In situ SAXS probing the evolution of the precursors and onset of nucleation of ZnSe colloidal semiconductor quantum dots

Abstract

The effect of diphenyl phosphine (HPPh2) on precursors conversion reaction and nucleation/growth of quantum dots (QDs) were in situ investigated by the combination of SAXS and UV-vis.

Transformation Pathway from CdSe Magic‐Size Clusters with Absorption Doublets at 373/393 nm to Clusters at 434/460 nm

“…To examine further our hypothesis of the PC-enabled transformation shown in Scheme 1, we carried out also synchrotron-based SAXS.W ith excellent statistics as well as simple and non-damaging sample preparation, SAXS has been applied to investigate various semiconductor nanostructures,i ncluding QDs, [46][47][48] MSCs, [9,13,19] and NPLs. [49,50] Figure 4a presents the SAXS profiles collected from purified Samples A( blue circular symbols) and B( red square symbols) at room temperature.T hree Bragg peaks are observed for both purified samples.A lso,P art ac ontains the corresponding traces for the data fitted assuming two unified Guinier-Porod levels (Level 1(L1) and Level 2(L2)) and three Lorentz peaks.S ee Experimental methods in Supplementary Information for the method used for the data fitting.The fitted SAXS data (the vertical values of Part a) are mathematically separated and presented in Figure 4b,c Fort he 2D species related scattering signals shown in Part b, these two sets of peaks appear at the same positions of 1.59 (q 1 ), 3.16 (q 2 ), and 4.77 nm À1 (q 3 ).…”

Crystal Nucleation and Growth of Inorganic Ionic Materials from Aqueous Solution: Selected Recent Developments, and Implications

“…Besides the above sophisticated and usually synchrotronbased techniques, simple UV-vis spectroscopy can yield valuable information if coupled to SAXS/WAXS [48,49] or analytical ultracentrifugation (AUC) [50] if suitable chromophores are present. This is particularly useful for the investigation of the early stages of semiconductor/metal nanoparticle nucleation and growth since UV/Vis spectra contain information about size, shape, crystallinity, and chemical information.…”

“…This is particularly useful for the investigation of the early stages of semiconductor/metal nanoparticle nucleation and growth since UV/Vis spectra contain information about size, shape, crystallinity, and chemical information. [49] For ion-based reactions, ion-selective and/or conductivity electrodes are suitable for time-resolved speciation of the reacting compounds. [51] 2D solid-state Nuclear Magnetic Resonance (NMR) experiments are very useful to characterize non-classical growth processes in complex multicomponent mixtures.…”

Small-angle scattering to reveal the colloidal nature of halide perovskite precursor solutions

“…Hence, the strong interaction seems to be a "quasi-crystalline prearrangement of colloidal particles as an early stage of crystallization. 27,28 To get further information about the colloidal network, the precursor solution was stepwise heated up to 60 °C (Figure 2a). With increasing temperature, an apparent reduction of the maximum intensity is observed.…”