Hydrazine-Mediated Construction of Nanocrystal Self-Assembly Materials

Abstract

Self-assembly is the basic feature of supramolecular chemistry, which permits to integrate and enhance the functionalities of nano-objects. However, the conversion of self-assembled structures to practical materials is still laborious. In this work, on the basis of studying one-pot synthesis, spontaneous assembly, and in situ polymerization of aqueous semiconductor nanocrystals (NCs), NC self-assembly materials are produced and applied to design high performance white light-emitting diode (WLED). In producing self-assembly materials, the additive hydrazine (N2H4) is curial, which acts as the promoter to achieve room-temperature synthesis of aqueous NCs by favoring a reaction-controlled growth, as the polyelectrolyte to weaken inter-NC electrostatic repulsion and therewith facilitate the one-dimensional self-assembly, and in particular as the bifunctional monomers to polymerize with mercapto carboxylic acid-modified NCs via in situ amidation reaction. This strategy is versatile for mercapto carboxylic acid-modified aqueous NCs, for example CdS, CdSe, CdTe, CdSe(x)Te(1-x), and Cd(y)Hg(1-y)Te. Because of the multisite modification with carboxyl, the NCs act as macromonomers, thus producing cross-linked self-assembly materials with excellent thermal, solvent, and photostability. The assembled NCs preserve strong luminescence and avoid unpredictable fluorescent resonance energy transfer, the main problem in design WLED from multiple NC components. These advantages allow the fabrication of NC-based WLED with high color rendering index (86), high luminous efficacy (41 lm/W), and controllable color temperature.

Silicon Nanocrystals: It's Simply a Matter of Size

“…This “mystery” of quantum yield versus size seems to be solved, but whether the trends applies to ncSi produced under other synthetic conditions or approaches remains a question, since the surface structure and properties will depend on the nature of the inorganic‐organic interface . A similar trend has been observed recently for ncCdTe . The maximum quantum yield has also been observed between 3–4 nm for a system of ncSi embedded in SiO 2 …”

“…[21] As imilar trend has been observed recently for ncCdTe. [22] The maximum quantum yield has also been observed between 3-4 nm for as ystem of ncSi embedded in SiO 2 . [23] Although the PL quantum yield of ncSi is not always as high as that of some of the best heavy metal QDs, it often indicates the higherp robabilityo fn on-radiative recombination of chargec arriers, causing the photothermal (PT) effect.…”

Room-temperature formation of CdS magic-size clusters in aqueous solutions assisted by primary amines

“…A few examples of aqueous-phase approaches for the synthesis of colloidal semiconductor QDs and MSCs have been reported, while these studies have been largely empirical [30][31][32][33][34][35][36][37][38][39][40][41] . The complexity of aqueous environments including ionic interactions has been claimed to inhibit understanding the formation pathways of QDs and MSCs 30,37 .…”

High-efficiency CdTe/CdS core/shell nanocrystals in water enabled by photo-induced colloidal hetero-epitaxy of CdS shelling at room temperature

“…There are limited reports on the application of CdTe in LEDs [17]. The major reason is that it is less stable than CdSe and can be easily oxidized.…”