-layered EA2PbBr4 (EA: ethylammonium) via a reprecipitation method. Both the doped and undo...

CH3 NH3 PbBr3 perovskite quantum dots (PQDs) are synthesized by using four different linear alkyl phosphonic acids (PAs) in conjunction with (3-aminopropyl)triethoxysilane (APTES) as capping ligands. The resultant PQDs are characterized by means of XRD, TEM, Raman spectroscopy, FTIR spectroscopy, UV/Vis, photoluminescence (PL), time-resolved PL, and X-ray photoelectron spectroscopy (XPS). PA chain length is shown to control the PQD size (ca. 2.9-4.2 nm) and excitonic absorption band positions (λ=488-525 nm), with shorter chain lengths corresponding to smaller sizes and bluer absorptions. All samples show a high PL quantum yield (ca. 46-83 %) and high PL stability; this is indicative of a low density of band gap trap states and effective surface passivation. Stability is higher for smaller PQDs; this is attributed to better passivation due to better solubility and less steric hindrance of the shorter PA ligands. Based on the FTIR, Raman, and XPS results, it is proposed that Pb2+ and CH3 NH3 + surface defects are passivated by R-PO3 2- or R-PO2 (OH)- , whereas Br- surface defects are passivated by R-NH3 + moieties. This study establishes the combination of PA and APTES ligands as a highly effective dual passivation system for the synergistic passivation of multiple surface defects of PQDs through primarily ionic bonding.

We demonstrate an ultrasonication-assisted synthesis without polar solvent of CsPbBr3 and Cs4PbBr6 perovskite nanocrystals (PNCs) and their reversible transformation. The as-prepared CsPbBr3 PNCs and Cs4PbBr6 PNCs exhibit different optical properties that depend on their morphology, size, and structure. The photoluminescence (PL) emission and quantum yield (QY) of the CsPbBr3 PNCs can be tuned by changing the ultrasound power, radiation time, and the height of the vibrating spear. The optimized CsPbBr3 PNCs show a good stability and high PL QY of up to 85%. In addition, the phase transformation between CsPbBr3 PNCs and Cs4PbBr6 PNCs can be obtained through varying the amount of oleylamine (OAm) and water. The mechanism of this transformation between the CsPbBr3 PNCs and Cs4PbBr6 PNCs and their morphology change are studied, involving ions equilibrium, anisotropic growth kinetics, and CsBr-stripping process.