Surface passivation of intensely luminescent all-inorganic nanocrystals and their direct optical patterning

Abstract

All-inorganic nanocrystals (NCs) are of great importance in a range of electronic devices. However, current all-inorganic NCs suffer from limitations in their optical properties, such as low fluorescence efficiencies. Here, we develop a general surface treatment strategy to obtain intensely luminescent all-inorganic NCs (ILANs) by using designed metal salts with noncoordinating anions that play a dual role in the surface treatment process: (i) removing the original organic ligands and (ii) binding to unpassivated Lewis basic sites to preserve the photoluminescent (PL) properties of the NCs. The absolute photoluminescence quantum yields (PLQYs) of red-emitting CdSe/ZnS NCs, green-emitting CdSe/CdZnSeS/ZnS NCs and blue-emitting CdZnS/ZnS NCs in polar solvents are 97%, 80% and 72%, respectively. Further study reveals that the passivated Lewis basic sites of ILANs by metal cations boost the efficiency of radiative recombination of electron-hole pairs. While the passivation of Lewis basic sites leads to a high PLQY of ILANs, the exposed Lewis acidic sites provide the possibility for in situ tuning of the functions of NCs, creating opportunities for direct optical patterning of functional NCs with high resolution.

Unraveling the Transformation Pathways in Semiconductor Clusters by Studying the Formation of Spectroscopically Pure (CdS)13 Magic-Size Clusters

“…Magic-sized clusters (MSCs) with ultrasmall size, well-defined atoms, and special electronic structures provide an ideal platform to study the formation of nanocrystals. 1−5 Fundamental studies on the evolution of semiconductor MSCs are essential to understand the nucleation and growth processes of the transition from molecules to nanocrystals and will pave the way for the rational design of colloidal functional nanomaterials enabling their potential applications in LEDs, 6,7 photodetectors, 8 and catalysis. 9 Following the initial observation of (CdSe) 33 and (CdSe) 34 in 2004, intense research activity has focused on the study of synthetic pathways and related formation mechanisms.…”

“…Unfortunately, nanocrystals (NCs) are typically grown by continuous and incremental addition of precursors, and slight differences in the growth process lead to inhomogeneities in size, shape, and even crystal structure, making it difficult to study the chemical transformations. Magic-sized clusters (MSCs) with ultrasmall size, well-defined atoms, and special electronic structures provide an ideal platform to study the formation of nanocrystals. − Fundamental studies on the evolution of semiconductor MSCs are essential to understand the nucleation and growth processes of the transition from molecules to nanocrystals and will pave the way for the rational design of colloidal functional nanomaterials enabling their potential applications in LEDs, , photodetectors, and catalysis …”

Visible Light-Mediated Quantum Dot Photocatalysis Enables Olefination Reactions at Room Temperature

“…On the contrary, a gradual enhancement in the QD PL was observed in the present study in both steady-state and time-resolved experiments upon the addition of 0.30 mmol PPh 3 (Figure a and inset of Figure b). PPh 3 is known to bind on the surface selenium sites of the CdSe QDs, resulting in the passivation of the surface trap states. − The binding of PPh 3 on the surface of QDs was proved using IR and NMR studies (Figures S12–S15). Consequently, an enhancement in the PL lifetime of PPh 3 -treated QDs was observed (Figure S16).…”

Ligand‐Mediated Revival of Degraded α‐CsPbI3 to Stable Highly Luminescent Perovskite

“…The increased radiative decay time of the DSH_1Day dispersion indicates improved passivation of the surface defect states as well as stabilization of the CsPbI 3 nanocrystals. [53,54] In comparison, the non-radiative recombination times were 5.3, 5.1, 4.9, and 4.1 ns for the as-synthesized, aged, DSH_instant, and DSH_1Day samples. On the basis of the results above, the overall ligand-mediated revival of CsPbI 3 dispersion is schematically summarised in Figure 3c with the captured digital images.…”